MICROWAVE-SPECTRUM, DIPOLE-MOMENT, AND CONFORMATION OF METHYL VINYL SULFONE

The microwave spectrum of methyl vinyl sulfone, CH2CHSO2CH3, has been investigated in the frequency region 26.5 to 40 GHz. The assigned tran sitions are consistent with a conformation in which one of the S=O bon ds nearly eclipses the C=C bond. This eclipsed conformer has been foun d to be at least 0.7 kcal/mole more stable than the s-cis form. From t he second-order Stark effect measurements the electric dipole moment h as been determined. A lower limit of 2800 cal/mole has been establishe d for the V-3 barrier to the methyl group internal rotation. (C) 1994 Academic Press, Inc.