Question 1

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

Accepted Answer

The answer of Predict the number of distinct quartets expected...

Question 2

Deduce the identity of the compound whose molecular formula is C4H8O3 from the spectral data provided: IR (cm-1): 2800-3300 (broad), 2950, 1750; 13C NMR (δ): 17.7 (q), 65.4 (q), 72.3 (d), 210.8 (s) (ppm)

Accepted Answer

Question 3

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

Accepted Answer

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

Question 4

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

Accepted Answer

Question 5

Predict the number of signals expected, their splitting, and their relative area in the 1H NMR spectrum of 2-methylpropane (isobutane).

Accepted Answer

2 signals:

Question 6

Give one reason why 13C NMR is less sensitive than 1H NMR.

Accepted Answer

Natural isotopic abundance of

Question 7

Deduce the identity of the following compound from the spectral data given.
C4H8O2: 1H NMR, δ 1.23 (3H, triplet), 2.00 (3H, singlet), 4.02 (2H, quartet) (ppm); IR, 2980,

Accepted Answer

Question 8

Deduce the identity of the following compound from the spectral data given.
C9H10O2: 13C NMR, δ 18.06 (quartet), 45.40 (doublet), 127.32 (doublet), 127.55 (doublet), 128.61 (doublet), 139.70 (singlet) (ppm), 180.98 (singlet); IR, broad 3500-2800,

Accepted Answer

Question 9

Deduce the identity of the following compound from the 1H NMR data given.
C6H8O4: δ 3.9 (6H, singlet), 6.1 (2H, singlet) (ppm)

Accepted Answer

Question 10

Which of the following reasons best explains why aromatic protons have a larger chemical shift than protons one carbon removed from a halogen?

Accepted Answer

A)  An aromatic ring is more electron withdrawing than a halogen. 
B)  A halogen is more electron withdrawing than an aromatic ring. 
C)  Electron movement induces a magnetic field opposing the external field. 
D)  Electron movement induces a magnetic field reinforcing the external field. 
A)  An aromatic ring is more electron withdrawing than a halogen. 
B)  A halogen is more electron withdrawing than an aromatic ring. 
C)  Electron movement induces a magnetic field opposing the external field. 
D)  Electron movement induces a magnetic field reinforcing the external field.

Question 11

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

Accepted Answer

A)  2 
B)  3 
C)  4 
D)  5 
E)  6 
A)  2 
B)  3 
C)  4 
D)  5 
E)  6

Question 12

The energy difference between the allowed spin states for an 1H nucleus is ________ the strength of the external magnetic field in which it is placed.

Accepted Answer

A)  independent of 
B)  directly proportional to 
C)  inversely proportional to 
D)  exponentially related to 
E)  logarithmically related to 
A)  independent of 
B)  directly proportional to 
C)  inversely proportional to 
D)  exponentially related to 
E)  logarithmically related to

Question 13

Deduce the identity of the following compound from the 1H NMR data given.
C5H10O: δ 1.1 (6H, doublet), 2.2 (3H, singlet), 2.5 (1H, septet) (ppm)

Accepted Answer

Question 14

Predict the number of signals expected in the proton spin decoupled 13C spectrum of 3-hexanone, CH3CH2COCH2CH2CH3.

Accepted Answer

Question 15

Which compound generates positive peaks for the carbonyl in both its DEPT-90 and DEPT-135 spectra?

Accepted Answer

A)  CH3CH2CHO 
B)  CH3CH2COCH3 
C)  CH3CO2CH2CH3 
D)  CH3CH2CONH2 
E)  H2CO 
A)  CH3CH2CHO 
B)  CH3CH2COCH3 
C)  CH3CO2CH2CH3 
D)  CH3CH2CONH2 
E)  H2CO

Question 16

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 17

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

Accepted Answer

a singlet

Question 18

Predict the number of signals expected (disregarding splitting) in the 1H spectrum of m-xylene (1,3-dimethylbenzene).

Accepted Answer

Question 19

Predict the number of signals expected (disregarding splitting) in the 1H spectrum of dibutyl ether.

