GB976939A - Production of pyrrolidone - Google Patents

Abstract

Pyrrolidone is made by the reaction in the liquid phase of a compound of the formula HOOC-A-COOH, where A represents -CH2-CH2-or-CH=CH -with ammonia and hydrogen at 150-280 DEG C. and at a pressure of 20-400 atmospheres in the presence of sintered Co, Ni, Cu and/or Fe as a catalyst. The catalysts (see Division B1) which may be supported on carriers, e.g. pumice, clay or silicates, may be used singly or as mixtures or alloys of two, three or all of the metals and may also contain manganese, silver or cadmium, either singly or in admixture with one another. The catalysts are sintered by heating to slightly, e.g., 20-80 DEG C., below the melting point of the metal, the lowest melting component of a mixture or of the alloy. Particularly active catalysts are obtained from sintering metal oxides, or compounds which can be converted into oxides on heating, at temperatures preferably above 1000 DEG C. and subsequently hydrogenating, preferably at 250-400 DEG C. Suitable dibasic acids are succinic, maleic and fumaric acids. The ammonia, preferably in 5-20 molar excess of the diacid, may be added in the gaseous or liquid state or dissolved in water and/or an inert organic solvent, e.g. cyclic ethers. In the former two instances it is usual to add 60-90%, by weight of diacid, of water and/or organic solvent to the reaction mixture. Alternatively the ammonia can be combined with the diacid as, e.g. the acid or neutral salt, the monoamide of succinic acid or maleic acid or the ammonium salts thereof, or as the diamide of the unsaturated acids, preferably with additional free ammonia. The hydrogen may be diluted with an inert gas, e.g. nitrogen or saturated hydrocarbons. The reaction is carried out for, e.g. 5-25 hours, at temperatures between 150-280 DEG C., preferbly 170-250 DEG C. and particularly 190-230 DEG C. and at hydrogen pressures of 20-400, preferably 45-250 atmospheres. Examples describe the preparation of pyrrolidone using a cobalt catalyst with diammonium succinate, succinic acid, amide ammonium salt of succinic acid, maleic acid; ammonium salt of maleic acid, ammonium amide salt of maleic acid and the diammonium salt of fumaric acid, a nickel catalyst and diammonium succinate and a cobalt/manganese catalyst and ammonium maleate.ALSO:Sintered Co, Ni, Cu and Fe, or mixtures or alloys of two, three or all of these metals are used as catalysts in the preparation of pyrrolidone from a compound HOOC-A-COOH, in which A is -CH2-CH2- or -CH=CH-, ammonia and hydrogen in the liquid phase. The catalysts can also contain manganese, silver and/or cadmium and may be supported on carriers, e.g. pumice, clay or silicates, which can amount to 50-95% by weight of the total suported catalyst. The catalysts are sintered by heating to slightly, e.g. 20-80 DEG C., below the melting point of the metal, the lowest melting component of a mixture or of the alloy. Particularly active catalysts are obtained by sintering the metal oxide, or compounds which can be converted into oxides on heating, e.g. hydroxides, carbonates, nitrates or nitrites, at temperatures preferably above 1000 DEG C., but 20 DEG C. below the melting point of the compound. The oxide is subsequently reduced at temperatures between 150-600 DEG C. Example 1 describes the preparation of sintered cobalt in pellet form, Example 5 describes the reduction of sintered nickel oxide, and Example 2 describes the preparation of a cobalt/manganese catalyst.