Hoechst Aktiengesellschaft

Adolf Metzger

Reinhold Graser

Karl-Heinz Henke

Heinz Karl Hofmeister

Horst Schreiber

Rolf Konrad

Ammonium sulfamate is prepared continuously, starting from ammonia and sulfur trioxide, by introducing liquid sulfur trioxide and liquid ammonia in a molar ratio NH.sub.3 /SO.sub.3 greater than 2.0:1 into a pressure reactor containing molten reaction product. Excess ammonia is removed continuously from the reactor. The liquid sulfur trioxide is introduced into the melt, while the liquid ammonia is fed onto the surface of the melt.

Process for the preparation of ammonium sulfamate

When sulfur trioxide is reacted with ammonia, a melted reaction product containing mainly the ammonium salts of amidosulfonic acid and imido-disulfonic acid is obtained. According to the invention the melted reaction product is introduced into mineral acids. From the resulting solution, free amidosulfonic acid precipitates in high yield.

Process for the preparation of amidosulfonic acid

Crystallized ammonium thiosulfate is manufactured by converting ammonia with oxygen containing sulfur dioxide in ammonium thiosulfate solution to ammonium bisulfite and ammonium sulfite in a first step, while maintaining a pH of from 5.5 to 7.0 and a reaction temperature of up to 80.degree.C. In a second step, the ammonium bisulfite and ammonium sulfite in the solution are converted with ammonia and sulfur to ammonium thiosulfate.

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Wiesbaden, Germany

Adolf Metzger