Go with the most obvious one first... Carboxylic Acids: will have a really broad and large absorption range in the 3500-2500cm-1 area (aka. the \"valley of the acid\") as well as a carbonyl peak in the 1700cm-1 area. That would be spectrum 4. Alcohols:will also have a strong and broad absorption in the 3500-3000cm-1 region, but nowhere near as broad as the acid. It just looks like a really fat absorption line, rather than a well... Anyway, the characteristic spectrum for the alcohol is spectrum 5. Amines:lucky for you, the amine given in this question is a primary amine. There\'s going to be two N-H stretching peaks in the 3300cm-1 region. There\'s also no carbonyl on the structure given, so there should be no C=O stretching at 1700cm-1.This is spectrum 3. Don\'t worry about the small absorption in the 1500-1700cm-1 area. Now for the fine details... The ester and aldehyde spectra are pretty similar, but aldehydes absorb at around 2750cm-1. It\'s not totally clear on the spectra in the question but it looks like there\'s a 2750cm-1 absorption in spectrum 2, so I\'d say that spectrum 2 is the aldehyde, and spectrum 1 is the ester. Summary: Spectrum 1 = structure B Spectrum 2 = structure E Spectrum 3 = structure C Spectrum 4 = structure D Spectrum 5 = structure A Solution Go with the most obvious one first... Carboxylic Acids: will have a really broad and large absorption range in the 3500-2500cm-1 area (aka. the \"valley of the acid\") as well as a carbonyl peak in the 1700cm-1 area. That would be spectrum 4. Alcohols:will also have a strong and broad absorption in the 3500-3000cm-1 region, but nowhere near as broad as the acid. It just looks like a really fat absorption line, rather than a well... Anyway, the characteristic spectrum for the alcohol is spectrum 5. Amines:lucky for you, the amine given in this question is a primary amine. There\'s going to be two N-H stretching peaks in the 3300cm-1 region. There\'s also no carbonyl on the structure given, so there should be no C=O stretching at 1700cm-1.This is spectrum 3. Don\'t worry about the small absorption in the 1500-1700cm-1 area. Now for the fine details... The ester and aldehyde spectra are pretty similar, but aldehydes absorb at around 2750cm-1. It\'s not totally clear on the spectra in the question but it looks like there\'s a 2750cm-1 absorption in spectrum 2, so I\'d say that spectrum 2 is the aldehyde, and spectrum 1 is the ester. Summary: Spectrum 1 = structure B Spectrum 2 = structure E Spectrum 3 = structure C Spectrum 4 = structure D Spectrum 5 = structure A.

1. Go with the most obvious one first...
Carboxylic Acids: will have a really broad and large absorption range in the 3500-2500cm-1 area
(aka. the "valley of the acid") as well as a carbonyl peak in the 1700cm-1 area. That would be
spectrum 4.
Alcohols:will also have a strong and broad absorption in the 3500-3000cm-1 region, but nowhere
near as broad as the acid. It just looks like a really fat absorption line, rather than a well...
Anyway, the characteristic spectrum for the alcohol is spectrum 5.
Amines:lucky for you, the amine given in this question is a primary amine. There's going to be
two N-H stretching peaks in the 3300cm-1 region. There's also no carbonyl on the structure
given, so there should be no C=O stretching at 1700cm-1.This is spectrum 3. Don't worry about
the small absorption in the 1500-1700cm-1 area.
Now for the fine details...
The ester and aldehyde spectra are pretty similar, but aldehydes absorb at around 2750cm-1. It's
not totally clear on the spectra in the question but it looks like there's a 2750cm-1 absorption in
spectrum 2, so I'd say that spectrum 2 is the aldehyde, and spectrum 1 is the ester.
Summary:
Spectrum 1 = structure B
Spectrum 2 = structure E
Spectrum 3 = structure C
Spectrum 4 = structure D
Spectrum 5 = structure A
Solution
Go with the most obvious one first...
Carboxylic Acids: will have a really broad and large absorption range in the 3500-2500cm-1 area
(aka. the "valley of the acid") as well as a carbonyl peak in the 1700cm-1 area. That would be
spectrum 4.
Alcohols:will also have a strong and broad absorption in the 3500-3000cm-1 region, but nowhere
near as broad as the acid. It just looks like a really fat absorption line, rather than a well...
Anyway, the characteristic spectrum for the alcohol is spectrum 5.
Amines:lucky for you, the amine given in this question is a primary amine. There's going to be
two N-H stretching peaks in the 3300cm-1 region. There's also no carbonyl on the structure
given, so there should be no C=O stretching at 1700cm-1.This is spectrum 3. Don't worry about
the small absorption in the 1500-1700cm-1 area.

2. Now for the fine details...
The ester and aldehyde spectra are pretty similar, but aldehydes absorb at around 2750cm-1. It's
not totally clear on the spectra in the question but it looks like there's a 2750cm-1 absorption in
spectrum 2, so I'd say that spectrum 2 is the aldehyde, and spectrum 1 is the ester.
Summary:
Spectrum 1 = structure B
Spectrum 2 = structure E
Spectrum 3 = structure C
Spectrum 4 = structure D
Spectrum 5 = structure A