PROCESS FOR PREPARING 1,2-BENZOISOTHIAZOLIN-3-ONES

摘要

Sodium sulfide hydrate is at least partially dehydrated by heating with N-methyl 2-pyrrolidone. 2-Chlorobenzamide is added to the mixture which is heated further. The mixture is cooled and treated with aqueous hydrogen peroxide to give the sodium salt of 1,2-benzisothiazolin-3-one in good yield. Acidification if desired gives rise to the free 1,2-benzisothiazolin-3-one.

主权项

1. A process for preparing a compound of Formula I where R is selected from the group consisting of H or C1-C8 straight or branched chain alkyl said process comprising the steps of i) heating a mixture of sodium sulfide hydrate and N-methyl-2-pyrrolidone ii) distilling from said mixture water and optionally at least a portion of said N-methyl-2-pyrrolidone to leave water-depleted sodium sulfide and optionally water and/or N-methyl-2-pyrrolidone, iii) reacting at least one benzamide substituted at the 2-position with a group selected from the group consisting of —Cl, —Br, —F, —NO2, —CN, sulfonate, sulfonate ester such as tosyl, mesyl and benzenesulfonyl, carbonyl groups such as carboxylic acid and ester functionality such as —COOR′ where R′ is C1-6 branched or straight chain alkyl, trichloromethyl or trifluoromethyl and —OR″ is C1-6 branched or straight chain alkyl and optionally substituted at the amide functionality by a C1-C8 straight or branched chain alkyl group with the water-depleted sodium sulfide and iv) subjecting the product of step iii) to oxidative cyclisation.