SULFUR-TRIOXIDE SULFONATION OF DIPHENYL ETHER, DIPHENYL SULFIDE, DIBENZO[B,E][1,4]DIOXIN, AND XANTHENE

The sulfur trioxide sulfonation of diphenyl ether (1), diphenyl sulfid e (2), and the related tricyclic dibenzo[b,e][1,4]dioxin (3) and xanth ene (4) has been studied. The substrates I and 2 both yield initially the 4-sulfonic acid derivative (4-S) and subsequently the 4,4'-S-2. In a large excess of 104.5 wt-% H2SO4 the further sulfonation of 1-4,4'- S-2 gave the 1-2,4,4'-S-3 and subsequently Some 1-2,4,2',4'-S-4. Sulfo nation of the dibenzodioxin 3 with 4.0 mol-equiv. of SO3 gave the 2-S derivative, whereas with 12.0 mol-equiv. of SO3 a mixture of the 2,7-S -2 and 2,8-S-2 was obtained in yields of 57 and 43%, respectively. Sul fonation of xanthene (4) with 4.0 mol-equiv, of SO3 yielded the 2,7-S- 2 derivative.