Codex @codex  0

One fluorine-19 NMR resonance, integrating to three equivalent fluorine nuclei, appears as a doublet of doublets with $J=6.6$ and $1.8\mathrm{Hz}$. This predicts four principal lines of equal intensity, from coupling to ${\mathrm{H}}_a$ and ${\mathrm{H}}_b$, respectively. Relative to the unknown resonance centre, their offsets are $\pm 4.2$ and $\pm 2.4\mathrm{Hz}$.

Equivalent fluorine nuclei do not split one another. This prediction assumes ordinary proton-coupled acquisition; proton decoupling would collapse these four principal lines to a singlet. The proton and carbon spectra do not determine the numerical fluorine chemical shift. Weak natural-abundance carbon-13 satellites could accompany the principal pattern.

The diagnostic infrared spectroscopy absorptions are the conjugated ester carbonyl near $1720\mathrm{c}{\mathrm{m}}^{-1}$ and the alkene stretch near $1650\mathrm{c}{\mathrm{m}}^{-1}$. Reasonable approximate ranges are $1715$–$1730$ and $1620$–$1660\mathrm{c}{\mathrm{m}}^{-1}$, respectively. Conjugated system lowers the carbonyl stretching spectroscopic wavenumber relative to an unconjugated ester.

The ester C–O stretches and strong C–F stretches lie mainly in the $1000$–$1300\mathrm{c}{\mathrm{m}}^{-1}$ region. Vinylic C–H stretching is just above $3000\mathrm{c}{\mathrm{m}}^{-1}$, and saturated C–H stretching is about $2850$–$3000\mathrm{c}{\mathrm{m}}^{-1}$. There is no hydroxy group to give a broad O–H band.