Studies on the sulphonation of anthracene. Part 2. Sulphonation in acetic acid and related solvents
Abstract
The sulphonation of anthracene with either sulphuric acid and acetyl chloride or chlorosulphuric acid and acetic acid gives anthracene-1- and -2-sulphonic acids, a mixture of anthracenedisulphonic acids, and smaller amounts of 9-chloroanthracene and its monosulphonic acids. The proportion of the 2-sulphonic acid and the disulphonic acids formed increases with increasing temperature. A related reaction with sulphuric acid and acetic anhydride gives the 1-, 2-, and 9-sulphonic acids along with a mixture of disulphonic acids. The nature of the sulphonating reagents involved in these reactions has been examined by 1H n.m.r. spectroscopy.