TRANSMISSION OF POLAR EFFECTS .18. IONIZATION AND ESTERIFICATION WITH DIAZODIPHENYLMETHANE OF A SERIES OF 3-(8-SUBSTITUTED-1-NAPHTHYL)PROPIOLIC AND (E)-3-(8-SUBSTITUTED-1-NAPHTHYL)ACRYLIC ACIDS AND THE ALKALINE-HYDROLYSIS OF THE METHYL-ESTERS OF THE FORMER SERIES

The pKa values of 3-(1-naphthyl)propiolic acid, together with the 8-bromo- and 8-chloro-substituted derivative, and of (E)-3-(1-naphthyl) acrylic acid, together with the 8-bromo- and 8-chloro-substituted derivatives, 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. The rate coefficients for the alkaline hydrolysis of the corresponding methyl propiolates have been determined in 70% (v/v) dioxane-water at both 30.0 and 50.1°C. In the ionisation and esterification reactions, reversed dipolar substituent effects were observed. The ApKa values are quantitatively accounted for either by comparison with the results for simple model compounds or by Kirkwood-Westheimer calculations. The retardations observed for the effect of 8-halo substituents in the alkaline hydrolysis reaction are in agreement with a reversed dipolar effect and no steric 'bulk' effects are observed.