Effect of a Substituent in the Benzene Ring upon the Kinetics of Acid-Catalyzed Hydrolysis of exo-2-Norbornyl Phenyl Ether.
作者:Martti Lajunen、Marja Himottu、Kirsi Tanskanen-Lehti、Maamar Hamdi、Suzanne Fery-Forgues、Wenjun Shi、Stenbjörn Styring、Cecilia Tommos、Kurt Warncke、Bryan R. Wood
DOI:10.3891/acta.chem.scand.51-0515
日期:——
The rate constants of hydrolysis for exo-2-norbornyl phenyl ether without substituent and with p-Me, p-Ac, m-CN, p-CN or p-NO2 group in the benzene ring were measured in concentrated perchloric acid solutions spectrophotometrically and/or by capillary GC. The effect of the substituent on the rate constants and other kinetic parameters of hydrolysis is small. The parameters are in agreement with the A-1 mechanism. The ether oxygen of the exo-epimer is much more basic than that of the endo-epimer (pK(a,exo)-pK(a,endo)approximate to 2), which causes a greater part of the exo/endo rate ratio than do the initial state energies and rate constants of the rate limiting stage, i.e. of the formation of the norbornyl cation and the substituted phenol.