Nuclear Quadrupole Resonance and Stereochemistry I. α – Chloro ethers

Abstract
35Cl nuclear quadrupole resonance spectra of cyclic α‐chloro ethers of known configuration are presented. The resonance frequencies of chlorine atoms in equatorial positions are in every case some 2.5 MHz higher than those of corresponding chlorine atoms in axial positions. Similar results are obtained for open‐chain trichloromethyl ethers and the effect is sufficiently well‐defined to distinguish between configurational isomers and establish their conformation. These results may be rationalised in terms of a model in which the lone‐pair electrons on the oxygen atom hyperconjugate with the electrons of the CCl bond.