The difference between C=O stretching frequencies for butanal centered at 1746 cm − 1 and for butan-2-one centered at 1735 cm − 1 is to be explained. Concept introduction: IR spectroscopy enables us to identify different functional groups in the molecule. One of the greatest advantages of IR spectroscopy is that the frequency of a particular type of vibration is typically found within a characteristic range of frequencies regardless of the functional group with which the vibration is associated. The fact that absorptions by certain vibrations appear with characteristic frequency ranges enables us to use IR spectroscopy to obtain structural information about a molecule. The resonance effect alters the bond absorption frequency of C=O in IR spectrum. Greater the stabilization of carbocation greater is the contribution from the resonance structure. This weakens the bond, and hence lowers the vibrational frequency.

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Definition Definition Organic compounds that have a carbonyl group, C=O, as their functional group. The carbonyl group in aldehydes is placed at the end of the molecular structure, which means the C=O is attached to one hydrogen atom and an alkyl group or a benzene ring. Just like all the other homologous series in organic chemistry, the naming of aldehydes uses the suffix “-al”. The general molecular formula is C n H 2n O.

Chapter 15, Problem 15.50P

Interpretation Introduction

Interpretation:

The difference between C=O stretching frequencies for butanal centered at 1746 cm−1 and for butan-2-one centered at 1735 cm−1 is to be explained.

Concept introduction:

IR spectroscopy enables us to identify different functional groups in the molecule.

One of the greatest advantages of IR spectroscopy is that the frequency of a particular type of vibration is typically found within a characteristic range of frequencies regardless of the functional group with which the vibration is associated. The fact that absorptions by certain vibrations appear with characteristic frequency ranges enables us to use IR spectroscopy to obtain structural information about a molecule. The resonance effect alters the bond absorption frequency of C=O in IR spectrum. Greater the stabilization of carbocation greater is the contribution from the resonance structure. This weakens the bond, and hence lowers the vibrational frequency.

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Answer 2

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Definition Definition Organic compounds that have a carbonyl group, C=O, as their functional group. The carbonyl group in aldehydes is placed at the end of the molecular structure, which means the C=O is attached to one hydrogen atom and an alkyl group or a benzene ring. Just like all the other homologous series in organic chemistry, the naming of aldehydes uses the suffix “-al”. The general molecular formula is C n H 2n O.

Chapter 15, Problem 15.50P

Interpretation Introduction

Interpretation:

The difference between C=O stretching frequencies for butanal centered at 1746 cm−1 and for butan-2-one centered at 1735 cm−1 is to be explained.

Concept introduction:

IR spectroscopy enables us to identify different functional groups in the molecule.

One of the greatest advantages of IR spectroscopy is that the frequency of a particular type of vibration is typically found within a characteristic range of frequencies regardless of the functional group with which the vibration is associated. The fact that absorptions by certain vibrations appear with characteristic frequency ranges enables us to use IR spectroscopy to obtain structural information about a molecule. The resonance effect alters the bond absorption frequency of C=O in IR spectrum. Greater the stabilization of carbocation greater is the contribution from the resonance structure. This weakens the bond, and hence lowers the vibrational frequency.

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Check out a sample textbook solution

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Answer 3

Question

Definition Definition Organic compounds that have a carbonyl group, C=O, as their functional group. The carbonyl group in aldehydes is placed at the end of the molecular structure, which means the C=O is attached to one hydrogen atom and an alkyl group or a benzene ring. Just like all the other homologous series in organic chemistry, the naming of aldehydes uses the suffix “-al”. The general molecular formula is C n H 2n O.

Chapter 15, Problem 15.50P

Interpretation Introduction

Interpretation:

The difference between C=O stretching frequencies for butanal centered at 1746 cm−1 and for butan-2-one centered at 1735 cm−1 is to be explained.

Concept introduction:

IR spectroscopy enables us to identify different functional groups in the molecule.

One of the greatest advantages of IR spectroscopy is that the frequency of a particular type of vibration is typically found within a characteristic range of frequencies regardless of the functional group with which the vibration is associated. The fact that absorptions by certain vibrations appear with characteristic frequency ranges enables us to use IR spectroscopy to obtain structural information about a molecule. The resonance effect alters the bond absorption frequency of C=O in IR spectrum. Greater the stabilization of carbocation greater is the contribution from the resonance structure. This weakens the bond, and hence lowers the vibrational frequency.

Expert Solution & Answer

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Check out a sample textbook solution

See solution

Answer 4

Question

Definition Definition Organic compounds that have a carbonyl group, C=O, as their functional group. The carbonyl group in aldehydes is placed at the end of the molecular structure, which means the C=O is attached to one hydrogen atom and an alkyl group or a benzene ring. Just like all the other homologous series in organic chemistry, the naming of aldehydes uses the suffix “-al”. The general molecular formula is C n H 2n O.

Chapter 15, Problem 15.50P

Interpretation Introduction