consider the ir spectrum of an unknown compound. an ir spectrum, with a large stretch at 1685 inverse centimeters. there are no key stretches with higher wavenumbers. there is a series of minor stretches around 1500 to 1600. there is nothing at 1650. compound a contains two conjugated alkenes. compound b is a benzene ring with an aldehyde substituent. compound c is an aldehyde bound to a propyl group. compound d contains a cyclohexane with three carbonyl groups on carbons 1, 3 and 5. compound e is a cyclic amide with two conjugated double bonds. compound f has two aryl ketones. which compound matches the ir spectrum best
Compound B, which is a benzene ring with an aldehyde substituent, matches the IR spectrum best. This is because the large stretch at 1685 inverse centimeters indicates the presence of a carbonyl (C=O) group, which is characteristic of aldehydes. Additionally, the absence of any key stretches at higher wavenumbers suggests the absence of additional functional groups. Compound B satisfies these criteria as it contains both a benzene ring and an aldehyde group.
Based on the information provided, the compound that matches the IR spectrum best is Compound E, which is a cyclic amide with two conjugated double bonds.
Here's the breakdown of the information:
1. A large stretch at 1685 cm^-1: This suggests the presence of a carbonyl group. Compound E contains a cyclic amide, which has a carbonyl group (C=O) that typically shows a strong stretch around this wavenumber.
2. No key stretches with higher wavenumbers: This rules out Compound A, which contains two conjugated alkenes that would have higher wavenumber stretches.
3. A series of minor stretches around 1500 to 1600 cm^-1: This matches the concept of conjugation, which is present in Compound E due to the conjugated double bonds in the cyclic amide.
4. Nothing at 1650 cm^-1: This does not match the characteristics of any of the given compounds.
5. Compound B is a benzene ring with an aldehyde substituent, and Compound C is an aldehyde bound to a propyl group. Neither of these compounds match the information given.
6. Compound D contains a cyclohexane with three carbonyl groups on carbons 1, 3, and 5, but the IR spectrum does not mention multiple carbonyl stretches. Therefore, this does not match the information given.
7. Compound F has two aryl ketones, but the IR spectrum does not contain any stretches characteristic of aryl ketones.
In conclusion, Compound E, a cyclic amide with two conjugated double bonds, matches the given IR spectrum best.