6-methyl-2,2-dioxooxathiazin-4-one

Conditions: temp:40.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Different quantities of water were added to 150 ml of acetone. 10.1 g (0.1 mol) of acetoacetamide and 69 g (0.5 mol) of finely powdered, dry K2CO3 were added to each of these mixtures. 15.3 g (0.15 mol) of sulfuryl fluoride gas were then passed in--initially at room temperature. The temperature of the reaction mixture increased to about 40° C. during this process. The mixture was stirred for a further 2 hours and the product was filtered off with suction. The filter residue contained Acesulfam K, which was found to be identical to a reference sample by thin layer chromatography (silica gel, solvent system: ethyl acetate/glacial acetic acid 5:1). The filter residue was introduced into a mixture of excess hydrochloric acid with ice and extracted with ethyl acetate. The ethyl acetate extract was dried over Na2SO4 and evaporated in vacuo. Crystalline 6-methyl-3,4-dihydro-1,2,3-oxathiazin-4-one 2,2-dioxide was obtained and this was converted to Acesulfam K with methanolic KOH. The results are collated in the table which follows. In the last experiment listed in the table, the K2CO3 was used as a 50% aqueous solution. initially at room temperature the product was filtered off with suction The filter residue was introduced into a mixture of excess hydrochloric acid with ice extracted with ethyl acetate The ethyl acetate extract was dried over Na2SO4 evaporated in vacuo

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A mixture, with a total volume of 50 ml, of 40.4 g (0.4 mol) of triethylamine and liquid SO2 was added dropwise, at -10° C., to a solution of 20.2 g (0.2 mol) of acetoacetamide and 23.7 g (0.2 mol) of chlorosulfonyl fluoride in 70 ml of liquid SO2. The mixture was stirred for 2 hours and the liquid SO2 was then distilled off, a vacuum being applied at the end. The residue was added dropwise to 400 ml of aqueous NaOH, acidified with concentrated hydrochloric acid, with ice-cooling, and extracted with ethyl acetate. After treatment of the ethyl acetate phase with animal charcoal and Na2SO4, the extract was evaporated in vacuo. 15 g (approx. 20% of theory) of 6-methyl-3,4-dihydro-1,2,3-oxathiazin-4-one 2,2-dioxide were obtained. the liquid SO2 was then distilled off The residue was added dropwise to 400 ml of aqueous NaOH cooling extracted with ethyl acetate After treatment of the ethyl acetate phase with animal charcoal and Na2SO4, the extract was evaporated in vacuo

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: cyclizing the acetoacetamide derivative; the process comprises using, as the sulfamic acid derivative in stage (a), a salt of sulfamic acid which is at least partly soluble in the inert organic solvent employed, cyclizing the acetoacetamide-N-sulfonate formed in this stage or the free acetoacetamide-N-sulfonic acid in stage (b) by the action of an at least approximately equimolar amount of SO3, if appropriate in an inert inorganic or organic solvent, to give 6-methyl-3,4-dihydro-1,2,3-oxathiazin-4-one 2,2-dioxide, and then, if desired, also neutralizing with a base, in a stage (c), the product obtained here in the acid form. formed in this stage

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: cyclizing the acetoacetamide derivative; the process comprises using, as the sulfamic acid derivative in stage (a), a salt of sulfamic acid which is at least partly soluble in the inert organic solvent employed, cyclizing the acetoacetamide-N-sulfonate formed in this stage or the free acetoacetamide-N-sulfonic acid in stage (b) by the action of an at least approximately equimolar amount of SO3, if appropriate in an inert inorganic or organic solvent, to give 6-methyl-3,4-dihydro-1,2,3-oxa-thiazin-4-one 2,2-dioxide, and then, if desired, also neutralizing with a base, in a stage (c), the product obtained here in the acid form. formed in this stage