2+1 road, By country, Germany
The "2+1-System" refers to expressways with three lanes on a single carriageway where bypassing on the lane of the opposite direction is prohibited so that speed restriction is not required to increase safety. These expressways are grade-separated with a design speed of 100 to 120 km/h (60 to 75 mph) and the side of two lanes (allowing to bypass lower speed vehicles) alternates about every 1.5 to 2 kilometres. In hilly parts the uphill direction is usually the one with two lanes to allow overtaking of heavy, slow vehicles.


2+1 road, By country, Germany
In many cases there is no median barrier or it consists of concrete blocks – additional safety measures are mostly needed near the end of the two lane section where some motorists tend to pull in very late so that a longer no-traffic section needs to be inserted on the middle lane.


2+1 road, By country, Germany
After some good experiences with test roads the system has been used often in places where the amount of traffic does not justify construction of a dual carriageway expressway but remote rural areas should be connected to major towns with a high speed road. Existing examples are B 1, B 4 near Uelzen, B 16, B 20, B 31n near Stockach (120 km/h (75 mph)), B 33, B 54, B 56n, B 67 between Bocholt and Rhede, B 72, B 210, B 300, B 482, and parts of the A 98.


2+1 road, By country, Ireland
In the Republic of Ireland, a 2+1 road was trialled on a short section of the N20 near Mallow, County Cork and the N2 near Castleblayney, County Monaghan. Following the pilot, the National Roads Authority announced in July 2007 that 2+1 roads were unsuitable and that new lower capacity trunk routes would instead be built as 2+2 roads (officially known as "Type 2 Dual Carriageways") – at grade dual-carriageways with a narrow median and no hard shoulder.


2+1 road, By country, Lithuania
The first rural 2+1 road section finished in Lithuania was a short 1.5 km road section of A11 between Šiauliai and the junction with the A18 road (Šiauliai Bypass). It was opened in late 2017.


2+1 road, By country, Lithuania
All 1+1 sections of Via Baltica north of Kaunas up to the Latvian border are planned to be converted to 2+1 by 2035. The first section, the A17 road or Panevėžys Bypass was constructed in 2019. Work took place in stages. The first 10 km section between junctions with the A8 and the A9 was finished in summer 2018. The remaining section up to the A10 road was completed in 2019.


2+1 road, By country, New Zealand
In New Zealand, there are few 2+1 roads, although regular isolated 'passing lanes' exist frequently throughout the country, mainly in heavy trafficked areas and on hills. A trial of a 2+1 road with wire-rope median barrier was undertaken on SH1 between Longswamp and Rangiriri south of Auckland, and there are plans to introduce more 2+1 roads. NZ research also investigated design and operational effects of 2+1 roads to establish the most appropriate configurations for the country.


2+1 road, By country, Portugal
In Portugal, there are plenty of 2+1 roads. Almost every national road in the country has a 2+1 profile, but the biggest part is located in the north because of the hills (for example, in Beira Baixa, or Viseu). One example of this is the N2 road, which goes from Faro (Algarve) to Chaves. Also, this type of road isn't frequently used on parts of roads that have a village near, except in the Lisbon District where most of them have that profile.


2+1 road, By country, Portugal
In Portugal, there are 4 (major) types of roads: a national road (N) which sometimes contains the 2+1 profile, an complementary route (IC), which always contains the 2+1 profile, except inside villages, a principal route (IP) which either contains the 2+1 profile (with the IC profile) or the 2+2 profile (with the A profile) and a highway (A) which has its own profiles, like 2+2, 3+3 or 4+4.


2+1 road, By country, Romania
The 2+1 road format in Romania often refers to sections, usually on steep inclines, where there is another lane, designed to be used by slow vehicles to avoid congestion when going uphill.


2+1 road, By country, Romania
The first 2+1 "alternative" road opened between Lazaret and Turnul Spart in 2018 on the Olt Valley section of the DN7. This section lacks cable barriers, but provisions have been made to install one, if needed. The next 2+1 road section to open will be between Sinești and Movilița on the DN2. The DN2 is currently configured as a 13 m wide road with emergency lanes, in the same style as 13 m wide roads in Sweden, however, drivers improperly use the emergency lanes, leading to the current high number of crashes.


2+1 road, By country, Romania
Once the roadworks will be completed, the 2+1 road is supposed to reduce the number of crashes, but it will lack the essential cable barrier. This is because the only cable barrier installed in Romania, at Afumați on the same DN2 was damaged because the lanes were too close to it and a truck hit it, but instead, the Romanian Roads Administration (CNADNR) blamed the "unsafety" of the barrier.


2+1 road, By country, Russia
Some federal roads use the 2+1 design. The length of overtaking sections is 400 to 3,000 metres. Unlike in Western Europe, the majority of Russian 2+1 roads are not equipped with barriers. The most well-known example of a 2+1 is the M-10 road section between Tver and Novgorod oblast. This 2+1 is particularly popular in Krasnodar Kraj and Sakhalin Island.


2+1 road, By country, Sweden
In Sweden, many 13-metre-wide (43 ft) roads have been built, especially in the period 1955–1980. These have two 3.5-metre-wide (11 ft) lanes, and two 3-metre-wide (9.8 ft) shoulders, in the beginning planned as emergency strip, due to the relative unreliability of cars of that period.


2+1 road, By country, Sweden
Around 1990, the idea emerged to build fences in the middle of them and to have 2+1 lanes. This was thought to be a cheap way of increasing traffic safety since these roads had a bad safety record of many head-on collisions at high speeds. Some people were, for example, overtaking against meeting traffic assuming meeting cars would go to the side. The roads are a little narrow for 3 lanes, but trials were carried out on a few roads.


2+1 road, By country, Sweden
It turned out that not only did safety improve, but it was also easier to overtake than before as the 2-lane sections provide safe overtaking opportunities. After the year 2000, more than 1,000 km (620 mi) of roads in Sweden have been converted from wide ordinary roads into 2+1-road, all with barriers.


2+1 road, By country, Sweden
Until around 2005, the roads had the original 90 km/h (56 mph) speed limit in use on most highways. As a result of this, many people drove at 90 km/h at 1-lane parts but 110 km/h (68 mph) at 2-lane parts, this being the speed limit on motorways. The speed limit has now been changed to 100 km/h (62 mph) with a notably smoother traffic flow. There is a problem that some people want to overtake as many slow cars as possible in two-lane section, sometimes with small margins at the end of the section.


2+1 road, By country, United Kingdom
In the UK, 2+1 roads are known as 'Wide single 2+1 roads'. According to the Design Manual for Roads and Bridges, they should only be used on rural all-purpose single carriageways. The overtaking lane sections can be between 800 metres and 1500 metres. This is because this length allows for cars to overtake, but does not cause frustration for drivers on single-lane sections. It is recommended to use hatching with double solid lines to separate traffic flows to stop single-lane traffic from using the oncoming overtaking lane. 2+1 roads can also be used for climbing lanes, to allow slower vehicles to be overtaken by other vehicles when travelling uphill on a single carriageway. They should be used where the road is longer than 500 metres at a gradient of 2%.


2+1 road, By country, Elsewhere
Divided 2+1 roads are rare outside of Europe, though they are seen in a few places, such as the Canadian provinces of Ontario and Quebec, California, New Hampshire and Missouri states in the US, and Australia. The most prominent example is Interstate 93 in Franconia Notch State Park (before dropping down to a single lane in each direction, plus steel divider).


2+1 road, By country, Elsewhere
The mode is not unknown in the United States off the Interstate roads, including for example California State Route 1 between Malibu and Oxnard, Arizona State Route 77 north of Oracle and the section of Missouri Route 5 between the towns of Lebanon and Camdenton. In Japan, a 2+1 road was implemented in the northern island of Hokkaido.


2+1 road, By country, Elsewhere
In the United States, this term is not used and roads that would be in a configuration that could be described as 2+1 usually have an extra added climbing lane on steep grades for trucks and slow vehicles to climb, or are dropping or expanding to 2 or 4 lanes respectively.


2+1 road, By country, Elsewhere
Sometimes, during freeway reconstruction, a barrier transfer machine will be used on one half of the freeway while the other is being reconstructed.


2+1 road, By country, Elsewhere
A similar concept is utilized with 3-lane setups where 2 lanes have right of way, and the opposing side has to yield to the oncoming side on major highways that are mostly 2 lanes, of which those are more common.


2+1 road, By country, Elsewhere
These roads also exist in Texas, called "Super 2", as that term has more than one definition.


2+1 road, By country, Elsewhere
In the 1950s, New York state built many highways which totaled 3 lanes wide, with traffic moving in either direction permitted to use the center lane for passing. After less than ten years of a frighteningly high head-on collision rate, all were re-striped into either two wide lanes, or a one-direction passing lane, or alternating between the two systems.


2+2 (2012 film)
2+2 (Spanish: Dos más dos) is a 2012 Argentine comedy-drama film directed by Diego Kaplan and starring Adrián Suar, Carla Peterson, Julieta Díaz and Juan Minujín. The plot revolves around two successful friendly couples: Diego and Emilia, and Betina and Richard. One night, Richard and Betina reveal to Diego and Emilia that they are swingers and would like to swap partners with them, tempting Emilia.


2+2 (2012 film), Plot
Diego (Adrían Suar) and Richard (Juan Minujín) are two renowned cardiovascular surgeons who own an important specialist hospital located in Puerto Madero, Buenos Aires. Diego is married to Emilia (Julieta Díaz), a weather forecaster, with whom he has a 14-year-old son called Lucas (Tomás Wicz) and an organized family life. Richard is in a ten-year relationship with Betina (Carla Peterson), a fashion designer; they have no children and a more unstructured life.


2+2 (2012 film), Plot
One night, after Diego and Richard are given a recognition for their work at a congress, the two couples go out and have dinner to celebrate. In the restroom, Betina reveals to Emilia that she and Richard are swingers and that they should go to a swinger party with them. That night, Emilia can not stop thinking about it and awakens Diego to tell him. In the following days Emilia tries to be more sexually active and urges Diego to go to the party. Although he is uncomfortable with the idea, he accepts.


2+2 (2012 film), Plot
The party is held in the house of a man named Pablo (Alfredo Casero) because of his birthday. Although Emilia enjoys the party, Diego is shocked and uneasy with everybody's promiscuity and leaves early with her. She then begins to be more open about their sexuality and wants to talk about her fantasies with Diego. Richard, Betina and Emilia insist on swapping partners until Diego agrees. The two couples have dinner and have sex despite Diego's refusal at the beginning. The following morning Emilia cries and tells Diego that she thinks that they "did wrong", but that she feels no regret.


2+2 (2012 film), Plot
A few months later, Diego and Emilia are used to the swinging lifestyle and are comfortable with it. In Lucas' birthday party, Betina tells Emilia that she thinks Richard is cheating on her and becomes emotionally unstable the following days. It is revealed that Emilia and Richard have been meeting secretly, and one night Emilia tells him she has fallen in love with him and the swinging must end.


2+2 (2012 film), Plot
One night, Betina violently enters Diego and Emilia's house because she finds out about the affair and the two couples discuss. Diego decides not to be partners with Richard anymore, quitting his job at the hospital. He decides to separate and leaves the house. Meanwhile, Richard apologizes to Betina and begs her to get back together, but she refuses.


2+2 (2012 film), Plot
Two years later, the two couples, who are back together, coincidentally meet in the cinema. Betina is nearly eight months pregnant and Richard expresses his desire to be friends again with them. They respectfully greet each other and go to see the films.


2+2 (2012 film), Reception
The film received mixed to positive reviews. Most critics praised the performance of the cast. Debate has centered on the conservatism of the ending, while the film was publicized as transgressive.


2+2 (2012 film), Reception
Catalina Dlugi of Todo Noticias called the film "spicy and funny". La Prensa''s Isabel Croce highlighted Julieta Díaz's performance and described the film as "a good comedy starring an attractive foursome". La Capital called Alfredo Casero's role "noteworthy" and wrote "it is a movie with risky events and direct, crude language, but fails to exceed the occurrence of Un novio para mi mujer.


