GB313233A - Manufacture of anhydrides of alkoxy-aliphatic acids - Google Patents

Abstract

313,233. Dreyfus, H. March 24, 1928. Alkoxy aliphatic anhydrides.-Alkoxy aliphatic anhydrides or their substitution products are prepared by bringing metallic salts of corresponding acids or mixtures thereof into reaction with sulphur and chlorine or with sulphur-chlorine compounds mixed or not with chlorine. Preferably, the anhydrous pulverulent alkali-metal salts are employed and the reaction is conducted in an inert medium with the use of about six atoms of chlorine for each eight acidyl radicles taken as salt. The inert medium may be the anhydride to be produced, and the process may then be conducted continuously. The anhydrides may be freed from traces of sulphur or its compounds by treatment with suitable metals or metal compounds, such as lead oxide or copper oxide, or by treatment with chlorine and a metal salt of the acid corresponding to the anhydride. In the examples, (1) dry powdered sodium methoxyacetate mixed with methoxyacetic anhydride is treated with sulphur dichloride at 0-10‹ C.; the product is distilled in vacuo when the reaction is complete; (2) a mixture of sulphur dichloride and chlorine is used instead of sulphur dichloride alone; (3) methoxyacetic anhydride containing a little sulphur is treated with sodium methoxy acetate and chlorine; the purified product is distilled off. Reference is made also to the use of sulphur monochloride and to the preparation of anhydrides from the ethyl and propyl ethers of glycollic acid and the methyl, ethyl, and propyl ethers of lactic and hydracrylic acids.