Chapter 16, Problem 16.62P

Interpretation Introduction

(a)

Interpretation:

The number of expected ${}^{13}\text{C}$ NMR signals for the given molecule is to be given.

Concept introduction:

${}^{13}\text{C}$ NMR provides valuable information about the carbon skeleton. Each signal in ${}^{13}\text{C}$ NMR equals the number of distinct carbon atoms in the given unknown. In most of the ${}^{13}\text{C}$ NMR spectra, almost every time, all the signals would appear as singlets. The saturated carbon atoms appear in the range $\text{δ}\text{0-35 ppm}$ if it is a simple alkane fragment. If it is attached to any electronegative element such as halogens or nitrogen, then the range is $\text{δ}\text{25-70 ppm}$. Triple bonded carbon atoms range from $\text{δ}\text{65-85 ppm}$. Alkene carbons range from $\text{δ}\text{105-150 ppm}$. Carbonyl carbon atoms in acids, esters, amides, and anhydrides range from $\text{δ}\text{120-185 ppm}$. Carbonyl carbons in aldehydes and ketones range from $\text{δ}\text{190-220 ppm}$.

Answer to Problem 16.62P

The number of expected ${}^{13}\text{C}$ NMR signals for the given molecule is two. It can be shown as below:

Explanation of Solution

The structure of the given molecule is

The molecule has a plane of symmetry, which divides the molecule in two equal halves, and thus it has two distinct carbons indicated as $\text{A}$ and $\text{B}$. So, there must be two signals in ${}^{13}\text{C}$ NMR spectrum.

Conclusion

Every chemically distinct carbon atom in a molecule produces one ${}^{13}\text{C}$ NMR signal.

Interpretation Introduction

(b)

Interpretation:

The number of expected ${}^{13}\text{C}$ NMR signals for the given molecule is to be given.

Concept introduction:

${}^{13}\text{C}$ NMR provides valuable information about the carbon skeleton. Each signal in ${}^{13}\text{C}$ NMR equals the number of distinct carbon atoms in the given unknown. In most of the ${}^{13}\text{C}$ NMR spectra, almost every time, all the signals would appear as singlets. The saturated carbon atoms appear in the range $\text{δ}\text{0-35 ppm}$ if it is a simple alkane fragment. If it is attached to any electronegative element such as halogens or nitrogen, then the range is $\text{δ}\text{25-70 ppm}$. Triple bonded carbon atoms range from $\text{δ}\text{65-85 ppm}$. Alkene carbons range from $\text{δ}\text{105-150 ppm}$. Carbonyl carbon atoms in acids, esters, amides, and anhydrides range from $\text{δ}\text{120-185 ppm}$. Carbonyl carbons in aldehydes and ketones range from $\text{δ}\text{190-220 ppm}$.

Answer to Problem 16.62P

The number of expected ${}^{13}\text{C}$ NMR signals for the given molecule is three. It can be shown as below:

Explanation of Solution

The structure of the given molecule is

The molecule has a plane of symmetry, which divides the molecule in two equal halves, and thus it has three distinct carbons indicated as $\text{A, B}$, and $\text{C}$. So, there must be three signals in ${}^{13}\text{C}$ NMR spectrum.

Conclusion

Every chemically distinct carbon atom in a molecule produces one ${}^{13}\text{C}$ NMR signal.

Interpretation Introduction

(c)

Interpretation:

The number of expected ${}^{13}\text{C}$ NMR signals for the given molecule is to be given.

