sulfolane(CH2)4SO21,1-dioxidetetrahydrothiofuran1,1-dioxidetetrahydrothiophene1,1-dioxothiolan2,3,4,5-tetrahydrothiophene-1,1-dioxidecyclic tetramethylene sulfonecyclotetramethylene sulfonedioxothiolansulfolantetrahydrothiophene 1-dioxidetetramethylene sulfonethiacyclopentane dioxidethiolane-1,1-dioxidethiophan sulfonethiophane dioxide