Chemical process for producing citric acid
US3962287A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 13, 1973 |
| Grant date | Jun 8, 1976 |
| Priority date | — |
| Expiry date | Mar 13, 1993 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC07C51/412
- WIPO fieldOrganic fine chemistry
- WIPO sectorChemistry
Abstract
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 …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.