Kinetic Study on Reactions of O- Y-substituted Phenyl Thionobenzoates with Quinuclidine: Factors Governing Reactivity and Reaction Mechanism.

Second-order rate constants ( kquin) for the reactions of O- Y-substituted phenyl thionobenzoates ( 3a-3i) with quinuclidine have been measured spectrophotometrically. Comparison of kquin with the rate constants reported previously for the corresponding reactions with benzylamine ( kBzNH2) has revealed that quinuclidine is less reactive than benzylamine toward 3a-3i although the former is 2.1 p Ka units more basic than the latter. Steric hindrance exerted by quinuclidine has been suggested to be responsible for the decreased reactivity of the tertiary amine. The Brønsted-type plot for the reactions of 3a-3i with quinuclidine is linear with βlg = −0.37. The Hammett plot correlated with [ABSTRACT FROM AUTHOR]