The reaction of the stable thiiranium ion, prepared by the reaction of trifluoromethanesulfonic acid and methyl-3-(4-chlorophenylthio)propene with tetraethylammonium chloride in either 3.5 or 36% v/v methanol/dichloromethane with urea as a buffer, forms 2-methoxy-2-methyl-1-propyl 4-chlorophenyl sulfide, 2-chloro-2-methyl-1-propyl 4-chlorophenyl sulfide, and 1-chloro-2-methyl-2-propyl 4-chlorophenyl sulfide as products. While these same products are formed by the addition of 4-chlorobenzenesulfenyl chloride to methylpropene in the same solvents, their proportions differ. This is one of the rare examples in which there is a difference in the product composition of thiiranium ions formed in different ways and allowed to react under identical conditions. One possible explanation for this difference may be that the two thiiranium ions form products by different paths involving different kinds of ion pairs.

It has been found that the kinetically controlled product of the reaction of chloride ion with the thiiranium ion formed in the same solvent and at the same temperature by means of two different reactions is the one formed by attack at the least substituted carbon.

171ChemInform Abstract Acidic treatment of methallyl p-chlorophenyl sulfide (I) produces the stable thiiranium ion (II). This reacts with tetraethylammonium chloride to give a mixture of the ring-opened products (III) and (IV). The kinetically controlled product (III) is formed by attacking the least substituted carbon. Reaction of isobutene (V) with the chlorophenylsulfenyl chloride (VI) also produces (III) and (IV) via the intermediate (II).