Hydrazine - Synthesis and Manufacture

Synthesis and Manufacture

Theodor Curtius synthesized free hydrazine for the first time in 1889 via a circuitous route.

Hydrazine is produced in the Olin Raschig process from sodium hypochlorite (the active ingredient in many bleaches) and ammonia, a process announced in 1907. This method relies on the reaction of chloramine with ammonia:

NH₂Cl + NH₃ → H₂N-NH₂ + HCl

Another route of hydrazine synthesis involves oxidation of urea with sodium hypochlorite:

(H₂N)₂C=O + NaOCl + 2 NaOH → N₂H₄ + H₂O + NaCl + Na₂CO₃

Hydrazine can be synthesized from ammonia and hydrogen peroxide in the Pechiney-Ugine-Kuhlmann process, according to the following formula:

2NH₃ + H₂O₂ → H₂N-NH₂ + 2H₂O

In the Atofina–PCUK cycle, hydrazine is produced in several steps from acetone, ammonia, and hydrogen peroxide. Acetone and ammonia first react to give the imine followed by oxidation with hydrogen peroxide to the oxaziridine, a three-membered ring containing carbon, oxygen, and nitrogen, followed by ammonolysis to the hydrazone, a process that couples two nitrogen atoms. This hydrazone reacts with one more equivalent of acetone, and the resulting acetone azine is hydrolyzed to give hydrazine, regenerating acetone. Unlike the Raschig process, this process does not produce salt. The PCUK stands for Produits Chimiques Ugine Kuhlmann, a French chemical manufacturer.

Hydrazine can also be produced via the so-called ketazine and peroxide processes.