Deck 13: Nuclear Magnetic Resonance Spectroscopy

Question 1

How many sets of equivalent protons are there in hexane?

A) 2
B) 3
C) 6
D) 7

Answer 1

3

Question 2

Which of the following is not true regarding ¹H NMR spectroscopy?

A) "shielding" leads to peaks at lower values of d
B) a "downfield" peak appears at a higher value of d
C) d for a particular proton depends on the magnetic field strength of the instrument used.
D) on a 300 MHz instrument, a proton that adsorbs irradiation at a frequency 1200 Hz higher than the adsorption of TMS appears at d 4 ppm.

Answer 2

d for a particular proton depends on the magnetic field strength of the instrument used.

Question 3

Which C₄H₉Br compound gives a triplet at approximately 3.5 ppm in the ¹H NMR spectrum?

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

Answer 3

1

Question 4

What is the appearance of the signal corresponding to the CH₂ protons in the ¹H NMR spectrum of ethyl methyl ether, CH₃CH₂OCH₃?

A) a doublet
B) a triplet
C) a quartet
D) a septet

Question 5

How many sets of equivalent protons are there in 3-methylhexane?

A) 2
B) 3
C) 6
D) 7

Question 6

Which feature in the ¹H NMR spectrum provides information about the number of neighboring protons of each proton in the compound?

A) number of signals
B) integral
C) multiplicity
D) chemical shift

Question 7

What is the splitting of the signal in the ¹H NMR spectrum for the methyl protons of ethane?

A) singlet
B) doublet
C) triplet
D) quartet

Question 8

Which feature in the ¹H NMR spectrum provides information about the relative number of each type of proton in a compound?

A) number of signals
B) integral
C) splitting
D) chemical shift

Question 9

How many sets of equivalent protons are there in 2-methylhexane?

A) 2
B) 3
C) 6
D) 7

Question 10

Which of the following combinations of peaks appears in the ¹H NMR spectrum of 2-methylpropane?

A) two singlets
B) a singlet and a nonet
C) a singlet and a decet
D) a doublet and a decet

Question 11

Which of the following combinations of peaks appears in the ¹H NMR spectrum of 1,4-dimethyoxyethane, CH₃OCH₂CH₂CH₂CH₂OCH₃?

A) three singlets
B) a singlet, a triplet, and a quintet
C) a singlet and two triplets
D) a doublet and a triplet

Question 12

Which of the following combinations of peaks appears in the ¹H NMR spectrum of 1,2-dimethyoxyethane, CH₃OCH₂CH₂OCH₃?

A) two singlets
B) a singlet and a triplet
C) a singlet and two triplets
D) a doublet and a triplet

Question 13

Which feature in the ¹H NMR spectrum provides information about the number of types of different protons in a compound?

A) number of signals
B) integral
C) splitting
D) chemical shift

Question 14

What is the splitting of the signal in the ¹H NMR spectrum for the methyl protons of 1-bomo-2-methylpropane?

A) singlet
B) doublet
C) triplet
D) nonet

Question 15

Which of the following is not true regarding ¹H NMR spectroscopy?

A) a "downfield" peak appears at a lower value of d
B) on a 300 MHz instrument, a proton that adsorbs irradiation at a frequency 900 Hz higher than the adsorption of TMS appears at d 3 ppm.
C) d for a particular proton is independent of the magnetic field strength of the instrument used.
D) "deshielding" leads to peaks at higher values of d

Question 16

Which of the following combinations of peaks appears in the ¹H NMR spectrum of butane?

A) a triplet and a doublet
B) a triplet and a quartet
C) a triplet and a sextet
D) two singlets

Question 17

Which of the following combinations of peaks appears in the ¹H NMR spectrum of 2,3-dimethylbutane?

A) two doublets
B) a doublet and a septet
C) a singlet and two doublets
D) a doublet and an octet

Question 18

Which of the following combinations of peaks appears in the ¹H NMR spectrum of diethyl ether, CH₃CH₂OCH₂CH₃?

A) a triplet and a doublet
B) a quartet and a sextet
C) two singlets
D) a triplet and a quartet

Question 19

What is the splitting of the signal in the ¹H NMR spectrum for the methyl protons of propane?

A) singlet
B) doublet
C) triplet
D) quartet

Question 20

Which feature in the ¹H NMR spectrum provides information about the electronic environment of the protons in a compound?

A) number of signals
B) integral
C) splitting
D) chemical shift

Question 21

How many signals appear in the proton-decoupled ¹³C NMR spectrum of 1,4-dibromobenzene?

