formaldehyde formaldehyde formaldehyde (/fɔːrˈmældɪhaɪd/ (listen) for-mal-di-hide, us also /fər-/ (listen) fər-) (systematic name methanal) is a naturally occurring organic compound with the formula ch2o and structure h−cho. the pure compound is a pungent, colourless gas that polymerises spontaneously into paraformaldehyde (refer to section forms below), hence it is stored as an aqueous solution (formalin), which is also used to store animal specimens. it is the simplest of the aldehydes (r−cho) and one of the simplest of the carbohydrates. the common name of this substance comes from its similarity and relation to formic acid. "methanal" redirects here. not to be confused with methanol or menthol. formaldehyde structural formula of formaldehyde (with hydrogens) spacefill model of formaldehyde names preferred iupac name formaldehyde systematic iupac name methanal other names methyl aldehydemethylene glycol (diol forms in aqueous solution)methylene oxideformalin (aqueous solution)formolcarbonyl hydridemethanoneoxomethane identifiers cas number 50-00-0 y 3d model (jsmol) interactive image 3dmet b00018 beilstein reference 1209228 chebi chebi:16842 y chembl chembl1255 y chemspider 692 y drugbank db03843 y echa infocard 100.000.002 ec number 200-001-8 e number e240 (preservatives) gmelin reference 445 iuphar/bps 4196 kegg d00017 y mesh formaldehyde pubchem cid 712 rtecs number lp8925000 unii 1hg84l3525 y un number 2209 comptox dashboard (epa) dtxsid7020637 inchi inchi=1s/ch2o/c1-2/h1h2 ykey: wsfssnumvmoomr-uhfffaoysa-n yinchi=1/ch2o/c1-2/h1h2key: wsfssnumvmoomr-uhfffaoyat smiles c=o properties chemical formula ch2o molar mass 30.026 g·mol−1 appearance colorless gas density 0.8153 g/cm3 (−20 °c) (liquid) melting point −92 °c (−134 °f; 181 k) boiling point −19 °c (−2 °f; 254 k) solubility in water 400 g/l log p 0.350 vapor pressure > 1 atm acidity (pka) 13.27 (hydrate) magnetic susceptibility (χ) −18.6·10−6 cm3/mol dipole moment 2.330 d structure point group c2v molecular shape trigonal planar thermochemistry heat capacity (c) 35.387 j·mol−1·k−1 std molarentropy (s⦵298) 218.760 j·mol−1·k−1 std enthalpy offormation (δfh⦵298) −108.700 kj·mol−1 gibbs free energy (δfg⦵) −102.667 kj·mol−1 std enthalpy ofcombustion (δch⦵298) 571 kj·mol−1 pharmacology atcvet code qp53ax19 (who) hazards ghs labelling: pictograms signal word danger hazard statements h301, h311, h314, h317, h331, h335, h341, h350, h370 precautionary statements p201, p280, p303+p361+p353, p304+p340+p310, p305+p351+p338, p308+p310 nfpa 704 (fire diamond) 3 4 0cor flash point 64 °c (147 °f; 337 k) autoignitiontemperature 430 °c (806 °f; 703 k) explosive limits 7–73% lethal dose or concentration (ld, lc): ld50 (median dose) 100 mg/kg (oral, rat) lc50 (median concentration) 333 ppm (mouse, 2 h)815 ppm (rat, 30 min) lclo (lowest published) 333 ppm (cat, 2 h) niosh (us health exposure limits): pel (permissible) twa 0.75 ppm st 2 ppm (as formaldehyde and formalin) rel (recommended) ca twa 0.016 ppm c 0.1 ppm idlh (immediate danger) ca safety data sheet (sds) msds(archived) related compounds related aldehydes acetaldehyde butyraldehyde decanal heptanal hexanal nonanal octadecanal octanal pentanal propionaldehyde related compounds methanolformic acid except where otherwise noted, data are given for materials in their standard state (at 25 °c , 100 kpa). y verify (what is yn ?) infobox references formaldehyde is an important precursor to many other materials and chemical compounds. in 2006, the global production rate of formaldehyde was estimated at 12 million tons per year. it is mainly used in the production of industrial resins, e.g., for particle board and coatings. forms formaldehyde is more complicated than many simple carbon compounds in that it adopts several diverse forms. these compounds can often be used interchangeably and can be interconverted. molecular formaldehyde. a colorless gas with a characteristic pungent, irritating odor. it is stable at about 150 °c, but polymerizes when condensed to a liquid. 1,3,5-trioxane, with the formula (ch2o)3. it is a white solid that dissolves without degradation in organic solvents. it is a trimer of molecular formaldehyde. paraformaldehyde, with the formula ho(ch2o)nh. it is a white solid that is insoluble in most solvents. methanediol, with the formula ch2(oh)2. this compound also exists in equilibrium with various oligomers (short polymers), depending on the concentration and temperature. a saturated water solution, of about 40% formaldehyde by volume or 37% by mass, is called "100% formalin". a small amount of stabilizer, such as methanol, is usually added to suppress oxidation and polymerization. a typical commercial-grade formalin may contain 10–12% methanol in addition to