BackAnswer each of the following questions based on the images below.
a) Which compounds show an intense peak ~ 1700 cm-1?
b) Which compound shows an intense, broad peak at ~ 3400 cm-1?
c) Which compound has a peak at ~1700 cm-1, but no peaks at 2700 cm-1?
d) Which compound has no signal beyond the fingerprint region?
Identify which carbonyl group will exhibit a signal at a lower wavenumber
The infrared spectra for three compounds are provided. Each compound has one or more of the following functional groups: conjugated ketone, ester, amide, nitrile, and alkyne. Determine the functional group(s) in each compound, and assign the major peaks above 1600 cm–1.
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Spectra are given for three compounds. Each compound has one or more of the following functional groups: alcohol, amine, ketone, aldehyde, and carboxylic acid. Determine the functional group(s) in each compound, and assign the major peaks above 1600 cm–1.
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A common lab experiment is the dehydration of cyclohexanol to cyclohexene.
(a) Explain how you could tell from the IR spectrum whether your product was pure cyclohexene, pure cyclohexanol, or a mixture of cyclohexene and cyclohexanol. Give approximate frequencies for distinctive peaks.
(b) Explain why mass spectrometry might not be a good way to distinguish cyclohexene from cyclohexanol.
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
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.
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.