Deck 9: Nuclear Magnetic Resonance and Mass Spectrometry: Tools for Structure Determination

Question 1

Which one of the following best represents the predicted approximate chemical shift and coupling for the hydrogen(s)indicated with the arrow?

A) 3.00 ppm,doublet
B) 3.00 ppm,triplet
C) 5.00 ppm,triplet
D) 1.00 ppm,doublet
E) 3.00 ppm,singlet

Answer 1

5.00 ppm,triplet

Question 2

How many ¹H NMR signals would trans-1,2-dichlorocyclopropane give?

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

Answer 2

2

Question 3

Which one of the following best represents the predicted approximate chemical shift and coupling for the hydrogen(s)indicated with the arrow?

A) 1.10 ppm,singlet
B) 2.10 ppm,doublet
C) 3.40 ppm,singlet
D) 4.5 ppm,singlet
E) 3.5 ppm,quartet

Answer 3

3.40 ppm,singlet

Question 4

Which one of the following best represents the predicted approximate chemical shift and coupling for the hydrogen(s)indicated with the arrow?

A) 1.00 ppm,doublet
B) 2.00 ppm,singlet
C) 2.00 ppm,triplet
D) 2.00 ppm,doublet
E) 1.00 ppm,triplet

Question 5

For the C2 methylene group in 1-bromopropane,the theoretical multiplicity in the ¹H NMR spectrum,presuming that J_ab is sufficiently different from J_bc and that the instrument has sufficient resolving power,is which of these?

A) 2
B) 5
C) 6
D) 8
E) 12

Question 6

A downfield ( $\delta$ 9-10)singlet is observed in the ¹H NMR spectrum of:

A)

B)

C)

D)

E)

Question 7

Which one of the following best represents the predicted approximate chemical shift and coupling for the hydrogen(s)indicated with the arrow?

A) 1.10 ppm,singlet
B) 2.10 ppm,triplet
C) 3.40 ppm,triplet
D) 4.5 ppm,singlet
E) 5.3 ppm,doublet

Question 8

Which one of the following best represents the predicted approximate chemical shift and coupling for the hydrogen(s)indicated with the arrow?

A) 1.00 ppm,quartet
B) 2.40 ppm,singlet
C) 2.40 ppm,quartet
D) 3.00 ppm,quartet
E) 2.40 ppm,triplet

Question 9

Which one of the following best represents the predicted approximate chemical shift and coupling for the hydrogen(s)indicated with the arrow?

A) 1.00 ppm,singlet
B) 2.10 ppm,singlet
C) 2.10 ppm,quartet
D) 3.00 ppm,singlet
E) 2.10 ppm,triplet

Question 10

Which one of the following best represents the predicted approximate chemical shift and coupling for the hydrogen(s)indicated with the arrow?

A) 5.40 ppm,multiplet
B) 2.00 ppm,multiplet
C) 2.00 ppm,doublet
D) 2.00 ppm,quartet
E) 5.40 ppm,doublet

Question 11

How many chemically distinct ¹H NMR signals are there in the following compound?

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

Question 12

How many ¹H NMR signals would cis-1,2-dichlorocyclopropane give?

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

Question 13

An organic compound absorbs strongly in the IR at 1687 cm^-1.Its ¹H NMR spectrum consists of two signals,a singlet at 2.1 ppm and a multiplet centered at 7.1 ppm.Its mass spectrum shows significant peaks at m/z 120,m/z 105 and m/z 77.This information is consistent with which of the following structures?

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

Question 14

Which proton(s)of the compound below would appear as a septet in the ¹H NMR spectrum?

A) The protons on carbon I
B) The protons on carbon II
C) The protons on carbon III
D) The protons on carbon IV
E) The protons on carbon V

Question 15

The ¹H NMR signal for which of the indicated protons occurs farthest downfield?

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

Question 16

Which one of the following best represents the predicted approximate chemical shift and coupling for the hydrogen(s)indicated with the arrow?

