Deck 14: Nmr Spectroscopy

Question 1

Determine the number of signals for isopentylamine in the ¹H NMR spectrum.

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

Answer 1

5

Question 2

How many signals would you expect to see in the ¹H NMR spectrum of the following compound? CH₃CH₂CH₂CH₃

A)1
B)3
C)2
D)4
E)6

Answer 2

2

Question 3

How many proton NMR singlets will 2-bromo-3-methyl-2-butene exhibit?

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

Answer 3

3

Question 4

If the frequency for flipping a ¹H nucleus at an applied field of 1.4092 Tesla is 60 MHz,what would be the applied magnetic field if the frequency is 360 MHz?

A)8)4552 Tesla
B)0)2349 Tesla
C)1)4092 Tesla
D)4)2577 Tesla
E)3)0439 Tesla

Question 5

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

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

Question 6

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

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

Question 7

Determine the number of signals for 4-methyl-1-propylbenzene in the ¹H NMR spectrum.

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

Question 8

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

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

Question 9

How many signals would you expect to see in the ¹H NMR spectrum of the following compound? ClCH₂CH₂Cl

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

Question 10

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

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

Question 11

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

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

Question 12

Which of the following spectroscopic techniques uses the lowest energy of the electromagnetic radiation spectrum?

A)UV
B)visible
C)IR
D)X-ray
E)NMR

Question 13

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

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

Question 14

Which of the following electromagnetic wave types is used in nuclear magnetic resonance spectroscopy?

A)X-ray
B)infrared
C)visible
D)radio
E)ultraviolet

Question 15

If a chemical shift of an NMR signal is 7.2 ppm measured in a 60 MHz NMR spectrometer,how many Hz would this signal be from the TMS signal?

A)8)3 Hz
B)432 Hz
C)0)12 Hz
D)72 Hz
E)60 Hz

Question 16

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

A)1
B)2
C)4
D)3
E)6

Question 17

¹H nuclei located near electronegative atoms tend to be ________ relative to ¹H nuclei which are not.

A)shielded
B)deshielded
C)resonanced
D)split
E)none of the above

Question 18

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

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

Question 19

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

A)7
B)3
C)4
D)2
E)8

Question 20

Why is Fourier transform NMR spectroscopy preferred over continuous wave as a technique for ¹³C NMR?

Question 21

Which of the following protons gives an NMR signal with the highest chemical shift value (farthest downfield)? (CH₃)₂CH-O-CH₂CH₂CH₃
1 2 3 4 5

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

Question 22

Which of the following protons gives an NMR signal with the lowest chemical shift value (farthest upfield)? F-CH₂CH₂CH₂CH₂CH₂-Br
1 2 3 4 5

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

Question 23

How many distinct triplets would you expect in the ¹H NMR of the compound below?

A)0
B)2
C)4
D)6
E)8

Question 24

What splitting pattern is observed in the proton NMR spectrum for the indicated hydrogens?

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

Question 25

What is the ratio of the protons in the following compound?

A)3:3:2
B)3:2
C)6:2:1
D)3:1
E)3:2:1

Question 26

Which of the following compounds gives the highest chemical shift value (farthest downfield)in the NMR spectrum?

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

Question 27

What is the ratio of the protons in the following compound?

A)3:3:3:2
B)6:3:2
C)9:2
D)3:2
E)6:2

Question 28

Describe the difference between a ketone and an aldehyde in the ¹H NMR spectrum.

A)An aldehyde has a signal at 9.0 - 10.0 ppm.
B)An aldehyde has a signal at 2.1 ppm.
C)An aldehyde has a signal at 5.0 ppm.
D)An aldehyde has a signal at 3.5 ppm.
E)An aldehyde has a signal at 8.0 ppm.

Question 29

H-H coupling is observed in the ¹H NMR spectrum of CH₃CH₂OCH₃ and the signal from the methylene H's does not appear as a single peak.How does this signal appear? Explain in detail what is occurring.

Question 30

Give the splitting pattern for each proton in the ¹H NMR spectrum.

A)a = triplet; b = doublet; c = doublet; d = multiplet; e = triplet
B)a = doublet; b = triplet; c = doublet; d = multiplet; e = doublet
C)a = triplet; b = quartet; c = triplet; d = multiplet; e = triplet
D)a = singlet; b = doublet; c = singlet; d = multiplet; e = singlet
E)a = triplet; b = quartet; c= triplet; d = multiplet; e = doublet

Question 31

If two signals differ by 3 ppm,how do they differ in Hertz in a 60 MHz spectrometer?

A)20 Hz
B)300 Hz
C)360 Hz
D)180 Hz
E)90 Hz

Question 32

Predict the integration for each proton in the ¹H NMR spectrum.

