PROCESS FOR CONVERTING A HYDROXYCARBOXYLIC ACID, OR SALTS THEREOF, TO AN UNSATURATED CARBOXYLIC ACID AND/OR ITS ESTERS

摘要

A process for converting a hydroxycarboxylic acid or its salts into an unsaturated carboxylic acid and/or its esters is provided to convert an unsaturated carboxylic acid corresponding to the ammonium salts of a hydroxycarboxylic acid and to recirculate the ammonia induced by the acidification of the ammonium salts of the hydroxycarboxylic acid. A process for converting a hydroxycarboxylic acid or its salts into an unsaturated carboxylic acid and/or its esters comprises (a) a step for providing the solution including the ammonium salts of the hydroxycarboxylic acid; (b) a step for converting the ammonium salts of the hydroxycarboxylic acid into the hydroxycarboxylic acid and ammonium cation; and (c) a step for remaining a hydroxycarboxylic acid in the solution by separating the ammonium cation from the solution.