GB371555A - An improved process for the manufacture of acetamide and acetic acid - Google Patents

Abstract

Acetamide is obtained by causing hydrogen to react on formamide, or on a mixture of carbon monoxide and ammonia, under the influence of ultra-violet or infra-red radiations. The reaction between hydrogen and formamide takes place at ordinary pressure and at temperatures between 200 and 500 DEG C. When carbon monoxide and ammonia are used, pressures of at least 100 kg. per sq. cm. and temperatures between 100 and 300 DEG C. are employed. Catalysts consisting of pumicestone, carbon powder, finely divided metals, particularly copper, or metal oxides such as aluminium oxide may be present. According to an example, formamide vapour mixed with hydrogen is passed at 250-300 DEG C. through a quartz tube containing pumicestone, carbon powder, copper powder, aluminium oxide, or a mixture of the two latter substances, under the influence of ultra-violet light from mercury vapour lamps. By cooling the exit gases, acetamide is obtained. The Specification as open to inspection under Sect. 91 (3) (a) describes also the production of di- and tri-acetamide and of glycocoll by the reaction referred to above. This subject-matter does not appear in the Specification as accepted.ALSO:Acetamide, which may subsequently be converted to acetic acid by hydrolysis, is obtained by causing hydrogen to react on formamide, or on a mixture of carbon monoxide and ammonia. The reaction between hydrogen and formamide may take place at ordinary-pressure and at a temperature between 200 and 500 DEG C. When carbon monoxide and ammonia are substituted for formamide, pressures of at least 100 Kg. per sq. cm. and temperatures between 100 and 300 DEG C. are employed. Both reactions are facilitated by the presence of catalysts consisting of pumicestone, carbon powder, finely divided metals, particularly copper, or metal oxides such as aluminium oxide, and by the influence of ultra-violet or infra-red radiations. According to examples, (1) formamide vapour mixed with hydrogen is passed at 250-300 DEG C. through a quartz tube containing pumicestone, carbon powder, copper powder, aluminium oxide, or a mixture of the two latter substances, under the influence of ultra-violet light from mercury vapour lamps. By cooling the exit gases, acetamide is obtained, which is hydrolysed in known manner to acetic acid; steam may be added to the initial mixture to facilitate the reaction; and (2) a mixture of carbon monoxide and hydrogen obtained, for example, by passing steam over red-hot carbon, is passed together with ammonia under a pressure of 100 Kg. per cm., and at 250-300 DEG C. over the same catalysts as in (1) above, the acetamide obtained being hydrolysed to acetic acid as before. The Specification as open to inspection under Sect. 91 (3) (a) refers also to the production of di- and triacetamide and of glycocoll by the action of hydrogen on formamide. This subject-matter does not appear in the Specification as accepted.