Studies on the sulphonation of anthracene. Part 1. Sulphonation in neutral or basic solvents

Abstract

The reaction of anthracene with chlorosulphuric acid produces anthracene-1-, -2-, and -9-sulphonic acids, a mixture of anthracenedisulphonic acids, 9-chloroanthracene, 9, 9′-bianthryl, and anthracene polymers, but the yield and formation of each depends on the experimental conditions and on whether chloroform, dioxan, or a mixture of pyridine and isoparaffin is used as solvent. Sulphonation also occurs with the pyridine–sulphur trioxide complex in isoparaffin. In basic systems, reversible suphonation at the 9-position is accompanied by irreversible sulphonation at the 1- and 2-positions. The formation of dimeric and polymeric species in some of these reactions is believed to occur via the anthracene proton complex.