A)a = 2H; b = 3H; c = 2H; d = 3H; e = 2H
B)a = 2H; b = 3H; c = 2H; d = 5H; e = 2H
C)a = 5H; b = 5H; c = 7H; d = 7H; e = 7H
D)a = 3H; b = 2H; c = 2H; d = 2H; e = 3H
E)a = 3H; b = 2H; c = 2H; d = 3H; e = 2H

Question 33

Which of the following methyl groups will exhibit the most downfield (highest)chemical shift in ¹H NMR spectroscopy?

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

Question 34

What splitting pattern is observed in the proton NMR spectrum for the indicated hydrogens? CH₃OCH₂CH₂OCH₃
↑

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

Question 35

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

Question 36

What splitting pattern is observed in the proton NMR spectrum for the indicated hydrogens?

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

Question 37

Which of the following protons gives an NMR signal with the lowest chemical shift value (farthest upfield)?

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

Question 38

Using a 60 MHz spectrometer,the protons in dichloromethane appear at 5.30 ppm.When the same sample is placed in a 100 MHz instrument,where does the signal appear?

A)8)33 ppm
B)3)18 ppm
C)5)30 ppm
D)cannot be determined from information given

Question 39

Which of the following protons gives an NMR signal with the highest chemical shift value (farthest downfield)? F-CH₂CH₂CH₂CH₂CH₂-Br
1 2 3 4 5

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

Question 40

What splitting pattern is observed in the proton NMR spectrum for the indicated hydrogens?

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

Question 41

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),180.98 (singlet); IR,broad 3500-2800,1708 cm^-1

Question 42

Which of the compounds below most closely matches the following ¹H NMR data:
7.6 (2H,d),7.3 (2H,d),3.5 (3H,s),2.2 (3H,s)?

Question 43

Predict the number of signals expected,their splitting,and their relative area in the ¹H NMR spectrum of CH₃CH₂OCH₃.

Question 44

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); IR,2980,1740 cm-1

Question 45

An unknown compound,C₃H₅Cl₃,gave the following proton NMR data:
Doublet at 1.70 ppm (3H)
Multiplet at 4.32 ppm (1H)
Doublet at 5.85 ppm (1H)
What is the structure of the compound?

Question 46

Predict the number of signals expected,their splitting,and their relative area in the ¹H NMR spectrum of (CH₃)₃CCHO.

Question 47

An unknown compound,C₄H₁₀O,gave the following proton NMR data:
Triplet at 1.13 ppm
Quartet at 3.38 ppm
What is the structure of the compound?

Question 48

Deduce the identity of the following compound from the ¹H NMR data given.
C₄H₇BrO: δ 2.2 (3H,singlet),3.5 (2H,triplet),4.5 (2H,triplet)

Question 49

Which of the following compounds has a triplet at 9.8 in its ¹H NMR spectrum?

Question 50

An unknown compound,C₄H₈Br₂,gave the following proton NMR data:
Singlet at 1.97 ppm (6H)
Singlet at 3.89 ppm (2H)
What is the compound?

Question 51

Deduce the identity of the compound from the data provided.
C₁₀H₁₄O: IR (cm^-1): 3200-3500 (broad),3050,2950,1610
¹H NMR(δ): 1.0 (s,6H),2.0 (s,3H),2.8 (broad s,1H),
7.3 (d,2H),7.6 (d,2H)

Question 52

Deduce the structure from the data given: C₇H₁₆O; ¹H NMR δ (integration,coupling): 0.9 (9H,s),1.5 (2H,t),3.5 (3H,s),3.8 (2H,t).

Question 53

Which of the following technique(s)can readily distinguish between: ^?

A)NMR
B)IR
C)MS
D)A and B
E)A and C

Question 54

An unknown compound,C₉H₁₂,gave the following NMR spectrum: Triplet at 1.21 ppm (3H)Singlet at 2.30 ppm (3H)Quartet at 2.60 ppm (2H)Singlet at 7.04 ppm (4H)
What is the structure of the compound?

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

Question 55

Deduce the identity of the following compound from the spectral data given.
C₅H₁₀O: ¹H NMR,δ 1.2 (6H,doublet),2.1 (3H,singlet),2.8 (1H,septet); IR,2980,1710 cm^-1; MS,m/z 71,

Question 56

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,singlet)

Question 57

Give the integration and splitting pattern for the indicated signals in the ¹H NMR spectrum.

A)a = 3H,triplet; d = 1H,singlet
B)a = 2H,triplet; d = 1H,singlet
C)a = 3H,triplet,d = 1H,singlet
D)a = 2H,triplet; d = 2H,doublet
E)a = 3H,triplet; d = 1H,triplet

Question 58

Predict the number of signals expected,their splitting,and their relative area in the ¹H NMR spectrum of 1,2-dichloroethane (ClCH₂CH₂Cl).

Question 59

Which compound has a ¹H NMR spectrum consisting of the following peaks: 0.9 (6H,d),1.0 (3H,t),2.2 (2H,q),and 4.0 (1H,septet)?

