KINETICS AND MECHANISM OF THE HYDROLYSIS OF 2-(4-METHOXY-PHENYL)-1,3-DITHIANE IN AQUEOUS PERCHLORIC-ACID

In concentrated (7-9 mol dm-3) aqueous perchloric acid, 2-aryl-1,3-dit hianes normally hydrolyse to give a high yield of aldehyde and propane -1,3-dithiol in a two-stage process via an initially formed equilibriu m mixture of aldehyde, dithiol, hemithioacetal and unreacted dithiane; kinetic studies using especially 2-(4-methoxyphenyl)-1,3-dithiane (I) suggest that these relatively unreactive cyclic dithioacetals lead to the hemithioacetal by an A2 mechanism.