Abstract Aryl substituent effects upon the rate constants for the esterification of a series of 1- arylethanols in trifluoroacetic acid are in accordance with a reverse A AL 1 mechanism, for which the Hammett reaction constant ϱ=− 3.69 has been determined by correlation with σ+ substituent constants. The rates of reaction are ca. 50-fold faster than those for corresponding benzyl alcohols which bear an electron-donating aryl substituent and ...