A)(CH₃)₂CHCH₂O₂CCH₃
B)(CH₃)₂CHCH₂CO₂CH₃
C)(CH₃)₂CHO₂CCH₂CH₃
D)(CH₃)₂CHCO₂CH₂CH₃
E)(CH₃)₂CHOCH₂CH₃

Question 60

Deduce the identity of the following compound from the spectral data given.
C₇H₁₀O₂: ¹H NMR,δ 1.16 (3H,singlet),2.21 (2H,singlet); ¹³C NMR,δ 216.25 (singlet),52.57 (singlet),34.51 (triplet),20.22 (quartet)

Question 61

What multiplicities are observed in the spin coupled ¹³C NMR spectrum of 2,3-dimethyl-2-butene?

Question 62

Can alkenes and aromatics be easily distinguished from each other in an ¹³C NMR spectrum?

Question 63

How might the proton spectrum of ultrapure dimethylamine,(CH₃)₂NH,differ from the spectrum of this compound to which D₂O has been added?

Question 64

Give the structure of a compound that has a formula of C₄H₇ClO₂ and has a triplet (3H,1.1 ppm),quintet (2H,1.2 ppm),triplet (1H,4.4 ppm),and singlet (1H,11.6 ppm)in the ¹H NMR spectrum.

A)
B)
C)
D)
E)

Question 65

How might the two trimethylcyclohexane isomers shown below be most readily distinguished using NMR?

Question 66

How many distinct carbon signals are expected in the proton-decoupled ¹³C NMR spectrum of the compound below?

Question 67

Give the structure of a compound that has a formula of C₅H₁₀O_2, and has a triplet (3H,1.1 ppm),sextet (2H,1.8 ppm),triplet (2H,2.3 ppm)and a singlet (3H,3.8 ppm)in the ¹H NMR spectrum.

A)
B)
C)
D)
E)

Question 68

Deduce the structure from the data given: C₈H₁₀O; ¹³C NMR δ (coupling): 140 (s),128 (d),126 (d),122 (d),60 (t),15 (q).

Question 69

Which of the following compounds has a signal disappear when D₂O is added to it,ethyl alcohol or ethyl chloride?

Question 70

Deduce the identity of the compound from the data provided. C₅H₈O₄: IR (cm^-1): 2800-3300 (broad),2950,1740
¹³C NMR (δ,splitting): 17.3 (q),44.3 (s),210.5 (s)

A)HO₂CC(CH₃)₂CO₂H
B)CH₃O₂CCH₂CO₂CH₃
C)HO₂CCH₂CH₂CH₂CO₂H
D)CH₃O₂CCH₂CH₂CO₂H
E)CH₃O₂CCO₂CH₂CH₃

Question 71

How many distinct carbon signals are expected in the proton-decoupled ¹³C NMR spectrum of the compound below?

Question 72

A compound gave a signal at 203 ppm in the ¹³C NMR spectrum.How would it be possible to tell if the compound is an aldehyde or a ketone in a proton-coupled ¹³C NMR spectrum?

Question 73

The chair form of cyclohexane has protons in two distinct environments,axial and equatorial.When the proton NMR of cyclohexane is run on a 100 MHz instrument at 23°C,only one signal for the compound is observed.Explain this apparent contradiction.

Question 74

Deduce the identity of the compound from the data provided. C₇H₁₂: IR (cm^-1): 3300,2950,2220; ¹³C NMR: 5 signals

A)1,2-dimethylcyclopentene
B)5-methyl-2-hexyne
C)3,3-dimethyl-1-pentyne
D)4,4-dimethyl-1-pentyne
E)2,4-dimethyl-2-pentene

Question 75

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

Question 76

Why is carbon-hydrogen coupling not generally seen in ¹H NMR spectra?

Question 77

Give the structure of a compound that has a formula of C₆H₁₂O and has a triplet (3H,1.1 ppm),doublet (6H,1.2 ppm),quartet (2H,2.4 ppm),and septet (1H,2.7 ppm)in the ¹H NMR spectrum.

A)
B)
C)
D)
E)

Question 78

Deduce the identity of the compound from the data provided. C₈H₁₃Br: IR (cm^-1): 2950,2150
¹H NMR (δ,splitting,integral): 3.5 (t,2H),1.8 (t,2H),
0)9 (s,9H)
¹³C NMR: 6 signals

A)CH₃CHBrCCC(CH₃)₃
B)HCCCH₂C(CH₃)₂CH₂CH₂Br
C)3-bromo-1,2-dimethylcyclohexene
D)4-bromo-1,2,4-trimethylcyclopentene
E)BrCH₂CH₂CCC(CH₃)₃

Question 79

Deduce the identity of the compound from the data provided.
C₅H₁₀O₂: IR (cm^-1): 2950,1740; ¹³C NMR (δ,splitting): 15.8 (q),19.7 (q),68.4 (d),195.3 (s)

Question 80

How many distinct carbon signals are expected in the proton-decoupled ¹³C NMR spectrum of the compound below?