hydrazine hydrazine hydrazine skeletal formula of hydrazine with all explicit hydrogens added spacefill model of hydrazine stereo, skeletal formula of hydrazine with all explicit hydrogens added ball and stick model of hydrazine hydrazine hydrate names iupac name hydrazine systematic iupac name diazane other names diaminetetrahydridodinitrogen(n-n)diamidogen identifiers cas number 302-01-2 y 3d model (jsmol) interactive image 3dmet b00770 beilstein reference 878137 chebi chebi:15571 y chembl chembl1237174 n chemspider 8960 y echa infocard 100.005.560 ec number 206-114-9 gmelin reference 190 kegg c05361 y mesh hydrazine pubchem cid 9321 rtecs number mu7175000 unii 27rfh0gb4r y un number 2029 comptox dashboard (epa) dtxsid3020702 inchi inchi=1s/h4n2/c1-2/h1-2h2 ykey: oakjqqaxsvqmhs-uhfffaoysa-n yinchi=1/h4n2/c1-2/h1-2h2key: oakjqqaxsvqmhs-uhfffaoyaz smiles nn properties chemical formula n2h4 molar mass 32.0452 g/mol appearance colorless, fuming, oily liquid odor ammonia-like density 1.021 g/cm3 melting point 2 °c; 35 °f; 275 k boiling point 114 °c; 237 °f; 387 k solubility in water miscible log p 0.67 vapor pressure 1 kpa (at 30.7 °c) acidity (pka) 8.10 (+) basicity (pkb) 5.90 conjugate acid hydrazinium refractive index (nd) 1.46044 (at 22 °c) viscosity 0.876 cp structure molecular shape triangular pyramidal at n dipole moment 1.85 d thermochemistry std molarentropy (s⦵298) 121.52 j/(k·mol) std enthalpy offormation (δfh⦵298) 50.63 kj/mol hazards ghs labelling: pictograms signal word danger hazard statements h226, h301, h311, h314, h317, h331, h350, h410 precautionary statements p201, p261, p273, p280, p301+p310, p305+p351+p338 nfpa 704 (fire diamond) 4 2 3 flash point 52 °c (126 °f; 325 k) autoignitiontemperature 24 to 270 °c (75 to 518 °f; 297 to 543 k) explosive limits 1.8–99.99% lethal dose or concentration (ld, lc): ld50 (median dose) 59–60 mg/kg (oral in rats, mice) lc50 (median concentration) 260 ppm (rat, 4 hr)630 ppm (rat, 1 hr)570 ppm (rat, 4 hr)252 ppm (mouse, 4 hr) niosh (us health exposure limits): pel (permissible) twa 1 ppm (1.3 mg/m3) rel (recommended) ca c 0.03 ppm (0.04 mg/m3) idlh (immediate danger) ca safety data sheet (sds) icsc 0281 related compounds other anions tetrafluorohydrazinehydrogen peroxidediphosphanediphosphorus tetraiodide other cations organic hydrazines related binary azanes ammoniatriazane related compounds diazenetriazenetetrazenediphosphene except where otherwise noted, data are given for materials in their standard state (at 25 °c , 100 kpa). n verify (what is yn ?) infobox references for the class of antidepressants, see hydrazine (antidepressant). not to be confused with hydralazine or hydroxyzine. hydrazine is an inorganic compound with the chemical formula n2h4. it is a simple pnictogen hydride, and is a colourless flammable liquid with an ammonia-like odour. hydrazine is highly toxic unless handled in solution as, for example, hydrazine hydrate (n2h4·xh2o). hydrazine is mainly used as a foaming agent in preparing polymer foams, but applications also include its uses as a precursor to polymerization catalysts, pharmaceuticals, and agrochemicals, as well as a long-term storable propellant for in-space spacecraft propulsion. additionally, hydrazine is used in various rocket fuels and to prepare the gas precursors used in air bags. hydrazine is used within both nuclear and conventional electrical power plant steam cycles as an oxygen scavenger to control concentrations of dissolved oxygen in an effort to reduce corrosion. as of 2000, approximately 120,000 tons of hydrazine hydrate (corresponding to a 64% solution of hydrazine in water by weight) were manufactured worldwide per year. hydrazines refer to a class of organic substances derived by replacing one or more hydrogen atoms in hydrazine by an organic group. etymology the nomenclature is a bi-valent form, with prefix hydr- used to indicate the presence of hydrogen atoms and suffix beginning with -az-, from azote, the french word for nitrogen. applications gas producers and propellants the largest use of hydrazine is as a precursor to blowing agents. specific compounds include azodicarbonamide and azobisisobutyronitrile, which produce 100–200 ml of gas per gram of precursor. in a related application, sodium azide, the gas-forming agent in air bags, is produced from hydrazine by reaction with sodium nitrite. hydrazine is also used as a long-term storable propellant on board space vehicles, such as the dawn mission to ceres and vesta, and to both reduce the concentration of dissolved oxygen in and control ph of water used in large industrial boilers. the