RECOVERY OF ANHYDROUS ALKANESULPHONIC ACIDS

摘要

The present invention is a process for removing water from an alkanesulfonic acid such as methanesulfonic acid or ethanesulfonic acid by mixing an azeotropic excess of a phenolic compound with water and the alkanesulfonic acid, then boiling off substantially all of the water, and leaving as a remnant substantially all the alkanesulfonic acid and some of the phenol. This process is particularly useful for recycling an alkanesulfonic acid for a reaction which requires the phenolic compound as one of the reagents. One such reaction is the alkanesulfonic acid catalyzed condensation reaction of a phenolic compound with an alpha -haloketone to form a chlorinated intermediate of a dihydroxy- alpha -alkylstilbene such as 4,4'-dihydroxy- alpha -alkylstilbene (DHAMS).