Abstract
The transformation reactions, i.e., transguanylation and cyclization, of AET and APT were investigated with the potentiometric titration technique. Both reactions, which proceed probably through the similar intermediate, were promoted with the increasing amounts of alkali added initially. In the initial stage of the reaction, the transguanylation occupied larger part in the transformation of AET, as well as in APT. The half life of the conjugate base, which is an active species for the transguanylation, was increased linearly with the reciprocal of the initial concentration of the conjugate base. From the concentration dependence of the half life, measured in the addition of 0.5 equivalent alkali, it was deduced that the transguanylation is second order with respect to the isothiuronium salt. The Arrhenius plots of the rates in AET and in APT gave straight and parallel lines.