Accepted Answer

Question 20

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

Exam 13: Nuclear Magnetic Resonance Spectroscopy

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

Deduce the identity of the compound whose molecular formula is C4H8O3 from the spectral data provided: IR (cm-1): 2800-3300 (broad), 2950, 1750; 13C NMR (δ): 17.7 (q), 65.4 (q), 72.3 (d), 210.8 (s) (ppm)

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

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

Predict the number of signals expected, their splitting, and their relative area in the 1H NMR spectrum of 2-methylpropane (isobutane).

Give one reason why 13C NMR is less sensitive than 1H NMR.

Deduce the identity of the following compound from the spectral data given. C4H8O2: 1H NMR, δ 1.23 (3H, triplet), 2.00 (3H, singlet), 4.02 (2H, quartet) (ppm); IR, 2980,

Deduce the identity of the following compound from the spectral data given. C9H10O2: 13C NMR, δ 18.06 (quartet), 45.40 (doublet), 127.32 (doublet), 127.55 (doublet), 128.61 (doublet), 139.70 (singlet) (ppm), 180.98 (singlet); IR, broad 3500-2800,

Deduce the identity of the following compound from the 1H NMR data given. C6H8O4: δ 3.9 (6H, singlet), 6.1 (2H, singlet) (ppm)

Which of the following reasons best explains why aromatic protons have a larger chemical shift than protons one carbon removed from a halogen?

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

The energy difference between the allowed spin states for an 1H nucleus is ________ the strength of the external magnetic field in which it is placed.

Deduce the identity of the following compound from the 1H NMR data given. C5H10O: δ 1.1 (6H, doublet), 2.2 (3H, singlet), 2.5 (1H, septet) (ppm)

Predict the number of signals expected in the proton spin decoupled 13C spectrum of 3-hexanone, CH3CH2COCH2CH2CH3.

Which compound generates positive peaks for the carbonyl in both its DEPT-90 and DEPT-135 spectra?

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?

Predict the number of signals expected (disregarding splitting) in the 1H spectrum of m-xylene (1,3-dimethylbenzene).

Predict the number of signals expected (disregarding splitting) in the 1H spectrum of dibutyl ether.

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

Structure and Bonding

Acids and Bases; Functional Groups

Structure and Stereochemistry of Alkanes

The Study of Chemical Reactions

Stereochemistry

Alkyl Halides; Nucleophilic Substitution

Structure and Synthesis of Alkenes; Elimination

Reactions of Alkenes

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

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Filters

Deduce the identity of the compound whose molecular formula is C₄H₈O₃ from the spectral data provided: IR (cm^-1): 2800-3300 (broad), 2950, 1750; ¹³C NMR (δ): 17.7 (q), 65.4 (q), 72.3 (d), 210.8 (s) (ppm)

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

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

Predict the number of signals expected, their splitting, and their relative area in the ¹H NMR spectrum of 2-methylpropane (isobutane).

Give one reason why ¹³C NMR is less sensitive than ¹H NMR.

Deduce the identity of the following compound from the spectral data given. C₄H₈O₂: ¹H NMR, δ 1.23 (3H, triplet), 2.00 (3H, singlet), 4.02 (2H, quartet) (ppm); IR, 2980,

Deduce the identity of the following compound from the spectral data given. C₉H₁₀O₂: ¹³C NMR, δ 18.06 (quartet), 45.40 (doublet), 127.32 (doublet), 127.55 (doublet), 128.61 (doublet), 139.70 (singlet) (ppm), 180.98 (singlet); IR, broad 3500-2800,

Deduce the identity of the following compound from the ¹H NMR data given. C₆H₈O₄: δ 3.9 (6H, singlet), 6.1 (2H, singlet) (ppm)

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

The energy difference between the allowed spin states for an ¹H nucleus is ________ the strength of the external magnetic field in which it is placed.

Deduce the identity of the following compound from the ¹H NMR data given. C₅H₁₀O: δ 1.1 (6H, doublet), 2.2 (3H, singlet), 2.5 (1H, septet) (ppm)

Predict the number of signals expected in the proton spin decoupled ¹³C spectrum of 3-hexanone, CH₃CH₂COCH₂CH₂CH₃.

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?

Predict the number of signals expected (disregarding splitting) in the ¹H spectrum of m-xylene (1,3-dimethylbenzene).

Predict the number of signals expected (disregarding splitting) in the ¹H spectrum of dibutyl ether.

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