MICROWAVE SPECTRUM OF METHYLCYCLOPROPYL KETONE.

Abstract

The microwave spectrum of methylcyclopropyl ketone has been examined in the 8-36 GHz region. A very rich spectrum has been observed in which b-type transitions have been assigned for a species with the carbonyl group cis to the cyclopropyl ring. The transitions are split into doublets by the internal rotation of the methyl group. Transitions have been assigned for species in the first three excited states of the torsional motion in which the acetyl group rotates with respect to the cyclopropane ring. The rotational constants for the ground state are $A = 7204.33 MHz, B = 2630.88 MHz$, and $C = 2301.11$ MHz. The height of the barrier to internal rotation of the methyl group is 1175 cal/mole.