Jt 1 A Uhcl Orgo Ii Exam2.0 Questions Ch13

Front 1

1) A nucleus with an __________ atomic number or an __________ mass number has a nuclear spin that can be observed by the NMR spectrometer.
A) even, odd
B) odd, even
C) odd, odd
D) even, even

Back 1

C) odd, odd

Front 2

2) How many nuclear spin states are allowed for the 1H nucleus?
A) 1
B) 2
C) 3
D) 4
E) 10

Back 2

B) 2

Front 3

3) 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.
A) independent of
B) directly proportional to
C) inversely proportional to
D) exponentially related to
E) logarithmically related to

Back 3

B) directly proportional to

Front 4

4) 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

Back 4

B) deshielded

Front 5

5) Electromagnetic radiation in the __________ region is used in 1H NMR spectroscopy.
A) radio wave
B) ultraviolet
C) infrared
D) microwave
E) X-ray

Back 5

A) radio wave

Front 6

6) If a molecule contains 4 elements of unsaturation and signals in the 1H NMR spectrum between δ 7.0 and 8.0 ppm, what structural group is likely to be present?
A) a carbonyl group
B) an aromatic ring
C) a hydroxyl group
D) a cyclohexyl ring
E) a carbon-carbon triple bond

Back 6

B) an aromatic ring

Front 7

7) Which of the following functional groups has the most deshielded proton and would be predicted to show an NMR signal that is the farthest downfield?
A) benzylic - H
B) allylic - H
C) aldehyde - H
D) aromatic - H
E) acetylenic - H

Back 7

C) aldehyde - H

Front 8

8) 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
B) 5.30
C) 3.18
D) cannot be determined from information given

Back 8

B) 5.30

Front 9

11) What is the relative area of each peak in a quartet spin-spin splitting pattern?
A) 1:2:1
B) 1:2:2:1
C) 1:1:1:1
D) 1:4:4:1
E) 1:3:3:1

Back 9

E) 1:3:3:1

Front 10

12) What compound exhibits only two signals in its 1H NMR spectrum, a triplet and a quintet?
A) BrCH2CH2CH2Br
B) BrCH2CH2CH2Cl
C) (CH3)2CHCH(CH3)2
D) CH3CH2CH2CH3
E) (CH3)2CHOCH(CH3)2

Back 10

A) BrCH2CH2CH2Br

Front 11

15) Describe the number of signals and their splitting in the 1H NMR spectrum of (CH3)2CHOCH3.
A) 3 signals: 2 doublets and a septet
B) 2 signals: a doublet and a septet
C) 3 signals: a doublet, a quartet, and a septet
D) 4 signals: 2 doublets, a singlet, and a septet
E) 3 signals: a singlet, a doublet, and a septet

Back 11

E) 3 signals: a singlet, a doublet, and a septet

Front 12

16) In the 1H NMR spectrum of bromoethane the methylene group is split into a quartet by the α and β nuclear spins of the protons on the neighboring methyl group. If the external magnetic field, Bº, directs upward, which sequence of nuclear spins contributes to the second farthest peak down field within the spin-spin splitting pattern?
A) ↑↓↓
B) ↑↓↑
C) ↑↑↑
D) ↓↓↓
E) ↑↑↓↓

Back 12

B) ↑↓↑

Front 13

20) Any process faster than __________ will be recorded as an average by NMR spectroscopy.
A) 0.0005 seconds
B) 0.1 seconds
C) 0.01 seconds
D) 0.001 seconds
E) 1 minute

Back 13

C) 0.01 seconds

Front 14

21) If a signal is observed in the 170 to 200 ppm range in a C-13 NMR sectrum, what is the most likely type of functional group associated with that carbon atom?
A) carbonyl carbon
B) allylic carbon
C) aromatic carbon
D) carbon/carbon triple bond
E) carbon/carbon double bond

Back 14

A) carbonyl carbon

Front 15

22) What is the approximate chemical shift of an alkynyl carbon in 13C NMR spectroscopy?
A) 10 ppm
B) 30 ppm
C) 70 ppm
D) 120 ppm
E) 200 ppm

Back 15

C) 70 ppm

Front 16

23) An NMR spectrometer that operates at a frequency of 60 MHz for 13C NMR spectra, operates at what frequency for 1H NMR spectra?
A) 15 MHz
B) 30 MHz
C) 60 MHz
D) 120 MHz
E) 240 MHz