2+2 (2012 film), Reception
La Voz del Interior considered "one of the successes of 2+2 is the choice of the cast" and that it has "very funny moments, risky and very well done erotic scenes, tense situations that give nuance to the story." Página/12's Horacio Bernades described the film as "not only very worthy, technically flawless and very enjoyable, but unusually accomplished and provocative, for the needy Argentine film industry standards."


2+2 (2012 film), Reception
Julio Nakamurakare of the Buenos Aires Herald called 2+2 "so predictable and narrow-minded as to negate what's been previously proclaimed out loud as a war cry." Javier Porta Fouz of HiperCrítico panned Iván Wyszogrod's musicalization of the film, and described the film as "condescending, awkward, scrawny, besieged by its 'concept of selling'." Función Agotada's Nicolás Viademonte particularly criticized the ending, writing "[Kaplan] gets to throw away in 20 minutes what had been built with very good pulse in 80" and that the last thirty minutes of the movie "lacked the 'revolutionary', fresh, youthful spirit that carried in its starting time."


2+2 (TV channel)
2+2 (Ukrainian: два плюс два, dva plyus dva) is a national Ukrainian-language TV channel, owned by the 1+1 Media Group. Its program content is mainly aimed at a male audience, targeting a core age group of 25–44.


2+2 (TV channel)
Due to the Crimean crisis 2014, 2+2 broadcasts in Sevastopol ended on 9 March 2014, at 2.30pm East European time.


2+2 (TV channel)
2+2 broadcasts sporting events, particularly football and boxing matches. Other content includes foreign and Russian TV series, movies of various genres (action, sci-fi, adventure, comedy, detective, horror, disaster and historical), crime dramas and thrillers, cartoons and comedy programs, sports and entertainment shows made using in-house production, and erotica.


2+2 (TV channel), History
The TV channel 2+2 was launched in July 2006 under the name Kino. In the summer of 2010 it changed both its name and its positioning. During six years of broadcasting the channel's technical penetration in cities with a population of over 50,000 increased from 18.5% to 89.3%, and Ukraine-wide it exceeded 83.7%. The channel's share of viewers was 2.7% at prime time (19:00–23:00) and 2.6% over the whole day for an audience aged between 18 and 54 in cities with a population of over 50,000.


2+2 (TV channel), History
In 2009 the 2+2 TV channel, then using the name Kino,  received the award for Best Movie Channel from the specialist magazine Mediasat.


2+2 (TV channel), History
In 2011 it received the Mediasat award for the Best Regional TV Channel.


2+2 (TV channel), History
In 2012, 2+2 was awarded the title Best Men's Channel by Mediasat, and it also obtained the rights to broadcast UEFA Champions League and UEFA Europa League matches for the season 2012–2015. Beginning in the autumn of 2012 live streams of Football Championship of Ukraine, UEFA Champions League and UEFA Europa League games have been made available on the channel's site.


2+2 (TV channel), Criticism
In 2014 the 2+2 TV channel was criticised for broadcasting Russian serials. According to the results of monitoring carried out by activists of the Boycott Russian Films campaign during the period 8–14 September 2014 there were 8 hours of Russian content per day. According to monitoring made on 27 September 2014 the proportion of Russian content on the channel was 42%.


2+2 (TV channel), Football programs
2+2 is the official broadcaster of the Ukrainian Premier League. Since 30 August 2010 there has been a football round-up program called ProFootball (ПроФутбол) every Sunday. Ihor Tsyganyk is the main football reporter on the show. Experts invited onto the show include Andriy Nesmachnyi (former), Viktor Leonenko (former), Serhiy Kandaurov, Serhiy Nahornyak, Ihor Shukhovtsev, Oleh Venhlinskyi, Maksym Kalynychenko, Eduard Tsykhmeystruk, Oleksandr Ishchenko.


2+2 (album)
2+2 is an eponymous album of a vocal quartet called 2+2 with music by the Latin jazz ensemble known as Salsa Picante that was led by the American keyboardist/composer-arranger Clare Fischer. It was recorded in September 1980 and released in February 1981 by Pausa Records, and in Germany on the MPS label, as Foreign Exchange – The First Album. Tracks 1, 2, 3, 6 and 7 would be reissued on CD in 1999, and as a digital download in 2012, as Latin Patterns, a compilation of remastered highlights from four of Fischer's MPS LPs from this period.


2+2 (album)
The album represents a number of firsts for Fischer, including his first Grammy (specifically, the album's final track, "Guajira Pa' La Jeva", named 1981's Best Latin Recording), as well as a pair of recording debuts, first, that of 2+2, the vocal quartet with which Fischer supplemented his Latin jazz ensemble (thus tying together two key components of his wide-ranging musical universe), and, of equal if not greater import, that of his son Brent Fischer, marking the beginning of a fruitful – and more than three-decade-long – professional association.


2+2 (album), Reception
Los Angeles Times jazz critic Leonard Feather awarded the album four stars, making particular note of the album's seamless blend of vocal and instrumental units:


2+2 (album), Reception
Their blend is splendid, they are at times expertly integrated with the band through Fischer's compositions, lyrics and arrangements; and they are quadrilingual, starting in German and proceeding to English, Spanish and doo-be-doo, the Esperanto of jazz. The rhythm, generally timbales-oriented, could have used more bottom. Darlene Koldenhoven, the lead soprano, is a striking discovery.


2+2 (car body style)
The 2+2 is a version of the coupé car-body style that has two small rear seats for children or occasional usage, along with two front seats for the driver and front passenger. Manufacturers which sell coupés both with and without rear seats often market the versions that include rear seats as "2+2"or as 2-plus-2.


2+2 (car body style), Definition
By definition, all cars in the 2+2 category have two front seats and two rear seats. Other common characteristics for 2+2 cars include relatively little room for the rear passengers and a coupé body with two doors.


2+2 (car body style), Definition
Although many convertible, targa top and hatchback cars meet the literal definition of a 2+2, they are rarely considered 2+2s.


2+2 (car body style), Usage
There are many coupé which meet the definition of a 2+2, but have not been described by the manufacturer as such. This is because the term 2+2 is most often used to distinguish cars from a 2-seat open version of the same model. Prominent examples are the classic Jaguar E-type fixed-head coupé 2+2, the Lotus Elan 2+2, the Nissan 300ZX 2+2, the Chevrolet Monza 2+2, the 1965–1966 Mustang 2+2 and the Pontiac 2+2 models.


2+2 (car body style), Usage
The 1965 and 1966 Mustang Fastback was marketed as the "Mustang 2+2", because a fold-down rear seat was included as standard equipment. Where the standard (two-seat) Mustang had a "MUSTANG" emblem, the 2+2 model had a "MUSTANG 2+2" emblem. In 1967, the rear seat became optional, and the "2+2" designation was dropped.


2+2 road
A 2+2 road is a specific type of dual-carriageway that exists primarily in Ireland, Sweden, Estonia and Finland, consisting of two lanes in each direction separated by a steel cable barrier.


2+2 road
These roads do not have hard shoulders and therefore cannot be designated as motorways in the future. However, they may be designated as limited-access roads, as such roads do not require the physical standard of motorways to be designated as expressways. The Irish variant has 3.5-metre-wide (11 ft) lanes where there are a number of Swedish variants some with 3.25-metre-wide (10.7 ft) lanes.


2+2 road
Junctions are generally at-grade roundabouts and minor roads cross under or over the mainline without connecting. They are also known as "type 2 dual-carriageways" by the Irish National Roads Authority. These roads look similar to expressways, except that expressways often have interchanges, large medians or concrete barriers between traffic.


2+2 road, History, First Irish 2+2
In Ireland first purpose-built road of this type opened in December 2007 as a new greenfield section of the N4 national primary route which joins Dublin to Sligo.


2,000 Feet Away
2,000 Feet Away is a play by British playwright Anthony Weigh. The play is a portrait of small-town life in the Midwest. It is set primarily in Eldon, Iowa, which provided the setting for Grant Wood's famous painting American Gothic. The opening and closing scenes are set in the Art Institute of Chicago where the painting is now preserved. The title of the play alludes to a state law preventing sex offenders from living within 2,000 feet (610 m) of any place where children may gather.


2,000 Feet Away
The play premiered in Sydney, Australia and opened in London at the Bush Theatre during the 2008 summer season. The director of the Bush production was Josie Rourke, while the main character of the Deputy Sheriff was played by Joseph Fiennes, better known for his lead role in the film Shakespeare in Love. 2,000 Feet Away opened to generally positive reviews in the London press.


2,000 Guineas Trial Stakes
The 2,000 Guineas Trial Stakes was a Group 3 flat horse race in Great Britain open to three-year-old thoroughbred colts and geldings. It was run over a distance of 7 furlongs (1,408 metres), and it was scheduled to take place each year in early April.


2,000 Guineas Trial Stakes, History
The event was originally held at Ascot. The present grading system was introduced in 1971, and the race was classed at Group 3 level. It was staged at Newmarket in 1978, and transferred to Salisbury in 1979. It was discontinued after 1986.


2,000 Guineas Trial Stakes, History
The race served as a trial for the 2000 Guineas Stakes. The last horse to win both events was Sir Ivor in 1968.


2,000 Guineas Trial Stakes, History
The equivalent race for fillies was the 1,000 Guineas Trial Stakes.


2,000,000 Voices
2,000,000 Voices is Angelic Upstarts's  third album, released in 1981.


2,000-yard club
The 2,000-yard club is a group of eight National Football League (NFL) running backs who have rushed for 2,000 yards (1,800 meters) or more in a regular season. These eight rushing seasons rank as the highest single-season rushing totals in NFL history, and reaching the 2,000-yard mark is considered a significant achievement for running backs. No running back has yet achieved this feat twice. The first 2,000-yard season was recorded in 1973 by Buffalo Bills running back O. J. Simpson.


2,000-yard club
Simpson is the only player ever to have surpassed 2,000 yards in a 14-game season, as all others occurred in 16-game seasons; he finished the season with 2,003 rushing yards, averaging six yards per carry and an NFL-record 143.1 rushing yards per game. Los Angeles Rams running back Eric Dickerson, who had broken the single-season rookie rushing record in 1983, recorded the second 2,000-yard season in 1984. Dickerson rushed for 2,105 yards, the current NFL rushing record, and averaged 131.6 rushing yards per game.


2,000-yard club
Detroit Lions running back Barry Sanders recorded the third 2,000-yard season in 1997, rushing for 2,053 yards. At the age of 29, Sanders was the oldest back to surpass 2,000 yards. Sanders had opened the season with only 53 yards through two games, but ran for 100 yards or more in each of the last 14 games of the season and averaged 6.1 yards per carry during the season. In 1998 Denver Broncos running back Terrell Davis became the fourth player to rush for over 2,000 yards, running for 2,008 yards.


2,000-yard club
Davis also recorded 21 rushing touchdowns in his 2,000-yard season, the only 2,000 yard rusher to do so. To date, Davis is the only member of the 2,000 yard club to win a Super Bowl in the year they rushed for 2,000 yards. Davis had reached the 1,000-yard mark only seven games into the season . Baltimore Ravens running back Jamal Lewis surpassed 2,000 yards in the 2003 season, recording 2,066 yards over the course of the season.


2,000-yard club
500 of these yards were recorded in two games against the Cleveland Browns, with Lewis rushing for a then-NFL record 295 yards in the first and recording 205 rushing yards in the second. Tennessee Titans running back Chris Johnson ran for 2,006 yards in 2009, averaging 5.6 yards per carry, and also recorded an NFL-record 2,509 yards from scrimmage. Minnesota Vikings back Adrian Peterson is the second most recent player to have surpassed 2,000 yards rushing, having finished the 2012 season with 2,097 yards rushing, just 8 yards short of Dickerson's record.


2,000-yard club
Peterson had torn two ligaments in his left knee the previous year, making him the only player to have surpassed 2,000 yards after having reconstructive knee surgery the prior season. Titans running back Derrick Henry reached the mark on January 3rd, 2021, making the Titans the first franchise to have multiple 2,000-yard rushers.


