Smith 6th Edition Exam Prep

Organic Chemistry, 6e (Smith)

Spectroscopy C Nuclear Magnetic Resonance Spectroscopy

1) How many unique protons are present in each of the following compounds?

A) I = 6; II = 3; III = 6

B) I = 5; II = 4; III = 6

C) I = 6, II = 4, III = 4

D) I = 6; II = 4; III = 6

2) How many peaks would be observed for each of the circled protons in the compounds below?

A) I = 2; II = 6; III = 1

B) I = 3; II = 5; III = 2

C) I = 1; II = 5; III = 1

D) I = 2; II = 6; III = 2

3) Into how many peaks will each of the circled protons be split? (Assume complete resolution of all NMR peaks is possible)

A) I = 3; II = 8; III = 1; IV = 4; V = 3

B) I = 9; II = 8; III = 2; IV = 4; V = 4

C) I = 4; II = 8; III = 2; IV = 4; V = 5

D) I = 4; Ii = 7; III = 2; IV = 4; V = 3

4) How many peaks would be observed for each of the circled protons in the compounds below?

A) I = 8; II = 4; III = 3; IV = 3

B) I = 7; II = 4; III = 3; IV = 4

C) I = 7; II = 3; III = 3; IV = 3

D) I = 7; II = 4; III = 2; IV = 4

5) How many different kinds of protons are present in each of the following molecules?

A) I = 3; II = 5; III = 5; IV = 4; V = 3

B) I = 4; II = 5; III = 4; IV = 4; V = 3

C) I = 4; II = 5; III = 5; IV = 4; V = 3

D) I = 4; II = 5; III = 5; IV = 3; V = 4

6) Into how many peaks will each of the circled protons be split? (Assume complete resolution of all NMR peaks is possible)

A) I = 3; II = 7; III = 4

B) I = 2; II = 7; III = 4

C) I = 2; II = 7; III = 3

D) I = 2; II = 6; III = 4

7) How many peaks would be observed for each of the circled protons in the compounds below?

A) I = 6; II = 2; III = 3

B) I = 7; II = 3; III = 3

C) I = 7; II = 1; III = 3

D) I = 7; II = 2; III = 3

8) How many peaks would be observed for each of the circled protons in the compounds below?

A) I = 1; II = 4; III = 7

B) I = 3; II = 3; III = 7

C) I = 2; II = 4; III = 7

D) I = 2; II = 4; III = 6

9) How many different kinds of protons are present in each of the following compounds?

A) I = 4; II = 3; III = 1

B) I = 4; II = 4; III = 1

C) I = 4; II = 4; III = 2

D) I = 3; II = 3; III = 1

10) How many different kinds of protons are present in each of the following compounds?

A) I = 2; II = 4; III = 6

B) I = 2; II = 4; III = 4

C) I = 3; II = 3; III = 5

D) I = 2; II = 4; III = 5

11) How many different kinds of protons are present in each of the following compounds?

A) I = 6; II = 5; III = 3

B) I = 7; II = 5; III = 3

C) I = 7; II = 6; III = 3

D) I = 6; II = 6; III = 3

12) How many different kinds of protons are present in each of the following molecules?

A) I = 6; II = 3; III = 4

B) I = 5; II = 3; III = 4

C) I = 6; II = 4; III = 5

D) I = 6; II = 4; III = 4

13) How many different kinds of protons are present in each of the following compounds?

A) I = 2; II = 3; III = 4

B) I = 2; II = 3; III = 3

C) I = 3; II = 3; III = 3

D) I = 3; II = 3; III = 4

14) How many different kinds of protons are present in each of the following compounds?

A) I = 4; II = 4; III = 4

B) I = 4; II = 4; III = 5

C) I = 3; II = 3; III = 5

D) I = 3; II = 4; III = 5

15) Which of the labeled protons absorbs furthest upfield in the 1H NMR spectrum?

