Reactions of 2-(p-Methoxyphenyl)-1,3-dithiolan-2-yl Cation with Water and Other Nucleophiles in aqueous Solution

Article abstract of DOI:10.1021/ja00315a034

2-(p-Methoxyphenyl)-1,3-dithiolan-2-yl cation (1) was isolated as a perchlorate and its reaction with water was examined kinetically in 10percent aqueous acetonitrile at 30 ^oC.Hydration of 1 to form a 2-hydroxydithiolane intermediate 2 is rate determining at pH >6, but the decomposition of 2 to lead to a thiolester product becomes a slow step at pH <3.At intermediate pH near the pK_R (4.1) of 1, both of the steps become partially rate determining.Hydration of 1 is unusually slow as compared with that of the oxygen analogues and is catalyzed by general bases with wide ranges of basicity (pK_a = 1.3-7.7); the Bronsted β = 0.18.In the presence of nucleophiles like thiol and primary and secondary amines, they can complete with water to form an adduct, 4.At higher acidity, the nucleophilic reaction becomes a rapid equilibrium which is followed by the slow hydrolysis of 1; biphasic kinetics were observed.