Question 1

Predict the number of distinct quartets expected in the off-resonance decoupled 13C NMR spectrum of the compound shown below.

Accepted Answer

Question 2

You have a sample and its 1H NMR spectrum. You know your sample contains O atoms but not N atoms, and you suspect that your sample may be an alcohol. What common spectroscopic technique might you use to confirm your suspicion?

Accepted Answer

Take an IR spectrum and look f

Question 3

Explain the difference between off-resonance decoupling and broadband decoupling and how each affects the C-13 NMR spectrum. In your discussion include a short description of how a chemist interprets the different spectra.

Accepted Answer

Decoupling is a technique used to remove

Question 4

Deduce the identity of the following compound from the 1H NMR data given.
C8H10O: δ 3.4 (3H, singlet), 4.5 (2H, singlet), 7.2 (5H, apparent singlet) (ppm)

Accepted Answer

Question 5

Why is Fourier transform NMR spectroscopy preferred over continuous wave as a technique for

Accepted Answer

¹³C nuclei have a low sensitivity which re

Question 6

Provide a structure that is consistent with the data below.
C5H8Cl2
IR (cm-1): 2950
1H NMR ( d): 1.4 (4H, t), 1.2 (4H, t)
13C NMR (d ): 62 (s), 26 (t), 23 (t)

Accepted Answer

Question 7

How many nuclear spin states are allowed for the 1H nucleus?

Accepted Answer

A)  1 
B)  2 
C)  3 
D)  4 
E)  10 
A)  1 
B)  2 
C)  3 
D)  4 
E)  10

Question 8

What compound exhibits only two signals in its 1H NMR spectrum, a triplet and a quintet?

Accepted Answer

A)  BrCH2CH2CH2Br 
B)  BrCH2CH2CH2Cl 
C)  (CH3)2CHCH(CH3)2 
D)  CH3CH2CH2CH3 
E)  (CH3)2CHOCH(CH3)2 
A)  BrCH2CH2CH2Br 
B)  BrCH2CH2CH2Cl 
C)  (CH3)2CHCH(CH3)2 
D)  CH3CH2CH2CH3 
E)  (CH3)2CHOCH(CH3)2

Question 9

What multiplicities are observed in the off-resonance decoupled 13C spectrum of 2,3-dimethyl-but-2-ene?

Accepted Answer

a singlet

Question 10

What type of carbon environment does not generate a signal in the DEPT-90 spectrum and gives a positive peak in the DEPT-135 spectrum?

Accepted Answer

A)  quaternary 
B)  methine 
C)  methylene 
D)  methyl 
E)  carbonyl 
A)  quaternary 
B)  methine 
C)  methylene 
D)  methyl 
E)  carbonyl

Question 11

________ is commonly used as an internal reference in NMR spectroscopy; its signal is assigned d = 0 in 1H and 13C NMR spectroscopy.

Accepted Answer

Tetramethy

Question 12

Provide a structure that is consistent with the data below.
C5H10O
IR (cm-1): 2950, 1720
1H NMR ( d): 2.6 (1H, septet), 2.1 (3H, s), 1.0 (6H, d)
13C NMR (d ): 195 (s), 42 (d), 18 (q), 11 (q)

Accepted Answer

Question 13

The protons marked Ha and Hb in the molecule below are ________.

Accepted Answer

A)  chemically equivalent 
B)  enantiotopic 
C)  diastereotopic 
D)  endotopic 
E)  none of the above 
A)  chemically equivalent 
B)  enantiotopic 
C)  diastereotopic 
D)  endotopic 
E)  none of the above

Question 14

Predict the number of signals expected in the proton spin decoupled 13C NMR spectrum of p-diethylbenzene (1,4-diethylbenzene).

Accepted Answer

Question 15

What multiplicities are observed for the signals in the off-resonance decoupled 13C spectrum of 2-chloropropene?

