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an acyclic hydrazo compound; a colorless transparent liquid with a sharp organic amine odor. Two isomeric dimethylhydrazines are known: symmetrical dimethylhydrazine, CH3NH―NHCH3, and unsymmetrical dimethylhydrazine, (CH3)2N―NH2.
Unsymmetrical dimethylhydrazine is of practical significance. Boiling point, 63°C; melting point, −57.2°C; density, 0.795 g/cm3 (20°C); heat of formation ΔH0298 (liquid), 47.4 ± 3 kilojoules per mole, or 11.3 ± 0.7 kilocalories per mole. It is soluble in water and organic solvents (for example, alcohol); it is hygroscopic; and its aqueous solutions exhibit weakly alkaline reactions. In air, (CH3)2N—NH2 oxidizes slowly and ignites spontaneously at 270° C. Mixtures of its vapor with air are explosive within the limits of 2-99 percent (by volume). It is not sensitive to impact and detonation and is highly poisonous. Dimethylhydrazine is produced by the nitrosation of dimethylamine followed by the reduction of the dimethylnitrosamine with hydrogen
or by the reaction of dimethylamine with chloramine
(CH3)2 + NH2Cl + NaOH → (CH3)2NNH2 + NaCl + H2O
Unsymmetrical dimethylhydrazine is used as the combustible component of liquid rocket fuel.
REFERENCESMotornye i raketnye topliva, 4th ed. Edited by K. K. Papok and E.G. Semenido. Moscow, 1962.
Sarner, S. Khimiia raketnykh topliv. Moscow, 1969. (Translated from English.)
V. S. LAPIK