Substituent and solvent effects on the 31P NMR chemical shifts of substituted diethyl phenylphosphonates

Abstract

The effect of various substituent groups on the 31P NMR chemical shifts of a series of substituted diethyl phenylphosphonates in acetone and ethanol has been observed. The linear correlation of the 31P chemical shifts with the Hammett σ constants was opposite to that expected on the basis of the electron-withdrawing ability of the substituent as was also found in the case of the acid analogs. Several hydrogen-bonding "mechanisms" are proposed to account for the solvent effect on the chemical shifts of both the esters and the acids. © 1971.