Monomethylhydrazine

  • Methylhydrazine
  • MMH

Colorless, hygroscopic liquid with ammoniacal odor

Liquid

0.88 g · cm -3

-52 ° C

87 ° C

  • 50 hPa ( 20 ° C)
  • 88 hPa ( 30 ° C)
  • 235 hPa ( 50 ° C)

Soluble in water

1.4325 (20 ° C)

Risk

54.2 kJ / mol

Template: Infobox chemical / molecular formula search available

Monomethylhydrazine dec MMH is a chemical compound that consists of a Hydrazingrundkörper that is simple methylated. It has the molecular formula CH6N2.

History

Monomethylhydrazine is increasingly in place of 1,1- dimethylhydrazine used since the 1990s due to its slightly larger density and therefore a bit higher performance than storable rocket fuel together with the oxidizer nitrogen tetroxide. In satellites, it will, however, have been used since the 1980s as a fuel.

Occurrence and behavior in the environment

There are known natural sources of monomethyl hydrazine. The in morel ( Gyromitra esculenta ) and some other Ascomycetes as a poison existing Gyromitrin is a derivative of monomethyl hydrazine. Due to its high reactivity ( especially against ozone) is not expected to be long-range distribution of entry into the environment, and there is a rapid degradation.

Production and representation

Of methylamine and ammonia ( dehydrating condensation on catalysts) or methylation of hydrazine.

Properties

Physical / Chemical Properties

Colorless, fishy -smelling liquid which fumes in the air. The vapors of Monomethylhydrazine can irritate or corrode under heavy load the skin and mucous membranes (eyes, respiratory tract).

  • Enthalpy of vaporization: 875 kJ / kg
  • Specific heat capacity: 2.921 kJ / kg · K (20 ° C); 3.077 kJ / kg · K ( 119.85 ° C)
  • Dynamic viscosity: 0.855 · 10-3 Pa · s (20 ° C); 0.40 · 10-3 Pa · s ( 70.85 ° C)

Use

Monomethylhydrazine is the combustible component of liquid hypergolic rocket fuels, and it is used in combination with nitrogen tetroxide as oxidant. The Aestus engine of the EPS upper stage of the Ariane 5 uses this fuel combination.

Physiology

Monomethylhydrazine is easily absorbed through the skin and has proven in animal studies clearly carcinogenic.

CAS registry number PubChem Vapor pressure Dangerous Substances Directive (67/548/EEC) Unsymmetrical dimethylhydrazine Hypergolic propellant CRC Handbook of Chemistry and Physics
566207
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