Solvent effects in nuclear magnetic resonance spectroscopy. Part V. Solvent shifts in 11-oxo-steroids. The geometry of a benzene–ketone complex

Abstract

The chemical shifts of a number of proton resonances in sixteen 11-oxo-5α-steroids have been determined in carbon terachloride, chloroform, benzene, and pyridine solutions. The Johnson–Bovey calculations for the magnetic field around a benzene ring have been used to indicate that the benzene solvent shifts (relative to carbon tetrachloride) induced in 5α-androstan-11-one are due to an association between benzene and the oxo-group. The modifications, due to additional polar substituents, or solvent shifts which are characteristic of an isolated carbonyl function are discussed.