Process for the preparation of unsaturated aliphatic carboxylic acids

摘要

The invention relates to a process for the preparation of unsaturated aliphatic carboxylic acids by thermal cracking of the polymeric intermediate product ("polyester") which is formed in the catalytic reaction of aldehydes or ketones with ketene. The reaction mixture containing polyester is heated with water, and the polyester is then isolated and subjected to cracking. Or the polyester is first isolated and then heated with water and finally subjected to cracking. In both cases the temperature when the mixture is heated with water is the same as the boiling point, or is less than 40 DEG C. below the boiling point, of the aqueous mixture.