Monomethylhydrazine (mono-methyl hydrazine, MMH) is a highly

toxic Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a subs ...

, volatile

hydrazine Hydrazine is an inorganic compound with the chemical formula . It is a simple pnictogen hydride, and is a colourless flammable liquid with an ammonia-like odour. Hydrazine is highly toxic unless handled in solution as, for example, hydrazin ...

derivative with the

chemical formula In chemistry, a chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, ...

. It is used as a

rocket propellant Rocket propellant is the reaction mass of a rocket. This reaction mass is ejected at the highest achievable velocity from a rocket engine to produce thrust. The energy required can either come from the propellants themselves, as with a chemical ...

bipropellant rocket A liquid-propellant rocket or liquid rocket utilizes a rocket engine that uses liquid propellants. Liquids are desirable because they have a reasonably high density and high specific impulse (''I''sp). This allows the volume of the propellant ta ...

engine An engine or motor is a machine designed to convert one or more forms of energy into mechanical energy. Available energy sources include potential energy (e.g. energy of the Earth's gravitational field as exploited in hydroelectric power gene ...

s because it is hypergolic with various oxidizers such as

nitrogen tetroxide Dinitrogen tetroxide, commonly referred to as nitrogen tetroxide (NTO), and occasionally (usually among ex-USSR/Russia rocket engineers) as amyl, is the chemical compound N2O4. It is a useful reagent in chemical synthesis. It forms an equilibrium ...

() and

nitric acid Nitric acid is the inorganic compound with the formula . It is a highly corrosive mineral acid. The compound is colorless, but older samples tend to be yellow cast due to decomposition into oxides of nitrogen. Most commercially available nitri ...

(). As a propellant, it is described in specification MIL-PRF-27404. MMH is a

derivative that was once used in the

orbital maneuvering system In spaceflight, an orbital maneuver (otherwise known as a burn) is the use of propulsion systems to change the orbit of a spacecraft. For spacecraft far from Earth (for example those in orbits around the Sun) an orbital maneuver is called a ...

(OMS) and reaction control system (RCS) engines of NASA's

Space Shuttle The Space Shuttle is a retired, partially reusable launch system, reusable low Earth orbital spacecraft system operated from 1981 to 2011 by the U.S. National Aeronautics and Space Administration (NASA) as part of the Space Shuttle program. I ...

, which used MMH and MON-3 (a mixture of nitrogen tetroxide with approximately 3% nitric oxide). This chemical is

and

carcinogenic A carcinogen is any substance, radionuclide, or radiation that promotes carcinogenesis (the formation of cancer). This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes. Several radioactive substan ...

, 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 A rocket engine uses stored rocket propellants as the reaction mass for forming a high-speed propulsive jet of fluid, usually high-temperature gas. Rocket engines are reaction engines, producing thrust by ejecting mass rearward, in accordanc ...

. The

European Space Agency , owners = , headquarters = Paris, Île-de-France, France , coordinates = , spaceport = Guiana Space Centre , seal = File:ESA emblem seal.png , seal_size = 130px , image = Views in the Main Control Room (120 ...

(ESA) has attempted to seek new options in terms of

combinations to avoid using deadly chemicals such as MMH and its relatives. MMH is believed to be the main cause of the toxicity of

mushroom A mushroom or toadstool is the fleshy, spore-bearing fruiting body of a fungus, typically produced above ground, on soil, or on its food source. ''Toadstool'' generally denotes one poisonous to humans. The standard for the name "mushroom" is t ...

s of genus '' Gyromitra'', especially the false morel (''

Gyromitra esculenta ''Gyromitra esculenta'' is an ascomycete fungus from the genus '' Gyromitra'', widely distributed across Europe and North America. It normally fruits in sandy soils under coniferous trees in spring and early summer. The fruiting body, or mush ...

''). In these cases, MMH is formed by the

hydrolysis Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution, elimination, and solvation reactions in which water is the nucleophile. Biological hydrolys ...

of gyromitrin. Monomethylhydrazine is considered to be a possible occupational carcinogen, and the occupational exposure limits to MMH are set at protective levels to account for the possible carcinogenicity. A known use of MMH is in the synthesis of suritozole. MMH is also assumed to be the active methylating agent in the drug Temozolomide.

References

External links

* {{Hydrazines Rocket fuels Mycotoxins Hydrazines Monoamine oxidase inhibitors Vitamin B6 antagonists Organic compounds with 1 carbon atom