The Reaction of Oxiranes with Carbon Disulfide under High Pressure

Article abstract of DOI:10.1246/bcsj.61.921

The reaction of 2,2-dimethyloxirane with carbon disulfide in the presence of triethylamine was accelerated under high pressure to give 5,5-dimethyl-1,3-oxathiolane-2-thione in a high yield, while 2-hexyl-oxirane under the same reaction condition formed 4-hexyl-1,3-dithiolane-2-thione (2b) as the main product and 5-hexyl-1,3-oxathiolane-2-thione (1b) as a minor product.A feasible mechanism for this formation is that 1b and 2-hexylthiirane (4b) are produced in the first stage of reaction, and that 2b is then formed by the reaction of 1b or 4b with carbon disulfide.In reactions of a variety of oxiranes with carbon disulfide, 1,3-dithiolane- 2-thiones were obtained in high yields under 800 MPa at 100 deg C within 20 h.Concerning the effect of substituents in oxiranes, the selectivity for product 2b is in the decreasing order; 2-phenyl- > 2-methyl- > 2-ethyl- > 2-hexyl- > 2,3-tetramethylene- > 2,2-dimethyl- > 2-(chloromethyl)- .Tertiary amines, such as N,N-dimethyl-ethylamine, pyridine, and N-methylmorpholine, serve as good catalysts for the reaction.