Deck 15: Nuclear Magnetic Resonance Spectroscopy

Question 1

Protons H_a and H_b in the following compound are _________.

A) homotopic
B) enantiotopic
C) diastereotopic
D) mesotopic
E) none of these

Answer 1

homotopic

Question 2

_______ protons experience a net magnetic field strength that is higher than the _____ protons.

A) Deshielded, shielded
B) Shielded, deshielded
C) Paramagnetic, diamagnetic
D) Shielded, diamagnetic
E) none of these

Answer 2

Deshielded, shielded

Question 3

Which of the following is not a common solvent used for acquiring a ¹H NMR spectrum?

A) CDCl₃
B) CCl₄
C) CD₃CN
D) CH₃OH
E) D₂O

Answer 3

CH₃OH

Question 4

Protons H_a and H_b in the following compound are _________.

A) homotopic
B) enantiotopic
C) diastereotopic
D) mesotopic
E) none of these

Question 5

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

A) 1
B) 2
C) 4
D) 5
E) none of these

Question 6

Which of the following type(s) of protons are chemically non-equivalent?

A) homotopic
B) enantiotopic
C) diastereotopic
D) A & B
E) B & C

Question 7

Which of the following electromagnetic radiation is used in NMR spectroscopy?

A) UV
B) IR
C) visible
D) γ-rays
E) radio wave

Question 8

Which of the following nuclei cannot be analyzed by an NMR spectrometer?

A) nucleus with odd number of protons & odd number of neutrons
B) nucleus with odd number of protons &even number of neutrons
C) nucleus with even number of protons & odd number of neutrons
D) nucleus with even number of protons & even number of neutrons
E) none of these

Question 9

NMR is an abbreviation for ____________ ____________ __________.

Question 10

Which of the following is true about the area under each signal in a ¹H NMR spectrum?

A) it indicates the number of neighboring protons
B) it indicates the electronic environment of neighboring protons
C) it indicates the number of different protons
D) it indicates the electronic environment of absorbing protons
E) it indicates the relative number of protons in the signal

Question 11

The strength of the magnetic field is a determining factor for the range of _______that must be used for NMR spectrometer.

A) temperature
B) frequencies
C) tesla
D) none of these
E) spin states

Question 12

Which of the following is true about the number of signals in a ¹H NMR spectrum?

A) it indicates the number of neighboring protons
B) it indicates the electronic environment of neighboring protons
C) it indicates the number of different kinds of protons
D) it indicates the electronic environment of absorbing protons
E) it indicates the number of protons in the signal

Question 13

In an NMR spectrometer, the receiver coil records a complex signal, called a ________________, which is converted into a spectrum via a mathematical technique called a ____________________.

Question 14

Which of the following is true about the shape (multiplicity) of the signal in a ¹H NMR spectrum?

A) it indicates the number of neighboring protons
B) it indicates the electronic environment of neighboring protons
C) it indicates the number of different protons
D) it indicates the electronic environment of absorbing protons
E) it indicates the number of protons in the signal

Question 15

Which of the following is true about the location of signals in a ¹H NMR spectrum?

A) it indicates the number of neighboring protons
B) it indicates the electronic environment of neighboring protons
C) it indicates the number of different protons
D) it indicates the electronic environment of absorbing protons
E) it indicates the number of protons in the signal

Question 16

List the most common nuclei that are used in NMR.

Question 17

Which of the following is true about the relationship between the energy gap (∆E) between the spin states for a ¹H nucleus and the strength of the external magnetic field?

A) they are inversely proportional
B) they are directly proportional
C) there is no relationship
D) the magnetic field is slightly less
E) none of these

Question 18

_______ protons experience a net magnetic field strength that is smaller than the applied magnetic field.

A) Deshielded
B) Shielded
C) Paramagnetic
D) Diamagnetic
E) none of these

Question 19

Identify the nuclei that cannot be analyzed by NMR.
A. ¹⁵N
B. ¹⁴C
C. ¹⁹F
D. ³¹P
E. ¹H

Question 20

Which of the following type(s) of protons are chemically equivalent?