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

Question 22

Which of the protons in the following molecule appear furthest downfield in the ¹H NMR spectrum?

A) i
B) ii
C) iii
D) iv

Question 23

Which of the protons in the following molecule appear furthest downfield in the ¹H NMR spectrum?

A) i
B) ii
C) iii
D) iv

Question 24

How many signals appear in the proton-decoupled ¹³C NMR spectrum of 3-bromotoluene?

A) 3
B) 4
C) 5
D) 7

Question 25

Which of the protons in the following molecule appear at the highest d-value in the ¹H NMR spectrum?

A) i
B) ii
C) iii
D) iv

Question 26

Which C₄H₉Br compound(s) gives a ¹³C NMR spectrum consisting of two signals?

A) only 1
B) only 2
C) only 2 and 3
D) 1, 2, 3 and 4

Question 27

How many signals appear in the proton-decoupled ¹³C NMR spectrum of 2-bromotoluene?

A) 3
B) 4
C) 5
D) 7

Question 28

Which of the protons in the following molecule appear at the highest d-value in the ¹H NMR spectrum?

A) i
B) ii
C) iii
D) iv

Question 29

Which C₄H₉Br compound gives a doublet at approximately 3.3 ppm in the ¹H NMR spectrum?

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

Question 30

How many signals appear in the proton-decoupled ¹³C NMR spectrum of 4-bromotoluene?

A) 3
B) 4
C) 5
D) 7

Question 31

How many signals appear in proton-decoupled ¹³C NMR spectrum of 2,5-dimethylhexane?

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

Question 32

Which C₄H₉Br compound(s) gives a ¹³C NMR spectrum consisting of four signals?

A) only 1
B) only 1 and 2
C) only 2 and 3
D) 1, 2, 3 and 4

Question 33

How many signals appear in the proton-decoupled ¹³C NMR spectrum of 1,2-dibromobenzene?

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

Question 34

What is the relative area of the six peaks in a septet in an ¹H NMR spectrum?

A) 1:2:3:4:3:2:1
B) 1:3:6:12:6:3:1
C) 1:6:15:30:15:6:1
D) 1:6:15:20:15:6:1

Question 35

How many signals appear in the proton-decoupled ¹³C NMR spectrum of 1,3-dibromobenzene?

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

Question 36

Which of the following compounds gives a ¹H NMR spectrum consisting of two singlets and a ¹³C NMR consisting of consisting of three signals?

A) only i
B) only iii
C) only ii and iii
D) only ii, iii and iv

Question 37

Which of the protons in the following molecule appear at the highest d-value in the ¹H NMR spectrum?

A) i
B) ii
C) iii
D) iv

Question 38

Which of the protons in the following molecule appear furthest downfield in the ¹H NMR spectrum?

A) i
B) ii
C) iii
D) iv

Question 39

What is the relative area of the six peaks in a sexet in an ¹H NMR spectrum?

A) 1:2:3:3:2:1
B) 1:3:6:6:3:1
C) 1:5:10:10:5:1
D) 1:6:15:15:6:1

Question 40

How many signals appear in proton-decoupled ¹³C NMR spectrum of 3,4-dimethylhexane?

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

Question 41

Which of the following compounds gives a ¹H NMR spectrum consisting of only a singlet?

A) 1,1-dibromopropane
B) 1,2-dibromopropane
C) 1,3-dibromopropane
D) 2,2-dibromopropane

Question 42

Which of the following is true for pair of homotropic protons?
1.They will appear at the same chemical shift in an achiral (i.e., nonchiral) environment
2.They will appear at the same chemical shifts in a chiral environment

A) only 1
B) only 2
C) neither 1 nor 2
D) both 1 and 2

Question 43

Which of the following compounds have enantiotopic protons? 1.propane
2.butane
3.2-methylpropane

A) only 1
B) only 2
C) only 1 and 2
D) 1, 2 and 3

Question 44

Which of the following compounds have homotopic protons?
1.propane
2.butane
3.2-methylpropane

A) only 1
B) only 2
C) only 1 and 2
D) 1, 2 and 3

Question 45

Which of the following compounds gives a ¹H NMR spectrum consisting of only two singlets?

A) CH₃OCH₂CH₂OCH₂CH₃
B) CH₃OCH₂CH₂CH₂CH₂OH
C) CH₃OC(CH₃)₂OCH₃
D) CH₃OCH₂CH(CH₃)OCH₃

Question 46

The chemical shift of the protons of acetone, CH₃COCH₃, is 2.1 ppm when the spectrum is obtained at 250 MHz. What is the chemical shift of these protons when the spectrum is acquired at 500 MHz?

