Rotational isomerism in propargyl formate as studied by infrared and microwave spectroscopy

Abstract

The microwave and infrared spectra of propargyl formate have been studied in the respective ranges 40–15 GHz and 4 000–50 cm^–1. Evidence is presented for the coexistence of rotational isomers, one of which (probably the more stable) is shown to have a planar arrangement of heavy atoms with the alkyl group s-cis with respect to the carbonyl bond and with the acetylenic group directed away (trans) from the carbonyl group. The dipole moment was measured in dilute benzene solution at 297 K to be 1.94 ± 0.02 D.