2,000-yard club
Out of the eight players to have recorded a 2,000-yard rushing season, all but one (Dickerson) won the AP NFL Offensive Player of the Year Award the year that they rushed for 2,000 yards. Dickerson would go on to win the award though after the 1986 NFL season. Simpson, Sanders, Davis, and Peterson also won the AP Most Valuable Player (MVP) award.


2,000-yard club
Simpson, Dickerson, Sanders and Davis are each members of the Pro Football Hall of Fame, which "honor[s] individuals who have made outstanding contributions to professional football"; Lewis has not been voted in, and Johnson, Peterson, and Henry are not yet eligible. Johnson has retired from the NFL, but Peterson and Henry have not.


2,1,3-Benzothiadiazole
2,1,3-Benzothiadiazole is a bicyclic molecule composed of a benzene ring that is fused to a 1,2,5-thiadiazole.


2,1,3-Benzothiadiazole, Preparation and structure
2,1,3-Benzothiadiazole has been known since the 19th century. It is readily prepared in at least 85% yield from o-phenylenediamine by reaction with two equivalents of thionyl chloride in pyridine. The by-products are sulfur dioxide and HCl.


2,1,3-Benzothiadiazole, Preparation and structure
There are a number of alternative methods used to make this heterocycle and these have been reviewed. The crystal structure of the compound was determined in 1951, when it had the common name piazthiol(e).


2,1,3-Benzothiadiazole, Reactions
The extent of the aromaticity of the compound was examined by a study of its proton NMR spectrum and comparison with naphthalene, which allowed the conclusion that it and related oxygen and selenium heterocycles did behave as 10-electron systems in which the 2-heteroatom contributed its lone pair to the ring current, in accordance with Hückel's rule.


2,1,3-Benzothiadiazole, Reactions
As a result, 2,1,3-benzothiadiazole undergoes the standard chemistry of aromatic compounds, for example readily forming nitro and chloro derivatives. The chemistry of this heterocycle and its simple derivatives has been reviewed.


2,1,3-Benzothiadiazole, Reactions
Under reducing conditions, 2,1,3-benzothiadiazoles can be converted back to the 1,2-diaminobenzene compounds from which they were prepared. This can be a useful way to protect a pair of reactive amino groups while other transformations are performed in the benzene ring to which they are attached.


2,1,3-Benzothiadiazole, Applications
2,1,3-Benzothiadiazole has been of interest as a redox-active organic component in flow batteries owing to its favourable solubility, low reduction potential and fast electrochemical kinetics.


2,1,3-Benzothiadiazole, Applications
Such properties in derivatives containing this heterocycle have made it of growing interest in dyestuffs, white light-emitting polymers, solar cells, and in luminescence studies.


2,1-fructan:2,1-fructan 1-fructosyltransferase
In enzymology, a 2,1-fructan:2,1-fructan 1-fructosyltransferase (EC ) is an enzyme that catalyzes the chemical reaction


2,1-fructan:2,1-fructan 1-fructosyltransferase
Thus, the two substrates of this enzyme are [ [ [beta-D-fructosyl-(2->1)-]]m]] and [ [beta-D-fructosyl-(2->1)-]]n]], whereas its two products are [ [beta-D-fructosyl-(2->1)-]]m-1]] and [ [beta-D-fructosyl-(2->1)-]]n+1]].


2,1-fructan:2,1-fructan 1-fructosyltransferase
This enzyme belongs to the family of glycosyltransferases, specifically the hexosyltransferases. The systematic name of this enzyme class is 2,1-beta-D-fructan:2,1-beta-D-fructan 1-beta-D-fructosyltransferase. Other names in common use include 1,2-beta-D-fructan 1F-fructosyltransferase, fructan:fructan fructosyl transferase, FFT, 1,2-beta-fructan 1F-fructosyltransferase, 1,2-beta-D-fructan:1,2-beta-D-fructan, 1F-beta-D-fructosyltransferase, and fructan:fructan 1-fructosyl transferase.


2,100 Asanas
2,100 Asanas: The Complete Yoga Positions is a 2015 non-fiction book written by Mr. Yoga, Daniel Lacerda.


2,100 Asanas, Contents
2,100 Asanas: The Complete Yoga Positions features 2,100 yoga poses, photographed in color by Lacerda. The models in the book are all yoga students of Lacerda.


2,100 Asanas, Reception
The book received mixed reviews, but was listed in the Health and Fitness section of the Toronto Star bestseller list in December 2015, as well as The Indie Healthy Living Bestseller List of the American Booksellers' Association and The New York Times list of bestselling health books, for the same month.


2,100 Asanas, Reception
In an interview in Yoga Journal, Lacerda stated that he had catalogued 8.4 million yoga poses mentioned in Hatha Yoga Pradipika. He said that 2,100 Asanas was the first edition, and that he was working on a second edition, to be called 50,000 Asanas.


2,147,483,647
The number 2,147,483,647 is the eighth Mersenne prime, equal to 231 − 1. It is one of only four known double Mersenne primes.


2,147,483,647
The primality of this number was proven by Leonhard Euler, who reported the proof in a letter to Daniel Bernoulli written in 1772. Euler used trial division, improving on Pietro Cataldi's method, so that at most 372 divisions were needed. It thus improved upon the previous record-holding prime, 6,700,417, also discovered by Euler, forty years earlier. The number 2,147,483,647 remained the largest known prime until 1867.


2,147,483,647
In computing, this number represents the largest value that a signed 32-bit integer field can hold.


2,147,483,647, Barlow's prediction
At the time of its discovery, 2,147,483,647 was the largest known prime number. In 1811, Peter Barlow, not anticipating future interest in perfect numbers, wrote (in An Elementary Investigation of the Theory of Numbers):


2,147,483,647, Barlow's prediction
Euler ascertained that 231 − 1 = 2147483647 is a prime number; and this is the greatest at present known to be such, and, consequently, the last of the above perfect numbers [i.e., 230(231 − 1)], which depends upon this, is the greatest perfect number known at present, and probably the greatest that ever will be discovered; for as they are merely curious, without being useful, it is not likely that any person will attempt to find one beyond it.


2,147,483,647, Barlow's prediction
He repeated this prediction in his 1814 work A New Mathematical and Philosophical Dictionary.


2,147,483,647, Barlow's prediction
In fact a larger prime was discovered in 1855 by Thomas Clausen (67,280,421,310,721), though a proof was not provided. Furthermore, 3,203,431,780,337 was proven to be prime in 1867.


2,147,483,647, In computing
The number 2,147,483,647 (or hexadecimal 7FFFFFFF16) is the maximum positive value for a 32-bit signed binary integer in computing. It is therefore the maximum value for variables declared as integers (e.g., as int) in many programming languages. The appearance of the number often reflects an error, overflow condition, or missing value. In December 2014, it was reported that PSY's music video "Gangnam Style" had exceeded the 32-bit integer limit for YouTube view count, necessitating that YouTube upgrade the counter to a 64-bit integer. In fact, this was an "easter egg" joke shared by the company, as Google had reportedly switched to a 64-bit integer several months prior.


2,147,483,647, In computing
The data type time_t, used on operating systems such as Unix, is a signed integer counting the number of seconds since the start of the Unix epoch (midnight UTC of 1 January 1970), and is often implemented as a 32-bit integer. The latest time that can be represented in this form is 03:14:07 UTC on Tuesday, 19 January 2038 (corresponding to 2,147,483,647 seconds since the start of the epoch). This means that systems using a 32-bit time_t type are susceptible to the Year 2038 problem.


2,147,483,647, In video games
The number 2,147,483,647 is often used as the hard limit in most video games for score, money, points, etc. Going over this limit by legitimate means, or modding or hacking the game, results in many different outcomes. The most common are the number going into the negatives, thus the limit being extended to 4,294,967,295, also known as the unsigned 32-bit integer limit. There is also a chance of the game crashing, thus meaning there was no failsafe implemented in case someone reached the 32-bit limit.


2,2',2''-Nitrilotriacetonitrile
Nitrilotriacetonitrile (NTAN) is a precursor for nitrilotriacetic acid (NTA, a biodegradable complexing agent and building block for detergents), for tris(2-aminoethyl)amine (a tripodal tetradentate chelating agent known under the abbreviation tren) and for the epoxy resin crosslinker aminoethylpiperazine.


2,2',2''-Nitrilotriacetonitrile, Production
The synthesis of nitrilotriacetonitrile is based on the basic building blocks ammonia, formaldehyde and hydrogen cyanide, which are reacted (via the triple cyanomethylation of the ammonia) in acidic aqueous medium in discontinuous or continuous processes.


2,2',2''-Nitrilotriacetonitrile, Production
Ammonia is introduced as a gas, in form of hexamethylenetetramine or as ammonium sulfate together with formaldehyde as aqueous solution (usually 37% by weight) at pH values <2 and treated with aqueous blue acid solution or liquid hydrogen cyanide at temperatures around 100 °C. Blue acid is used directly from the Andrussow process or the BMA process of Evonik Degussa without pre-purification if necessary. When the mother liquors are returned, yields of more than 90% are achieved.


2,2',2''-Nitrilotriacetonitrile, Production
Problematic, particularly in the case of a continuous process, is the tendency of NTAN to precipitate at temperatures below 90 °C which can lead to clogging of tube reactors and conduits and thermal runaway of the reaction.


2,2',2''-Nitrilotriacetonitrile, Properties
Nitrilotriacetonitrile is a colorless and odorless solid which dissolves hardly in water but dissolves well in nitromethane and acetone.


2,2',2''-Nitrilotriacetonitrile, Use
Nitrilotriacetonitrile can be homopolymerized or copolymerized with iminodiacetonitrile in the melt in the presence of basic catalysts such as sodium methoxide to form dark-colored solid polymers which can be carbonized to form nitrogen-containing and electrically conductive polymers at temperatures above 1000 °C. The products obtained have not found application as conductive polymers.


2,2',2''-Nitrilotriacetonitrile, Use
The hydrogenation of NTAN first converts a cyano group into an imino group which attacks a cyano group (which are adjacent and sterically suitable for forming a six-membered ring) rather than being further hydrogenated to the primary amino group. The end product of the catalytic hydrogenation of nitrilotriacetonitrile is therefore 1-(2-aminoethyl)piperazine.


2,2',2''-Nitrilotriacetonitrile, Use
If the catalytic hydrogenation of NTAN is carried out with e. g. Raney nickel in the presence of a large excess of ammonia, it gives tris(2-aminoethyl)amine.


2,2',2''-Nitrilotriacetonitrile, Use
Tris(2-aminoethyl)amine is used as a tetrazident complexing agent (abbreviated as "tren"), which forms stable chelates, particularly with divalent and trivalent transition metal ions.


2,2',2''-Nitrilotriacetonitrile, Use
Nitrilotriacetonitrile reacts with methanal at pH 9.5 to give 2,2-dihydroxymethyl-nitrilotriacetonitrile, which is hydrolyzed with sodium hydroxide solution at 100 °C to give the trisodium salt of 2-hydroxymethylserine-N,N-diacetic acid, from which the free acid can be obtained by acidification in 51% yield.


2,2',2''-Nitrilotriacetonitrile, Use
The compound is suitable as a complexing agent for heavy metal ions or alkaline earth metal ions, as a stabilizer for bleaching agents (e.g. for sodium perborate, in solid detergent preparations) and as a builder in detergents for inhibiting the formation of incrustations in textiles during laundering.


2,2',2''-Nitrilotriacetonitrile, Use
The hydrolysis of nitrilotriacetonitrile with water in concentrated sulfuric acid yields under gentle conditions practically quantitatively nitrilotriacetamide, which has been investigated as a neutral tetradentate ligand for metal complexation. At elevated temperature, 3,5-dioxopiperazine-1-acetamide is formed by ring closure, which can be quantitatively converted into the nitrilotriacetamide after neutralization and heating with excess aqueous ammonia.


