Ultraviolet absorption spectra of alkyl benzyl sulphides. Conformational analysis of alkyl aryl sulphides

Abstract

The u.v. spectra of a series of alkyl benzyl sulphides are consistent with the presence of a band which arises from mixed charge-transfer and locally excited states of very weakly π-conjugated sulphide and aryl groups. The u.v. spectra of alkyl aryl sulphides (including thioanisole) are consistent with the presence of one preferred conformation in which the alkylthio group is partially twisted out of plane of the aryl ring. p–π Overlap is sufficiently reduced to allow d-orbital participation to be detected.