Monomethylhydrazine
Template:Chembox Monomethylhydrazine (MMH) is a highly toxic, volatile hydrazine derivative with the chemical formula Template:Chem2. It is used as a rocket propellant in bipropellant rocket engines because it is hypergolic with various oxidizers such as nitrogen tetroxide (Template:Chem2) and nitric acid (Template:Chem2). As a propellant, it is described in specification MIL-PRF-27404.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
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,<ref>Monomethylhydrazine as toxic and carcinogenic chemical substance</ref> 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 using deadly chemicals such as MMH and its relatives.<ref>Template:Cite conference</ref>
MMH is believed to be the primary active mycotoxin found in mushrooms of the genus Gyromitra, especially the false morel (Gyromitra esculenta). In these cases, MMH is formed by the hydrolysis of gyromitrin.<ref name=Pyysalo1975>Template:Cite journal</ref>
Monomethylhydrazine is considered to be a possible occupational carcinogen,<ref>Template:Cite report</ref> and the occupational exposure limits to MMH are set at protective levels to account for the possible carcinogenicity.<ref>Template:Cite report</ref>
A known use of MMH is in the synthesis of suritozole.<ref>Template:Cite journal</ref>
MMH is also assumed to be the active methylating agent in the drug temozolomide.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>