various metallic impurities. "formaldehyde" was first used as a generic trademark in 1893 following a previous trade name, "formalin". main forms of formaldehyde monomeric formaldehyde (subject of this article). trioxane is a stable cyclic trimer of formaldehyde. paraformaldehyde is a common form of formaldehyde for industrial applications. methanediol, the predominant species in dilute aqueous solutions of formaldehyde. structure and bonding molecular formaldehyde contains a central carbon atom with a double bond to the oxygen atom and a single bond to each hydrogen atom. this structure is summarised by the condensed formula h2c=o. the molecule is planar, y-shaped and its molecular symmetry belongs to the c2v point group. the precise molecular geometry of gaseous formaldehyde has been determined by gas electron diffraction and microwave spectroscopy. the bond lengths are 1.21 å for the carbon–oxygen bond and around 1.11 å for the carbon–hydrogen bond, while the h–c–h bond angle is 117°, close to the 120° angle found in an ideal trigonal planar molecule. some excited electronic states of formaldehyde are pyramidal rather than planar as in the ground state. occurrence processes in the upper atmosphere contribute up to 90% of the total formaldehyde in the environment. formaldehyde is an intermediate in the oxidation (or combustion) of methane, as well as of other carbon compounds, e.g. in forest fires, automobile exhaust, and tobacco smoke. when produced in the atmosphere by the action of sunlight and oxygen on atmospheric methane and other hydrocarbons, it becomes part of smog. formaldehyde has also been detected in outer space. formaldehyde and its adducts are ubiquitous in living organisms because it is produced naturally. food may contain formaldehyde at level 1-100 mg/kg. formaldehyde, formed in the metabolism of the amino acids serine and threonine, is found in the bloodstream of humans and other primates at concentrations of approximately 0.1 millimolar. experiments in which animals are exposed to an atmosphere containing isotopically labeled formaldehyde have demonstrated that even in deliberately exposed animals, the majority of formaldehyde-dna adducts found in non-respiratory tissues are derived from endogenously produced formaldehyde. formaldehyde does not accumulate in the environment, because it is broken down within a few hours by sunlight or by bacteria present in soil or water. humans metabolize formaldehyde quickly, converting it to formic acid, so it does not accumulate. it nonetheless presents significant health concerns, as a contaminant. interstellar formaldehyde formaldehyde appears to be a useful probe in astrochemistry due to prominence of the 110←111 and 211←212 k-doublet transitions. it was the first polyatomic organic molecule detected in the interstellar medium. since its initial detection in 1969, it has been observed in many regions of the galaxy. because of the widespread interest in interstellar formaldehyde, it has been extensively studied, yielding new extragalactic sources. a proposed mechanism for the formation is the hydrogenation of co ice: h + co → hco hco + h → ch2o hcn, hnc, h2co, and dust have also been observed inside the comae of comets c/2012 f6 (lemmon) and c/2012 s1 (ison). synthesis and industrial production laboratory synthesis formaldehyde was first reported in 1859 by the russian chemist aleksandr butlerov (1828–86) in his paper, butlerov referred to formaldehyde as "dioxymethylen" (methylene dioxide) because his empirical formula for it was incorrect (c4h4o4). it was conclusively identified by august wilhelm von hofmann, who first announced the production of formaldehyde by passing methanol vapor in air over hot platinum wire. with modifications, hoffmann's method remains the basis of the present day industrial route. solution routes to formaldehyde also entail oxidation of methanol or methyl iodide. industry formaldehyde is produced industrially by the catalytic oxidation of methanol. the most common catalysts are silver metal, iron(iii) oxide, iron molybdenum oxides with a molybdenum-enriched surface, or vanadium oxides. in the commonly used formox process, methanol and oxygen react at ca. 250–400 °c in presence of iron oxide in combination with molybdenum and/or vanadium to produce formaldehyde according to the chemical equation: 2 ch3oh + o2 → 2 ch2o + 2 h2o the silver-based catalyst usually operates at a higher temperature, about 650 °c. two chemical reactions on it simultaneously produce formaldehyde: that shown above and the dehydrogenation reaction: ch3oh → ch2o + h2 in principle, formaldehyde could be generated by oxidation of methane, but this route is not industrially viable because the methanol is more easily