Hk. Oh et al., AMINOLYSIS OF ARYL DITHIO-2-THIOPHENATES AND DITHIO-2-FUROATES IN ACETONITRILE, International journal of chemical kinetics, 30(11), 1998, pp. 849-857
The aminolyses of the title substrates with anilines and benzylamines
are investigated in acetonitrile. A clean second-order kinetics is obt
ained with a first-order rate law in the amine concentration, which is
uncomplicated by the fast proton transfer step. The large magnitude o
f rho(z) (rho(1g)) as well as rho(x) (rho(nuc)) together with relative
ly large positive p(xz) values is consistent with a stepwise mechanism
in which thiophenolate ion expulsion from the intermediate is rate li
miting. For the reactions of aryl dithio-2-thiophenates with benzylami
nes the magnitude of rho(x) and rho(z) values is relatively smaller su
ggesting that both the addition and expulsion of thiophenolate are par
tially rate determining. Relatively large secondary kinetic isotope ef
fects, k(H)/k(D) greater than or equal to 1.7, with deuterated nucleop
hiles, support involvement a concurrent proton transfer to the departi
ng thiophenolate ion in the transition state. (C) 1998 John Wiley & So
ns, Inc.