Accepted Answer

A)  3 singlets 
B)  2 singlets and a doublet 
C)  a singlet and 2 doublets 
D)  a singlet, a doublet and a triplet 
E)  a singlet, a triplet, and a quartet 
A)  3 singlets 
B)  2 singlets and a doublet 
C)  a singlet and 2 doublets 
D)  a singlet, a doublet and a triplet 
E)  a singlet, a triplet, and a quartet

Question 16

Predict the number of signals expected in the proton spin decoupled 13C NMR spectrum of the compound shown below.

Accepted Answer

Question 17

Deduce the identity of the following compound from the 1H NMR data given.
C4H11N: δ 0.90 (3H, triplet), 1.07 (3H, doublet), 1.14 (2H, broad singlet), 1.34 (2H, multiplet), 2.79 (1H, multiplet) (ppm)

Accepted Answer

Question 18

Deduce the identity of the following compound from the 13C NMR data given.
C9H12: δ 21.3 (quartet), 127.2 (doublet), 138.0 (singlet) (ppm)

Accepted Answer

1,3,5-trim

Question 19

Given that compound X has a molecular formula of C6H8O2, gave two peaks in its
13C NMR spectrum (37 ppm and 208 ppm) but just one in its 1H NMR spectrum (2.5 ppm), provide a structure for compound X.

Accepted Answer

Question 20

How many peaks appear in the proton spin decoupled 13C NMR spectrum of the compound below?

Accepted Answer

Exam 13: Nuclear Magnetic Resonance Spectroscopy

Predict the number of distinct quartets expected in the off-resonance decoupled 13C NMR spectrum of the compound shown below.

You have a sample and its 1H NMR spectrum. You know your sample contains O atoms but not N atoms, and you suspect that your sample may be an alcohol. What common spectroscopic technique might you use to confirm your suspicion?

Explain the difference between off-resonance decoupling and broadband decoupling and how each affects the C-13 NMR spectrum. In your discussion include a short description of how a chemist interprets the different spectra.

Deduce the identity of the following compound from the 1H NMR data given. C8H10O: δ 3.4 (3H, singlet), 4.5 (2H, singlet), 7.2 (5H, apparent singlet) (ppm)

Why is Fourier transform NMR spectroscopy preferred over continuous wave as a technique for

Provide a structure that is consistent with the data below. C5H8Cl2 IR (cm-1): 2950 1H NMR ( d): 1.4 (4H, t), 1.2 (4H, t) 13C NMR (d ): 62 (s), 26 (t), 23 (t)

How many nuclear spin states are allowed for the 1H nucleus?

What compound exhibits only two signals in its 1H NMR spectrum, a triplet and a quintet?

What multiplicities are observed in the off-resonance decoupled 13C spectrum of 2,3-dimethyl-but-2-ene?

What type of carbon environment does not generate a signal in the DEPT-90 spectrum and gives a positive peak in the DEPT-135 spectrum?

________ is commonly used as an internal reference in NMR spectroscopy; its signal is assigned d = 0 in 1H and 13C NMR spectroscopy.

Provide a structure that is consistent with the data below. C5H10O IR (cm-1): 2950, 1720 1H NMR ( d): 2.6 (1H, septet), 2.1 (3H, s), 1.0 (6H, d) 13C NMR (d ): 195 (s), 42 (d), 18 (q), 11 (q)

The protons marked Ha and Hb in the molecule below are ________.

Predict the number of signals expected in the proton spin decoupled 13C NMR spectrum of p-diethylbenzene (1,4-diethylbenzene).

What multiplicities are observed for the signals in the off-resonance decoupled 13C spectrum of 2-chloropropene?

Predict the number of signals expected in the proton spin decoupled 13C NMR spectrum of the compound shown below.

Deduce the identity of the following compound from the 1H NMR data given. C4H11N: δ 0.90 (3H, triplet), 1.07 (3H, doublet), 1.14 (2H, broad singlet), 1.34 (2H, multiplet), 2.79 (1H, multiplet) (ppm)

Deduce the identity of the following compound from the 13C NMR data given. C9H12: δ 21.3 (quartet), 127.2 (doublet), 138.0 (singlet) (ppm)

Given that compound X has a molecular formula of C6H8O2, gave two peaks in its 13C NMR spectrum (37 ppm and 208 ppm) but just one in its 1H NMR spectrum (2.5 ppm), provide a structure for compound X.

