Aromatic sulphonation. Part 66. Sulphonation of some biphenyl derivatives

Abstract

The sulphonation of a number of biphenyl derivatives, viz. 2,2′-Me₂, 3,3′-Me₂, 4,4′-Me₂, 3,5-Ph₂, 2,2′-(SO₃H)₂, 2,4′-(SO₃H)₂, 4,4′-(SO₃H)₂-, 2,2′-SO₂-, 2,2′-(NO₂)₂, and 2,4,6-(NO₂)₃ in sulphuric acid at 25 °C has been studied; product analysis was by multicomponent ¹H n.m.r. analysis. Sulphonation of 2,2′-dimethylbiphenyl resulted in a 5 : 19 : 76 mixture of the 3,3′-, 3,5′-, and 5,5′-disulphonic acids. Further sulphonation yielded the 3,3′,5,5′-tetrasulphonic acid. 3,3′-Dimethylbiphenyl yielded a 52 : 48 mixture of the 4,4′- and 4,6′-disulphonic acid. Further sulphonation of each of the disulphonic acids yielded the 4,4′,6,6′-tetrasulphonic acid. 4,4′-Dimethylbiphenyl yielded a 34 : 66 mixture of the 2,3′- and 3,3′-disulphonic acids. Further sulphonation of the latter yielded the 3,3′,5,5′-tetrasulphonic acid. 1,3,5-Triphenylbenzene gave exclusively the 4′,4″,4‴-trisulphonic acid, which could not be further sulphonated. Biphenyl-2,4′- and -4,4′-disulphonic acid both yielded the 2,2′,4,4′-tetrasulphonic acid, which is not obtained from biphenyl-2,2′-disulphonic acid. Dibenzothiophen 5,5-dioxide gave the 3,7-disulphonic acid. 2,2′-Dinitrobiphenyl yielded the 4,4′-disulphonic acid, but 2,4,6-trinitrobiphenyl only a mixture of monosulphonic acids which contained 88% of the 4′-acid.