Microwave Spectrum of Acryloyl Fluoride

The microwave spectrum of HF||H2C=C–C=O has been studied in the region 8–26 GHz. Two planar rotational isomers have been assigned. Only a-type transitions have been assigned for ground-state and first and second torsional excited states of the s-trans form. Both a- and b-type transitions have been assigned for the ground-state and first and second torsional excited states of the s-cis form. The ground-state energy difference between the two forms was found to be 90 ± 100 cal/mole with the s-trans the more stable form. The electric dipole moment of the s-trans form has been found to be 3.26 D oriented 29° from the carbon–oxygen bond. The dipole moment of the s-cis form was found to be 3.21 D oriented 53° from the carbon-oxygen bond.