ON THE POSITIONAL REACTIVITY ORDER IN THE SULFONATION OF BIPHENYL AND A SERIES OF OXY DERIVATIVES

The sulfonation of biphenyl (1) and its 2- and 4-methoxy, 3,3'- and 4,4'-dimethoxy, and 4,4'-dimesyloxy derivatives with sulfur trioxide in dichloromethane as solvent at 22 degrees C has been studied. Sulfonation of biphenyl leads to the subsequent formation of the 4-sulfonic acid (4-S), 4,4'-S-2, 2,4,4'-S-3 and traces of 2,4,2',4'-S-4. The sulfonation of the oxy substituted biphenyls also occurs successively in the one phenyl and then in the other. In case of the asymmetrical 2- and 4-methoxybiphenyl the substitution starts in the anisyl moiety

THE POSITIONAL REACTIVITY ORDER IN THE SULFUR-TRIOXIDE SULFONATION OF BENZENE AND NAPHTHALENE DERIVATIVES CONTAINING AN ELECTRON-WITHDRAWING SUBSTITUENT

The reaction of sulfur trioxide with derivatives of benzene and naphthalene containing an electron-withdrawing substituent, viz.-SO3H, -SO(2)Ph, -NO2, -CHO, -COPh, -CO2H, and -CO(2)Me, in dichloromethane as solvent at approximate to 22 degrees C has been studied by analysis of the resulting mixtures of the sulfo derivatives with H-1-NMR. The initial sulfonation of the benzene derivatives yields the corresponding 3-sulfonic acid (3-S) and subsequently, with the exception of nitrobenzene and methyl benzoate, small amounts of 3,5-S-2. Benzenesulfonic acid in addition undergoes sulfonylation giving 3,3'-di- and 3,5,3'-trisulfodiphenyl sulfone. Monosulfonation of naphthalene-1-S yields the 1,5-S-2, 1,6-S-2 and 1,7-S-2 derivatives in a ratio of 71:20:9. On using a large excess of SO3, the eventual products are 1,3,5-S-3, 1,3,6-S-3 and 1,3,5,7-S-4. Monosulfonation of naphthalene yields 5-S, 6-S, 7-S and 8-S in a 55:9:6:30 ratio, that of 1-benzoylnaphthalene 5-S, 6-S and 7-S in a ratio of 83:11:6, and 1-nitronaphthalene only the 5-S. The absence of peri sulfonation with 1-sulfo-, 1-benzoyl- and 1-nitronaphthalene is due to prohibitive steric hindrance. 1-Naphthoic acid and its methyl ester upon SO, sulfonation and aqueous work-up both yield 5-and 8-sulfonaphthoic acid in a ratio of 65:35 and 77:21, respectively. The initially formed peri-substituted product is the intramolecular anhydride of 8-sulfo-1-naphthoic acid (5). All the 2-substituted naphthalenes yield 5-S and 8-S upon SO3 sulfonation of which the former sulfo isomer is far in excess. The positional reactivity orders for the SO3 sulfonation of the monosubstituted naphthalene derivatives are discussed in terms of the difference in reactivity of the alpha- and beta-positions, and the steric and electronic effects of the deactivating substituent

ON THE POSITIONAL REACTIVITY ORDER IN THE SULFONATION OF PHENYL-SUBSTITUTED AND NAPHTHYL-SUBSTITUTED NAPHTHALENES WITH SO3

The sulfonation of 1- and 2-phenylnaphthalene, 1,1'- and 2,2'-binaphthyl, and that of the 2,2'-dihydroxy, 2,2'-dimethoxy and 2,2'-dimesyloxy derivatives of 1,1'-binaphthyl with SO3 in dichloromethane as solvent was studied at 22 +/- 2-degrees-C. Sulfonation of 1-phenylnaphthalene and 1,1'-binaphthyl leads to substitution at (each of) the alpha-naphthyl moieties, initially at the 4-position and subsequently at the 6- and 7-position, in a ratio of approximately 8:92 and 14:86, respectively. Upon sulfonation the more planar 2-phenylnaphthalene and 2,2'-binaphthyl both give initially the 8-sulfonic acid derivative (8-S) and subsequently a mixture of 8,4'-S2 and 8,8'-S2, respectively; their further sulfonation affords mixtures of the 4,8,4'-S3 + 6,8,4'-S3 and of the 4,8,8'-S3 + 6,8,8'-S3, respectively, both in an isomer ratio of approximately 19:81. Sulfonation of 2,2'-dimethoxy-1,1'-binaphthyl gives initially the 3-S and 6-S derivatives in an isomer ratio of approximately 13:87 subsequently the 3,6'-S2 and 6,6'-S2 derivatives and eventually the 3,6,4',6'-S4 and 4,6,4'6'-S4 derivatives. Monosulfonation of 2,2'-dimesyloxy-1,1'-binaphthyl gives the 5-S and 6-S in a ratio of 58:42. With a large excess of SO3, 4,6,4',6'-S4, 4,6,5',7'-S4 and 5,7,5',7'-S4 are eventually formed. Sulfonation of 2,2'-dihydroxy-1,1'-binaphthyl gives initially the 5-S and 6-S, the ratio of which increases upon increasing the amount of SO3 employed from approximately 35:65 on using less-than-or-equal-to 1.0 mol-equiv. of SO3 to approximately 62:38 on using > 6.0 mol-equiv. of SO3. Under the latter conditions the substrate species undergoing sulfonation is proposed to be the di-sulfated species 3