摘要:
Peroxymonosulfate ion, HSO5-, as Oxone, readily converts phosphorus(V) esters of thiols into the phosphorus(V) and sulfonic acids. The esters were Ph2PO . SC6H4R(p) with R=MeO (1a), Me (1b), H (1c), Cl (1d) and NO2 (1e), (EtO)(2)PO . SPh (2), Ph2OI . SEt (3) and PhPO(OEt)SEt (4). Reactions are first order in each reactant and second-order rate constants, k(2), for 1a-e fit the Hammett equation with rho=-0.46. The rate constants increase markedly with increasing water content of H2O-MeCN, the activation enthalpies are low and the entropies are negative. Despite the low value of - rho, these esters are much less reactive than thiol ethers, but the rate constants of reactions of these compounds and acyl thiols qualitatively follow the ionization potentials of the ethers and the esters. (C) 1997 by John Wiley & Sons. Ltd.