2,2',2''-Nitrilotriacetonitrile, Use
Nitrilotriacetonitrile serves mainly as a raw material for the production of the biodegradable, but carcinogen suspected complexing agent nitrilotriacetic acid by acid or base-catalyzed hydrolysis of the cyano groups.


2,2',2''-Nitrilotriacetonitrile, Use
Undesirable residual contents of cyanide ions in the hydrolyzate can be removed by post-treatment with oxidizing agents such as sodium hypochlorite at pH 8.


2,2'-Azobis(2-amidinopropane) dihydrochloride
2,2'-Azobis(2-amidinopropane) dihydrochloride (AAPH) is a chemical compound used to study the chemistry of the oxidation of drugs.


2,2'-Azobis(2-amidinopropane) dihydrochloride
It is a free radical-generating azo compound. It is gaining prominence as a model oxidant in small molecule and protein therapeutics for its ability to initiate oxidation reactions via both nucleophilic and free radical mechanisms.


2,2'-Azobis(2-amidinopropane) dihydrochloride
2,2′-azobis (2-amidinopropane) dihydrochloride has been used in experiments on linoleic acid subjected to induced oxidation with different combinations of binary mixtures of natural phenolics. The experiments show that some binary mixtures can lead to a synergetic antioxidant effect while other mixtures lead to an antagonistic effect.


2,2'-Biphenol
2,2′-Biphenol is an organic compound with the formula (C6H4OH)2. It is one of three symmetrical isomers of biphenol. A white solid, it is a precursor to diphosphite ligands that are used to support industrial hydroformylation catalysis.


2,2'-Biphenol, Synthesis
Ring-opening of Dibenzofuran affords 2,2′-biphenol. Alternatively, it can be produced from 2,4-di-tert-butylphenol in two steps. The first step entails oxidative coupling to give the 2,2′-biphenol with four tert-Bu substituents. This species then undergoes debutylation.


2,2'-Biphenylene phosphorochloridite
2,2′-Biphenylene phosphorochloridite is the name for a polycyclic organophosphorus compound with the formula C12H8O2PCl. It is a precursor to diphosphite ligands such as BiPhePhos by reaction with suitable diols. 2,2′-Biphenylene phosphorochloridites, which is a white solid, is prepared from 2,2′-biphenol and phosphorus trichloride. It is prepared by the reaction of 2,2′-biphenol and phosphorus trichloride.


2,2'-Bipyrimidine
2,2′-Bipyrimidine is an organic compound with the formula (C4H3N2)2. It is a derivative of the heterocycle pyrimidine. It is a white solid. The compound is used as a bridging ligand in coordination chemistry.


2,2'-Biquinoline
2,2′-Biquinoline is an organic compound with the formula (C9H6N)2. It is one of several dimers of the bicyclic heterocycle called quinoline. It is prepared by reductive coupling of 2-chloroquinoline. It is a colorimetric indicator for organolithium compounds.


2,2'-Bis(2-indenyl) biphenyl
2,2′-Bis(2-indenyl) biphenyl is an organic compound with the formula [C6H4C9H7]2. The compound is the precursor, upon deprotonation, to ansa-metallocene complexes within the area of transition metal indenyl complexes.


2,2'-Bis(2-indenyl) biphenyl
Metals studied with 2,2′-bis(2-indenyl) biphenyl include titanium, zirconium, and hafnium. The ligand and its complexes have been prepared by the research group of the late Brice Bosnich at The University of Chicago. Zirconium and hafnium complexes made from this ligand were found to be active catalysts for the polymerization of the smallest alkenes – compounds with carbon-carbon double bonds—namely, ethylene and propylene. The use of such complexes in the polymerization of alkenes has since been reported, and patented by DSM Research.


2,2'-Bithiophene
2,2′-Bithiophene is the organic compound. It is a colorless solid, although commercial samples are often greenish. It is the most common of the three isomers with formula (C4H3S)2. The other two isomers have the connectivity 2,3′- and 3,3′-. The compound is typically prepared by cross-coupling starting from 2-halothiophenes.


2,2'-Bithiophene
X-ray crystallography shows that the two rings are coplanar, unlike the situation for biphenyl.


2,2'-Bithiophene, Occurrence
A number of bi- as well as terthiophenes exist naturally, invariably with substituents at the positions flanking sulfur. In terms of the biosynthesis, bithiophenes are proposed to be derived from polyacetylenic precursors, which in turn are the products of dehydrogenation of oleic acid. According to some hypotheses, these polyalkynes form labile 1,2-dithiins via a reaction with H2S2 or its equivalent.


2,2'-Difluorofentanyl
2,2'-Difluorofentanyl is an opioid analgesic that is an analog of fentanyl which has been sold as a designer drug.


2,2'-Difluorofentanyl, Side effects
Side effects of fentanyl analogs are similar to those of fentanyl itself, which include itching, nausea and potentially serious respiratory depression, which can be life-threatening. Fentanyl analogs have killed hundreds of people throughout Europe and the former Soviet republics since the most recent resurgence in use began in Estonia in the early 2000s, and novel derivatives continue to appear. A new wave of fentanyl analogues and associated deaths began in around 2014 in the US, and have continued to grow in prevalence; especially since 2016 these drugs have been responsible for hundreds of overdose deaths every week.


2,2'-Difluorofentanyl, Legal status
As a ring-substituted derivative of fentanyl, 2,2'-difluorofentanyl is banned under drug analog laws in the United States and other jurisdictions around the world.


2,2'-Dipyridylamine
2,2′-Dipyridylamine is an organic compound with the formula (C5H4N)2NH. It consists of a pair of 2-pyridyl groups (C5H4N) linked to a secondary amine. The compound forms a range of coordination complexes. Its conjugate base, 2,2′-dipyridylamide, forms extended metal atom chains.


2,2'-Dipyridylamine, Formation
2,2′-Dipyridylamine can be formed by heating pyridine with sodium amide. Alternatively, 2-aminopyridine can be heated with 2-chloropyridine over barium oxide.


2,2'-Dipyridyldisulfide
2,2′-Dipyridyldisulfide, sometimes known as DPS, is used for preparing thiols and activating carboxylic acid for coupling reactions, as in the following reaction:


2,2'-Dipyridyldisulfide, Uses
It is also used in molecular biology as an oxidising agent, for example to oxidise free thiols to form disulfide bonds in proteins.


2,2'-Dipyrromethene
2,2'-Dipyrromethene, often called just dipyrromethene or dipyrrin, is a chemical compound with formula C9H8N2 whose skeleton can be described as two pyrrole rings C5N connected by a methyne bridge =CH– through their nitrogen-adjacent (position-2) carbons; the remaining bonds being satisfied by hydrogen atoms. It is an unstable compound that is readily attacked by nucleophylic compounds above −40 °C.


2,2'-Dipyrromethene
2,2'-Dipyrromethene and its more stable and easily prepared derivatives—formally obtained by replacing one or more hydrogen atoms by other functional groups—are important precursors for the family of BODIPY fluorescent dies. The derivatives include salts of the dipyrrinato anion C9H7N–2 and of the cation C9H9N+2.


2,2'-Dipyrromethene, Preparation
2,2'-Dipyrromethene and its derivatives can be  obtained from suitable pyrrole derivatives by several methods.


2,2'-Dipyrromethene, Preparation
The unsubstituted compound can be prepared by oxidation of 2,2'-dipyrrolemethane with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) at −78 °C in dry dichloromethane solution. An alternative synthesis that avoids the oxidation step is the condensation of 2-formyl pyrrole and pyrrole catalyzed by trifluoroacetic acid, followed by deprotonation with N,N-diisopropylethylamine.


2,2'-Dipyrromethene, Preparation
More generally, one starts with a pyrrole with suitable substituents at positions 3, 4, or 5 (but not 2). Condensation of two such molecules at their 2 positions with a bridging compound gives the corresponding 2,2'-dipyrromethane. The condensation may use, for example, the Knorr pyrrole synthesis, with an aromatic aldehyde in the presence of TFA. The dipyrromethane core is then oxidized to dipyrromethene using a quinone oxidant such as DDQ or p-chloranil.


2,2'-Dipyrromethene, Preparation
Alternatively, one may use an activated carboxylic acid derivative, usually an acyl chloride. As another possibility, one may condense a substituted pyrroles with a 2-acylpyrrole; this route allows the synthesis of unsymmetrical dipyrromethenes.


2,2'-Dipyrromethene, Reactions
Dipyrrin is unstable above −40 °C. However, its acts as a base, and its chloride [C9H9N+2] [Cl−] is sufficiently stable in solution.


2,2'-Dipyrromethene, Reactions
The so-called BODIPY dyes can be obtained by reacting 2,2'-dipyrromethene or its derivatives with boron trifluoride-diethyl ether complex (BF3·(C2H5)2O) in the presence of triethylamine or 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU).


2,2'-Dipyrromethene, Reactions
Dipyrrin and its derivatives for coordination complexes with transition metals. For example, the derivative anion 5-phenyl dipirrinato (pdp) forms the neutral iron(III) complex Fe(pdp)3 (dark green monoclinic crystals, soluble in benzene, orange solution in dichloromethane), where the Fe3+ ion is coordinated to six nitrogen atoms of the dipyrrin cores in distorted octahedral geometry. A similar cobalt(III) complex has also been reported, as well as a complex with copper(II) Cu(pdp)2


2,2,2-Trichloroethanol
2,2,2-Trichloroethanol is the chemical compound with formula Cl3C−CH2OH. Its molecule can be described as that of ethanol, with the three hydrogen atoms at position 2 (the methyl group) replaced by chlorine atoms. It is a clear flammable liquid at room temperature, colorless when pure but often with a light yellow color.


2,2,2-Trichloroethanol
The pharmacological effects of this compound in humans are similar to those of its prodrug chloral hydrate, and of chlorobutanol. Historically, it has been used as a sedative hypnotic. The hypnotic drug triclofos (2,2,2-trichloroethyl phosphate) is metabolized in vivo to 2,2,2-trichloroethanol. Chronic exposure may result in kidney and liver damage.


2,2,2-Trichloroethanol
2,2,2-Trichloroethanol can be added to SDS-PAGE gels in order to enable fluorescent detection of proteins without a staining step, for immunoblotting or other analysis methods.


2,2,2-Trichloroethanol, Use in organic synthesis
2,2,2-trichloroethanol is an effective protecting group for carboxylic acids due to its ease in addition and removal.


2,2,2-Trichloroethoxycarbonyl chloride
Trichloroethyl chloroformate is used in organic synthesis for the introduction of the trichloroethyl chloroformate (Troc) protecting group for amines, thiols and alcohols. It readily cleaves vs other carbamates and can be used in an overall protecting group strategy.


2,2,2-Trichloroethoxycarbonyl chloride
The troc group is traditionally removed via Zn insertion in the presence of acetic acid, resulting in elimination and decarboxylation.


2,2,2-Trichloroethoxycarbonyl chloride, Amine protection – 2,2,2-Trichloroethoxycarbonyl (Troc)
2,2,2-Trichloroethoxycarbonyl (Troc) group is largely used as a protecting group for amines in organic synthesis.


2,2,2-Trifluoroethanol
2,2,2-Trifluoroethanol is the organic compound with the formula CF3CH2OH. Also known as TFE or trifluoroethyl alcohol, this colourless, water-miscible liquid has a smell reminiscent of ethanol. Due to the electronegativity of the trifluoromethyl group, this alcohol exhibits a stronger acidic character compared to ethanol.


2,2,2-Trifluoroethanol, Synthesis
Trifluoroethanol is produced industrially by hydrogenation or the hydride reduction of derivatives of trifluoroacetic acid, such as the esters or acyl chloride.


2,2,2-Trifluoroethanol, Synthesis
TFE can also be prepared by hydrogenolysis of compounds of generic formula CF3−CHOH−OR (where R is hydrogen or an alkyl group containing from one to eight carbon atoms), in the presence of a palladium containing catalyst deposited on activated charcoal. As a co-catalyst for this conversion tertiary aliphatic amines like triethylamine are commonly employed.


