Cyclohexene and phosphorus pentasulfide in a mole ratio of 20: l react slowly at rdux temperature, with the liberation of hydrogen sulfide, to yield a crystalline product (CBHBP&)~. Hydrolysis of this product gave A2-cyclohexene phosphonic acid. This suggests that the structure of the product is a dimeric thio-anhydride of A2-cyclohexene trithiophosphonic acid,
