TECHNICAL DESCRIPTION

The invention relates to a method for synthesising a hydrazine by reaction of the amine corresponding to said hydrazine with hydroxylamine-O-sulphonic acid, including the following consecutive steps: (a) reacting an excess of said amine with said hydroxylamine-O-sulphonic acid in an aqueous medium such as to form said hydrazine and amino sulphate; (b) neutralizing the amino sulphate formed in step (a) by adding at least two molar equivalents of sodium hydroxide relative to the amount of hydroxylamine-O-sulphonic acid used in step (a), leading to the formation of sodium sulphate; (c) solubilising the sodium sulphate formed in step (b); (d) demixing the reaction medium obtained after step (c) in an aqueous phase and in an organic phase and recovery of the organic phase; and (e) isolating the hydrazine from the organic phase obtained in the preceding step, optionally followed by a step of purifying said hydrazine.