A) 1.00 ppm,quartet
B) 2.40 ppm,singlet
C) 2.40 ppm,quartet
D) 3.00 ppm,quartet
E) 1.00 ppm,triplet

Question 17

Which one of the following best represents the predicted approximate chemical shift and coupling for the hydrogen(s)indicated with the arrow?

A) 5.40 ppm,doublet
B) 1.00 ppm,multiplet
C) 2.00 ppm,doublet
D) 1.00 ppm,doublet
E) 5.40 ppm,multiplet

Question 18

If all the protons of 1-fluoropentane could be discerned,which would you expect to be at the lowest field in the ¹H NMR spectrum of this compound?

A) Protons on carbon I
B) Protons on carbon II
C) Protons on carbon III
D) Protons on carbon IV
E) Protons on carbon V

Question 19

Which one of the following best represents the predicted approximate chemical shift and coupling for the hydrogen(s)indicated with the arrow?

A) 3.00 ppm,doublet
B) 3.00 ppm,triplet
C) 5.00 ppm,triplet
D) 1.00 ppm,doublet
E) 5.40 ppm,multiplet

Question 20

The ¹H NMR spectrum of which of these compounds would consist of a triplet,singlet and quartet only?

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 21

A compound with the molecular formula C₆H₁₅N gave the following ¹H NMR spectrum: triplet, $\delta$ 0.90
Quartet, $\delta$ 2.4
There were no other signals.The most likely structure for the compound is:

A)

B)

C) CH₃CH₂CH₂CH₂CH₂CH₂NH₂
D)

E)

Question 22

The ¹H NMR spectrum of which of the compounds below,all of formula C₇H₁₂O₂,would consist of two singlets only?

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

Question 23

Which proton(s)of the compound below would appear as a doublet in the ¹H NMR spectrum?

A) The protons on carbon I
B) The protons on carbon II
C) The protons on carbon III
D) The protons on carbon IV
E) The protons on carbon V

Question 24

What is the structure of the compound in the following ¹H-NMR spectrum with the molecular formula C₈H₁₄? Relative integration is shown.

A)

B)

C)

D)

E)

Question 25

What is the structure of the compound in the following ¹H-NMR spectrum with the molecular formula C₁₀H₂₀? Relative integration is shown.

A)

B)

C)

D)

E)

Question 26

The ¹H NMR spectrum of which of the compounds below,all of formula C₇H₁₂O₂,would consist of three singlets only?

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

Question 27

A compound with the molecular formula C₁₀H₁₃Cl gave the following ¹H NMR spectrum: singlet, $\delta$ 1.6
Singlet, $\delta$ 3.1
Multiplet, $\delta$ 7.2 (5H)
The most likely structure for the compound is:

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

Question 28

What is the structure of the compound in the following ¹H-NMR spectrum with the molecular formula C₉H₁₄O? IR data shows no characteristic peak around 1700 cm^-1.The ¹³C-NMR chemical shifts (ppm): 108.4,50.9,31.6,23.5,2.0.Relative integration is known.

A)

B)

C)

D)

E)

Question 29

Predict the splitting pattern you would observe for the proton at C3 of 2,3-dimethyl-2-phenylbutane.

A) Doublet
B) Singlet
C) Quartet
D) Septet
E) Octet

Question 30

Which of these compounds will not be represented by a singlet only in the ¹H NMR spectrum?

