Hydrazine Production from Ammonia via Azine' Hiromu Hayashi,' Aklhiko Kalnoh, Masayoshi Katayama, Kengo Kawasaki, and Tatsuya Okaraki Department of Chemical Engineering, Tokushima University, Minamijosanjima, Tokushima, 770 Japan
Benzophenone azine, which gives hydrazine quantitatively on acid hydrolysis, was obtained in a single reactor by passing ammonia and oxygen through benzophenone at 200 OC under 1-8 atm pressure in the presence of zinc chloride and cuprous chloride. When cuprous chloride was absent, the reaction stopped at the stage of formation of diphenylmethanimine.In the presence of cuprous chloride with zinc chloride, the intermediate product imine suffered in situ oxidative coupling to azine. A higher pressure of ammonia resulted in the accumulation of imine, and a condition of 1 atm of "3, with 1-2 atm of 02, was revealed to be suitable for the direct synthesis of azine. Nitrogen dilution with increasing total pressure did not affect the azine yield. Thus air was recommended as the oxygen source to avoid the explosion range. Catalysts were recycled four times at a condition of 49 f 2 % of one-pass yield of azine, and an 81 % overall yield was attained.
Introduction An aerial oxidation process is given for the synthesis of benzophenone azine in the liquid phase under pressure. Ph2C=NN=CPh2 (I) was obtained in a single stage by passing NH3 and 0 2 through Ph2CO at 200 "C under 1-8 atm in the presence of ZnClp and CuC1. Intermediate Ph&=NH (11) suffers in situ oxidative coupling, and no I was formed without 0 2 or CuC1. From the effect of pressure of NH3 and 0 2 a suitable condition was found to be 1atm of NHs with 1-2 atm of 0 2 . The minimum catalyst requirements were 0.3 and 0.5 wt % of ZnClp and CuCl, respectively. Dilution by Nz with increasing total pressure did not affect the yield of I, and air was recommended as the 0 2 source for safety. It is profitable to avoid excess NHs, which increases the load on the recovery tower and results in the accumulation of I1 without improving the yield of I. The catalysts were recycled four times, and an 81% overall yield of I was attained. The Raschig synthesis of hydrazine involves the oxidation of ammonia by hypochlorite, which entails drawbacks arising from the current difficult chlorine situation and the environmental problems of disposing of the large quantities of by-product chloride (Chem.Eng. News, 1974).Abendroth and Henrich (1959) developed a modification by using acetone, which forms diaziridine
/\AH \
/"
in the presence of chlorine and excess ammonia. The subsequent react,ion of diaziridine with an additional ketone gives azine, >C=NN=C
