Solution

ID: past-exam-of-the-chemistry-course-of-the-year-1-of-the-natural-sciences-course-of-the-university-of-cambridge/2025/1/a/solution

The diagnostic infrared spectroscopy absorptions are the conjugated ester carbonyl near and the alkene stretch near . Reasonable approximate ranges are – and –, 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 – region. Vinylic C–H stretching is just above , and saturated C–H stretching is about –. There is no hydroxy group to give a broad O–H band.

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