A) Ha

B) Hb

C) Hc

D) Hd

16) Which of the following compounds does not show only one signal in its 1H NMR spectrum?

A) I

B) II

C) III

D) IV

17) Which of the indicated protons in the molecules below would absorb furthest downfield in a 1H NMR spectrum?

A) I

B) II

C) III

D) IV

18) Which of the labeled protons would absorb furthest downfield in a 1H NMR spectrum?

A) I

B) II

C) III

D) IV

19) Which of the indicated protons would absorb furthest downfield in a 1H NMR spectrum?

A) I

B) II

C) III

D) IV

20) Which compound does not give four sets of absorptions in its 1H NMR spectrum (i.e., which compound does not have four unique hydrogens)?

A) I

B) II

C) III

D) IV

21) Compound X has a molecular formula C8H10 and gives the 1H NMR spectrum below. What is the structure of X?

A) A

B) B

C) C

D) D

22) How many different kinds of protons are present in each of the following compounds?

A) a: 5; b: 6

B) a: 5; b: 5

C) a: 4; b: 6

D) a: 4; b: 5

23) Into how many peaks will the circled proton be split?

A) 5

B) 6

C) 7

D) 8

24) Which of the indicated protons absorbs furthest downfield?

A) Ha

B) Hb

C) Hc

D) Hd

25) For each of the following compounds, indicate how many 13C NMR signals will be observed.

A) a: 4; b: 4; c: 7; d: 4

B) a: 5; b: 4; c: 7; d: 3

C) a: 4; b: 7; c: 7; d: 3

D) a: 5; b: 4; c: 6; d: 5

26) For each of the following compounds, indicate how many 13C NMR signals will be seen.

A) a: 3; b: 3; c: 5; d: 3

B) a: 4; b: 3; c: 5; d: 3

C) a: 3; b: 4; c: 5; d: 3

D) a: 4; b: 3; c: 3; d: 3

27) Which of the following compounds would give rise to a 13C spectrum with 6 peaks?

A) I

B) II

C) III

D) IV

28) An unknown compound X has the empirical formula C3H6O and a molecular ion in its mass spectrum at 116. Compound X shows no IR absorption at 3200-3600 cm-1 but shows a peak at 1700 cm-1. The 1H NMR spectral data of X is shown below. What is the structure of compound X?

A) I

B) II

C) III

D) IV

29) What is the relationship between Ha and Hb in the following compound?

A) Homotopic

B) Enantiotopic

C) Diastereotopic

D) Mesotopic

30) What is the relationship between Ha and Hb in the following compound?

A) Homotopic

B) Enantiotopic

C) Diastereotopic

D) Mesotopic

31) An unknown compound X has the molecular formula C6H14O. Compound X shows a strong peak in its IR spectrum at 3000 cm-1. The 1H NMR spectral data of compound X is given below. What is the structure of compound X?

A) I

B) II

C) III

D) IV

32) An unknown compound X has the molecular formula C7H13OBr. Compound X shows a strong peak in its IR spectrum at 1700 cm-1. The 1H NMR spectral data of compound X is given below. What is the structure of compound X?

A) I

B) II

C) III

D) IV

33) An unknown compound X has the molecular formula C6H12O2. Compound X shows a strong peak in its IR spectrum at 1700 cm-1. The 1H NMR spectral data of compound X is given below. What is the structure of compound X?

A) I

B) II

C) III

D) IV

34) An unknown compound X has the molecular formula C6H14O. Compound X shows a peak in its IR spectrum at 3200-3600 cm-1. The 1H NMR spectral data for compound X is given below. What is the structure of compound X?

A) I

B) II

C) III

D) IV

35) An unknown compound X has the molecular formula C10H11O2Br. Compound X shows a strong absorption in its IR spectrum at 1700 cm-1. The 1H NMR spectral data for compound X is given below. What is the structure of compound X?

A) Only I

B) Only II

C) Only III

D) I or II

36) How could spectroscopy be used to distinguish between the following compounds?

