EFFECT OF SUBSTITUENTS ON THE REACTIVITY OF MONOSUBSTITUTED BENZYL MERCAPTANS IN HYDROGEN-ISOTOPE EXCHANGE-REACTION

In order to reveal to what extent each substituent of monosubstituted benzyl mercaptan can affect the reactivity of the material, the hydrog en-isotope exchange reaction (T-for-H exchange reaction) between one o f monosubstituted benzyl mercaptans in a p-xylene solution and a poly( vinyl alcohol) labeled with tritium has been observed in a liquid-soli d system at a range of 50 similar to 90 degrees C. The rate constants for the materials were obtained by applying the A ''-McKay plot method to the data observed. Comparing the rate constants and the results ob tained previously has led to the following three conclusions. (1) The reactivity of each monosubstituted benzyl mercaptan is somewhat affect ed by the type of substituent in the material, and by the reaction tem perature. (2) The reactivity of monosubstituted benzyl mercaptans foll ows the Hammett rule, and is enhanced with one of the electron-attract ive substituents. (3) The increasing order of the effect of the substi tuents on the reactivity of monosubstituted aromatic compounds is as f ollows: (monosubstituted thiophenol) < (monosubstituted aniline) < (mo nosubstituted benzyl mercaptan) <(monosubstituted benzaldehyde) < (mon osubstituted benzylamine) < (monosubstituted phenol).