Knowledge Bank

“The microwave spectrum of cis 1-fluoropropene (cis $CH3CH=CHF)$ was studied in the region 8,000 to 36,000 me with a conventional stark modulated spectrograph. The moments of inertia indicate that the heavy atoms lie in a plane. Determination of the barrier to internal rotation in the ground torsional state leads to remarkably low barrier of 1,030 cal. The low value will be compared with the barriers of propylene, 2-fluoropropene, and trans 1-fluoropropene. Possible causes for this anomaly will also be discussed.”