申请人:Ethyl Corporation
公开号:US03962287A1
公开(公告)日:1976-06-08
It is disclosed that citric acid or its salts are obtained by the hydrolysis of an alkaline earth metal adduct obtained by reacting a 3-carbamoyl-3-hydroxy-4-halobutyric acid with cyanide ions and with alkaline earth metal hydroxide, preferably in the ratio of from about one to about two gram-atoms of calcium and one gram-mol of cyanide (CN).sup.- per gram-mol of 3-carbamoyl-3-hydroxy-4-halobutyric acid, that 3-carbamoyl-3-hydroxy-4-halobutyric acid is preferably obtained by hydrolysis of a 3-cyano-3-hydroxy-4-halobutyric acid in an acidic system (in the presence of cyanide ions), that 3-cyano-3-hydroxy-4-halobutyric acid is preferably obtained by the hydrocyanation of 3-oxo-4-halobutyric acid with HCN in an aqueous system in the presence of excess cyanide ions and preferably in the presence of alkaline earth metal cyanide or alkali metal cyanide, that 3-oxo-4-halobutyric acid is obtained by hydrolysis of a 3-oxo-4-halobutyryl halide produced from diketene by halogenation. Preferred halogens involved in the process are chlorine and, to a lesser extent, bromine. Preferred alkaline earth metal adducts of the present invention are compounds of calcium. A preferred ratio of gram-atoms of calcium to gram-mols of 3-carbamoyl-3-hydroxy-4-chlorobutyric acid is about 2:1.
本文披露了柠檬酸或其盐是通过将3-氨基甲酰基-3-羟基-4-卤丁酸与氰离子和碱土金属氢氧化物反应获得的碱土金属加合物的水解得到的,最好的反应比例是每克摩尔的3-氨基甲酰基-3-羟基-4-卤丁酸中添加约1至2克原子的钙和1克摩尔的氰离子(CN)。优选的3-氨基甲酰基-3-羟基-4-卤丁酸是在酸性体系中(存在氰离子的情况下)通过3-氰基-3-羟基-4-卤丁酸的水解获得的,优选的3-氰基-3-羟基-4-卤丁酸是通过在水性体系中在过量氰离子和优选的碱土金属氰化物或碱金属氰化物的存在下,将3-氧代-4-卤丁酸与HCN进行氰化反应获得的,3-氧代-4-卤丁酸是通过将二酮通过卤代反应获得的。本方法中优选的卤素是氯,其次是溴。优选的碱土金属加合物是钙化合物。优选的钙原子数与3-氨基甲酰基-3-羟基-4-氯丁酸的摩尔数比为2:1。