2,5-Dihydrothiophene 1,1-dioxide 2,5-Dihydrothiophene dioxide 2,5-Dihydrothiophene sulfone 3-Sulfolene 77-79-2 Butadiene sulfone NCI-C04557 NSC56373 Thiophene, 2,5-dihydro-, 1,1-dioxide WLN: T5SW CUTJ