f-16 fighter jet, eurofighter typhoon, space shuttle, and u-2 spy plane use hydrazine to fuel their emergency start system in the event of an engine stall. precursor to pesticides and pharmaceuticals fluconazole, synthesized using hydrazine, is an antifungal medication. hydrazine is a precursor to several pharmaceuticals and pesticides. often these applications involve conversion of hydrazine to heterocyclic rings such as pyrazoles and pyridazines. examples of commercialized bioactive hydrazine derivatives include cefazolin, rizatriptan, anastrozole, fluconazole, metazachlor, metamitron, metribuzin, paclobutrazol, diclobutrazole, propiconazole, hydrazine sulfate, diimide, triadimefon, and dibenzoylhydrazine. hydrazine compounds can be effective as active ingredients in insecticides, miticides, nematicides, fungicides, antiviral agents, attractants, herbicides, or plant growth regulators. small-scale, niche, and research the italian catalyst manufacturer acta (chemical company) has proposed using hydrazine as an alternative to hydrogen in fuel cells. the chief benefit of using hydrazine is that it can produce over 200 mw/cm2 more than a similar hydrogen cell without requiring (expensive) platinum catalysts. because the fuel is liquid at room temperature, it can be handled and stored more easily than hydrogen. by storing the hydrazine in a tank full of a double-bonded carbon-oxygen carbonyl, the fuel reacts and forms a safe solid called hydrazone. by then flushing the tank with warm water, the liquid hydrazine hydrate is released. hydrazine has a higher electromotive force of 1.56 v compared to 1.23 v for hydrogen. hydrazine breaks down in the cell to form nitrogen and hydrogen which bonds with oxygen, releasing water. hydrazine was used in fuel cells manufactured by allis-chalmers corp., including some that provided electric power in space satellites in the 1960s. a mixture of 63% hydrazine, 32% hydrazine nitrate and 5% water is a standard propellant for experimental bulk-loaded liquid propellant artillery. the propellant mixture above is one of the most predictable and stable, with a flat pressure profile during firing. misfires are usually caused by inadequate ignition. the movement of the shell after a mis-ignition causes a large bubble with a larger ignition surface area, and the greater rate of gas production causes very high pressure, sometimes including catastrophic tube failures (i.e. explosions). from january–june 1991, the u.s. army research laboratory conducted a review of early bulk-loaded liquid propellant gun programs for possible relevance to the electrothermal chemical propulsion program. the united states air force (usaf) regularly uses h-70, a 70% hydrazine 30% water mixture, in operations employing the general dynamics f-16 “fighting falcon” fighter aircraft and the lockheed u-2 “dragon lady” reconnaissance aircraft. the single jet engine f-16 utilizes hydrazine to power its emergency power unit (epu), which provides emergency electrical and hydraulic power in the event of an engine flame out. the epu activates automatically, or manually by pilot control, in the event of loss of hydraulic pressure or electrical power in order to provide emergency flight controls. the single jet engine u-2 utilizes hydrazine to power its emergency starting system (ess), which provides a highly reliable method to restart the engine in flight in the event of a stall. rocket fuel anhydrous (pure, not in solution) hydrazine being loaded into the messenger space probe. the technician is wearing a safety suit. hydrazine was first used as a component in rocket fuels during world war ii. a 30% mix by weight with 57% methanol (named m-stoff in the german luftwaffe) and 13% water was called c-stoff by the germans. the mixture was used to power the messerschmitt me 163b rocket-powered fighter plane, in which the german high test peroxide t-stoff was used as an oxidizer. unmixed hydrazine was referred to as b-stoff by the germans, a designation also used later for the ethanol/water fuel for the v-2 missile. hydrazine is used as a low-power monopropellant for the maneuvering thrusters of spacecraft, and was used to power the space shuttle's auxiliary power units (apus). in addition, mono-propellant hydrazine-fueled rocket engines are often used in terminal descent of spacecraft. such engines were used on the viking program landers in the 1970s as well as the mars landers phoenix (may 2008), curiosity (august 2012), and perseverance (february 2021). a mixture of hydrazine and red fuming nitric acid was used in the soviet space program where it was known as