Knowledge Bank

“The microwave spectra of acetone and acetone-$drms$ have been observed. From a number of low J transitions, the average rotational constants were determined. A preliminary structure consistent with these constants and using some parameters from the structure of acetaldehyde1 is as follows: {d}{ee}=1.511\pm 0.005 \AA{d}{eo}=1.216 \AA \mbox{(assumed)}{d}{ch}={d}{eo}=1.087 \AA \mbox{(assumed)}<{CCC}=116^\circ37^{\prime}=1^\circ<{HCH}-<{DCD}-108^\circ16^{\prime}\mbox{(assumed)} Stark effect measurements gave a dipole moment of $2.00\pm 0.03$ Debye. Each transition consisted of a multiplet structure caused by the internal rotation of the methyl groups. This multiplet pattern is being analyzed to determine the potential energy hindering internal rotation. The theory of internal rotation for the case of two symmetric tops attached to an asymmetric frame will also be discussed.”