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Monomethylhydrazine

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Monomethylhydrazine
Monomethylhydrazine
Ball-and-stick model of methylhydrazine
Names
IUPAC name
Methylhydrazine
Identifiers
ECHA InfoCard 100.000.429 Edit this at Wikidata
EC Number
  • 200-471-4
RTECS number
  • MV5600000
Properties
CH3(NH)NH2
Molar mass 46.07 g/mol
Density 0.88 g/cm3
Melting point −52 °C
Boiling point 87 °C
very soluble
Solubility in alcohol, ether soluble
Hazards
GHS labelling:
Flammable liquid cat. 1 GHS06: Toxic GHS08: Health hazard GHS09: Environmental hazard
Danger
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 4: Very short exposure could cause death or major residual injury. E.g. VX gasFlammability 3: Liquids and solids that can be ignited under almost all ambient temperature conditions. Flash point between 23 and 38 °C (73 and 100 °F). E.g. gasolineInstability 2: Undergoes violent chemical change at elevated temperatures and pressures, reacts violently with water, or may form explosive mixtures with water. E.g. white phosphorusSpecial hazards (white): no code
4
3
2
Flash point −8.3 ºC
Explosive limits 2.5–97%
Related compounds
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

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.

Notes

  1. ^ International Conference on Green Propellant for Space Propulsion, European Space Agency
  2. ^ Greenwood, Norman N.; Earnshaw, Alan (1984). Chemistry of the Elements. Oxford: Pergamon Press. p. 492. ISBN 978-0-08-022057-4.

Sources

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