2,2,2-Trifluoroethanol, Uses
Trifluoroethanol is used as a solvent in organic chemistry. Oxidations of sulfur compounds using hydrogen peroxide are effectively conducted in TFE. It can also be used as a protein denaturant. In biology TFE is used as a co-solvent in protein folding studies with NMR spectroscopy: this solvent can effectively solubilize both peptides and proteins. Depending upon its concentration, TFE can strongly affect the three-dimensional structure of proteins.


2,2,2-Trifluoroethanol, Uses
Industrially trifluoroethanol is employed as a solvent for nylon as well as in applications of the pharmaceutical field.


2,2,2-Trifluoroethanol, Uses
Trifluoroethanol is a key precursor for the inhaled anaesthetic isoflurane, listed on the World Health Organization's List of Essential Medicines.


2,2,2-Trifluoroethanol, Uses
Trifluoroethanol is also used in biochemistry as an inhibitor to study enzymes. It competitively inhibits alcohol dehydrogenase for example.


2,2,2-Trifluoroethanol, Reactions
Oxidation of trifluoroethanol yields trifluoroacetaldehyde or trifluoroacetic acid. It  also serves as a source of the trifluoroethoxy group for various chemical reactions (Still-Gennari modification of HWE reaction).


2,2,2-Trifluoroethanol, Reactions
2,2,2-Trifluoroethyl vinyl ether, an inhaled drug introduced clinically under the tradename Fluoromar, features a vinyl ether of trifluorethanol. This species was prepared by the reaction of trifluoroethanol with acetylene.


2,2,2-Trifluoroethanol, Reactions
TFE forms stable complexes with Lewis bases such as THF or pyridine through hydrogen bonding, yielding 1:1 adducts. CF3CH2OH is classified as a  hard Lewis acid and its acceptor properties are discussed in the ECW model yielding EA = 2.07 and CA = 1.06.


2,2,2-Trifluoroethanol, Safety
Trifluoroethanol is classified as toxic to blood, the reproductive system, bladder, brain, upper respiratory tract and eyes. Research has shown it to be a testicular toxicant in rats and dogs.


2,2,3,3-Tetramethylsuccinic acid
In chemistry, 2,2,3,3-tetramethylsuccinic acid or 2,2,3,3-tetramethylbutane-1,4-dioic acid is a dicarboxylic acid with the formula C8H14O4, or HOOC- C(CH3)2-C(CH3)2-COOH.


2,2,3,3-Tetramethylsuccinic acid
It can be seen as derivative of succinic acid (butane-1,4-dioic acid) with two methyl groups replacing two hydrogen atoms on each of the central carbon atoms of the chain.


2,2,3,3-Tetramethylsuccinic acid, Synthesis and chemistry
The compound can also be obtained by thermal decomposition of 2,2,3,3-tetramethyl-4-one-glutaric acid with release of a carbon monoxide molecule.


2,2,3,3-Tetramethylsuccinic acid, Synthesis and chemistry
On heating it forms a heterocyclic anhydride, 3,3,4,4-tetramethyltetrahydrofuran-2,5-dione, with loss of one molecule of water.


2,2,4,4-Tetramethyl-1,3-cyclobutanediol
2,2,4,4-Tetramethyl-1,3-cyclobutanediol (CBDO) is an aliphatic diol. This diol is produced as a mixture of cis- and trans-isomers, depending on the relative stereochemistry of the hydroxyl groups. It is used as a monomer for the synthesis of polymeric materials. CBDO is currently being researched as an alternative to bisphenol A (BPA). BPA is a precursor used in the production of a wide range of polymers including polycarbonates, polyesters, polysulfones, and polyester ketones.


2,2,4,4-Tetramethyl-1,3-cyclobutanediol, Replacement for BPA
The controversies associated with BPA in large quantities are ultimately related to its endocrine disrupting abilities. Like BPA, CBDO is a diol with a structure suitable for making polyesters. CBDO’s C4 ring is sufficiently rigid to prevent the two OH groups from forming cyclic structures. Unlike BPA, there is no current evidence of carcinogenic or toxic effects from CBDO-based consumer products. There are, however, few studies on the toxicology of CBDO for both long term and short term effects.


2,2,4,4-Tetramethyl-1,3-cyclobutanediol, Replacement for BPA
CBDO has potential advantages relative to BPA as a building block for production of polyesters. CBDO is very stable thermally and mechanically. Polyesters prepared from CBDO are rigid materials, but the combination of CBDO with flexible diols results in materials with high impact resistance, low color, thermal stability, good photooxidative stability and transparency. As an added bonus, CBDO-derived polymers have high ductility. The thermal and mechanical properties of CBDO-derived polyesters are often superior to conventional polyesters.


2,2,4,4-Tetramethyl-1,3-cyclobutanediol, Preparation
Synthesis of CBDO involves pyrolysis of isobutyric anhydride followed by hydrogenation of the resulting 2,2,4,4-tetramethylcyclobutanedione. This synthesis resembles the method used to produce CBDO today. The first step involves conversion of the isobutyric acid or its anhydride into the ketene. This ketene then dimerizes to form a four-membered ring with two ketone groups.


2,2,4,4-Tetramethyl-1,3-cyclobutanediol, Preparation
The product ring is hydrogenated to give a diol. The last step commonly involves catalytic hydrogenation with ruthenium, nickel, or rhodium catalysts. Hydrogenation of the diketone ring results in both cis and trans isomers. A simplified scheme for the production of CBDO is presented below.


2,2,4,4-Tetramethyl-1,3-cyclobutanediol, Structure and properties
The C4 ring of the cis isomer of CBDO is non-planar. For simple non-planar cyclobutanes, dihedral angles range from 19 to 31°. CBDO’s cis isomer crystallizes as two conformers with an average dihedral angle of 17.5° in the solid state. However, the trans isomer has a dihedral angle of 0°.


2,2,4,4-Tetramethyl-1,3-cyclobutanediol, Polyesterification
The current economic method for the production of polyesters is direct esterification of dicarboxylic acids with diols. This condensation polymerization adds monomeric units to a chain. Individual chains react with one another through carboxyl and hydroxyl terminal groups. Finally, transesterification occurs within the chain. Although CBDO is most often used in polyesters, mixed copolycarbonates of CBDO and a series of bisphenols have also been synthesized. The differing reactivities of the cis and trans isomers have not been studied in depth.


2,2,4,4-Tetramethyl-3-t-butyl-pentane-3-ol
2,2,4,4-Tetramethyl-3-t-butyl-pentane-3-ol or tri-tert-butylcarbinol is an organic compound with formula C13H28O, ((H3C)3C)3COH, or tBu3COH. It is an alcohol that can be viewed as a structural analog of a tridecane isomer (2,2,4,4-tetramethyl-3-t-butylpentane) where the central hydrogen has been replaced by a hydroxyl group -OH.


2,2,4,4-Tetramethyl-3-t-butyl-pentane-3-ol
Tri-tert-butylcarbinol is arguably the most sterically hindered alcohol that has been prepared to date. In contrast to all other known alcohols, the infrared spectrum of the liquid does not exhibit a broad OH absorption associated with intermolecular hydrogen bonding, making it interesting for research in spectroscopy. The bulky tert-butyl groups (H3C)3C- groups attached to the central carbon prevent the formation of a O–H---O hydrogen bond with another molecule, an intermolecular interaction typical of alcohols.


2,2,4,4-Tetramethyl-3-t-butyl-pentane-3-ol
Another structural analog, in which the COH group is replaced by N, is tri-tert-butylamine, a molecule predicted to be stable but has never been prepared.


2,2,4,4-Tetramethylcyclobutanedione
2,2,4,4-Tetramethylcyclobutanedione is the organic compound with the formula (CH3)4C4O2. The compound is a diketone of cyclobutane, bearing four methyl groups. It is a white solid that is used as a precursor to diverse industrial products.


2,2,4,4-Tetramethylcyclobutanedione, Synthesis and reactions
2,2,4,4-Tetramethylcyclobutanedione is the head-to-tail dimer of dimethylketene. It arises spontaneously when dimethylketene is produced by dehydrohalogenation of isobutyryl chloride with triethylamine.


2,2,4,4-Tetramethylcyclobutanedione, Synthesis and reactions
The 2,2,4,4-tetramethylcyclobutanedione isomerizes to the lactone called dimethylketene dimer (4-isopropylidene-3,3-dimethyl-2-oxetanone). Dimethylketene dimer is a precursor to various alkyl ketene dimers, which are used in papermaking.


2,2,4,4-Tetramethylcyclobutanedione, Synthesis and reactions
Hydrogenation of 2,2,4,4-tetramethylcyclobutanedione gives 2,2,4,4-tetramethylcyclobutanediol, which is of interest in polymer chemistry.


2,2,4-Trimethylpentane
2,2,4-Trimethylpentane, also known as isooctane or iso-octane, is an organic compound with the formula (CH3)3CCH2CH(CH3)2. It is one of several isomers of octane (C8H18). This particular isomer is the standard 100 point on the octane rating scale (the zero point is n-heptane). It is an important component of gasoline, frequently used in relatively large proportions to increase the knock resistance of the fuel.


2,2,4-Trimethylpentane
Strictly speaking, if the standard meaning of ‘iso’ is followed, the name isooctane should be reserved for the isomer 2-methylheptane. However, 2,2,4-trimethylpentane is by far the most important isomer of octane and so, historically, it has been assigned this name.


2,2,4-Trimethylpentane, Production
Isooctane is produced on a massive scale in the petroleum industry by alkylation of isobutene with isobutane. The process is conducted in alkylation units in the presence of acid catalysts.


2,2,4-Trimethylpentane, Production
It can also be produced from isobutylene by dimerization using an Amberlyst catalyst to produce a mixture of iso-octenes. Hydrogenation of this mixture produces  2,2,4-trimethylpentane.


2,2,4-Trimethylpentane, History
Engine knocking is an unwanted process that can occur during high compression ratios in internal combustion engines. Graham Edgar in 1926 added different amounts of n-heptane and 2,2,4-trimethylpentane to gasoline, and discovered that the knocking stopped when 2,2,4-trimethylpentane was added. This work was the origin of the octane rating scale. Test motors using 2,2,4-trimethylpentane gave a certain performance that was standardized as 100 octane. The same test motors, run in the same fashion, using heptane, gave a performance which was standardized as 0 octane. All other compounds and blends of compounds then were graded against these two standards and assigned octane numbers.


2,2,5,5-Tetramethyltetrahydrofuran
2,2,5,5-tetramethyltetrahydrofuran (TMTHF) or 2,2,5,5-tetramethyloxolane (TMO) is a heterocyclic compound with the formula C8H16O, or (CH3)2(C(CH2)2OC)(CH3)2. It can be seen as derivative of tetrahydrofuran (oxolane) with four methyl groups replacing four hydrogen atoms on each of the carbon atoms in the ring that are adjacent to the oxygen. The absence of hydrogen atoms adjacent to the oxygen means that TMTHF (TMO) does not form peroxides, unlike other common ethers such as tetrahydrofuran, diethyl ether and CPME.


2,2,5,5-Tetramethyltetrahydrofuran
The compound has been demonstrated as a non-polar solvent in research chemistry, having similar properties to toluene and as a reagent in chemical synthesis.


2,2,5,5-Tetramethyltetrahydrofuran, Natural occurrence
The compound is produced in small quantities by the mycelium of Tuber borchii, a mushroom similar to the truffle.


2,2,5,5-Tetramethyltetrahydrofuran, Synthesis and chemistry
The compound is easily prepared by the ring closure of 2,5-dimethylhexane-2,5-diol using acid catalysts. Zeolites have been shown to be particularly high yielding but sulfuric acid can also be used.


2,2,5,5-Tetramethyltetrahydrofuran, Synthesis and chemistry
TMTHF reacts with benzene in the presence of triflic acid to form 1,1,4,4-dimethyltetralin and symmetric tetramethyloctahydroanthracene. This and other similar reactions can be used for the selective preparation of derivatives of naphthalene, anthracene, and tetracene, and other fused-ring aromatic hydrocarbons.


