Potassium Carbonate → HCID 5046240, compound

Participants

Reaction Conditions

Reaction Steps

Dimethylformamide (DMF), 100 ml, was poured into a 4 l indented 3 neck round bottom flask equipped with a nitrogen bubbler and an overhead stirrer (glass shaft, teflon Paddle). The hot 2-bromo-2-methylpropionic acid was then added to the flask through a powder funnel. The flask and the funnel were rinsed with 4×100 ml portions of DMF and were added to the reaction flask. A thermometer was placed in the third neck and the stirred solution was cooled under an atmosphere of nitrogen to -45° C. by placing it in a methanol/water 50:50 dry ice bath. The thermometer was removed and potassium carbonate 250.21 g (1.810 mol, 100 M %) was added through a powder funnel over a 5 minute period. The reaction mixture warmed to -40° C. but there was no apparent reaction and the carbonate did not dissolve. The solution was diluted with 200 ml DMF and potassium thioacetate 407.10 g (3.564 mol, 196.9 M %) was added through a powder funnel over a 5 minute period. The powder funnel was rinsed with 300 ml DMF which was added to the reaction solution which had warmed to -30° C. The reaction was allowed to slowly warm up as the dry ice was consumed. When the reaction temperature reached -10° C. the reaction began to bubble. The reaction was allowed to warm slowly to room temperature and was stirred under nitrogen for 22 hours. Water, 2 1, and 500 ml concentrated hydrochloric acid were mixed and cooled to 9° C. in an ice bath. The tan colored reaction mixture was slowly poured into the stirred acid solution over a 25 minute period. The reaction flask was washed with 2×100 ml portions of deionized water which was added to the acid solution (10° C., pH 1.5). The acid solution was poured into a 4 l separatory funnel and was extracted sequentially with 3×500 ml and 1×250 ml ethyl acetate. Each organic extract was washed with a separate 100 ml portion of saturated sodium chloride solution. The organic extracts were combined and dried over 400 g of anhydrous sodium sulfate. The solution was filtered through a fluted filter paper into a 2,000 ml round bottom flask and the solvent was removed in two portions under reduced pressure on the rotary evaporator. The sodium sulfate was washed with 3×100 ml portions of ethyl acetate which were filtered into the 2,000 ml round bottom. After all the solvent was removed, the rotary evaporator was connected to the high-vacuum pump and the water bath was heated to 100° C. The product was removed after 1.5 hour to afford 241.07 g of the crude brown oily product which crystallized on cooling. The crystalline mass was placed under high vacuum at 22° C. for 16 hours to afford 240.51 g (82% yield) of the crude crystalline 2-acetylthio-2-methylpropanoic acid.

Provenance & Evidence