oxidized than methane. in nature the amino acid serine is a source of natural formaldehyde according to this reaction, which produces glycine: hoch2ch(nh2)co2h → ch2o +h2c(nh2)co2h this reaction is catalyzed by serine hydroxymethyltransferase, a plp-containing enzyme. formaldehyde can also be produced by methylotrophic microbes from methanol through the reaction: ch3oh → ch2o + 2e- + 2h+ this reaction is catalyzed by the enzyme methanol dehydrogenase. organic chemistry formaldehyde is a building block in the synthesis of many other compounds of specialised and industrial significance. it exhibits most of the chemical properties of other aldehydes but is more reactive. polymerization and hydration pure gaseous formaldehyde polymerizes on the active sites of the vessel walls, but the mechanism of the reaction is unknown. small amounts of hydrogen chloride (or boron trifluoride, or stannic chloride) presented in gaseous formaldehyde provide the catalytic effect and make the polymerization rapid. monomeric ch2o is a gas and is rarely encountered in the laboratory. formaldehyde in aqueous solutions, unlike some other small aldehydes (which need specific conditions to oligomerize through aldol condensation) oligomerizes spontaneously at common state. the trimer is 1,3,5-trioxane ((ch2o)3) is typical oligomer. many cyclic oligomers of other sizes have been isolated. similarly, formaldehyde hydrates to give the geminal diol methanediol, which condenses further to form hydroxy-terminated oligomers ho(ch2o)nh. the polymer is called paraformaldehyde. the higher concentration of formaldehyde — the more equillibrium shifts towards polymerization. diluting with water or increasing the solution temperature, as well as adding alcohols (such as methanol or ethanol) lowers that tendency. oxidation and reduction it is readily oxidized by atmospheric oxygen into formic acid. for this reason, commercial formaldehyde is typically contaminated with formic acid. formaldehyde can be hydrogenated to methanol. hydroxymethylation and chloromethylation formaldehyde reacts with many compounds, resulting in hydroxymethylation: x-h + ch2o → x-ch2oh (x = r2n, rc(o)nr', sh). the resulting hydroxymethyl derivatives typically react further. thus, amines give hexahydro-1,3,5-triazines: 3 rnh2 + 3 ch2o → (rnch2)3 + 3 h2o similarly, when combined with hydrogen sulfide, it forms trithiane: 3 ch2o + 3 h2s → (ch2s)3 + 3 h2o in the presence of acids, it participates in electrophilic aromatic substitution reactions with aromatic compounds resulting in hydroxymethylated derivatives: arh + ch2o → arch2oh when conducted in the presence of hydrogen chloride, the product is the chloromethyl compound, as described in the blanc chloromethylation. if the arene is electron-rich, as in phenols, elaborate condensations ensue. with 4-substituted phenols one obtains calixarenes. phenol results in polymers. base reactions cannizzaro reaction in the presence of basic catalysts to produce formic acid and methanol. uses industrial applications formaldehyde is a common precursor to more complex compounds and materials. in approximate order of decreasing consumption, products generated from formaldehyde include urea formaldehyde resin, melamine resin, phenol formaldehyde resin, polyoxymethylene plastics, 1,4-butanediol, and methylene diphenyl diisocyanate. the textile industry uses formaldehyde-based resins as finishers to make fabrics crease-resistant. two steps in formation of urea-formaldehyde resin, which is widely used in the production of particle board. when treated with phenol, urea, or melamine, formaldehyde produces, respectively, hard thermoset phenol formaldehyde resin, urea formaldehyde resin, and melamine resin. these polymers are permanent adhesives used in plywood and carpeting. they are also foamed to make insulation, or cast into moulded products. production of formaldehyde resins accounts for more than half of formaldehyde consumption. formaldehyde is also a precursor to polyfunctional alcohols such as pentaerythritol, which is used to make paints and explosives. other formaldehyde derivatives include methylene diphenyl diisocyanate, an important component in polyurethane paints and foams, and hexamine, which is used in phenol-formaldehyde resins as well as the explosive rdx. condensation with acetaldehyde affords pentaerythritol, a chemical necessary in synthesizing petn, a high explosive. condensation with phenols gives phenol-formaldehyde resins. disinfectant and biocide an aqueous solution of formaldehyde can be useful as a disinfectant as it kills most bacteria and fungi (including their spores). it is used as an additive in vaccine manufacturing to inactivate toxins and pathogens. formaldehyde releasers