Monomethylhydrazine

Monomethylhydrazine
IUPAC name	Methylhydrazine
Identifiers
CAS number	60-34-4 Y
EC number	200-471-4
RTECS number	MV5600000
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
EU Index	Not listed
GHS pictograms
GHS signal word	DANGER
NFPA 704	3 4 2
Flash point	−8.3 ºC
Autoignition temperature	196 ºC
Explosive limits	2.5–97%
Related compounds
Related compounds	Hydrazine Dimethylhydrazine
Y (what is this?)  (verify) 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 fuel in bipropellant rocket engines, and frequently in hypergolic mixtures.

MMH is very commonly applied notably in the orbital maneuvering system (OMS) engines of NASA's Space Shuttle. 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. ^[1]

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 1:1 mixture of MMH and UDMH as one part of the rocket fuel for lunar landings and take-off: the rocket motors formed a hypergolic mixture of the hydrazines with liquid dinitrogen tetroxide as the oxidizer. About three tons of mixed hydrazines and four and one half tons of oxidizer were required for each landing, and about one-third of those amounts for the lunar take-off to orbit. ^[2]

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.

References