Chen G Yu

US Patent:

42595215, Mar 31, 1981

Filed:

Oct 9, 1979

Appl. No.:

6/083186

Inventors:

John Kazan - Bridgewater NJ
Chen S. Yu - Middlesex NJ

Assignee:

American Cyanamid Company - Stamford CT

International Classification:

C07B 2000

US Classification:

562401

Abstract:

An improved process is disclosed for resolving DL-mandelic acid using optically active 2-amino-1-butanol. The known process comprises: (a) reacting DL-mandelic acid with optically active 2-amino-1-butanol in an alcohol or alcohol mixture to form an optically active mandelate salt; (b) cooling and recovering the salt; (c) mixing the salt with water and distilling off any residual alcohol; (d) acidifying the mixture with a mineral acid; and (e) cooling and recovering the optically active mandelic acid. The improvement comprises: recycling the mother liquor of step (b) into step (a); heating the mother liquor with an alkalizing agent to obtain a racemic solution; neutralizing the racemic solution to precipitate an alkali or alkaline earth metal salt; separating the metal salt; recycling the mother liquor from the separating step into step (a); and recycling the mother liquor from step (e) into step (c).

US Patent:

42608155, Apr 7, 1981

Filed:

Oct 9, 1979

Appl. No.:

6/083183

Inventors:

John Kazan - Bridgewater NJ
Chen S. Yu - Middlesex NJ

Assignee:

American Cyanamid Company - Stamford CT

International Classification:

C07B 2000

US Classification:

562401

Abstract:

A process for preparing a solution of DL-mandelic acid is disclosed. The process consists essentially of heating a solution consisting essentially of an optically active 2-amino-1-butanol mandelate and an alkalizing agent, with or without an alcohol solvent; neutralizing the resulting solution with a mineral acid or a mineral acid salt to precipitate an alkali or alkaline earth metal salt; separating the metal salt; and recovering the solution of DL-mandelic acid.