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
SMILES N(N)C
InChI InChI=1S/CH6N2/c1-3-2/h3H,2H2,1H3 Y Key: HDZGCSFEDULWCS-UHFFFAOYSA-N Y InChI=1/CH6N2/c1-3-2/h3H,2H2,1H3 Key: HDZGCSFEDULWCS-UHFFFAOYAV
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
Y (verify) (what is: Y/N?) 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.