Question 1

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

Accepted Answer

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) ."E) B) and C)
F) A) and D)

Question 2

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

Accepted Answer

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 = 3E) None of the above
F) B) and C)

Question 3

Which compound does not give four sets of absorptions in its 1H NMR spectrum (i.e.,which compound does not have four unique hydrogens) ? 1H NMR spectrum (i.e.,which compound does not have four unique hydrogens) ?   A) I B) II C) III D) IV" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)  I
B)  II
C)  III
D)  IVE) A) and D)
F) B) and C)

Question 4

Which of the indicated protons would absorb furthest downfield in a 1H NMR spectrum? 1H NMR spectrum?   A) I B) II C) III D) IV" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)  I
B)  II
C)  III
D)  IVE) A) and B)
F) None of the above

Question 5

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

Accepted Answer

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.E) B) and D)
F) A) and B)

Question 6

What is the relationship between Ha and Hb in the following compound? a and Hb in the following compound?   A) Homotopic B) Enantiotopic C) Diastereotopic D) Mesotopic" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)  Homotopic
B)  Enantiotopic
C)  Diastereotopic
D)  MesotopicE) C) and D)
F) B) and D)

Question 7

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? 6H14O.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" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)  I
B)  II
C)  III
D)  IVE) A) and C)
F) A) and D)

Question 8

What is the relationship between Ha and Hb in the following compound? a and Hb in the following compound?   A) Homotopic B) Enantiotopic C) Diastereotopic D) Mesotopic" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)  Homotopic
B)  Enantiotopic
C)  Diastereotopic
D)  MesotopicE) A) and D)
F) All of the above

Question 9

How many different kinds of 13C peaks will be seen? 13C peaks will be seen?   A) 2 B) 3 C) 4 D) 5" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)  2
B)  3
C)  4
D)  5E) B) and D)
F) B) and C)

Question 10

Which of the following compounds does not show only one signal in its 1H NMR spectrum? 1H NMR spectrum?   A) I B) II C) III D) IV" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)  I
B)  II
C)  III
D)  IVE) A) and B)
F) B) and C)

Question 11

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

Accepted Answer

A)  2
B)  3
C)  4
D)  5E) None of the above
F) B) and D)

Question 12

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? 6H14O.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" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)  I
B)  II
C)  III
D)  IVE) B) and D)
F) A) and B)

Question 13

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

Accepted Answer

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 = 3E) All of the above
F) B) and D)

Question 14

How could spectroscopy be used to distinguish between the following compounds? 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." class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

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.E) A) and C)
F) C) and D)

Question 15

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

Accepted Answer

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.E) C) and D)
F) B) and D)

Question 16

Which of the indicated protons absorbs further downfield? A B) HB C) HC D) HD" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)  HA
B)  HB
C)  HC
D)  HDE) B) and C)
F) A) and D)

Question 17

Which of the labeled protons would absorb furthest downfield in a 1H NMR spectrum? 1H NMR spectrum?   A) I B) II C) III D) IV" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)  I
B)  II
C)  III
D)  IVE) C) and D)
F) A) and B)

Question 18

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. 9H12.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" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)  I
B)  II
C)  III
D)  IVE) None of the above
F) A) and B)

Question 19

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

Accepted Answer

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 = 5E) All of the above
F) B) and C)

Question 20

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? 10H11O2Br.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" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)  Only I
B)  Only II
C)  Only III
D)  I or IIE) C) and D)
F) B) and D)

Exam 32: Organic Spectroscopy Concepts

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?

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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.

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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?

Correct AnswerverifiedShow Answer

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?

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

Which of the indicated protons absorbs further downfield?

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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?

Correct Answer
verified

Correct Answer
verified

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.

Correct Answer
verified

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

Correct Answer
verified

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

Correct Answer
verified

Correct Answer
verified

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

Correct Answer
verified

Correct Answer
verified

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?

Correct Answer
verified

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?

Correct Answer
verified

What is the relationship between H_a and H_b in the following compound?

Correct Answer
verified

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

Correct Answer
verified

What is the relationship between H_a and H_b in the following compound?

Correct Answer
verified

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

Correct Answer
verified

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

Correct Answer
verified

Correct Answer
verified

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

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

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

Correct Answer
verified