A) Neopentane
B) Hexamethylbenzene
C) Isobutane
D) (Z)-1,2-Dichloroethene
E) (E)-1,2-Dichloroethene

Question 31

A compound with the molecular formula C₈H₉ClO gave the following ¹H NMR spectrum: triplet, $\delta$ 3.7
Triplet, $\delta$ 4.2
Multiplet $\delta$ 7.1
There was no evidence of an -OH band in the IR spectrum.The most likely structure for the compound is:

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

Question 32

A compound with the molecular formula C₄H₁₀O gives a ¹H NMR spectrum consisting only of a quartet centered at $\delta$ 3.5 and a triplet at $\delta$ 1.1.The most likely structure for the compound is:

A)

B)

C) CH₃CH₂CH₂CH₂OH
D) CH₃CH₂OCH₂CH₃
E)

Question 33

A compound with the molecular formula C₈H₉BrO gave the following ¹H NMR spectrum: triplet, $\delta$ 1.4
Quartet, $\delta$ 3.9
Multiplet, $\delta$ 7.0 (4H)
There was no evidence of an -OH band in the IR spectrum.A possible structure for the compound is:

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

Question 34

Consider the expected splitting of signal "b" in the ¹H NMR spectrum of 1-methoxy-2-methylpropane,shown below.Presuming that J_ab is sufficiently different from J_bc and that the instrument has sufficient resolving power,what is the theoretical multiplicity of signal "b"?

A) 8
B) 9
C) 12
D) 21
E) 24

Question 35

A compound with the molecular formula C₃H₆Cl₂ gave a ¹H NMR spectrum consisting only of a triplet centered at $\delta$ 3.7 and a quintet centered at $\delta$ 2.2.The most likely structure for the compound is:

A) CH₃CH₂CHCl₂
B) CH₃CHClCH₂Cl
C) ClCH₂CHClCH₃
D) ClCH₂CH₂CH₂Cl
E) CH₃CCl₂CH₃

Question 36

Determine the most likely structure of a compound,with the molecular formula C₉H₁₂,which gave a ¹H NMR spectrum consisting of: a doublet at $\delta$ 1.25
A septet at $\delta$ 2.90 and
A multiplet at $\delta$ 7.25 ]

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

Question 37

What is the structure of the compound in the following ¹H-NMR spectrum with the molecular formula C₆H₁₁N? In the IR spectrum you notice a stretch at about 2250 cm^-1.Relative integration is shown.

A)

B)

C)

D)

E)

Question 38

What is the structure of the compound in the following ¹H-NMR spectrum with the molecular formula C₉H₁₀O₂? Relative integration is shown.

A)

B)

C)

D)

E)

Question 39

Which proton(s)of the compound below would appear as a triplet in the ¹H NMR spectrum?

A) The protons on carbon II
B) The protons on carbon I and V
C) The protons on carbon III and V
D) The protons on carbon III and IV
E) The protons on carbon V

Question 40

The ¹H NMR spectrum of which of the compounds below,all of formula C₇H₁₂O₂,would consist of a singlet,a doublet and a triplet only?

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

Question 41

What is the structure of the compound in the following ¹H-NMR spectrum with the molecular formula C₆H₁₀O₂? Relative integration is shown.

A)

B)

C)

D)

E)

Question 42

What is the structure of the compound in the following ¹H-NMR spectrum with the molecular formula C₆H₁₀O₂? The ¹³C-NMR shows characteristic chemical shifts at 22.3,31.1,117.3,157.7,and 171.6 ppm.Relative integration is shown.

A)

B)

C)

D)

E)

Question 43

What is the structure of the compound in the following ¹H-NMR spectrum with the molecular formula C₉H₁₈O₂ and characteristic ¹³C-NMR peaks at 11.3,21.6,25.3,49.4,67.1,and 175.5 ppm? Relative integration is shown.

A)

B)

C)

D)

E)

Question 44

What is the structure of the compound in the following ¹H-NMR spectrum with the molecular formula C₆H₁₂? Relative integration is shown.

A)

B)

C)

D)

E)

Question 45

What is the structure of the compound in the following ¹H-NMR spectrum with the molecular formula C₆H₁₂O₂? Relative integration is shown.

A)

B)

C)

D)

E)

Question 46

What is the structure of the compound in the following ¹H-NMR spectrum with the molecular formula C₇H₁₂O₄? The ¹³C-NMR spectrum shows peaks at 14.1,40.8,61.0 and 166.8 ppm.Relative integration is shown.

