The reactions occurring during the refining of toluene with concentrated sulphuric acid. the heterogenous sulphonation of toluene and of 2‐ and 3‐methylthiophens

Abstract Results have been obtained which show that the quantities of 2‐ and 3‐methylthiophens sulphonated in the two‐phase refining process of toluene increase almost linearly with rise in acid concentration. The 2‐isomer is sulphonated at a faster rate than the 3‐isomer. The loss of toluene, associated with a given removal of methylthiophens, can be reduced to a minimum by use of 92%—94% w/w sulphuric acid, but such a procedure would be inefficient in other respects.