Concept introduction:

${}^{13}\text{C}$ NMR provides valuable information about the carbon skeleton. Each signal in ${}^{13}\text{C}$ NMR equals the number of distinct carbon atoms in the given unknown. In most of the ${}^{13}\text{C}$ NMR spectra, almost every time, all the signals would appear as singlets. The saturated carbon atoms appear in the range $\text{δ}\text{0-35 ppm}$ if it is a simple alkane fragment. If it is attached to any electronegative element such as halogens or nitrogen, then the range is $\text{δ}\text{25-70 ppm}$. Triple bonded carbon atoms range from $\text{δ}\text{65-85 ppm}$. Alkene carbons range from $\text{δ}\text{105-150 ppm}$. Carbonyl carbon atoms in acids, esters, amides, and anhydrides range from $\text{δ}\text{120-185 ppm}$. Carbonyl carbons in aldehydes and ketones range from $\text{δ}\text{190-220 ppm}$.

Answer to Problem 16.62P

The number of expected ${}^{13}\text{C}$ NMR signals for the given molecule is five. It can be shown as below:

Explanation of Solution

The structure of the given molecule is

The molecule has ring with two different substituents, and thus all five carbons are distinctly indicated as $\text{A, B, C, D}$, and $\text{E}$. So, there must be five signals in ${}^{13}\text{C}$ NMR spectrum.

Conclusion

Every chemically distinct carbon atom in a molecule produces one ${}^{13}\text{C}$ NMR signal.

Interpretation Introduction

(d)

Interpretation:

The number of expected ${}^{13}\text{C}$ NMR signals for the given molecule is to be given.

Concept introduction:

${}^{13}\text{C}$ NMR provides valuable information about the carbon skeleton. Each signal in ${}^{13}\text{C}$ NMR equals the number of distinct carbon atoms in the given unknown. In most of the ${}^{13}\text{C}$ NMR spectra, almost every time, all the signals would appear as singlets. The saturated carbon atoms appear in the range $\text{δ}\text{0-35 ppm}$ if it is a simple alkane fragment. If it is attached to any electronegative element such as halogens or nitrogen, then the range is $\text{δ}\text{25-70 ppm}$. Triple bonded carbon atoms range from $\text{δ}\text{65-85 ppm}$. Alkene carbons range from $\text{δ}\text{105-150 ppm}$. Carbonyl carbon atoms in acids, esters, amides, and anhydrides range from $\text{δ}\text{120-185 ppm}$. Carbonyl carbons in aldehydes and ketones range from $\text{δ}\text{190-220 ppm}$.

Answer to Problem 16.62P

The number of expected ${}^{13}\text{C}$ NMR signals for the given molecule is five. It can be shown as below:

Explanation of Solution

The structure of the given molecule is

The molecule has one carbonyl carbon, two methylene carbons, and two methyl carbons. The two methylene carbons are in different chemical environment as one is bonded to oxygen and another to carbonyl carbon; thus they are distinct carbons. Therefore, the methyl carbons bonded to these methylene carbons are also distinct. Hence the molecule has total five distinct carbons indicated as $\text{A, B, C, D}$, and $\text{E}$. So, there must be five signals in ${}^{13}\text{C}$ NMR spectrum.

Conclusion

Every chemically distinct carbon atom in a molecule produces one ${}^{13}\text{C}$ NMR signal.

Interpretation Introduction

(e)

Interpretation:

The number of expected ${}^{13}\text{C}$ NMR signals for the given molecule is to be given.

Concept introduction:

${}^{13}\text{C}$ NMR provides valuable information about the carbon skeleton. Each signal in ${}^{13}\text{C}$ NMR equals the number of distinct carbon atoms in the given unknown. In most of the ${}^{13}\text{C}$ NMR spectra, almost every time, all the signals would appear as singlets. The saturated carbon atoms appear in the range $\text{δ}\text{0-35 ppm}$ if it is a simple alkane fragment. If it is attached to any electronegative element such as halogens or nitrogen, then the range is $\text{δ}\text{25-70 ppm}$. Triple bonded carbon atoms range from $\text{δ}\text{65-85 ppm}$. Alkene carbons range from $\text{δ}\text{105-150 ppm}$. Carbonyl carbon atoms in acids, esters, amides, and anhydrides range from $\text{δ}\text{120-185 ppm}$. Carbonyl carbons in aldehydes and ketones range from $\text{δ}\text{190-220 ppm}$.

