Three common lab experiments are shown. In each case, describe how the IR spectrum of the product would differ from that of the reactant. Give approximate frequencies for distinctive peaks in the IR spectrum of the reactant and also that of the product.

Four infrared spectra are shown, corresponding to four of the following compounds. For each spectrum, determine the structure and explain how the peaks in the spectrum correspond to the structure you have chosen.

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Predict the characteristic infrared absorptions of the functional groups in the following molecules.

(d) pent-1-yne

(e) diethylamine

(f) pentanoic acid

Predict the characteristic infrared absorptions of the functional groups in the following molecules.

(a) cyclohexene

(b) pentan-2-ol

(c) pentan-2-one

These five structures all have distinguishing absorptions in the IR. Match each structure with its characteristic absorption.

(a) sharp, 2254 cm^–1

(b) very broad, centered about 3330 cm^–1

(c) strong, slightly broadened, 1645 cm^–1

(d) broad with spikes at 3367 and 3292 cm^–1

(e) strong, sharp 1717 cm^–1

Give approximate wavenumbers for the major characteristic IR absorption bands that would be given by each of the following compounds:

e.

f.

For each of the following pairs of compounds, name one absorption band that can be used to distinguish between them.

e.

f.

Norlutin and Enovid are ketones that suppress ovulation, so they have been used clinically as contraceptives. For which of these compounds would you expect the infrared carbonyl absorption (C=O stretch) to be at a higher frequency? Explain.

Give approximate wavenumbers for the major characteristic IR absorption bands that would be given by each of the following compounds:

a.

b.