INTRODUCTIONAzo-dyes containing chlorosulfonyl group are important intermediates of dyes for use in instant photography[1] and sulfonamido-containing disperse dyes[2].Chlorination of azo-dyes containing sulfonic acid group to the corresponding sulfonyl chlorides is an important method for the synthesis of this kind of compounds.Many approaches to performing the aforementioned conversion have been developed.One approach involves the use of chlorosulfonic acid[3],but the reagent is difficult to handle and can not be recycled.Another approach involves using phosphorous pentachloride as chlorination reagent[4], however,it is too expensive to be scaled up.The third one uses phosphoryl chloride-N,N-dimethylacetamide(POCl3-DMA)[2],in which acetonitrile and sulfolane are used as reaction medium[2],but a large amount of DMA is used and sulfolane can not be recycled easily due to its high boiling point.