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
CAS Number	60-34-4 Y
3D model (JSmol)	Interactive image
Beilstein Reference	635645
ChEMBL	ChEMBL160520 Y
ChemSpider	5837 Y
ECHA InfoCard	100.000.429
EC Number	200-471-4
MeSH	Monomethylhydrazine
PubChem CID	6061
RTECS number	MV5600000
UNII	UWA30B5Z1J Y
UN number	1244
CompTox Dashboard (EPA)	DTXSID4020874
InChI InChI=1S/CH6N2/c1-3-2/h3H,2H2,1H3 Y Key: HDZGCSFEDULWCS-UHFFFAOYSA-N Y
SMILES CNN
Properties
Chemical formula	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
Solubility in water	Miscible[2]
log P	−1.318
Vapor pressure	5.00 kPa (at 20 °C)
Refractive index (nD)	1.4325
Thermochemistry
Heat capacity (C)	134.93 J·K−1·mol−1
Std molar entropy (So298)	165.94 J·K−1·mol−1
Std enthalpy of formation (ΔfH⦵298)	54.14 kJ·mol−1
Std enthalpy of combustion (ΔcH⦵298)	−1305.8 – −1304.6 kJ·mol−1
Hazards
Safety data sheet	inchem.org
GHS pictograms
GHS Signal word	Danger
GHS hazard statements	H225, H300, H311, H314, H330, H351, H411
GHS precautionary statements	P210, P260, P273, P280, P284
NFPA 704 (fire diamond)	4 4 4
Flash point	−8 °C; 17 °F; 265 K [2]
Autoignition temperature	196 °C (385 °F; 469 K)
Explosive limits	2.5–92%[2]
Lethal dose or concentration (LD, LC):
LD50 (median dose)	32 mg·kg−1 (oral, rat)
LC50 (median concentration)	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	Methylamine Ethylamine Ethylenediamine
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.