Answer to Problem 16.62P

The number of expected ${}^{13}\text{C}$ NMR signals for the given molecule is three. It can be shown as below:

Explanation of Solution

The structure of the given molecule is

It has a plane of symmetry passing through $\text{C=O}$. The two methylene carbons are in the same chemical environment as they are bonded to oxygen; thus they must be chemically equivalent carbons. Therefore, the methyl carbons bonded to these methylene carbons are also chemically equivalent. Hence molecule has total three distinct carbons indicated as $\text{A, B}$, and $\text{C}$, so there must be three signals in ${}^{13}\text{C}$ NMR spectrum.

Conclusion

Every chemically distinct carbon atom in a molecule produces one ${}^{13}\text{C}$ NMR signal.

Interpretation Introduction

(f)

Interpretation:

The number of expected ${}^{13}\text{C}$ NMR signals for the given molecule is to be given.

Concept introduction:

${}^{13}\text{C}$ NMR provides valuable information about the carbon skeleton. Each signal in ${}^{13}\text{C}$ NMR equals the number of distinct carbon atoms in the given unknown. In most of the ${}^{13}\text{C}$ NMR spectra, almost every time, all the signals would appear as singlets. The saturated carbon atoms appear in the range $\text{δ}\text{0-35 ppm}$ if it is a simple alkane fragment. If it is attached to any electronegative element such as halogens or nitrogen, then the range is $\text{δ}\text{25-70 ppm}$. Triple bonded carbon atoms range from $\text{δ}\text{65-85 ppm}$. Alkene carbons range from $\text{δ}\text{105-150 ppm}$. Carbonyl carbon atoms in acids, esters, amides, and anhydrides range from $\text{δ}\text{120-185 ppm}$. Carbonyl carbons in aldehydes and ketones range from $\text{δ}\text{190-220 ppm}$.

Answer to Problem 16.62P

The number of expected ${}^{13}\text{C}$ NMR signals for the given molecule is four. It can be shown as below:

Explanation of Solution

The structure of the given molecule is

As the molecule is para disubstituted, it has a plane of symmetry passing through $\text{Br-C-C-OH}$, which divides the molecule in two equal halves. Hence the molecule has total four distinct carbons indicated as $\text{A, B, C}$, and $\text{D}$, so there must be four signals in ${}^{13}\text{C}$ NMR spectrum.

Conclusion

Every chemically distinct carbon atom in a molecule produces one ${}^{13}\text{C}$ NMR signal.

Interpretation Introduction

(g)

Interpretation:

The number of expected ${}^{13}\text{C}$ NMR signals for the given molecule is to be given.

Concept introduction:

${}^{13}\text{C}$ NMR provides valuable information about the carbon skeleton. Each signal in ${}^{13}\text{C}$ NMR equals the number of distinct carbon atoms in the given unknown. In most of the ${}^{13}\text{C}$ NMR spectra, almost every time, all the signals would appear as singlets. The saturated carbon atoms appear in the range $\text{δ}\text{0-35 ppm}$ if it is a simple alkane fragment. If it is attached to any electronegative element such as halogens or nitrogen, then the range is $\text{δ}\text{25-70 ppm}$. Triple bonded carbon atoms range from $\text{δ}\text{65-85 ppm}$. Alkene carbons range from $\text{δ}\text{105-150 ppm}$. Carbonyl carbon atoms in acids, esters, amides, and anhydrides range from $\text{δ}\text{120-185 ppm}$. Carbonyl carbons in aldehydes and ketones range from $\text{δ}\text{190-220 ppm}$.

