A colourless liquid or white crystalline solid, N₂H₄; r.d. 1.01 (liquid); m.p. 1.4°C; b.p. 113.5°C. It is very soluble in water and soluble in ethanol. Hydrazine is prepared by the Raschig synthesis in which ammonia reacts with sodium(I) chlorate (sodium hypochlorite) to give NH₂Cl, which then undergoes further reaction with ammonia to give N₂H₄. Industrial production must be carefully controlled to avoid a side reaction leading to NH₄Cl. The compound is a weak base giving rise to two series of salts, those based on N₂H₅⁺, which are stable in water (sometimes written in the form N₂H₄.HCl rather than N₂H₅⁺Cl⁻), and a less stable and extensively hydrolysed series based on N₂H₆²⁺. Hydrazine is a powerful reducing agent and reacts violently with many oxidizing agents, hence its use as a rocket propellant. It reacts with aldehydes and ketones to give hydrazones.