Solvent effects in nuclear magnetic resonance spectroscopy. Part XIII. Solvent shifts induced by benzene in some α,β-unsaturated compounds. An aid to the determination of stereochemistry

Abstract

The solvent shifts (Δ=δ_CCl4–δ_C6H6 or δ_CCl4–δ_C6D6 p.p.m.) of proton resonances in some α,β-unsaturated acids, esters, nitriles, halides, and nitro-compounds have been determined. In general preferential shielding in benzene solution of the protons trans to the polar substituent is observed. The solvent shifts are therefore of assistance in the determination of stereochemistry in such compounds. The solvent shift method is used to confirm previous stereochemical assignments in geranic and phytenoic acids.