(also called diamide), H2N—NH2, a colorless, hygroscopic liquid that fumes in air. Boiling point, 113.5° C; melting point, 2° C; density, 1,008 g/cm3 (at 20° C). Hydrazine is absolutely soluble in water and low alcohols. It is insoluble in hydrocarbons and other organic solvents. Aqueous solutions of hydrazine are basic (K
= 8.5 x 10−7). With acids it forms salts of hydrazone, such as N2H5C1 and N2H6C12. Hydrazine is characterized by a high dielectric constant (52.9 at 20° C) and is able to dissolve many inorganic salts.
Hydrazine is an endothermal compound; heat of formation ΔH
(1) = 50.24 kilojoules per mole (12.05 kilocalories per mole). Upon heating to 200°-300° C, hydrazine decomposes to N2 and NH3. In the presence of Fe203, it ignites at room temperature. A mixture of hydrazine vapor with air at a content of 4.67 percent or more by volume forms an explosive mixture. Liquid hydrazine is not sensitive to impact, friction, or detonation. It is toxic; the maximum permissible concentration in air is 0.0001 mg/l. Hydrazine is produced by oxidation of NH3 or urea by hypochloride. It is used in organic synthesis, as a component of liquid rocket fuels, and in the production of plastics, cured rubber, insecticides, and explosives.
V. S. LAPIK