ACID-CATALYZED HYDROLYSIS OF BRIDGED BICYCLIC AND TRICYCLIC COMPOUNDS.31. DEPENDENCES ON TEMPERATURE OF ALPHA-VALUES IN THE HYDRATION OF SOME NORBORNENES

Hydration rate constants of 2-norbornene and 5-methyl-exo- and -endo-5 -hydroxymethyl-2-norbornenes were measured in aqueous perchloric acid solution at different acid concentrations and temperatures. Disappeara nce of 2-norbornene was followed spectrophotometrically and those of t he substituted norbornenes by GLC. The excess acidity method was used to evaluate the alpha-values, which slightly decrease with rising temp erature (7-16% within 50 K), provided that the slope parameter m is in dependent of temperature. In the case of 5-methyl-5-hydroxy-methyl-2-n orbornenes the excess acidity plots, i.e. log k(a) vs. X0, were correc ted according to the partial protonation of the hydroxyl oxygen atom.