Question 1

The CH2 group indicated would most likely appear as what in the proton NMR spectrum?

Accepted Answer

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

Question 2

A chemist is evaluating a proton NMR spectrum taken on a 300 MHz NMR spectrometer.She wishes to determine the chemical shift in ppm of a singlet that appears at 1140 Hz from TMS.What is the chemical shift in ppm?

Accepted Answer

A)  0.26 ppm 
B)  3.8 ppm 
C)  7.6 ppm 
D)  300 ppm 
E)  None of the above. 
A)  0.26 ppm 
B)  3.8 ppm 
C)  7.6 ppm 
D)  300 ppm 
E)  None of the above.

Question 3

A compound of the formula C10H14 gave the 1H NMR spectrum shown below and exhibited three peaks in the 13C NMR spectrum.What compound might it be?

Accepted Answer

A) 
  
B) 
  
C) 
  
D) 
  
E) 
  
A) 
  
B) 
  
C) 
  
D) 
  
E)

Question 4

Which of the following is not true about the information from a proton NMR spectrum?

Accepted Answer

A)  It identifies the number of different types of hydrogens in a molecule. 
B)  It gives the ratios of one type of hydrogen to another. 
C)  It gives information about what environment each hydrogen is in. 
D)  It tells how many neighboring hydrogens each type of hydrogen has. 
E)  None of the above.Proton NMR gives all these types of information. 
A)  It identifies the number of different types of hydrogens in a molecule. 
B)  It gives the ratios of one type of hydrogen to another. 
C)  It gives information about what environment each hydrogen is in. 
D)  It tells how many neighboring hydrogens each type of hydrogen has. 
E)  None of the above.Proton NMR gives all these types of information.

Question 5

A bottle in a chemical stockroom was labeled simply "dichlorobenzene" without specifying which isomer was present.Capillary GC showed that it was a single pure compound,and the proton decoupled carbon NMR spectrum showed three peaks (not including solvent).You conclude that the bottle contained

Accepted Answer

A) 
  
B) 
  
C) 
  
D)  any of the dichlorobenzene isomers 
E)  none of the dichlorobenzene isomers 
A) 
  
B) 
  
C) 
  
D)  any of the dichlorobenzene isomers 
E)  none of the dichlorobenzene isomers

Question 6

The most downfield proton NMR signal (i.e.,signal most to the left in the spectrum)in the following molecule would be

Accepted Answer

A)  A 
B)  B 
C)  C 
D)  D 
E)  there is no way to tell 
A)  A 
B)  B 
C)  C 
D)  D 
E)  there is no way to tell

Question 7

The following spectra data was most likely obtained from which compound?

Accepted Answer

A) 
    
B) 
  
C) 
  
D) 
  
E) 
  
A) 
    
B) 
  
C) 
  
D) 
  
E)

Question 8

A very old bottle labeled only "chlorinated benzene" was found in the stockroom.Capillary GC showed (surprisingly)that the compound was pure,and a proton-decoupled 13C NMR spectrum showed only two peaks.Which of the following compounds was in the bottle?

Accepted Answer

A) 
  
B) 
  
C) 
  
D) 
  
E) 
  
A) 
  
B) 
  
C) 
  
D) 
  
E)

Question 9

Carbon-13 NMR is

Accepted Answer

A)  impossible since 13C has no magnetic moment. 
B)  complicated by 13C-13C splitting. 
C)  impossible since 13C does not occur in nature. 
D)  more difficult than 1H NMR. 
E)  None of the above. 
A)  impossible since 13C has no magnetic moment. 
B)  complicated by 13C-13C splitting. 
C)  impossible since 13C does not occur in nature. 
D)  more difficult than 1H NMR. 
E)  None of the above.

Question 10

Heating the 4-methylbenzenesulfonate ester of the isomer shown below in 2,2,2-trifluoroethanol (a highly ionizing solvent of low nucleophilicity)leads two products with the molecular formula C10H18.The major product displays 9 different signals in its 13C NMR spectrum.Two of them occur at relatively low field,about F1F1F1S1F1F1F10 = 120 and 145 ppm,respectively.The 1H NMR spectrum exhibits a multiplet near F1F1F1S1F1F1F10 = 5 ppm (1 H); all other signals are upfield of F1F1F1S1F1F1F10 = 3 ppm.Identify the compound.