2,2,5,5-Tetramethyltetrahydrofuran, Synthesis and chemistry
TMTHF undergoes photolysis by UV; in aqueous solution, the products are mainly methane, ethane, and 2-hydroxy-2,5,5-trimethyltetrahydrofuran. The dehydration of TMTHF yields alkenes like 2,5-dimethyl-2,4-hexadiene and 2,5-dimethyl-1,5-hexadiene.


2,2,5,5-Tetramethyltetrahydrofuran, Synthesis and chemistry
Reaction with fluorine substitutes it for all hydrogen atoms to yield perfluoro(2,2,5,5-tetramethyltetrahydrofuran) C8F16O (bp 99 C, mp -31 C).


2,2,6,6-Tetramethylpiperidine
2,2,6,6-Tetramethylpiperidine, abbreviated TMP, HTMP, or TMPH, is an organic compound of the amine class. In appearance, it is a colorless liquid and has a "fishy", amine-like odor. This amine is used in chemistry as a hindered base (hindered amine). Although TMP finds limited use per se, its derivatives are a mainstay of hindered amine light stabilizers.


2,2,6,6-Tetramethylpiperidine
TMP is the starting material for an even stronger base lithium tetramethylpiperidide and the radical species TEMPO. Another non-nucleophilic base is N,N-diisopropylethylamine.


2,2,6,6-Tetramethylpiperidine, Preparation
Many routes for the synthesis of TMP have been reported. One method starts with a conjugate addition reaction of ammonia to phorone. The intermediate triacetone amine is then reduced in a Wolff-Kishner reaction.


2,2-Di-2-furylpropane
2,2-Di-2-furylpropane is a condensation product of furan and acetone. It is a relatively high boiling liquid (boiling point: 85−90 °C at 13 torr) and is a precursor (via hydrogenation) to the rubber additive bis(tetrahydrofuryl)propane used in the manufacture of high vinyl content rubber for high performance tires.


2,2-Di-2-furylpropane, Synthesis
Furan and ketones react under the action of acidic catalysts yielding difuryl condensation products, higher oligomers, as well as cyclic furan tetramers (tetraoxaquterenes). If the number of furan moieties in the oligomer is denoted as n, the number of isopropylidene moieties (derived from acetone) is n-1. In the case of aldehydes only linear oligomers are formed. The simplest adduct of furan and acetone is 2,2-di-2-furylpropane, the title compound.


2,2-Di-2-furylpropane, Synthesis
This molecule is typically synthesized employing two equivalents of furan and one equivalent of acetone employing concentrated hydrochloric acid as the catalyst at ambient temperature and pressure. Alternatively, the reaction may be cooled during the addition of reagents and in the early phases.


2,2-Di-2-furylpropane, Synthesis
Inasmuch as the two furan moieties in 2,2-di-2-furylpropane may further react, at their respective unsubstituted 5-positions, with additional acetone the formation of oligomers can not be completely suppressed. However, the amount of oligomer is effected by reaction conditions, including the furan to acetone ratio and the amount of hydrochloric acid catalyst employed.


2,2-Di-2-furylpropane, Purification
2,2-Di-2-furylpropane may be obtained from crude aqueous acidic reaction mixtures (typically biphasic) by allowing phase separation followed by neutralization of the organic layer. Essentially pure product is obtained by vacuum distillation of the neutralized organic phase.


2,2-Dichloro-1,1,1-trifluoroethane
2,2-Dichloro-1,1,1-trifluoroethane or HCFC-123 is considered as an alternative to CFC-11 in low pressure refrigeration and HVAC systems, and should not be used in foam blowing processes or solvent applications.


2,2-Dichloro-1,1,1-trifluoroethane
Its ozone depletion potential is ODP = 0.012, and global warming potential is GWP = 76. HCFC-123 will eventually be phased out under the current schedule of the Montreal Protocol, but can continue to be used in new HVAC equipment until 2020 in developed countries, and will still be produced for service use of HVAC equipment until 2030. Developing countries can use in new equipment until 2030, and can be produced for use in service until 2040.


2,2-Dichloro-1,1,1-trifluoroethane
HCFC-123 is used in large tonnage centrifugal chiller applications, and is the most efficient refrigerant currently in use in the marketplace for HVAC applications. HCFC-123 is also used as a testing agent for bypass leakage of carbon adsorbers in gas filtration systems, and as the primary chemical in Halotron I fire-extinguishing agent.


2,2-Dichloro-1,1,1-trifluoroethane
Isomers are 1,2-dichloro-1,1,2-trifluoroethane (R-123a) with CAS 354-23-4 and 1,1-dichloro-1,2,2-trifluoroethane (R-123b) with CAS 812-04-4.


2,2-Dichloropropionic acid
2,2-Dichloropropionic acid is the organic compound with the formula CH3CCl2CO2H. A colorless liquid, it once was marketed under the name Dalapon as a selective herbicide used to control perennial grasses. The major use of dalapon was on food crops including sugarcane and sugar beets.


2,2-Dichloropropionic acid, Regulation
The National Institute for Occupational Safety and Health in the United States has identified it as a potential workplace hazard. The recommended time-weighted average exposure limit is 6 milligrams per cubic meter during a 10-hour workday.


2,2-Diethoxytetrahydrofuran
2,2-Diethoxytetrahydrofuran is a cyclic orthoester which can be reacted with diols to biodegradable polyorthoesters.


2,2-Diethoxytetrahydrofuran, Preparation
The synthesis of 2,2-diethoxytetrahydrofuran via γ-butyrolactone and the Meerwein salt (triethyloxonium tetrafluoroborate) in diethyl ether was first described by Hans Meerwein and co-workers. In the reaction the electrophilic ethyl cation attackes the carbonyl oxygen and forms the stable but extraordinarily hygroscopic O-ethyl-γ-butyrolactonium tetrafluoroborate (melting point 42 °C). The compound dissolves in dichloromethane, chloroform and 1,2-dichloroethane but is insoluble in diethyl ether, benzene and tetrachloromethane. The onium salt reacts practically quantitatively with an ethanolate anion from sodium ethoxide in ethanol forming 2,2-diethoxytetrahydrofuran.


2,2-Diethoxytetrahydrofuran, Preparation
2,2-Diethoxytetrahydrofuran can also be produced in a solvent-free one-pot reaction using γ-butyrolactone, orthoformic triethyl ester and gaseous boron trifluoride. This route avoids the use of diethyl ether and its side-products and sensible intermediates.


2,2-Diethoxytetrahydrofuran, Preparation
First diethoxymethylium tetrafluoroborate is formed from the triethyl orthoformate and boron trifluoride at -30 °C. This electrophilically attacks the carbonyl group of the γ-butyrolactone  and the O-ethyl-γ-butyrolactonium tetrafluoroborate. The addition of sodium ethoxide leads to the final product, which is obtained after distillation in 69% overall yield.


2,2-Diethoxytetrahydrofuran, Preparation
The reaction proceeds under gentle conditions (<0 °C) and the almost quantitative addition of ethanolate to O-ethyl-γ-butyrolactonium tetrafluoroborate can also be catalyzed by bases such as ammonia and triethylamine.


2,2-Diethoxytetrahydrofuran, Properties
2,2-Diethoxytetrahydrofuran is a clear liquid which boils at 10 mm Hg vacuum at 60 - 61.5 °C according to the original literature.


2,2-Diethoxytetrahydrofuran, Application
The cyclic orthoester 2,2-diethoxytetrahydrofuran is a reactive bifunctional monomer which forms biodegradable polyorthoesters of the type POE-I by transesterification with α, ω-diols.


2,2-Diethoxytetrahydrofuran, Application
Polyorthoesters are used as embedding media for pharmaceuticals in depot drug dosage forms for controlled drug release by surface erosion under physiological conditions.


2,2-Dimethoxy-2-phenylacetophenone
2,2-Dimethoxy-2-phenylacetophenone is a photoinitiator, which is used to initialise radical polymerization e.g. in the preparation of acrylate polymers. Under the influence of light the molecule will form radicals which initiate the radical polymerization. It can also be used as an initiator in the process of making an integrated circuit.


2,2-Dimethoxypropane
2,2-Dimethoxypropane (DMP) is an organic compound with the formula (CH3)2C(OCH3)2. A colorless liquid, it is the product of the condensation of acetone and methanol. DMP is used as a water scavenger in water-sensitive reactions. Upon acid-catalyzed reaction, DMP reacts quantitatively with water to form acetone and methanol. This property can be used to accurately determine the amount of water in a sample, alternatively to Karl Fischer method.


2,2-Dimethoxypropane
In histology, DMP is used for the dehydration of animal tissue.


2,2-Dimethyl-1-butanol
2,2-Dimethyl-1-butanol (IUPAC name: 2,2-dimethylbutan-1-ol) is an organic chemical compound. It is used as a solvent.


2,2-Dimethylbutane
2,2-Dimethylbutane, trivially known as neohexane, is an organic compound with formula C6H14 or (H3C-)3-C-CH2-CH3. It is therefore an alkane, indeed the most compact and  branched of the hexane isomers — the only one with a quaternary carbon and a butane (C4) backbone.


2,2-Dimethylbutane, Synthesis
2,2-Dimethylbutane can be synthesised by the hydroisomerisation of 2,3-dimethylbutane using an acid catalyst.


2,2-Dimethylbutane, Synthesis
It can also be synthesised by isomerization of n-pentane in the presence of a catalyst containing combinations of one or more of palladium, platinum, rhodium and rhenium on a matrix of zeolite, alumina, silicon dioxide or other materials. Such reactions create a mixture of final products including isopentane, n-hexane, 3-methylpentane, 2-methylpentane, 2,3-dimethylbutane and 2,2-dimethylbutane. Since the composition of the final mixture is temperature dependant the desired final component can be obtained choice of catalyst and by combinations of temperature control and distillations.


2,2-Dimethylbutane, Uses
Neohexane is used as an additive in fuels and in the manufacture of agricultural chemicals. It is also used in a number of commercial, automobile and home maintenance products, such as adhesives, electronic contact cleaners and upholstery polish sprays.


2,2-Dimethylbutane, Uses
In laboratory settings, it is commonly used as a probe molecule in techniques which study the active sites of metal catalysts. Such catalysts are used in hydrogen-deuterium exchange, hydrogenolysis, and isomerization reactions. It is well suited to this purpose as 2,2-dimethylbutane contains both an isobutyl and an ethyl group.


2,2-Dimethylpentane
2,2-Dimethylpentane is one of the isomers of heptane. It is also called neoheptane as it contains the (CH3)3C grouping. It has the most extreme properties of the isomers.


2,2-Dimethylpentane, Preparation
A method to produce high purity  2,2-dimethylpentane is to react the grignard reagent of n-propyl bromide (CH3CH2CH2MgBr) with tert-butyl chloride ((CH3)3CCl). n-PrMgCl can be used instead of the bromide.


2,2-Dimethylpentane, Properties
In 1929 Graham Edgar and George Calingaert made 2,2-dimethylpentane and measured its physical characteristics for the first time. The measurements were at 20 °C, not the standard conditions used in later times.


2,2-Dimethylpentane, Properties
For 2,2-dimethylpentane they measured a density of 0.6737 at 20 °C with a rate of change Δd/ΔT of 0.000855. The density and boiling are the lowest of the isomers of heptane. The dielectric constant is 1.915, the lowest of the heptane isomers. The critical temperature is 247.7 °C and critical pressure 28.4 atmospheres. The refractive index at 20° is 1.38233, the same as for 2,4-dimethylpentane, equal lowest for the heptane isomers. The adiabatic compressibility is 0.0001289 and isothermal compressibility is 0.00016279 atmospheres, highest for the heptanes. The velocity of sound is 1.080 km/s which is lowest of the heptanes. Coefficient of thermal expansion is 0.001268/°, highest of the heptanes. Surface tension is 17.80 dynes/cm. Viscosity is 0.00385. The heat of combustion is 11470 cal/g which is very similar to other heptanes.


