Monomethylhydrazine

Monomethylhydrazine (MMH) is a volatile hydrazine chemical with the chemical formula CH3(NH)NH2. It is used as a rocket propellant in bipropellant rocket engines because it is hypergolic with various oxidizers such as nitrogen tetroxide (N2O4) and nitric acid (HNO3). As a propellant, it is described in specification MIL-PRF-27404.[4]

Monomethylhydrazine
Names
IUPAC name
Methylhydrazine[1]
Systematic IUPAC name
Methyldiazane
Identifiers
3D model (JSmol)
635645
ChEMBL
ChemSpider
ECHA InfoCard 100.000.429
EC Number
  • 200-471-4
MeSH Monomethylhydrazine
RTECS number
  • MV5600000
UNII
UN number 1244
Properties
CH6N2
Molar mass 46.073 g·mol−1
Appearance Fuming, colourless liquid
Odor Fishy, ammoniacal
Density 875 mg·mL−1 (at 20 °C)
Melting point −52 °C (−62 °F; 221 K)
Boiling point 87.50 °C; 189.50 °F; 360.65 K
Miscible[2]
log P −1.318
Vapor pressure 5.00 kPa (at 20 °C)
1.4325
Thermochemistry
134.93 J·K−1·mol−1
165.94 J·K−1·mol−1
54.14 kJ·mol−1
−1305.8 – −1304.6 kJ·mol−1
Hazards
Safety data sheet inchem.org
GHS pictograms
GHS Signal word Danger
H225, H300, H311, H314, H330, H351, H411
P210, P260, P273, P280, P284
NFPA 704 (fire diamond)
Flammability code 4: Will rapidly or completely vaporize at normal atmospheric pressure and temperature, or is readily dispersed in air and will burn readily. Flash point below 23 °C (73 °F). E.g. propaneHealth code 4: Very short exposure could cause death or major residual injury. E.g. VX gasReactivity code 4: Readily capable of detonation or explosive decomposition at normal temperatures and pressures. E.g. nitroglycerinSpecial hazards (white): no code
4
4
4
Flash point −8 °C; 17 °F; 265 K [2]
196 °C (385 °F; 469 K)
Explosive limits 2.5–92%[2]
Lethal dose or concentration (LD, LC):
32 mg·kg−1 (oral, rat)
34 ppm (rat, 4 hr)
74 ppm (rat, 4 hr)
162 ppm (monkey, 1 hr)
195 ppm (dog, 30 min)
145 ppm (monkey, 30 min)
272 ppm (mouse, 30 min)
427 ppm (rat, 30 min)
56 ppm (mouse, 4 hr)
143 ppm (hamster, 4 hr)[3]
NIOSH (US health exposure limits):
PEL (Permissible)
 C 0.2 ppm (0.35 mg·m−3) [skin][2]
REL (Recommended)
 Ca C 0.04 ppm (0.08 mg·m−3) [2-hr][2]
IDLH (Immediate danger)
 Ca [20 ppm][2]
Related compounds
Related compounds
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

MMH is a hydrazine derivative that was once used in the orbital maneuvering system (OMS) and reaction control system (RCS) engines of NASA's Space Shuttle, which used MMH and MON-3 (a mixture of nitrogen tetroxide with approximately 3% nitric oxide). This chemical is toxic and carcinogenic in small amounts, but it is easily stored in orbit providing moderate performance for very low fuel tank system weight. MMH and its chemical relative unsymmetrical dimethylhydrazine (UDMH) have a key advantage that they are stable enough to be used in regeneratively cooled rocket engines. The European Space Agency (ESA) has attempted to seek new options in terms of bipropellant rocket combinations to avoid poisonous chemicals such as MMH and its relatives.[5]

MMH is believed to be the main cause of the toxicity of mushrooms of genus Gyromitra, especially the false morel (Gyromitra esculenta). In these cases, MMH is formed by the hydrolysis of gyromitrin.[6]

Monomethylhydrazine is considered to be a possible occupational carcinogen,[7] and the occupational exposure limits to MMH are set at protective levels to account for the possible carcinogenicity.[8]

A known use of MMH is in the synthesis of Suritozole.

References
  1. "Monomethylhydrazine - Compound Summary". PubChem Compound. USA: National Center for Biotechnology Information. 26 March 2005. Identification and Related Records. Retrieved 2 May 2012.
  2. NIOSH Pocket Guide to Chemical Hazards. "#0419". National Institute for Occupational Safety and Health (NIOSH).
  3. "Methylhydrazine". Immediately Dangerous to Life and Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
  4. MIL-PRF-27404 (1997-10-01). "Performance Specification, Propellant, Monomethylhydrazine". Archived from the original on 2012-03-20. Retrieved 2011-05-21.
  5. International Conference on Green Propellant for Space Propulsion, European Space Agency
  6. Pyysalo H. (1975). "Some new toxic compounds in false morels, Gyromitra esculenta". Naturwissenschaften. 62 (8): 395. Bibcode:1975NW.....62..395P. doi:10.1007/BF00625355. PMID 1238907. S2CID 178876.
  7. Documentation for Immediately Dangerous To Life or Health Concentrations (IDLHs), Centers for Disease Control and Prevention
  8. NIOSH Pocket Guide to Chemical Hazards, Centers for Disease Control and Prevention
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