How many peaks appear in the proton spin decoupled 13C NMR spectrum of the compound below?

Introduction and Review

Structure and Properties of Organic Molecules

Structure and Stereochemistry of Alkanes

The Study of Chemical Reactions

Stereochemistry

Alkyl Halides: Nucleophilic Substitution and Elimination

Structure and Synthesis of Alkenes

Reactions of Alkenes

Alkynes

Structure and Synthesis of Alcohols

Reactions of Alcohols

Infrared Spectroscopy and Mass Spectrometry

Ethers, Epoxides, and Thioethers

Conjugated Systems, Orbital Symmetry, and Ultraviolet Spectroscopy

Aromatic Compounds

Reactions of Aromatic Compounds

Ketones and Aldehydes

Amines

Carboxylic Acids

Carboxylic Acid Derivatives

Condensations and Alpha Substitutions of Carboxyl Compounds

Carbohydrates and Nucleic Acids

Amino Acids, Peptides, and Proteins

Lipids

Synthetic Polymers

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Predict the number of distinct quartets expected in the off-resonance decoupled ¹³C NMR spectrum of the compound shown below.

You have a sample and its ¹H NMR spectrum. You know your sample contains O atoms but not N atoms, and you suspect that your sample may be an alcohol. What common spectroscopic technique might you use to confirm your suspicion?

Deduce the identity of the following compound from the ¹H NMR data given. C₈H₁₀O: δ 3.4 (3H, singlet), 4.5 (2H, singlet), 7.2 (5H, apparent singlet) (ppm)

Provide a structure that is consistent with the data below. C₅H₈Cl₂ IR (cm^-1): 2950 ¹H NMR ( d): 1.4 (4H, t), 1.2 (4H, t) ¹³C NMR (d ): 62 (s), 26 (t), 23 (t)

How many nuclear spin states are allowed for the ¹H nucleus?

What compound exhibits only two signals in its ¹H NMR spectrum, a triplet and a quintet?

What multiplicities are observed in the off-resonance decoupled ¹³C spectrum of 2,3-dimethyl-but-2-ene?

________ is commonly used as an internal reference in NMR spectroscopy; its signal is assigned d = 0 in ¹H and ¹³C NMR spectroscopy.

Provide a structure that is consistent with the data below. C₅H₁₀O IR (cm^-1): 2950, 1720 ¹H NMR ( d): 2.6 (1H, septet), 2.1 (3H, s), 1.0 (6H, d) ¹³C NMR (d ): 195 (s), 42 (d), 18 (q), 11 (q)

The protons marked H_a and H_b in the molecule below are ________.

Predict the number of signals expected in the proton spin decoupled ¹³C NMR spectrum of p-diethylbenzene (1,4-diethylbenzene).

What multiplicities are observed for the signals in the off-resonance decoupled ¹³C spectrum of 2-chloropropene?

Predict the number of signals expected in the proton spin decoupled ¹³C NMR spectrum of the compound shown below.

Deduce the identity of the following compound from the ¹H NMR data given. C₄H₁₁N: δ 0.90 (3H, triplet), 1.07 (3H, doublet), 1.14 (2H, broad singlet), 1.34 (2H, multiplet), 2.79 (1H, multiplet) (ppm)

Deduce the identity of the following compound from the ¹³C NMR data given. C₉H₁₂: δ 21.3 (quartet), 127.2 (doublet), 138.0 (singlet) (ppm)

Given that compound X has a molecular formula of C₆H₈O₂, gave two peaks in its ¹³C NMR spectrum (37 ppm and 208 ppm) but just one in its ¹H NMR spectrum (2.5 ppm), provide a structure for compound X.

How many peaks appear in the proton spin decoupled ¹³C NMR spectrum of the compound below?