A)

B)

C)

D)

E)

Question 47

What is the structure of the compound in the following ¹H-NMR spectrum with the molecular formula C₆H₁₂O which shows no characteristic stretches in the IR between 3600-3300 cm^-1,but does around 1600 cm^-1? Relative integration is shown.

A)

B)

C)

D)

E)

Question 48

What is the structure of the compound in the following ¹H-NMR spectrum with the molecular formula C₈H₁₅ClO₃,which shows a characteristic stretch in the IR around 1750 cm^-1 but not around 3500 cm^-1,and a characteristic peak at 173 ppm in the ¹³C-NMR? Relative integration is shown.

A)

B)

C)

D)

E)

Question 49

What is the structure of the compound in the following ¹H-NMR spectrum with the molecular formula C₉H₁₂O? Relative integration is shown.

A)

B)

C)

D)

E)

Question 50

A compound C₄H₉Br gave the following ¹H NMR spectrum: triplet, $\delta$ 1.0 (3H);doublet, $\delta$ 1.7;multiplet, $\delta$ 1.8;multiplet, $\delta$ 4.1 (1H)
Which is a reasonable structure for the compound?

A) CH₃CH₂CHBrCH₃
B) CH₃CH₂CH₂CH₂Br
C) (CH₃)₂CHCH₂Br
D) (CH₃)₃CBr

Question 51

What is the structure of the compound in the following ¹H-NMR spectrum with the molecular formula C₈H₁₆O? Relative integration is shown.

A)

B)

C)

D)

E)

Question 52

What is the structure of the compound in the following ¹H-NMR spectrum with the molecular formula C₁₀H₁₂O₂? Relative integration is shown.

A)

B)

C)

D)

E)

Question 53

What is the structure of the compound in the following ¹H-NMR spectrum with the molecular formula C₅H₈O? The IR spectrum does show a characteristic stretch around 1700 cm^-1.Relative integration is shown.

A)

B)

C)

D)

E)

Question 54

What is the structure of the compound in the following ¹H-NMR spectrum with the molecular formula C₁₁H₁₄O₂? Looking at the ¹³C-NMR you notice a peak at 174 ppm.Relative integration is shown.

A)

B)

C)

D)

E)

Question 55

A compound C₅H₁₀O gave the following spectral data: ¹H NMR spectrum IR spectrum
Doublet, $\delta$ 1.10 strong peak
Singlet, $\delta$ 2.10 near 1720 cm^-1
Septet, $\delta$ 2.50
Which is a reasonable structure for the compound?

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

Question 56

What is the structure of the compound in the following ¹H-NMR spectrum with the molecular formula C₅H₁₀O? The IR spectrum does not show any characteristic stretches around 1700 cm^-1.Relative integration is shown.

A)

B)

C)

D)

E)

Question 57

What is the structure of the compound in the following ¹H-NMR spectrum with the molecular formula C₅H₁₁NO,which shows a characteristic stretch in the IR around 1700 cm^-1,and a characteristic peak at 202 ppm in the ¹³C-NMR? Relative integration is shown.

A)

B)

C)

D)

E)

Question 58

What is the structure of the compound in the following ¹H-NMR spectrum with the molecular formula C₄H₈O? Relative integration is shown.

A)

B)

C)

D)

E)

Question 59

What is the structure of the compound in the following ¹H-NMR spectrum with the molecular formula C₄H₇Br? Relative integration is shown.

A)

B)

C)

D)

E)

Question 60

What is the structure of the compound in the following ¹H-NMR spectrum with the molecular formula C₁₀H₁₁N? Looking at the ¹³C-NMR you notice 10 distinct peaks,and the IR has a characteristic peak around 2250 cm^-1.Relative integration is shown.

A)

B)

C)

D)

E)

Question 61

In NMR terminology,protons H_a and H_b are said to be:

A) Identical
B) Enantiotopic
C) Diastereotopic
D) Homotopic
E) Mesotopic

Question 62

-Which is the likely molecular ion (M ^- _$\bullet$ )?

