A stopped-flow/rapid-quenching study of the reaction of 1, 1-diphenylethylene sulfuric acid

The reaction of 1, 1-diphenylethylene with sulfuric acid was studied at 30ŶC in dichloroethane by stopped-flow/rapid-scan spectroscopy coupled with the rapid-quenching technique. Rapid-scan spectra showed the formation and decay of two species absorbing at 435 and 465 nm during a period of less than one second. These species were detected only when sulfuric acid was 100% or more. The 435-nm species was the monomeric cation formed by protonation, and the 465-nm species was conceivably a charge-transfer complex of diphenylethylene and SO₃. The latter species eventually gave cyclic sulfones.