The Reactivity of Monosubstituted Benzylamines in Hydrogen Isotope Exchange R eaction

Abstract

In order to reveal the reactivity of monosubstituted benzylamines, we observed the hydrogen isotope exchange reaction (liquid-solid reaction) between benzylamine (or one of monosubstitued benzylamines) dissolved in p-xylene and poly(vinyl alcohol) labeled with tritium at 70 °C. The rate constants for these materials have been obtained with the A"-McKay plot method. Comparing these rate constants (and the rate constants obtained previously)with each other, the followings have been clarified. ( 1) The reactivity of benzylamine can be enhanced with one of the substituents (which have the electron-attractive effect) since the reaction constant (ρ) for monosubstituted benzylamine in the reaction is greater than zero (p=1.6). ( 2 ) The degree of I-effect (or R-effect) of a certain substituent bonded to benzylamine can be expressed quantitatively when the effect of the substituent on the reactivity of CH2I\TH2 group is investigated with the rate constants. ( 3 ) It is fairly certain that the reactivity of monosubstituted benzylamines in the reaction follows the Hammett rule (not the Taft's equation). Accordingly, monosubstituted benzylamines may be regarded as aromatic compounds. ( 4 ) Comparing the reactivity of several compounds with each other using the rate constants obtained previously leads to the following equality: phenol: benzylamine: aniline: benzaldehyde =12: 6.6: 1 3 1.0