Japan Hydrazine Co., Ltd.

Masuda Chemical Industry Co., Ltd.

Sumio Otsuka

Shunji Hyoda

Masaharu Kita

Hirotoshi Sawada

Shuichi Nemugaki

Yoshitaka Miyawaki

Takahiro Ueta

Kohki Satoh

Hiroshi Taniguchi

Takashi Ogawa

Yuhki Kubo

A process for the preparation of a 5,5'-bi-1H-tetrazole diammonium salt by dropwisely adding the aqueous hydrogen peroxide to which a small amount of weakly acidic substance has been added, to a starting aqueous solution containing hydrogen cyanide or sodium cyanide or potassium cyanide, sodium azide and a catalytic amount of copper sulfate preferably at a low temperature to maintain the pH of the reaction solution over a range of from 5 to 6, heating the reaction solution to effect the oxidation and cyclization reaction, reacting the reaction product with ammonium chloride or an aqueous solution thereof, and recovering the formed ammonium salt in the form of sparingly soluble crystals. The desired product is obtained in a high yield and in a high purity from the starting materials which are cheaply available and are easy to handle through a decreased number of steps, i.e., through a one-pot reaction without requiring cumbersome after-treatment.

Process for the preparation of 5,5'-bi-1H-tetrazole salt

A process for the preparation of a 5,5'-bi-1H-tetrazole diammonium salt by using dicyan, sodium azide, ammonium chloride and water as a reaction medium. This process is industrially advantageous since the 5,5'-bi-1H-tetrazole diammonium salt is synthesized and, then, the precipitated crystals thereof are simply isolated by filtration to obtain the 5,5'-bi-1H-tetrazole diammonium salt maintaining an yield which is not lower than 90%. The 5,5'-bi-1H-tetrazole diammonium salt is a gas-generating agent for air bags, which is lowly toxic and is easy to handle.

Method for preparing 5,5'-bi-1H-tetrazole salt

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Takamatsu, Japan

Sumio Otsuka