To obtain a dicarboxylic acid in high yield by subjecting a long-chain saturated dicarboxylic acid and an unsaturated fatty acid to the cleavage of fatty acid and the oxidative ozonolysis, dissolving a mixture of medium-chain carboxylic acids in a short chain alcohol ester of the above carboxylic acid while heating the reaction product of the above process, cooling and recrystallizing the reaction product and removing the residual solvent.
A diamidodicarboxylic acid corresponding to a bis-dicarboxylic acid diamide is produced by the fatty acid cleavage of a 6-21C long-chain unsaturated fatty acid. The product is subjected to oxidative ozonolysis, the reaction product is heated and dissolved in a carboxylic acid and a short-chain alcohol ester of a 6-12C carboxylic acid used as a recrystallization solvent, the solution is cooled as far as possible to a temperature to cause the crystallization of the dicarboxylic acid, the crystal is separated by cooling in the form of a crystal sludge containing the residual recrystallization solvent containing the dissolved component, the crystal sludge is washed and finally the residual washing solvent is removed to obtain the crystallized dicarboxylic acid.
HEGWEIN KATJA
VOLKHEIMER JUERGEN
