Sulfonation of binaphthyl derivatives

Sulfonation of 1- and 2-phenylnaphthalene, 1, 1'-binaphthyl, 2, 2'-dihydroxy, 2, 2'-dimethoxy and 2, 2'-dimethoxy derivatives of 1, 1'-binaphthyl with SO3 in dichloromethane as solvent was studied. Sulfonation of 1-phenylnaphthalene and 1, 1'-binaphthyl leads to substitution at the 4-position and subsequently at the 6- and 7-position. Upon sulfonation the more planar 2-phenylnaphthalene and 2, 2'-binaphthyl both give initially the 8-sulfonic acid derivative and subsequently a mixture of 8, 4'- and 8, 8'-disulfonic acid derivative. Sulfonation of 2, 2'-dimethoxy-1, 1'-binaphthyl gives initiall the 3- and 6-sulfonic acid derivatives in an isomer ratio of aproximately 13: 87, monosulfonation of 2, 2'-dimesyloxy-1, 1'-binaphthyl gives the 5- and 6-sulfonic acid derivative in a ratio of 58:42. Sulfonation of 2, 2'-dihydroxy-1, 1'-binaphthyl gives initially the 5- and 6-solfonic acid derivative, the ratio of which increases upon increasing the amount of SO3 employed from approximately 35:65 on using ��1.0 mol. of SO3 to approximately 62:38 on using > 6.0 mol. of SO3.