Additivity of substituent effects on the acidity of alcohols

Abstract

Using Fourier Transform Ion Cyclotron Resonance Spectrometry, we have determined the gas-phase acidities (GA) of 1-phenylethanol, diphenylmethanol and triphenylmethanol. Combining these results with the available experimental data for other alcohols, we obtained three sets of experimental acidities for the families (CH3)nC-OH, (CF3)nC-OH and PhnC-OH (n = 1-3) as well for some other α-substituted alcohols combining these substituents. GA values for these alcohols were studied at the B3LYP/6-311 + G(d,p), MP2/6-311 + G(d,p), G3(MP2) and G3 levels. This allowed the prediction of a number of GA values for other alcohols. We also developed an empirical method for the estimation of these magnitudes and used it to predict the cases wherein simple additivity of substituent effects would break down. © 2013 John Wiley & Sons, Ltd.