Answer to Problem 16.62P

The number of expected ${}^{13}\text{C}$ NMR signals for the given molecule is six. It can be shown as below:

Explanation of Solution

The structure of the given molecule is

The molecule is meta disubstituted with different substituents and has no plane of symmetry; thus all carbons are chemically non-equivalent. Hence it has six chemically distinct carbons indicated as $\text{A, B, C, D, E}$, and $\text{F}$, so there must be six signals in ${}^{13}\text{C}$ NMR spectrum.

Conclusion

Every chemically distinct carbon atom in a molecule produces one ${}^{13}\text{C}$ NMR signal.

Interpretation Introduction

(h)

Interpretation:

The number of expected ${}^{13}\text{C}$ NMR signals for the given molecule is to be given.

Concept introduction:

${}^{13}\text{C}$ NMR provides valuable information about the carbon skeleton. Each signal in the ${}^{13}\text{C}$ NMR equals to the number of distinct carbon atoms in the given unknown. In most of the ${}^{13}\text{C}$ NMR spectra almost every time all the signals would appear as singlets. The saturated carbon atoms appear in the range $\text{δ}\text{0-35 ppm}$ if it is a simple alkane fragment. If it is attached to any electronegative element such as halogens, or nitrogen then the range is $\text{δ}\text{25-70 ppm}$. Triple bonded carbon atoms range from $\text{δ}\text{65-85 ppm}$. Alkene carbons range from $\text{δ}\text{105-150 ppm}$. Carbonyl carbon atoms in acids, esters, amides and anhydrides range from $\text{δ}\text{120-185 ppm}$. Carbonyl carbons in aldehydes and ketones range from $\text{δ}\text{190-220 ppm}$.

Answer to Problem 16.62P

The number of expected ${}^{13}\text{C}$ NMR signals for the given molecule is six. It can be shown as below:

Explanation of Solution

The structure of the given molecule is

The molecule is ortho disubstituted with different substituents and has no plane of symmetry; thus all carbons are chemically non-equivalent. Hence it has six chemically distinct carbons indicated as $\text{A, B, C, D, E}$, and $\text{F}$, so there must be six signals in ${}^{13}\text{C}$ NMR spectrum.

Conclusion

Every chemically distinct carbon atom in a molecule produces one ${}^{13}\text{C}$ NMR signal.

Interpretation Introduction

(i)

Interpretation:

The number of expected ${}^{13}\text{C}$ NMR signals for the given molecule is to be given.

Concept introduction:

${}^{13}\text{C}$ NMR provides valuable information about the carbon skeleton. Each signal in ${}^{13}\text{C}$ NMR equals the number of distinct carbon atoms in the given unknown. In most of the ${}^{13}\text{C}$ NMR spectra, almost every time, all the signals would appear as singlets. The saturated carbon atoms appear in the range $\text{δ}\text{0-35 ppm}$ if it is a simple alkane fragment. If it is attached to any electronegative element such as halogens or nitrogen, then the range is $\text{δ}\text{25-70 ppm}$. Triple bonded carbon atoms range from $\text{δ}\text{65-85 ppm}$. Alkene carbons range from $\text{δ}\text{105-150 ppm}$. Carbonyl carbon atoms in acids, esters, amides, and anhydrides range from $\text{δ}\text{120-185 ppm}$. Carbonyl carbons in aldehydes and ketones range from $\text{δ}\text{190-220 ppm}$.

Answer to Problem 16.62P

The number of expected ${}^{13}\text{C}$ NMR signals for the given molecule is eight. It can be shown as below:

Explanation of Solution

The structure of the given molecule is:\

The molecule is monosubstituted benzene; thus there are four types of aromatic carbons. The three methyl carbons are in the same chemical environment; thus they are identical. Hence it has eight chemically distinct carbons indicated as $\text{A, B, C, D, E, F, G}$, and $\text{H}$, so there must be eight signals in ${}^{13}\text{C}$ NMR spectrum.

Conclusion

Every chemically distinct carbon atom in a molecule produces one ${}^{13}\text{C}$ NMR signal.