Process for the preparation of 6-methyl-3,4-dihydro-1,2,3-oxathiazin-4-one 2,2-dioxide and for the purification thereof

US4806639A · kind A · utility

Assignee

• Hoechst GmbH · DE

Inventors

• Dieter Reuschling · Rockenberg, DE
• Adolf Linkies · Frankfurt, DE
• Walter Reimann · Hofheim, DE
• Otto E. Schweikert · Kelkheim, DE
• Karl E. Mack · Wiesbaden, DE

Key dates

• Filing date: Aug 29, 1986
• Grant date: Feb 21, 1989
• Expiry date: Aug 29, 2006

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07D291/06
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

6-Methyl-3,4-dihydro-1,2,3-oxathiazin-4-one 2,2-dioxide is prepared by cylcizing acetoacetamide-N-sulfonic acid or its salts with an at least approximately equimolar amount of SO.sub.3 in the presence of a water-immiscible, inert organic solvent and, if appropriate, also an inert, inorganic solvent. In the event that an equimolar amount of SO.sub.3 is employed, working up is effected by adding aqueous sulfuric acid when the cyclization reaction is complete; in the event that the amount of SO.sub.3 employed is more than equimolar, the 6-methyl-3,4-dihydro-1,2,3-oxathiazin-4-one 2,2-dioxide obtained in the form of the SO.sub.3 -adduct is hydrolyzed by adding water or ice, whereby sulfuric acid is formed from the SO.sub.3 combined in the SO.sub.3 -adduct. The inert, organic solvent is then removed from the resulting multi-phase mixture by distillation, and the 6-methyl-3,4-dihydro-1,2,3-oxathiazin-4-one 2,2-dioxide is obtained in a pure form from the remaining aqueous sulfuric acid phase by crystallization. Additionally, quite generally, crude 6-methyl-3,4-dihydro-1,2,3-oxathiazin-4-one 2,2-dioxide is purified by recrystallization from aqueous sulfuric acid. The non-toxic salts of 6-m…