NMR Study of Substituent Effects in 4-Substituted and 4,4'-Disubstituted Diphenyl Sulphoxides and Sulphones

Article abstract of DOI:10.1002/mrc.1260270412

The proton and carbon NMR spectra of nine 4-X-diphenyl sulphoxides, seven 4-X-4'-NO2-diphenyl sulphoxides, eight 4,4'-X2-diphenyl sulphoxides, eight 4-X-diphenyl sulphones, seven 4-X-4'-NO2-diphenyl sulphones and eight 4,4'-X2-diphenyl sulphones have been obtained.Correlation of the 13C chemical shifts with the appropriate substituent chemical shifts (SCS) for monosubstituted benzenes (Lynch plots) does not show the enhancement of substituent effect at C-1 (para to the substituent) that was a feature of the corresponding sulphides studied earlier.Dual substituent parameter (DSP) correlations of the 13C chemical shifts with ?_I/?_R⁰ are excellent for carbons meta (C-2,6) and para (C-1) to the substituent.The trends for the series sulphides, sulphoxides, sulphones, where a decreasing response to the change of substituent is the general observation, are discussed.Changes of molecular conformation may also influence the transmission of electronic effects to the ring not carrying the variable substituent X. KEY WORDS 1H NMR 13C NMR Diphenyl sulpoxides Diphenyl sulphones Substituent effects