A) homotopic
B) enantiotopic
C) diastereotopic
D) A & B
E) B & C

Question 21

Protons H_a and H_b in the following compound are _________.

A) homotopic
B) enantiotopic
C) diastereotopic
D) mesotopic
E) none of these

Question 22

Which of the indicated protons in the following compound would appear most upfield in the ¹H NMR spectrum?

A) I
B) II
C) III
D) IV

Question 23

Protons H_a and H_b in the following compound are _________.

A) homotopic
B) enantiotopic
C) diastereotopic
D) mesotopic
E) none of these

Question 24

How many signals would you expect in the ¹H NMR spectrum of the following compound?

Question 25

Protons H_a and H_b in the following compound are _________.

A) homotopic
B) enantiotopic
C) diastereotopic
D) mesotopic
E) none of these

Question 26

Protons H_a and H_b in the following compound are _________.

A) homotopic
B) enantiotopic
C) diastereotopic
D) mesotopic
E) none of these

Question 27

How many signals would you expect in the ¹H NMR spectrum of the following compound?

A) 4
B) 5
C) 6
D) 7
E) 8

Question 28

Which of the indicated protons in the following compound would appear most downfield in the ¹H NMR spectrum?

A) I
B) II
C) III
D) IV

Question 29

How many signals would you expect in the ¹H NMR spectrum of CH₃OCH₂CH₂OCH₃?

A) 1
B) 2
C) 3
D) 4
E) 5

Question 30

How many signals would you expect in the ¹H NMR spectrum of the following compound?

A) 4
B) 5
C) 6
D) 7
E) 8

Question 31

How many signals would you expect in the ¹H NMR spectrum of HOCH₂CH₂CH₂CH₂OH?

A) 1
B) 2
C) 3
D) 4
E) 5

Question 32

How many signals would you expect in the ¹H NMR spectrum of the following compound?

A) 4
B) 5
C) 6
D) 7
E) 9

Question 33

How many signals would you expect in the ¹H NMR spectrum of the following compound?

Question 34

The ¹H NMR spectrum of bromoethane shows a signal at 3.5 ppm when the spectrum is recorded using a 60 MHz spectrometer. Where do you expect to see the signal if a 300 MHz instrument is used instead?

A) 3.5 ppm
B) 7.5 ppm
C) 6.8 ppm
D) 5.8 ppm
E) none of these

Question 35

Protons H_a and H_b in the following compound are _________.

A) homotopic
B) enantiotopic
C) diastereotopic
D) mesotopic
E) none of these

Question 36

How many signals would you expect in the ¹H NMR spectrum of CH₃OCH₂CH₃?

A) 1
B) 2
C) 3
D) 4
E) 5

Question 37

______is used as a reference for recording NMR spectra and is assigned a chemical shift value of zero.

Question 38

Protons H_a and H_b in the following compound are _________.

A) homotopic
B) enantiotopic
C) diastereotopic
D) mesotopic
E) none of these

Question 39

How many signals would you expect in the ¹H NMR spectrum of (CH₃)₂CHCH₂CH₂CH₃?

A) 1
B) 2
C) 3
D) 4
E) 5

Question 40

How many signals would you expect in the ¹H NMR spectrum of the following compound?

Question 41

Which of the following protons appear most upfield in the ¹H NMR spectrum?

A) I
B) II
C) III
D) IV
E) none of these

Question 42

Aromatic protons produce signals in the range of 7 - 8 ppm, due to the _________effect of $\pi$ electrons

A) diamagnetic anisotropy
B) paramagnetic anisotropy
C) diamagnetic isotropy
D) paramagnetic isotropy
E) none of these

Question 43

Which of the following is the best prediction of the chemical shifts for the signals in the ¹H NMR spectrum for the following compound?