Back 16

E) 240 MHz

Front 17

24) What compound exhibits three singlets in its proton spin decoupled 13C NMR spectrum?
A) BrCH2CH2CH2Br
B) BrCH2CH2CH2Cl
C) (CH3)2CHCH(CH3)2
D) CH3CH2CH2CH3
E) (CH3)2CHOCH(CH3)2

Back 17

B) BrCH2CH2CH2Cl

Front 18

27) What type of carbon environment does not generate a signal in the DEPT-90 spectrum and gives a positive peak in the DEPT-135 spectrum?
A) quaternary
B) methine
C) methylene
D) methyl
E) carbonyl

Back 18

D) methyl

Front 19

28) What type of carbon environment does not generate a signal in the DEPT-90 spectrum and gives a negative signal in the DEPT-135 spectrum?
A) quaternary
B) methine
C) methylene
D) methyl
E) carbonyl

Back 19

C) methylene

Front 20

29) Which compound generates positive peaks for the carbonyl in both its DEPT-90 and DEPT-135 spectra?
A) CH3CH2CHO
B) CH3CH2COCH3
C) CH3CO2CH2CH3
D) CH3CH2CONH2
E) H2CO

Back 20

A) CH3CH2CHO

Front 21

30) What multiplicities are observed for the signals in the off-resonance decoupled 13C spectrum of 2-chloropropene?
A) 3 singlets
B) 2 singlets and a doublet
C) a singlet and 2 doublets
D) a singlet, a doublet and a triplet
E) a singlet, a triplet, and a quartet

Back 21

E) a singlet, a triplet, and a quartet

Front 22

9) The protons marked Ha and Hb in the molecule below are __________.

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

Back 22

A) chemically equivalent

Front 23

10) How many unique NMR signals (disregard splitting) would be predicted in the 1H spectrum of the following compound ?
A) 2
B) 3
C) 4
D) 5
E) 6
F) 7

Back 23

F) 7

Front 24

13) What 1H NMR spectral data is expected for the compound shown?
A) 3.8 (1H, septet), 2.1 (3H, s), 1.0 (6H, d)
B) 3.8 (1H, septet), 3.3 (3H, s), 1.0 (6H, d)
C) 3.3 (3H, s), 2.6 (3H, septet), 1.0 (6H, d)
D) 2.6 (1H, septet), 2.1 (3H, s), 1.0 (6H, d)

Back 24

A) 3.8 (1H, septet), 2.1 (3H, s), 1.0 (6H, d)

Front 25

14) What 1H NMR spectral data is expected for the compound shown?
A) 3.8 (1H, septet), 2.1 (3H, s), 1.0 (6H, d)
B) 3.8 (1H, septet), 3.3 (3H, s), 1.0 (6H, d)
C) 3.3 (3H, s), 2.6 (3H, septet), 1.0 (6H, d)
D) 2.6 (1H, septet), 2.1 (3H, s), 1.0 (6H, d)

Back 25

D) 2.6 (1H, septet), 2.1 (3H, s), 1.0 (6H, d)

Front 26

17) The following splitting pattern represents one of the vinyl protons of styrene. Identify which proton is represented and list all the coupling constants (J values) for the splitting pattern.

Back 26

Answer: Hb, Jab = 10 Hz (cis), Jbc = 2 Hz (geminal)

Front 27

18) The protons marked Ha and Hb in the molecule below are __________.
A) chemically equivalent
B) enantiotopic
C) diastereotopic
D) endotopic
E) none of the above

Back 27

C) diastereotopic

Front 28

19) The protons marked Ha and Hb in the molecule below are __________.
A) chemically equivalent
B) enantiotopic
C) diastereotopic
D) endotopic
E) none of the above

Back 28

B) enantiotopic

Front 29

25) How many peaks appear in the proton spin decoupled 13 C NMR spectrum of the compound below?
A) 1
B) 2
C) 3
D) 4
E) 5

Back 29

E) 5

Front 30

26) How many peaks appear in the proton spin decoupled 13C NMR spectrum of the compound below?
A) 2
B) 3
C) 4
D) 5
E) 6

Back 30

B) 3

Front 31

31) Which of the structures shown below is consistent with the C-13 NMR (off resonance splitting for each peak is shown as a table within the figure) and H-NMR spectra? (formula = C9H11OBr)

Back 31

B