A) Compound A has a triplet in its 1H NMR spectrum at 1.0 ppm.

B) Compound B has a peak at 3200-3500 cm-1 in its IR spectrum.

C) Compound A has a peak in its IR spectrum at 2900 cm-1.

D) Compound A has a triplet in its 1H NMR spectrum at 1.0 ppm and compound B has a peak at 3200-3500 cm-1 in its IR spectrum.

37) An unknown compound A has the molecular formula C7H14O2. Compound A absorbs strongly in the IR at 1700 cm-1. The 1H NMR spectral data for compound A are given below. What is the structure of compound A?

A) I

B) II

C) III

D) IV

38) An unknown compound A has the molecular formula C12H16O. Compound A absorbs strongly in the IR at 1700 cm-1. The NMR spectral data for compound A are given below. What is the structure of compound A?

A) I

B) II

C) III

D) IV

39) Which of the following statements about 13C NMR is not true?

A) In 13C proton-decoupled NMR spectra, all peaks are singlets.

B) 13C NMR spectra display peaks for only carbons that bear hydrogen atoms.

C) 13C NMR chemical shifts occur over a greater range than 1H NMR chemical shifts.

D) 13C NMR easily differentiates between the different hybridized carbons (sp3, sp2, and sp hybridized carbons).

40) What region of the electromagnetic spectrum does nuclear magnet resonance spectroscopy use?

A) Radio frequency

B) Microwave frequency

C) Infrared frequency

D) Visible frequency

E) Ultraviolet frequency

41) An unknown compound has the formula of C9H12. The following 1H NMR peaks were observed:

Doublet at Δ 1.22

Septet at Δ 2.83

Multiplet at Δ 7.09

From the data above, pick the compound below that fits the spectra data.

A) I

B) II

C) III

D) IV

42) Which of the following statements is true about electromagnetic radiation?

A) All molecules absorb electromagnetic radiation at some frequency.

B) Frequency is directly proportional to wavelength.

C) NMR uses the microwave region of the electromagnetic spectrum.

D) The radio frequency region of the electromagnetic spectrum has the largest energy per photon.

E) Energy is inversely proportional to frequency.

43) Which of the following spectroscopy methods does not involve the interaction of organic molecules with electromagnetic radiation?

A) Nuclear magnetic resonance

B) Infrared spectroscopy

C) Mass spectrometry

D) Ultraviolet spectroscopy

44) What effect does increasing the operating frequency of a 1H NMR spectrum have on the value of chemical shift in Δ?

A) Chemical shift in Δ will also increase.

B) Chemical shift in Δ will decrease.

C) Chemical shift in Δ will remain the same.

D) It is not possible to predict the change in chemical shift in Δ.

45) What effect does increasing the operating frequency of a 1H NMR spectrum have on the frequency of an absorption in Hz?

A) Frequency of an absorption in Hz will also increase.

B) Frequency of an absorption in Hz will decrease.

C) Frequency of an absorption in Hz will remain the same.

D) It is not possible to predict the change in frequency of an absorption in Hz.

46) What effect does increasing the operating frequency of a 1H NMR spectrum have on the magnitude of a coupling constant J in Hz?

A) Magnitude of coupling constant J in Hz will also increase.

B) Magnitude of coupling constant J in Hz will decrease.

C) Magnitude of coupling constant J in Hz will remain the same.

D) It is not possible to predict the change in the magnitude of coupling constant J in Hz.

47) Which of the indicated protons absorbs further downfield?

A) HA

B) HB

C) HC

D) HD

48) How many different kinds of protons are present in the following molecule?

A) 2

B) 3

C) 4

D) 5

49) How many different kinds of 13C peaks will be seen?

A) 2

B) 3

C) 4

D) 5

50) How many different kinds of protons are present in the following molecule?

A) 2

B) 3

C) 4

D) 5

51) How many different kinds of 13C peaks will be seen?

A) 2

B) 3

C) 4

D) 5