A) I = 3.9 ppm, II = 4.2 ppm, III = 2.2 ppm, IV = 3.4 ppm
B) I = 3.4 ppm, II = 2.2 ppm, III = 2.2 ppm, IV = 3.4 ppm
C) I = 3.4 ppm, II = 2.2 ppm, III = 4.2 ppm, IV = 3.4 ppm
D) I = 3.4 ppm, II = 4.2 ppm, III = 4.2 ppm, IV = 3.4 ppm
E) none of these

Question 44

Which of the following is the best prediction of the chemical shifts for the signals in the ¹H NMR spectrum for the following compound?

A) I=0.9 ppm, II=2.7 ppm, III=1.2 ppm, IV=0.9 ppm
B) I=1.1 ppm, II=3.2 ppm, III=1.4 ppm, IV=0.9 ppm
C) I=0.9 ppm, II=1.7 ppm, III=1.2 ppm, IV=1.1 ppm
D) I=0.9 ppm, II=1.9 ppm, III=3.4 ppm, IV=0.9 ppm
E) none of these

Question 45

Draw a structure, with a formula of C₄H₁₀O, which has an integration of 6H, 2H, 1H, and 1H.

Question 46

A compound with molecular formula C₈H₁₀O has the following ¹H NMR spectrum. Which of the following is the correct number of protons giving rise to each signal.

Question 47

Which of the following is the best prediction of the chemical shifts for the signals in the ¹H NMR spectrum for the following compound?

A) I = 0.9 ppm, II = 1.8 ppm, III = 4.2 ppm, IV = 1.9 ppm
B) I = 0.9 ppm, II = 1.2 ppm, III = 3.7 ppm, IV = 1.9 ppm
C) I = 0.9 ppm, II = 1.7 ppm, III = 3.4 ppm, IV = 2.4 ppm
D) I = 0.9 ppm, II = 1.7 ppm, III = 3.4 ppm, IV = 1.9 ppm
E) none of these

Question 48

Predict the chemical shifts for the signals in the ¹H NMR spectrum for the following compound.

Question 49

Which of the indicated protons in the following compound would appear most downfield in the ¹H NMR spectrum?

A) I
B) II
C) III
D) IV
E) V

Question 50

Draw a structure, with a formula of C₄H₉Br, which has an integration of 3H, 2H, 2H, and 2H.

Question 51

Draw a structure, with a formula of C₅H₁₃N, which has an integration of 9H, 3H, 1H.

Question 52

Which of the following is the best prediction of the chemical shifts for the signals in the ¹H NMR spectrum for the following compound?

A) I = 3.7 ppm, II = 2.7 ppm, III = 1.9 ppm
B) I = 3.7 ppm, II = 2.2 ppm, III = 1.9 ppm
C) I = 3.9 ppm, II = 2.7 ppm, III = 1.9 ppm
D) I = 3.9 ppm, II = 2.2 ppm, III = 2.4 ppm
E) none of these

Question 53

How many ¹H NMR signals does 2-chloro-3-methyl-2-butene exhibit?

A) 1
B) 2
C) 3
D) 4
E) 5

Question 54

Which of the following compounds displays two triplets and a singlet in its ¹H NMR spectrum?

A) CH₃CH(OCH₃)₂
B) CH₃OCH₂CH₂OCH₃
C) CH₃OCH₂CH(OH)CH₃
D) CH₃OCH₂CH₂CH₂CH₂OCH₃
E) CH₃CH₂OCH₂CH₃

Question 55

A compound with molecular formula C₈H₁₄ has the following ¹H NMR spectrum. Which of the following is the correct number of protons giving rise to each signal? SHAPE \* MERGEFORMAT

A) I - 3H, II - 9H, III - 2H
B) I - 2H, II - 9H, III - 3H
C) I - 4H, II - 6H, III - 4H
D) I - 3H, II - 6H, III - 2H

Question 56

Which of the indicated protons in the following compound would appear most upfield in the ¹H NMR spectrum?

A) I
B) II
C) III
D) IV
E) I & III

Question 57

Predict the chemical shifts for the signals in the ¹H NMR spectrum for the following compound.

