PURIFICATION OF CARBOXYLIC ACIDS

摘要

1350726 Purification of carboxylic acids MONSANTO CO 15 May 1972 [10 Nov 1971] 22643/72 Heading C2C Monocarboxylic acids (preferably 2-10 C) are purified from water and alkyl halide and/or hydrogen halide contaminants by introducing a product stream into the upper half of a distillation zone, removing an overhead fraction containing water and alkyl halide, removing a stream from the middle portion of the distillation zone but below the introduction point, and removing a purified stream from the lower part of the zone. In a modification the impure acid may be pre-distilled in a zone from which the bottom portion containing hydrogen halide is removed and the overhead stream is passed to the upper half of the distillation zone. The acid to be purified is preferably that prepared by the reaction of an alcohol or olefine with carbon monoxide in the presence of a catalyst system containing a Group VIII noble metal component and a halogen component, usually bromine or iodine. Examples describe the purification of acetic acid containing hydrogen iodide and methyl iodide.