Vinyl acetate, carbonyl group frequencies

In the spectra of vinyl or phenyl esters, with unsaturation adjacent to the C—O— group, a marked rise in the carbonyl frequency is observed along with a lowering of the C—O frequency. Vinyl acetate has a carbonyl band at 1776 cm-1 phenyl acetate absorbs at 1770 cm-1. 

R.F. Boyer Coupling between the alternating electric field and the electric dipole is direct that between the sinusoidal mechanical field and the "mechanical dipole" may be diffuse. One example of this which we studied (unpublished) is the glassy state response of poly(vinyl acetate) to an electric field which senses high frequency rotation of the dipole about the oxygen-carbonyl carbon bond in the side chain, and low frequency mechanical motion which probably detects local motion of the entire side group about the backbone. The latter occurs at 0.75 Tg (K) at 1 Hz and should be classified as a p relaxation the former occurs 0.75 Tg and is a y relaxation. The dipole oscillates about the backbone above Tg. 

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