Haloacetic acid method for preparing

Claim 1

IN THE PROCESS FOR PREPARING A 2R-2-R1-4-R2-3,5THIAMOPHOLINEDIONE WHEREIN R IS LOWER ALKYL, R1 IS SELECTED FROM THE CLASS CONSISTING OF LOWER ALKYL AND MONONUCLEAR ARYL, R2 IS SELECTED FROM THE CLASS CONSISTING OF HYDROGEN, LOWER ALKYL, LOWER ALKENYL, MONONUCLEAR ARYLLOWER ALKYL AND MONONUCLEAR ARYL-LOWER ALKENYL, THE STEPS COMPRISING CONTACTING A MIXTURE OF A-R-A-R1-A-MERCAPTOACETIC ACID AND A-R-A-R1-A-MERCAPTOACETAMIDE WITH MONOHALOACETIC ACID AND SUBSEQUENTLY ACIDIFYING THE REACTION MIXTURE OF FROM A PRECIPITATE CONSISTING OF A-R-A-R1-THIODIACETIC ACID AND THE CORRESPONDING MONOAMIDE, SEPARATING SAID THIODIACETIC ACID AND SAID MONOAMIDE BY FRACTIONAL CRYSTALLIZATION FROM AN ORGANIC SOLVENT, CONTACTING THE A-R-A-R1-THIODIACETIC ACID OBTAINED BY SAID FRACTIONAL CRYSTALLIZATION WITH A COMPOUND SELECTED FROM THE CLASS CONSISTING OF AMMONIA AND LOWER ALKYL PRIMARY AMINE, LOWER ALKENYL PRIMARY AMINE, MONONUCLEAR ARYL-LOWER ALKYL PRIMARY AMINE AND MONONUCLEAR ARYL-LOWER ALKENYL PRIMARY AMINE, AND THEN PYROLYZING THE PRODUCT OF THE LAST MENTIONED CONTACTING TO 2-R2-R1-4-R3-3,5-THIAMORPHOLINEDIONE.