Knowledge Bank

The microwave spectrum of methyl vinyl ketone has been studied in the region 7-33 Gc/sec. Both a-type and b-type transitions have been assigned. The barrier to internal rotation of the methyl group has been found to be $1250\pm 20$ cal/mole. The components of the dipole moment have been found to be $|\mu a|=2.52D$ and $|\mu b|=1.91D$. The observed spectrum is consistent with a planar configuration in which the two double bonds are trans with respect to each other.