Monomethylhydrazine

Monomethylhydrazine
IUPAC name

Methylhydrazine
Identifiers
CAS number 60-34-4 Y
PubChem 6061
ChemSpider 5837 Y
EC number 200-471-4
ChEMBL CHEMBL160520 Y
RTECS number MV5600000
Jmol-3D images Image 1
Properties
Molecular formula CH3(NH)NH2
Molar mass 46.07 g/mol
Density 0.88 g/cm3
Melting point

−52 °C
Boiling point

87 °C
Solubility in water very soluble
Solubility in alcohol, ether soluble
Hazards
MSDS ICSC 0180
GHS pictograms
GHS signal word DANGER
EU Index Not listed
NFPA 704
3
4
2
Flash point −8.3 °C
Autoignition
temperature		 196 °C
Explosive limits 2.5–97%
Related compounds
Related compounds Hydrazine
Dimethylhydrazine
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Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

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[1].

MMH is a hydrazine derivative used in the orbital maneuvering system (OMS) and reaction control system (RCS) engines of NASA's Space Shuttle, which use 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 outer space providing moderate performance for very low fuel tank system weight. Recently the European Space Agency (ESA) has attempted to seek new options in terms of bipropellant rocket combinations in order to avoid poisonous chemicals such as this and its relatives.[2]

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 Apollo Lunar Modules used a one-to-one mixture of hydrazine and UDMH (called Aerozine 50, or A-50) as one part of the rocket fuel for lunar landings and takeoff: the rocket motors formed a hypergolic mixture of the hydrazines with liquid dinitrogen tetroxide as the usual oxidizer. (Otherwise, red fuming nitric acid works.) About three tons of mixed hydrazines and four and one half tons of the oxidizer were required for each landing, and about one-third of those amounts for the lunar take-off to orbit.[3]

Monomethylhydrazine is believed to be the main cause of the toxicity of gyromitra species mushrooms, especially the false morel (gyromitra esculenta). In these cases, MMH is formed by the hydrolysis of gyromitrin.[4]

References

  1. ^ MIL-PRF-27404 (1997-10-01). "Performance Specification, Propellant, Monomethylhydrazine". https://assist.daps.dla.mil/quicksearch/basic_profile.cfm?ident_number=18796. Retrieved 2011-05-21. 
  2. ^ International Conference on Green Propellant for Space Propulsion, European Space Agency
  3. ^ Greenwood, Norman N.; Earnshaw, A. (1984). Chemistry of the Elements. Oxford: Pergamon. p. 492. ISBN 0-08-022057-6. 
  4. ^ a b Pyysalo H. (1975). "Some new toxic compounds in false morels, Gyromitra esculenta". Naturwissenschaften 62 (8): 395. doi:10.1007/BF00625355. PMID 1238907.