A) 1.05 ppm
B) 2.1 ppm
C) 4.2 ppm
D) 8.4 ppm

Question 47

Which of the following compounds gives a ¹H NMR spectrum consisting of only a singlet, triplet and quintet?

A) CH₃OCH₂CH₂CH₂CH₂OH
B) CH₃OCH₂CH₂OCH₂CH₃
C) CH₃OCH₂CH₂CH₂OCH₃
D) CH₃OCH₂CH(CH₃)OCH₃

Question 48

What is the hydrogen deficiency index for a compound with a molecular formula of C₆H₁₁N?

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

Question 49

Which of the protons in the following molecule appear at the highest d-value in the ¹H NMR spectrum?

A) i
B) ii
C) iii
D) iv

Question 50

What is the hydrogen deficiency index for a compound with a molecular formula of C₁₂H₁₆O?

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

Question 51

How many signals appear in the proton-decoupled ¹³C NMR spectrum of the following compound?

A) 6
B) 7
C) 8
D) 11

Question 52

Which of the following compounds would give a ¹H NMR spectrum consisting of two singlets and a ¹³C NMR consisting of consisting of three signals?

A) only i
B) only iii
C) only i and iii
D) iii and iv

Question 53

Which of the carbon atoms in the molecule appears furthest downfield in the ¹³C NMR spectrum?

A) i
B) ii
C) iii
D) iv

Question 54

Which of the following compounds gives a ¹H NMR spectrum consisting of only two triplets and a singlet?

A) CH₃CH(OCH₃)₂
B) CH₃OCH₂CH₂CH₂CH₂OCH₃
C) CH₃OCH₂CH₂OCH₃
D) CH₃OCH₂CH(OH)CH₃

Question 55

What is the hydrogen deficiency index for a compound with a molecular formula of C₁₀H₁₆O₂?

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

Question 56

Which of the carbon atoms in the following molecule appears furthest downfield in the ¹³C NMR spectrum?

A) i
B) ii
C) iii
D) iv

Question 57

What is the hydrogen deficiency index for a compound with a molecular formula of C₆H₆Br₂?

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

Question 58

Which of the following is true for pair of enantiotopic protons?
1.They will appear at the same chemical shift in an achiral (i.e., nonchiral) environment
2.They will appear at the same chemical shifts in a chiral environment

A) only 1
B) only 2
C) neither 1 nor 2
D) both 1 and 2

Question 59

How many signals appear in the proton-decoupled ¹³C NMR spectrum of the following compound?

A) 7
B) 8
C) 9
D) 11

Question 60

The coupling constant, J, between the protons of chloroethane is 7 Hz when the spectrum is obtained at 250 MHz. What is the coupling constant between these protons when the spectrum is acquired at 500 MHz?

A) 3.5 Hz
B) 7 Hz
C) 14 Hz
D) 21 Hz

Question 61

Identify the compound (C₈H₁₀) that gives the following ¹H NMR spectrum.

Question 62

Which of the following is true for pair of diastereotopic protons?
1.They will appear at the same chemical shift in an achiral (i.e., nonchiral) environment
2.They will appear at the same chemical shifts in a chiral environment

A) only 1
B) only 2
C) neither 1 nor 2
D) both 1 and 2

Question 63

Which C₈H₁₀ compound gives the following ¹H NMR spectrum?

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

Question 64

Which C₆H₁₂O₂ compound gives the following ¹H NMR spectrum?

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

Question 65

Identify the compound (C₈H₁₀) that gives the following ¹H NMR spectrum.

Question 66

Which C₆H₁₂O₂ compound gives the following ¹H NMR spectrum?

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

Question 67

Which C₉H₁₀O compound gives the following ¹H NMR spectrum?

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

Question 68

Identify the compound (C₄H₈O₂) that gives the following ¹H NMR spectrum.

Question 69

Identify the compound (C₄H₈O) that gives the following ¹H NMR spectrum.

Question 70

Identify the compound (C₄H₆O₂) that gives the following ¹H NMR spectrum.

Question 71

Which C₉H₁₀O compound gives the following ¹H NMR spectrum?

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

Question 72

Identify the compound (C₈H₁₀) that gives the following ¹H NMR spectrum.

Question 73

Which C₈H₁₀ compound gives the following ¹H NMR spectrum?

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