Question 1

Which of the indicated protons absorbs further downfield?

Accepted Answer

A) HA 
B) HB 
C) HC 
D) HD 
A) HA 
B) HB 
C) HC 
D) HD

Question 2

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. 
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.

Question 3

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

Accepted Answer

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

Question 4

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

Accepted Answer

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

Question 5

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

Accepted Answer

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

Question 6

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 = 3 
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

Question 7

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?

Accepted Answer

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

Question 8

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 = 3 
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

Question 9

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?

Accepted Answer

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

Question 10

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)." 
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)."

Question 11

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.

Accepted Answer

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

Question 12

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

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. 
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.

Question 13

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

Accepted Answer

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

Question 14

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. 
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.

Question 15

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

Accepted Answer

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

Question 16

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 = 5 
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

Question 17

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

Accepted Answer

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

Question 18

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

Accepted Answer

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

Question 19

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

Accepted Answer

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

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?

Accepted Answer

A) Only I 
B) Only II 
C) Only III 
D) I or II 
A) Only I 
B) Only II 
C) Only III 
D) I or II

Exam 32: Organic Spectroscopy Concepts

Which of the indicated protons absorbs further downfield?

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

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

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

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

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

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?

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

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?

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

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.

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

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

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

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

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

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

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

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

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?

Structure and Bonding

Acids and Bases

Introduction to Organic Molecules and Functional Groups

Alkanes

Stereochemistry

Understanding Organic Reactions

Alkyl Halides and Nucleophilic Substitution

Alkyl Halides and Elimination Reactions

Alcohols,ethers,and Related Compounds

Alkenes and Addition Reactions

Alkynes and Synthesis

Oxidation and Reduction

Radical Reactions

Conjugation, resonance, and Dienes

Benzene and Aromatic Compounds

Reactions of Aromatic Compounds

Introduction to Carbonyl Chemistry; Organometallic Reagents; Oxidation and Reduction

Aldehydes and Ketones - Nucleophilic Addition

Carboxylic Acids and the Acidity of the O-H Bond

Carboxylic Acids and Their Derivatives - Nucleophilic Acyl Substitution

Substitution Reactions of Carbonyl Compounds at the a Carbon

Carbonyl Condensation Reactions

Amines

Carbon-Carbon Bond-Forming Reactions in Organic Synthesis

Pericyclic Reactions

Carbohydrates

Amino Acids and Proteins

Synthetic Polymers

Lipids

Molecular Ion Peaks and Fragmentation Patterns

Analyzing Molecular Motion and Infrared Spectroscopy

Filters

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

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

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

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

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?

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?

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

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.

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

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

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

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

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

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?