Accepted Answer

A) 
    
B) 
  
C) 
  
D) 
  
E) 
  
A) 
    
B) 
  
C) 
  
D) 
  
E)

Question 11

Which compound most likely exhibits the following proton NMR?

Accepted Answer

A) 
    
B) 
  
C) 
  
D) 
  
E) 
  
A) 
    
B) 
  
C) 
  
D) 
  
E)

Question 12

The type of electromagnetic energy required to cause nuclear magnetic resonance is

Accepted Answer

A)  infrared. 
B)  radio. 
C)  ultraviolet. 
D)  visible. 
E)  microwave. 
A)  infrared. 
B)  radio. 
C)  ultraviolet. 
D)  visible. 
E)  microwave.

Question 13

Which of the following structures of formula C8H8Br2 would give the NMR spectrum shown below?

Accepted Answer

A) 
    
B) 
  
C) 
  
D) 
  
E) 
  
A) 
    
B) 
  
C) 
  
D) 
  
E)

Question 14

What structure would be consistent with the following NMR spectrum and data?

Accepted Answer

A) 
    
B) 
  
C) 
  
D) 
  
E) 
  
A) 
    
B) 
  
C) 
  
D) 
  
E)

Question 15

Describe the splitting that would be observed by Ha in the proton NMR spectrum,assuming Ha is coupled to all its neighboring protons in an equivalent manner.

Accepted Answer

A)  Ha will be split into a pentet. 
B)  Ha will be split into a sextet. 
C)  Ha will be split into a septet. 
D)  Ha will be split into an octet. 
E)  None of the above. 
A)  Ha will be split into a pentet. 
B)  Ha will be split into a sextet. 
C)  Ha will be split into a septet. 
D)  Ha will be split into an octet. 
E)  None of the above.

Question 16

How many magnetically different types of hydrogens and carbons are in the following compound?

Accepted Answer

A)  6 hydrogens,8 carbons 
B)  3 hydrgens,8 carbons 
C)  6 hydrogens,6 carbons 
D)  3 hydrogens,6 carbons 
E)  3 hydrogens,3 carbons 
A)  6 hydrogens,8 carbons 
B)  3 hydrgens,8 carbons 
C)  6 hydrogens,6 carbons 
D)  3 hydrogens,6 carbons 
E)  3 hydrogens,3 carbons

Question 17

Which compound C9H11Br would give the proton NMR spectrum shown below?

Accepted Answer

A) 
    
B) 
  
C) 
  
D) 
  
E) 
  
A) 
    
B) 
  
C) 
  
D) 
  
E)

Question 18

The molecular formulas and 13C NMR data (in ppm)are given below.The splitting pattern of each signal,taken from the non-decoupled spectrum is given in parentheses.Deduce the correct structure:

Accepted Answer

A) 
    
B) 
  
C) 
  
D) 
  
E) 
  
A) 
    
B) 
  
C) 
  
D) 
  
E)

Question 19

Which of the following nuclei are incapable of magnetic resonance?

Accepted Answer

A)  Hydrogen (1H) 
B)  Carbon (13
C)  
C)  Fluorine (19F) 
D)  Phosphorus (31P) 
E)  All are NMR active. 
A)  Hydrogen (1H) 
B)  Carbon (13
C)  
C)  Fluorine (19F) 
D)  Phosphorus (31P) 
E)  All are NMR active.

Question 20

How many different signals will be present in the proton NMR for ethylpropanoate? (Do not count TMS as one of the signals!)

Accepted Answer

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

Exam 10: Using Nuclear Magnetic Resonance Spectroscopy to Deduce Structure

The CH2 group indicated would most likely appear as what in the proton NMR spectrum?

A chemist is evaluating a proton NMR spectrum taken on a 300 MHz NMR spectrometer.She wishes to determine the chemical shift in ppm of a singlet that appears at 1140 Hz from TMS.What is the chemical shift in ppm?

A compound of the formula C10H14 gave the 1H NMR spectrum shown below and exhibited three peaks in the 13C NMR spectrum.What compound might it be?

Which of the following is not true about the information from a proton NMR spectrum?