devil's venom due to its dangerous nature. in all hydrazine mono-propellant engines, the hydrazine is passed over a catalyst such as iridium metal supported by high-surface-area alumina (aluminium oxide), which causes it to decompose into ammonia, nitrogen gas, and hydrogen gas according to the following reactions: n2h4 → n2 + 2 h2 3 n2h4 → 4 nh3 + n2 4 nh3 + n2h4 → 3 n2 + 8 h2 the first two reactions are extremely exothermic (the catalyst chamber can reach 800 °c in a matter of milliseconds,) and they produce large volumes of hot gas from a small volume of liquid, making hydrazine a fairly efficient thruster propellant with a vacuum specific impulse of about 220 seconds. reaction 2 is the most exothermic, but produces a smaller number of molecules than that of reaction 1. reaction 3 is endothermic and reverts the effect of reaction 2 back to the same effect as reaction 1 alone (lower temperature, greater number of molecules). the catalyst structure affects the proportion of the nh3 that is dissociated in reaction 3; a higher temperature is desirable for rocket thrusters, while more molecules are desirable when the reactions are intended to produce greater quantities of gas. since hydrazine is a solid below 2 °c, it is not suitable as a general purpose rocket propellant for military applications. other variants of hydrazine that are used as rocket fuel are monomethylhydrazine, ch3nhnh2, also known as mmh (melting point −52 °c), and unsymmetrical dimethylhydrazine, (ch3)2nnh2, also known as udmh (melting point −57 °c). these derivatives are used in two-component rocket fuels, often together with dinitrogen tetroxide, n2o4. a 50:50 mixture by weight of hydrazine and udmh was used in the titan ii icbms and is known as aerozine 50. these reactions are extremely exothermic, and the burning is also hypergolic (it starts burning without any external ignition). there are ongoing efforts in the aerospace industry to find a replacement for hydrazine, given its potential ban across the european union. promising alternatives include nitrous oxide-based propellant combinations, with development being led by commercial companies dawn aerospace, impulse space, and launcher. the first nitrous oxide-based system ever flown in space was by d-orbit onboard their ion satellite carrier in 2021, using six dawn aerospace b20 thrusters. occupational hazards health effects potential routes of hydrazine exposure include dermal, ocular, inhalation and ingestion. hydrazine exposure can cause skin irritation/contact dermatitis and burning, irritation to the eyes/nose/throat, nausea/vomiting, shortness of breath, pulmonary edema, headache, dizziness, central nervous system depression, lethargy, temporary blindness, seizures and coma. exposure can also cause organ damage to the liver, kidneys and central nervous system. hydrazine is documented as a strong skin sensitizer with potential for cross-sensitization to hydrazine derivatives following initial exposure. in addition to occupational uses reviewed above, exposure to hydrazine is also possible in small amounts from tobacco smoke. the official u.s. guidance on hydrazine as a carcinogen is mixed but generally there is recognition of potential cancer-causing effects. the national institute for occupational safety and health (niosh) lists it as a “potential occupational carcinogen”. the national toxicology program (ntp) finds it is "reasonably anticipated to be a human carcinogen". the american conference of governmental industrial hygienists (acgih) grades hydrazine as "a3—confirmed animal carcinogen with unknown relevance to humans". the u.s. environmental protection agency (epa) grades it as "b2—a probable human carcinogen based on animal study evidence". the international agency for research on cancer (iarc) rates hydrazine as "2a—probably carcinogenic to humans" with a positive association observed between hydrazine exposure and lung cancer. based on cohort and cross-sectional studies of occupational hydrazine exposure, a committee from the national academies of sciences, engineering and medicine concluded that there is suggestive evidence of an association between hydrazine exposure and lung cancer, with insufficient evidence of association with cancer at other sites. the european commission’s scientific committee on occupational exposure limits (scoel) places hydrazine in carcinogen “group b—a genotoxic carcinogen”. the genotoxic mechanism the committee cited references hydrazine's reaction with endogenous formaldehyde and formation of a dna-methylating agent. in the event of a hydrazine exposure-related emergency,