A) 15
B) 29
C) 44
D) 45
E) 100

Question 63

How many ¹³C signals would you expect from anisole?

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

Question 64

How will the methyl carbon appear in the proton off-resonance decoupled ¹³C spectrum of toluene?

A) Singlet
B) Doublet
C) Triplet
D) Quartet
E) Quintet

Question 65

Determine the likely structure for a compound A (C₆H₁₀O),which is found to decolorize bromine in carbon tetrachloride.Its spectral data is as follows: ¹H NMR IR
Triplet, $\delta$ 1.0 singlet, $\delta$ 2.4 2200 cm^-1 (sharp)
Singlet, $\delta$ 1.4 singlet, $\delta$ 3.4 3300 cm^-1 (sharp)
Quartet, $\delta$ 1.6 3500 cm^-1 (broad)

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

Question 66

How many ¹³C signals would 1,4-dimethylbenzene give?

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

Question 67

A prominent (M 1⁺ _$\bullet$ -18)peak suggests that the compound might be a(n):

A) Alkane
B) Alcohol
C) Ether
D) Ketone
E) Primary amine

Question 68

How many ¹³C signals would 1,3-dichlorobenzene give?

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

Question 69

The broadband proton-decoupled ¹³C NMR spectrum of a hexyl chloride exhibits five signals.Which of these structures could be the correct one for the compound?

A)

B)

C)

D)

E)

Question 70

How many signals will be recorded in the broadband proton-decoupled ¹³C spectrum of 4-chloro-1-ethylbenzene?

A) 2
B) 3
C) 4
D) 6
E) 7

Question 71

Select the structure of a compound C₆H₁₄ with a base peak at m/z 43.

A) CH₃CH₂CH₂CH₂CH₂CH₃
B) (CH₃CH₂)₂CHCH₃
C) (CH₃)₃CCH₂CH₃
D) (CH₃)₂CHCH(CH₃)₂
E) None of these

Question 72

A compound with the molecular formula C₁₀H₁₄ gave the following ¹H NMR spectrum: doublet, $\delta$ 1.2
Singlet, $\delta$ 2.3
Septet, $\delta$ 2.8
Multiplet, $\delta$ 7.1
A possible structure for the compound is:

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

Question 73

The C₇ compound which gives 3 signals in the broadband proton-decoupled ¹³C spectrum could be:

A) Heptane
B) 2-Methylhexane
C) 3,3-Dimethylpentane
D) 2,4-Dimethylpentane
E) 2,2,3-Trimethylbutane

Question 74

What is the structure of the compound in the following ¹H-NMR spectrum with the molecular formula C₅H₁₁NO? In the ¹³C-NMR spectrum you notice that the farthest peak downfield has a chemical shift of 173 ppm.Relative integration is shown.

A)

B)

C)

D)

E)

Question 75

What is the molecular formula of this compound? m/z
Intensity
78 M ⁺ _$\bullet$
10)00
79
1
80
3)3
81
0)3

A) C₆H₆
B) C₃H₅Cl
C) C₆H₈
D) C₆H₉
E) C₃H₇Cl

Question 76

Which is the base peak?

A) 15
B) 29
C) 44
D) 45
E) 100

Question 77

In the structure shown,H_b and H_c are classified as:

A) homotopic protons.
B) geminal protons.
C) enantiotopic protons.
D) diastereotopic protons.
E) isomeric protons.

Question 78

What is the molecular formula of this compound? m/z
Intensity
84 M ⁺ _$\bullet$
10)00
85
0)56
86
0)04

A) C₅H₁₀O
B) C₅H₈O
C) C₅H₂₄
D) C₆H₁₂
E) C₄H₆O₂

Question 79

How many ¹³C signals would 1,2-dimethylbenzene give?

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

Question 80

A bromodichlorobenzene which gives four signals in the broadband proton-decoupled ¹³C spectrum could be:

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