Toluene-2,4-disulfonyl chloride

Toluene-3,4-dithh>l. l,2-Dimercapto-4-methyl-benzene dithiol . C7H8S, mol wt 156-27. C 53.80%. H 5.16%. S 41-04%. Prepd from toluene-3.4-disulfonyl chloride with tin and hydrochloric add Mills, Clark, J. Chem. Soc. 1936, 178. 

However, the relative proportion of the o-isomer is never greater than 45%, even under the optimum conditions for the formation of this isomer the two isomers can be separated by freezing out the solid />-isomer (Chapter 2, p 17). The reaction generally affords a mixture of isomers,in which the yield of the p-isomer was substantially increased by addition of ammonium chloride and catalysts sometimes it was possible to isolate the /7-isomer as the sole product. The ratio of the o- to /7-isomers is dependent on the molar ratio of toluene and reagent. The isomers of toluenesulfonyl chloride can be prepared in a continuous process, and the reaction can be improved by use of an additive. Toluene 1 by heating with a large excess of chlorosulfonic acid at 140-150 °C affords mainly the 2,4-disulfonyl chloride 5 (Equation 2). ... 

---