| 摘要 |
1,165,012. Isocyanates; aminimides. UNIVERSITY OF IOWA. 25 Aug., 1966 [26 Aug., 1965], No. 38244/66. Heading C2C. Organic isocyanates are prepared by pyrolysing an organic aminimide. In particular an isocyanate of formula R(N = C = O) n in which R is an aliphatic, cycloaliphatic or aromatic group of valency n is prepared by pyrolysing an aminimide of formula in which R 1 R 2 and R 3 are alkyl or aryl groups or R 2 and R 3 may be joined to form a heterocyclic ring and n is an integer. The aminimides used as starting materials may be prepared by first forming an acyl hydrazine by reacting an acid anhydride or acid chloride with an unsymmetrical hydrazine and converting the acyl hydrazine to an aminimide by either reacting it with an alkyl halide in the presence of an alkali metal hydroxide or by reacting the acyl hydrazine with an alkyl halide or an ester of a strong organic acid such as a sulphonic acid to yield the hydrazonium salt and treating this with a base. Examples are given of the preparation of (a) phenyl isocyanate by reacting benzoyl chloride with unsymmetrical dimethyl hydrazine to give 1,1-dimethyl-2-benzoylhydrazine, forming a hydrazonium salt by treating the benzoyl hydrazine with methyl-p-toluene sulphonate; treating the salt with sodium hydroxide to given trimethylamine benzimide and pyrolysing this to give phenyl isocyanate; and (b) methyl isocyanate by reacting acetic anhydride with 1 - amino - 2 - phenylpyrrolidine to give 1-acetamino-2-phenyl-pyrrolidine: treating this with methyl iodide to give the hydrazonium salt; treating the hydrazonium salt with sodium hydroxide to give 1-methyl-2-phenylpyrrolidine acetimide and heating this to give methyl isocycanate. A list of suitable starting aminimides is given which would produce mono-, di- and tetra-isocyanates. |
