Low resolution microwave spectroscopy and the conformational analysis of 4,4-difluoropiperidine

The low resolution and high resolution microwave spectra of 4,4-difluoropiperidine and the N deutero analog have been recorded. Based on a low resolution microwave adaptation of Kraitchman's equations, the species giving rise to the single observed low resolution band series is seen to be the N-H equatorial conformer. This result is verified by obtaining the principal axis coordinates of the amine hydrogen atom via an assignment of the high resolution microwave spectra of the normal and N-D compounds. Consideration of the least intensity of the N-H axial conformer's spectrum that would be necessary for it to be observed, leads to the result: ΔG ? O.89 kcal/mole for the equatorial ? axial equilibrium.