Dpn. Satchell et al., THE KINETICS AND MECHANISM OF THE SILVER ION-PROMOTED HYDROLYSIS OF THIOLURETHANES IN AQUEOUS-SOLUTION, Perkin transactions. 2, (8), 1993, pp. 1543-1546
The hydrolysis of thiolurethanes p-RC6H4NHCOSEt (1, R = Cl, H, OMe) in
dilute aqueous acid is promoted by silver ions. The promoted hydrolys
is involves the slow decomposition of low concentrations of complexes
of 2 Ag+:1-thiolurethane stoichiometry, which are formed from relative
ly stable 1:1-complexes. The (positively charged) 1 : 1 -complex (2) u
ndergoes N-H dissociation to give a formally neutral 1 : 1 -complex, 3
. The 2:1 -complexes are formed f rom both 2 and 3. The formation cons
tants, K1, and the acid dissociation constants, K(a), of (2, R = Cl, H
, MeO) have been obtained from a kinetic analysis using a range of sil
ver and hydrogen ion concentrations, and different temperatures. The r
esults suggest that the 2:1-complexes undergo nucleophilic attack by w
ater in an overall A2-like process. Thiolurethanes 1 are ca. 10(5)-fol
d more reactive in Ag+ ion-promoted hydrolysis than are the correspond
ing ethyl thiolbenzoates.