2,2-Dimethylpentane, Reactions
2,2-Dimethylpentane can form a clathrate hydrate with helper gas molecules. The type of clathrate formed is called "clathrate H". 2,2-Dimethylpentane was the first compound for which the structure was determined. The clathrate has 34 molecules of water per molecule, and also has xenon and hydrogen sulfide as helper molecules. The crystals are hexagonal in form and melt at 0.6 °C. This substance is important as clathrate hydrates form problems by blocking natural gas pipelines.


2,2-Dimethylpentane, Reactions
2,2-Dimethylpentane does not react with bromine, iodine, nitric acid or  chlorosulfonic acid because there are no tertiary carbon atoms (a carbon atom with only one hydrogen attached).


2,2-Dimethylpentane, Reactions
Heating alkanes over an aluminium trichloride is used to reform to make different isomers. 2,2-Dimethylpentane does not participate in this process and so cannot be reformed, or created by reforming other heptanes.


2,2-Dimethylpentane, Natural occurrence
2,2-Dimethylpentane exists in some crude oils at low levels of about 0.01%.


2,2-Diphenylpropylamine
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2,2-dialkylglycine decarboxylase (pyruvate)
In enzymology, a 2,2-dialkylglycine decarboxylase (pyruvate) (EC ) is an enzyme that catalyzes the chemical reaction


2,2-dialkylglycine decarboxylase (pyruvate)
Thus, the two substrates of this enzyme are 2,2-dialkylglycine and pyruvate, whereas its 3 products are dialkyl ketone, CO2, and L-alanine.


2,2-dialkylglycine decarboxylase (pyruvate)
This enzyme belongs to the family of lyases, specifically the carboxy-lyases, which cleave carbon-carbon bonds. The systematic name of this enzyme class is 2,2-dialkylglycine carboxy-lyase (amino-transferring L-alanine-forming). Other names in common use include dialkyl amino acid (pyruvate) decarboxylase, alpha-dialkyl amino acid transaminase, 2,2-dialkyl-2-amino acid-pyruvate aminotransferase, L-alanine-alpha-ketobutyrate aminotransferase, dialkylamino-acid decarboxylase (pyruvate), and 2,2-dialkylglycine carboxy-lyase (amino-transferring). It employs one cofactor, pyridoxal phosphate.


2,2-dialkylglycine decarboxylase (pyruvate), Structural studies
As of late 2007, 16 structures have been solved for this class of enzymes, with PDB accession codes , , , , , , , , , , , , , , , and .


2,2′-Bipyridine
2,2′-Bipyridine (bipy or bpy, pronounced /ˈbɪpiː/) is an organic compound with the formula C10H8N2. This colorless solid is an important isomer of the bipyridine family. It is a bidentate chelating ligand, forming complexes with many transition metals. Ruthenium and platinum complexes of bipy exhibit intense luminescence, which may have practical applications.


2,2′-Bipyridine, Preparation, structure, and general properties
It is prepared by the dehydrogenation of pyridine using Raney nickel:


2,2′-Bipyridine, Preparation, structure, and general properties
Although uncoordinated bipyridine is often drawn with its nitrogen atoms in cis conformation, the lowest energy conformation both in solid state and in solution is in fact coplanar, with nitrogen atoms in trans position. Monoprotonated bipyridine adopts a cis conformation.


2,2′-Bipyridine, Preparation, structure, and general properties
Upon complexation, the related N,N-heterocyclic ligand phenanthroline does not incur an enthalpic and entropic penalty, and thus its complexes tend to be more stable. With respective pKa's of 4.86 and 4.3 for their conjugate acids, phenanthroline and bipy are of comparable basicity.


2,2′-Bipyridine, Preparation, structure, and general properties
Reflecting the popularity of this ligand design, many substituted variants of bipy have been described.


2,2′-Bipyridine, Coordination chemistry, Tris-bipy complexes
Bipyridine complexes absorb intensely in the visible part of the spectrum. The electronic transitions are attributed to metal-to-ligand charge transfer (MLCT). In the "tris(bipy) complexes" three bipyridine molecules coordinate to a metal ion, written as [M(bipy)3]n+ (M = metal ion; Cr, Fe, Co, Ru, Rh and so on; bipy = 2,2′-bipyridine). These complexes have six-coordinated, octahedral structures and two enantiomers as follows:


2,2′-Bipyridine, Coordination chemistry, Tris-bipy complexes
These and other homoleptic tris-2,2′-bipy complexes of many transition metals are electroactive. Often, both the metal centred and ligand centred electrochemical reactions are reversible one-electron reactions that can be observed by cyclic voltammetry. Under strongly reducing conditions, most tris(bipy) complexes can be reduced to neutral derivatives containing bipy− ligands. Examples include M(bipy)3, where M = Al, Cr, Si.


2,3,3,3-Tetrafluoropropene
2,3,3,3-Tetrafluoropropene, HFO-1234yf, is a hydrofluoroolefin (HFO) with the formula CH2=CFCF3. It is also designated R-1234yf as the first of a new class of refrigerants: it is marketed under the name Opteon YF by Chemours and as Solstice YF by Honeywell.


2,3,3,3-Tetrafluoropropene
HFO-1234yf has a global warming potential (GWP) of less than 1, compared to 1,430 for R-134a and 1 for carbon dioxide. This colorless gas is being used as a replacement for R-134a as a refrigerant in automobile air conditioners. As of 2018, 50% of new vehicles from "original equipment manufacturers" (OEMs) are estimated to use HFO-1234yf. It does break down into persistent organic pollutant short chain PFCAs.


2,3,3,3-Tetrafluoropropene, Adoption by automotive industry
HFO-1234yf was developed by a team at DuPont, led by Barbara Haviland Minor, which worked jointly with researchers at Honeywell. Their goal was to meet European directive 2006/40/EC, which went into effect in 2011 and required that all new car platforms for sale in Europe use a refrigerant in its AC system with a GWP below 150.


2,3,3,3-Tetrafluoropropene, Adoption by automotive industry
HFO-1234yf was initially considered to have a 100-year GWP of 4, and is now considered to have a 100-year GWP lower than 1. It can be used as a "near drop-in replacement" for R-134a, the product previously used in automobile AC systems, which has a 100-year GWP of 1430. This meant that automakers would not have to make significant modifications in assembly lines or in vehicle system designs to accommodate the product. HFO-1234yf had the lowest switching cost for automakers among the proposed alternatives.


2,3,3,3-Tetrafluoropropene, Adoption by automotive industry
The product can be handled in repair shops in the same way as R-134a, although it requires some different, specialized equipment to perform the service. One of the reasons for that is the mild flammability of HFO-1234yf. Another issue affecting the compatibility between HFO-1234yf and R-134a-based systems is the choice of lubricating oil.


2,3,3,3-Tetrafluoropropene, Adoption by automotive industry
Shortly after confirmation from automakers that HFO-1234yf would be adopted as a replacement of R-134a automotive air-conditioning refrigerant, in 2010, Honeywell and DuPont announced that they would jointly build a manufacturing facility in Changshu, Jiangsu Province, China to produce HFO-1234yf. In 2017, Honeywell opened a new plant in Geismar, Louisiana, USA to produce the new refrigerant as well. Although others claim to be able to make and sell HFO-1234yf, Honeywell and DuPont hold most or all of the patents issued for HFO-1234yf and are considered the leading players in this area as of 2018.


2,3,3,3-Tetrafluoropropene, Adoption by automotive industry, Flammability
Although the product is classified slightly flammable by ASHRAE, several years of testing by SAE International proved that the product could not be ignited under conditions normally experienced by a vehicle. In addition several independent authorities evaluated the safety of the product in vehicles and some of them concluded that it was as safe to use as R-134a, the product then in use in cars. In the atmosphere, HFO-1234yf degrades to trifluoroacetic acid, which is a mildly phytotoxic strong organic acid with no known biodegradation mechanism in water. In case of fire it releases highly corrosive and toxic hydrogen fluoride and the highly toxic gas carbonyl fluoride.


2,3,3,3-Tetrafluoropropene, Adoption by automotive industry, Flammability
In July 2008, Honeywell/Du-Pont published a report claiming "HFO-1234yf is very difficult to ignite with electric spark" detailing the tests they did passing the gas over a hot plate heated to various temperatures in the range of 500–900 °C. Ignition was only seen when HFO-1234yf was mixed with PAG oil and passed over a plate that was >900 °C.


2,3,3,3-Tetrafluoropropene, Adoption by automotive industry, Flammability
In August 2012, Mercedes-Benz showed that the substance ignited when researchers sprayed it and A/C compressor oil onto a car's hot engine. A senior Daimler engineer who ran the tests, stated "We were frozen in shock, I am not going to deny it. We needed a day to comprehend what we had just seen." Combustion occurred in more than two thirds of their simulated head-on collisions. The engineers also noticed etching on the windshield caused by the corrosive gases. On September 25, 2012, Daimler issued a press release and proposed a recall of cars using the refrigerant. The German automakers argued for development of carbon dioxide refrigerants, which they argued would be safer.


2,3,3,3-Tetrafluoropropene, Adoption by automotive industry, Flammability
In October 2012, SAE International established a new Cooperative Research Project, CRP1234-4, which included members of 13 automotive companies, to extend its previous testing and investigate Daimler's claims. A preliminary update as of December 2012 and a final report publicly released on July 24, 2013 agreed that R-1234yf was safe to use in automotive direct-expansion air conditioning systems. R-1234yf was believed not to increase the estimated risk of vehicle fire exposure. The report further stated that "the refrigerant release testing completed by Daimler was unrealistic" and "created extreme conditions that favored ignition". The final report was supported by Chrysler/Fiat, Ford, General Motors, Honda, Hyundai, Jaguar Land Rover, Mazda, PSA, Renault and Toyota. Daimler, BMW and Audi chose to withdraw from the SAE R-1234yf CRP Team.


2,3,3,3-Tetrafluoropropene, Adoption by automotive industry, Flammability
Following Mercedes' claims that the new refrigerant could be ignited, Germany's Kraftfahrt-Bundesamt (KBA, Federal Motor Transport Authority) conducted its own tests. They submitted a report to the European Union in August 2013. The Authority concluded that while R-1234yf was potentially more hazardous than previously used R-134a, it did not comprise a serious danger. Daimler disagreed with this conclusion and argued that the report supported their decision to continue to use older refrigerants.


2,3,3,3-Tetrafluoropropene, Adoption by automotive industry, Flammability
On July 23, 2010, General Motors announced that it would introduce HFO-1234yf in 2013 Chevrolet, Buick, GMC, and Cadillac models in the U.S.Cadillac became the first American car to use R-1234yf in 2012.


2,3,3,3-Tetrafluoropropene, Adoption by automotive industry, Flammability
Since then, Chrysler,GMC and Ford have all begun transitioning vehicles to R1234yf. Japanese automakers are also making the transition to R1234yf. Honda and Subaru began to introduce the new refrigerant with the 2017 models. From 2017 to 2018, BMW changed all of its models to R-1234yf. As of 2018, 50% of new vehicles from original equipment manufacturers (OEMs) are estimated to use R-1234yf.


2,3,3,3-Tetrafluoropropene, Adoption by automotive industry, Flammability
"The flammability issue has attracted a lot of attention, prompting the industry to conduct some serious third-party testing. The bottom line is this: The refrigerant will burn, but it takes a lot of heat to ignite it and it burns slowly. Almost every other fluid under the hood will light more easily and burn hotter than R1234yf, so the industry has determined that with proper A/C system design, it does not increase the chances of fire in the vehicle."


2,3,3,3-Tetrafluoropropene, Adoption by automotive industry, Flammability
Mixing HFO-1234yf with 10–11% R-134A is in development to produce a hybrid gas under review by ASHRAE for classification as A2L which is described as "virtually non-flammable". These gases are under review with the names of R451A and R451B. These mixes have GWP of ~147.


2,3,3,3-Tetrafluoropropene, Adoption by automotive industry, Flammability
Other additives have been proposed for lowering the flammability of HFO-1234yf, such as trifluoroiodomethane, which has a low GWP due to its short atmospheric lifetime, but is slightly mutagenic.