Question 58

Which of the following compounds will display only two singlets in its ¹H NMR spectrum?

A) I
B) II
C) III
D) IV
E) V

Question 59

A compound with molecular formula C₆H₁₁N has the following ¹H NMR spectrum. Which of the following is the correct number of protons giving rise to each signal? SHAPE \* MERGEFORMAT

A) I - 6H, II - 3H, III - 2H
B) I - 5H, II - 4H, III - 2H
C) I - 6H, II - 4H, III - 1H
D) I - 1H, II - 4H, III - 6H

Question 60

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

A) 1,1-dichloropropane
B) 1,3-dichloropropane
C) 1,2-dichloropropane
D) 2,2-dichloropropane
E) 1-chloropropane

Question 61

The ^{ADVANCE \u 21} ADVANCE \d 2H NMR spectrum of 1-propanol displays a singlet for the OH proton instead of a triplet. Explain why.

Question 62

The ^{ADVANCE \u 21} ADVANCE \d 2H NMR spectrum of ethanamine (CH₃CH₂NH₂) displays a singlet for the NH₂ protons instead of a triplet. Explain why.

Question 63

Which of the following is the maximum multiplicity observed for H_c protons in the following compound? Assume that J_cd and J_cb values are different.

A) 5
B) 6
C) 8
D) 12
E) none of these

Question 64

Determine the multiplicity of each signal in the expected ¹H NMR spectrum of the following compound.

Question 65

Determine the multiplicity of each signal in the expected ¹H NMR spectrum of the following compound.

Question 66

Which of the following J_bc values is consistent with the following structure?

A) 1.2 Hz
B) 6.5 Hz
C) 14 Hz
D) 20 Hz
E) none of these

Question 67

Determine the multiplicity of each signal in the expected ¹H NMR spectrum of the following compound.

Question 68

Which of the following J_ab values is consistent with the following structure?

A) 1.2 Hz
B) 6.5 Hz
C) 17 Hz
D) 20 Hz
E) 11 Hz

Question 69

Presence of which of the following protons is confirmed by D₂O exchange?

A) OH
B) NH₂
C) CH
D) A & B
E) none of these

Question 70

The ^{ADVANCE \u 21} ADVANCE \d 2H NMR spectrum of an alcohol displays a singlet for the OH protons in the range of 2 - 5 ppm. Explain how you can confirm the signal for the OH protons.

Question 71

Determine the multiplicity and predict the chemical shifts of each signal in the expected ¹H NMR spectrum of the following compound.

Question 72

The coupling constant (J) for bromoethane is 7 Hz when the ¹H NMR spectrum is acquired 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
E) 1 Hz

Question 73

Which of the following compounds will display a singlet, a triplet and a quartet in its ¹H NMR spectrum?

A) 2-chloro-4-methylpentane
B) 3-chloro-2-methylpentane
C) 3-chloropentane
D) 1-chloro-2,2-dimethylbutane
E) 3-chloro-3-methylpentane

Question 74

Which of the following J_ac values is consistent with the following structure?

A) 1.2 Hz
B) 6.5 Hz
C) 17 Hz
D) 20 Hz
E) 11 Hz

Question 75

Predict the multiplicity of each signal in the expected ¹H NMR spectrum of 2,3-dimethyl-2-pentanol.

Question 76

Determine the multiplicity of each signal in the expected ¹H NMR spectrum of the following compound.

Question 77

Determine the multiplicity of each signal in the expected ¹H NMR spectrum of the following compound.

Question 78

Which of the following is the maximum multiplicity observed for H_b protons in the following compound? Assume that J_ab and J_bc values are different.

A) 9
B) 12
C) 21
D) 24
E) none of these

Question 79

Which of the following compounds will display only three singlets in its ¹H NMR spectrum?

A) I
B) II
C) III
D) IV
E) V

Question 80

Determine the multiplicity of each signal in the expected ¹H NMR spectrum of the following compound.