Hydrogen Sulfide → 2-Methyl-4,5-trimethylene-4-isothiazolin-3-one

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Reaction Conditions

Reaction Steps

5 g of 2-(N-methylcarbamoyl)cyclopentanone are dissolved in 100 cc of anhydrous ethanol saturated by anhydrous HCl gas. Into this solution, cooled to 0° C., there is passed for 5 hours a current of H2S and HCl gas. After having de-gassed the reaction mixture, there is added, with agitation, 0.5 molar equivalent of sodium metaperiodate fixed on acidic alumina (Al2O3), the temperature being maintained at 0° C. One-half hour later the reaction mixture is filtered. The filtrate is concentrated under reduced pressure. The residue is taken up in a 1:1 mixture of ethyl acetate and water. The pH of the aqueous solution is then adjusted, with agitation, to about 6 by the addition of sodium bicarbonate. The aqueous phase is decanted, then extracted with chloroform. The chloroform phase is then dried on sodium sulfate, and concentrated. On evaporation, an amorphous white solid, melting at 111° C. is obtained. Mass spectroscopy gives the expected relative peak at m/e: 155 (C7H9NOS)

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