The proton and carbon NMR spectra of nine 4-X-diphenyl sulphides (series l), seven 4-X-4'-N02-diphenyl sulphides (series 2) and eight 4,4'-X2-diphenyl sulphides (series 3) have been obtained. Correlation of the I3C chemical shifts with the appropriate substituent chemical shifts (SCS) for monosubstituted benzenes (Lynch plots) show an enhancement of substituent effect at C-1 (carbon para to the substituent) in series 1 and 2, but not in series 3. The carbons of the unsubstituted ring in series 1 also correlate with C,-SCS, with slopes of less than unity; correlation for C-1' has a negative slope. Dual substituent parameter (DSP) correlations of the 13C chemical shifts with u,/u$ are good to excellent for all the carbons of series 1 compounds, except those ortho to the substituent X. The carbons meta to the substituent X correlate well, but with negative values for pI and pR, although showing a scattered Lynch plot. Similar correlations are found with some carbon shifts in series 2, and with C-1 shifts in series 3.It is concluded that (a) reverse resonance effects are operative at the position meta to the variable substituent by virtue of the sulphur substituent ortho to that carbon; (b) there is transmission of inductive (field) and resonance effects from one aryl ring to the other, except when both rings carry substituents of the same electronic character (series 3); (c) there is some evidence for m-polarization in the unsubstituted phenyl ring of series 1 compounds.

The proton and carbon NMR spectra of nine 2-substituted diphenyl sulphides (SZX), seven 3-substituted diphenyl sulphides (S-3-X), nine 2-substituted diphenyl sulphones (S02-2-X), nine hubstituted diphenyl sulphones (SO2-% X) and nine 4-substituted-2',6'-dimethyldiphenyl sulphides (Me2-S-4-X) were obtained. Correlations of the 'H and I3C chemical shifts were made with benzene substituent-induced chemical shifts (Lynch plots) and Hammett and dual-substituent parameters and the results were compared with those of 4-substituted diphenyl sulphides (S4-X) and sulphones (S02-4-X). The main conclusions are as follows: (i) the transmission of the substituent effects in substituted diphenyl sulphides decreases in the order S-4-X x S-2-X > Me,SQX > S-3-X; (ii) the inductive effects are transmitted to a larger extent than the resonance effects to the unsubstituted ring in Isubstituted diphenyl sulphides, while the reverse trend is observed in other substituted diphenyl sulphides; (iii) in 2-methoxy-, khloro-, 2-bromo-and 2-nitrodiphenyl sulphides, an increase in the size of the substituent causes an upfield shift for H d ascribable to the repulsion between the lone pairs of electrons on the sulphur and the substituent and its influence on the conformation; (iv) the diminished transmission of substituent effects to the remote rings in 4-substituted 2',6'-dimethyldiphenyl sulphides is probably due to the orthogonal orientation of the rings; and (v) the signal due to the H-6 of 2-substituted diphenyl sulphones suffers a downfield shift with an increase in the size of the substituent, this being ascribable to the increasing steric interaction between the 2-substituent and the sulphonyl oxygen and consequent changes in the conformation.

The proton and carbon NMR spectra of nine 4-Xdiphenyl sulphoxides, seven 4-X-4'-N02diphenyl sulphoxides, eight 4,4'-X,diphenyl sulphoxides, eight 4X-diphenyl sulphones, seven 4-X4'-N02diphenyl sulphones and eight 4,4'-X,diphenyl sulphones have been obtained. Correlation of the ' ' C 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 I3C chemical shifts with al/aao are excellent for carbons meta (C-2,6) and para (C-1) to the substituent. The trends for the series sulphides, sulpboxides, 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.

No abstract

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.