A bottle in a chemical stockroom was labeled simply "dichlorobenzene" without specifying which isomer was present.Capillary GC showed that it was a single pure compound,and the proton decoupled carbon NMR spectrum showed three peaks (not including solvent).You conclude that the bottle contained

The most downfield proton NMR signal (i.e.,signal most to the left in the spectrum)in the following molecule would be

The following spectra data was most likely obtained from which compound?

A very old bottle labeled only "chlorinated benzene" was found in the stockroom.Capillary GC showed (surprisingly)that the compound was pure,and a proton-decoupled 13C NMR spectrum showed only two peaks.Which of the following compounds was in the bottle?

Carbon-13 NMR is

Which compound most likely exhibits the following proton NMR?

The type of electromagnetic energy required to cause nuclear magnetic resonance is

Which of the following structures of formula C8H8Br2 would give the NMR spectrum shown below?

What structure would be consistent with the following NMR spectrum and data?

Describe the splitting that would be observed by Ha in the proton NMR spectrum,assuming Ha is coupled to all its neighboring protons in an equivalent manner.

How many magnetically different types of hydrogens and carbons are in the following compound?

Which compound C9H11Br would give the proton NMR spectrum shown below?

The molecular formulas and 13C NMR data (in ppm)are given below.The splitting pattern of each signal,taken from the non-decoupled spectrum is given in parentheses.Deduce the correct structure:

Which of the following nuclei are incapable of magnetic resonance?

How many different signals will be present in the proton NMR for ethylpropanoate? (Do not count TMS as one of the signals!)

Structure and Bonding in Organic Molecules

Structure and Reactivity: Acids and Bases,polar and Nonpolar Molecules

Reactions of Alkanes: Bond-Dissociation Energies,radical Halogenation,and Relative Reactivity

Cycloalkanes

Stereoisomers

Properties and Reactions of Haloalkanes: Bimolecular Nucleophilic Substitution

Further Reactions of Haloalkanes: Unimolecular Substitution and Pathways of Elimination

Hydroxy of Functional Group: Alcohols: Properties,preparation,and Strategy of Synthesis

Further Reactions of Alcohols and the Chemistry of Ethers

Alkenes: Infrared Spectroscopy and Mass Spectrometry

Reactions to Alkenes

Alkynes: the Carbon

Delocalized Pi Systems: Investigation by Ultraviolet and Visible Spectroscopy Interlude

Benzene and Aromaticity: Electrophilic Aromatic Substitution

Electrophilic Attack on Derivatives of Benzene: Substituents Control Regioselectivity

Aldehydes and Ketones: the Carbonyl Group

Enols,enolates,and the Aldol Condensation: A,b-Unsaturated Aldehydes and Ketones

Carboxylic Acids

Carboxylic Acid Derivatives

Amines and Their Derivatives: Functional Groups Containing Nitrogen

Chemistry of the Benzene Substituents: Alkylbenzenes,phenols,and Benzenamines

Ester Enolates and the Claisen Condensation: Synthesis of B-Dicarbonyl Compounds; Acyl Anion Equivalents

Carbohydrates: Polyfunctional Compounds in Nature

Heterocycles: Heteroatoms in Cyclic Organic Compounds

Amino Acids,peptides,proteins,and Nucleic Acids: Nitrogen-Containing Polymers in Nature

Filters

The CH₂ group indicated would most likely appear as what in the proton NMR spectrum?

A compound of the formula C₁₀H₁₄ gave the ¹H NMR spectrum shown below and exhibited three peaks in the ¹³C NMR spectrum.What compound might it be?

A very old bottle labeled only "chlorinated benzene" was found in the stockroom.Capillary GC showed (surprisingly)that the compound was pure,and a proton-decoupled ¹³C NMR spectrum showed only two peaks.Which of the following compounds was in the bottle?

Which of the following structures of formula C₈H₈Br₂ would give the NMR spectrum shown below?

Describe the splitting that would be observed by H_a in the proton NMR spectrum,assuming H_a is coupled to all its neighboring protons in an equivalent manner.

Which compound C₉H₁₁Br would give the proton NMR spectrum shown below?

The molecular formulas and ¹³C NMR data (in ppm)are given below.The splitting pattern of each signal,taken from the non-decoupled spectrum is given in parentheses.Deduce the correct structure: