Transmission of polar effects. Part 20. Ionisation and esterification, with diazo-diphenylmethane, of a series of 8-(2-substituted phenyl)-1-naphthoic and 2- and 4-(8-substituted 1-naphthyl)benzoic acids

Abstract

The pK_a-values of a series of 8-(2-substituted phenyl)-1-naphthoic and 2- and 4-(8-substituted 1-naphthyl)benzoic acids have been determined in 80%(w/w) 2-methoxyethanol-water at 25 °C. The rate coefficients for the esterification of these acids with diazodiphenylmethane have been measured in 2-methoxyethanol at 30 °C. For the reactivity of the 2- and 4-(8-bromo-1 -naphthyl)benzoic acids, reversed dipolar substituent effects were observed in both reactions. The reactivities are quantitatively accounted for by either comparison with the results for the 2- and 4-bromobenzoic acids or Kirkwood–Westheimer calculations. For the reactivity of the 8-(2-substituted phenyl)-1-naphthoic acids, both normal and reversed dipolar substituent effects were observed in the ionisation reaction; whereas, for the esterfication reaction, only normal effects were shown.