2,3,3,3-Tetrafluoropropene, Production
Typical methods for producing HFO-1234yf start with 1,2,3,3,3-pentafluoropropene. Hydrogenation of this alkene gives 1,2,3,3,3-pentafluoropropane, which upon heating with an Al-based catalyst undergoes dehydrofluorination:


2,3,3-Trimethylpentane
2,3,3-Trimethylpentane is a chemical compound in the family of hydrocarbons which has a formula of C8H18. It is an isomer of octane.


2,3,4,5-Tetrahydro-1,5-methano-1H-3-benzazepine
2,3,4,5-Tetrahydro-1,5-methano-1H-3-benzazepine is a drug originally researched as a potential opioid analgesic, but was found to be inactive in this assay, and relatively toxic to mice. Subsequently it was found to possess activity as an agonist at nicotinic acetylcholine receptors during the course of work that ultimately led to the discovery of the anti-smoking drug varenicline.


2,3,4,5-Tetrahydro-1,5-methano-1H-3-benzazepine
More recently this chemical compound is claimed to have been sold as a designer drug under the name A3A, but since the anecdotally reported effects of the product sold under this name do not seem to bear any resemblance to the known pharmacology of genuine 2,3,4,5-tetrahydro-1,5-methano-1H-3-benzazepine, it seems unlikely that this is actually the compound being sold.


2,3,4,5-Tetramethoxyamphetamine
Tetramethoxyamphetamine, or 2,3,4,5-tetramethoxyamphetamine, is a lesser-known psychedelic drug and a substituted amphetamine. Tetramethoxyamphetamine was first synthesized by Alexander Shulgin. In his book PiHKAL (Phenethylamines i Have Known And Loved), the minimum dosage is listed as 50 mg, and the duration unknown. Tetramethoxyamphetamine produces a threshold, mydriasis, and a headache. Limited data exists about its pharmacological properties, metabolism, and toxicity.


2,3,4,5-tetrahydropyridine-2,6-dicarboxylate N-succinyltransferase
In enzymology, a 2,3,4,5-tetrahydropyridine-2,6-dicarboxylate N-succinyltransferase (EC ) is an enzyme that catalyzes the chemical reaction


2,3,4,5-tetrahydropyridine-2,6-dicarboxylate N-succinyltransferase
The 3 substrates of this enzyme are succinyl-CoA, (S)-2,3,4,5-tetrahydropyridine-2,6-dicarboxylate, and H2O, whereas its two products are CoA and N-succinyl-L-2-amino-6-oxoheptanedioate.


2,3,4,5-tetrahydropyridine-2,6-dicarboxylate N-succinyltransferase
This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is succinyl-CoA:(S)-2,3,4,5-tetrahydropyridine-2,6-dicarboxylate N-succinyltransferase. Other names in common use include tetrahydropicolinate succinylase, tetrahydrodipicolinate N-succinyltransferase, tetrahydrodipicolinate succinyltransferase, succinyl-CoA:tetrahydrodipicolinate N-succinyltransferase, succinyl-CoA:2,3,4,5-tetrahydropyridine-2,6-dicarboxylate, and N-succinyltransferase. This enzyme participates in lysine biosynthesis.


2,3,4,5-tetrahydropyridine-2,6-dicarboxylate N-succinyltransferase, Structural studies
As of late 2007, 4 structures have been solved for this class of enzymes, with PDB accession codes , , , and .


2,3,4-Pentanetrione
2,3,4-Pentanetrione (or IUPAC name pentane-2,3,4-trione, triketopentane or dimethyl triketone) is the simplest linear triketone, a ketone with three C=O groups. It is an organic molecule with formula CH3COCOCOCH3.


2,3,4-Pentanetrione, Production
2,3,4-Pentanetrione can be made by oxidizing 2,4-pentanedione with selenium dioxide. Ludwig Wolff made the 2,3 oxime by reacting hydroxylamine with isonitrosoacetylacetone in cold, aqueous, concentrated solution.


2,3,4-Pentanetrione, Production
Yet other ways to make triones start from a β-dione, and oxidise the carbon at the α position, between the two ketone groups. Different methods include reaction with bromine to make a dibromide, and then reacting with acetaldehyde and hydrolysing. Nitrogen oxides can also be used. Another way is by reacting 2,4-pentandedione with p-nitroso-N,N-dimethylaniline; forming an α-diazo-β-dicarbonyl derivative compound, and then reacting that with triphenylphosphine, and then hydrolyzing with sodium nitrite solution. Or the α-diazo-β-dicarbonyl derivative can be treated with tert-butylhypochlorite.


2,3,4-Pentanetrione, Properties
2,3,4-Pentanetrione appears as an orangy-red oil. The more intense colour is due to the greater conjugation of double bonds, and potential resonance. The type of colour centre is called a dependent chromophore, as when there are fewer C=O groups the colour is less intense or absent. So diacetyl with two carbonyls groups is yellow, and acetone with one has no colour.


2,3,4-Pentanetrione, Properties
At a reduced pressure of 20 mmHg it boils at 60 °C. It is hygroscopic.


2,3,4-Pentanetrione, Reactions
On absorbing water, perhaps from the atmosphere, 2,3,4-pentanetrione forms a hydrate. The hydrate melts at 52 °C. The hydrate with formula CH3COC(OH)2COCH3 is colourless.


2,3,4-Pentanetrione, Reactions
2,3,4-Pentanetrione is a strong reducing agent. Thermal decomposition catalyzed by copper sulfate results in carbon dioxide and biacetal.


2,3,4-Pentanetrione, Reactions
2,3,4-Pentanetrione reacts with hydrogen peroxide to yield acetic acid and carbon monoxide. Adding HOOH between C2 and C4 yields a cyclic intermediate which decomposes.


2,3,4-Pentanetrione, Reactions
With light or organic peroxides, a free radical reaction can take place (as with triketones), whereby the molecule is slit into CH3COCO• and CH3CO• fragments. These can combine with intact molecules or each other to form other ketones.


2,3,4-Pentanetrione, Reactions
When heating 2,3,4-pentanetrione with oxygen, the oxidation products are diacetyl, acetic acid, water and carbon dioxide.


2,3,4-Pentanetrione, Reactions
2,3,4-Pentanetrione does a condensation reaction with o-phenylenediamine to yield methyl-quinoxaline-2-methylketone, a heterocyclic dicycle. In this the carbon number 2 and 3 react with the amine groups, leaving the CO on number 5 alone.


2,3,4-Pentanetrione, Reactions
Grignard agents react. Phenyl magnesium bromide in excess reacting with 2,3,4-pentanetrione gives phenylacetylcarbinol and also methyldyphenylcarbinol.


2,3,4-Pentanetrione, Derivatives
Derivatives include 2,3,4-pentanetrione-3-oxime, 2,3,4-pentanetrione-3-(O-methyloxime), 2,3,4-pentanetrione-2-oxime, 2,3,4-pentanetrione-2,3-dioxime, 2,3,4-pentanetrionetrioxime, 2,3,4-pentanetrione semicarbazone, 2,3,4-pentanetrione phenylhydrazone, 2,3,4-pentanetrione bis(phenylhydazone).


2,3,4-Pentanetrione, Derivatives
The 3-oxime melts at 75 °C and the bis(semicarbazone) has a melting point of 221 °C.


2,3,4-Trimethylpentane
2,3,4-Trimethylpentane is a branched alkane. It is one of the isomers of octane.


2,3,5,6,8-Pentahydroxy-1,4-naphthalenedione
2,3,5,6,8-Pentahydroxy-1,4-naphthalenedione, also called 2,3,5,6,8-pentahydroxy-1,4-naphthoquinone or spinochrome D, is an organic compound with formula C10H6O5, formally derived from 1,4-naphthoquinone through the replacement of five hydrogen atoms by hydroxyl (OH) groups.


2,3,5,6,8-Pentahydroxy-1,4-naphthalenedione
Spinochrome D occurs naturally as a brownish red pigment in the shell and spines of sea urchins such as the Japanese aka-uni (Pseudocentrotus depressus). It is soluble in diethyl ether and crystallizes as brownish red needles that sublime at 285−295 °C.


2,3,5,6,8-Pentahydroxy-1,4-naphthalenedione
The compound gives a yellowish brown solution when treated with sodium hydroxide, a bluish green solution with ferric chloride, and a violet precipitate with lead acetate. It forms a five-fold acetate ester, C10HO2(CH3COO)5, that crystallizes from methanol as yellow needles that melt at 185−186 °C.


2,3,5,7-Tetrahydroxy-1,4-naphthalenedione
2,3,5,7-Tetraahydroxy-1,4-naphthalenedione, also called 2,3,5,7-tetrahydroxynaphthoquinone or spinochrome B, is an organic compound with formula C10H6O4, formally derived from 1,4-naphthoquinone through the replacement of four hydrogen atoms by hydroxyl (OH) groups.


2,3,5,7-Tetrahydroxy-1,4-naphthalenedione
Spinochrome B occurs naturally as pigment in the shell and spines of sea urchins such as the Japanese dull red species aka-uni (Pseudocentrotus depressus), the greenish-black murasaki-uni (Heliocidaris crassispina), and the brown bafun-uni (Strongylocentrotus pulcherrimus). It is soluble in methanol and crystallizes as bright red needles that sublime above 200 °C.


2,3,5,7-Tetrahydroxy-1,4-naphthalenedione
The compound gives a greenish yellow solution when treated with sodium hydroxide, a green solution with ferric chloride, and a green precipitate with lead acetate. It forms a fourfold acetate ester, C10H2O2(CH3COO)4, that crystallizes from methanol as yellow needles that melt at 157 °C.


2,3,7,8-Tetrachlorodibenzodioxin
2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a polychlorinated dibenzo-p-dioxin (sometimes shortened, though inaccurately, to simply 'dioxin') with the chemical formula C12H4Cl4O2. Pure TCDD is a colorless solid with no distinguishable odor at room temperature. It is usually formed as an unwanted product in burning processes of organic materials or as a side product in organic synthesis.


2,3,7,8-Tetrachlorodibenzodioxin
TCDD is the most potent compound (congener) of its series (polychlorinated dibenzodioxins, known as PCDDs or simply dioxins) and became known as a contaminant in Agent Orange, a herbicide used in the Vietnam War. TCDD was released into the environment in the Seveso disaster. It is a persistent organic pollutant.


2,3,7,8-Tetrachlorodibenzodioxin, Mechanism of action
TCDD and dioxin-like compounds act via a specific receptor present in all cells: the aryl hydrocarbon (AH) receptor. This receptor is a transcription factor which is involved in the expression of genes; it has been shown that high doses of TCDD either increase or decrease the expression of several hundred genes in rats. Genes of enzymes activating the breakdown of foreign and often toxic compounds are classic examples of such genes (enzyme induction). TCDD increases the enzymes breaking down, e.g., carcinogenic polycyclic hydrocarbons such as benzo(a)pyrene.


2,3,7,8-Tetrachlorodibenzodioxin, Mechanism of action
These polycyclic hydrocarbons also activate the AH receptor, but less than TCDD and only temporarily. Even many natural compounds present in vegetables cause some activation of the AH receptor. This phenomenon can be viewed as adaptive and beneficial, because it protects the organism from toxic and carcinogenic substances. Excessive and persistent stimulation of AH receptor, however, leads to a multitude of adverse effects.


2,3,7,8-Tetrachlorodibenzodioxin, Mechanism of action
The physiological function of the AH receptor has been the subject of continuous research. One obvious function is to increase the activity of enzymes breaking down foreign chemicals or normal chemicals of the body as needed. There seem to be many other functions, however, related to the development of various organs and the immune systems or other regulatory functions. The AH receptor is phylogenetically highly conserved transcription factor with a history of at least 600 million years and is found in all vertebrates. Its ancient analogs are important regulatory proteins even in more primitive species. In fact, knock-out animals with no AH receptor are prone to illness and developmental problems. Taken together, this implies the necessity of a basal degree of AH receptor activation to achieve normal physiological function.