Question 1

An unknown compound,A,has the formula C7H14O.Elucidate the structure of A by scrutinizing its IR and1H NMR spectra,shown below.

Accepted Answer

Question 2

In the structure shown,Ha and Hb are classified as:

Accepted Answer

A) homotopic protons. 
B) vicinal protons. 
C) enantiotopic protons. 
D) diastereotopic protons. 
E) isomeric protons. 
A) homotopic protons. 
B) vicinal protons. 
C) enantiotopic protons. 
D) diastereotopic protons. 
E) isomeric protons.

Question 3

What is the structure of the compound in the following 1H-NMR spectrum with the molecular formula C10H20? Relative integration is shown.

Accepted Answer

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

Question 4

Which one of the following best represents the predicted approximate chemical shift and coupling for the hydrogen(s)indicated with the arrow in the compound nicotine?

Accepted Answer

A) 1.00 ppm,triplet 
B) 2.00 ppm,doublet 
C) 5.00 ppm,triplet 
D) 7.00 ppm.mulitplet 
E) None of these choices. 
A) 1.00 ppm,triplet 
B) 2.00 ppm,doublet 
C) 5.00 ppm,triplet 
D) 7.00 ppm.mulitplet 
E) None of these choices.

Question 5

In electron impact mass spectrometry,a beam of high-energy electrons initially dislodges one electron from the compound being studied.This produces a positively charged ion called the ___.

Accepted Answer

The answer of In electron impact mass spectrometry,a beam of...

Question 6

Consider the expected 1H NMR spectrum of 2,4-dimethyl-1,4-pentadiene.Which of the following is likely to be observed?

Accepted Answer

A) 7 signals: all singlets 
B) 4 signals: all singlets 
C) 3 signals: all singlets 
D) 3 signals: one singlet,2 doublets 
E) 4 signals: two singlets,two doublets 
A) 7 signals: all singlets 
B) 4 signals: all singlets 
C) 3 signals: all singlets 
D) 3 signals: one singlet,2 doublets 
E) 4 signals: two singlets,two doublets

Question 7

Which of these compounds will not be represented by a singlet only in the 1H NMR spectrum?

Accepted Answer

A) Neopentane 
B) Hexamethylbenzene 
C) Isobutane 
D) (Z)-1,2-Dichloroethene 
E) (
E) -1,2-Dichloroethene 
A) Neopentane 
B) Hexamethylbenzene 
C) Isobutane 
D) (Z)-1,2-Dichloroethene 
E) (
E) -1,2-Dichloroethene

Question 8

A bromodichlorobenzene which gives four signals in the broadband proton-decoupled 13C spectrum could be:

Accepted Answer

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

Question 9

Explain the key differences in the 2-dimensional NMR techniques known as COSY and heteronuclear correlations.

Accepted Answer

A COSY shows correlations betw

Question 10

In 13C NMR spectroscopy,the signal due to this type of carbon occurs furthest downfield.

Accepted Answer

A) -C$\equiv$N 
B)    
C)    
D)    
E) -C$\equiv$C- 
A) -C$\equiv$N 
B)    
C)    
D)    
E) -C$\equiv$C-

Question 11

The 1H NMR signal for which of the indicated protons will occur at the lowest frequency (most upfield signal)?

Accepted Answer

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

Question 12

In NMR terminology,protons Ha and Hb are said to be:

Accepted Answer

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

Question 13

Consider the expected splitting of signal "b" in the 1H NMR spectrum of N-methyl-1-propanamine,shown below.Presuming that Jab is sufficiently different from Jbc and that the instrument has sufficient resolving power,what is the theoretical multiplicity of signal "b"?

Accepted Answer

A) 2 
B) 5 
C) 6 
D) 8 
E) 12 
A) 2 
B) 5 
C) 6 
D) 8 
E) 12

Question 14

For the C2 methylene group in 1-bromopropane, the theoretical multiplicity in the 1H NMR spectrum,presuming that Jab is sufficiently different from Jbc and that the instrument has sufficient resolving power,is which of these?

Accepted Answer

A) 2 
B) 5 
C) 6 
D) 8 
E) 12 
A) 2 
B) 5 
C) 6 
D) 8 
E) 12

Question 15

Draw the structure for a compound that has the chemical formula C4H8O2 and shows one singlet,one triplet and one quartet in the proton NMR.

Accepted Answer

The IHD =

Question 16

What is the structure of the compound in the following 1H-NMR spectrum with the molecular formula C6H12? Relative integration is shown.

Accepted Answer

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

Question 17

An organic compound absorbs strongly in the IR at 1687 cm-1.Its 1H NMR spectrum consists of two signals,a singlet at 2.1 ppm and a multiplet centered at 7.1 ppm.Its mass spectrum shows significant peaks at m/z 120,m/z 105 and m/z 77.This information is consistent with which of the following structures?

Accepted Answer

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

Question 18

What is the structure of the compound in the following 1H-NMR spectrum with the molecular formula C5H10O? The IR spectrum does not show any characteristic stretches around 1700 cm-1.Relative integration is shown.

Accepted Answer

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

Exam 9: Nuclear Magnetic Resonance and Mass Spectrometry

An unknown compound,A,has the formula C7H14O.Elucidate the structure of A by scrutinizing its IR and1H NMR spectra,shown below.

In the structure shown,Ha and Hb are classified as:

What is the structure of the compound in the following 1H-NMR spectrum with the molecular formula C10H20? Relative integration is shown.

Which one of the following best represents the predicted approximate chemical shift and coupling for the hydrogen(s)indicated with the arrow in the compound nicotine?

In electron impact mass spectrometry,a beam of high-energy electrons initially dislodges one electron from the compound being studied.This produces a positively charged ion called the ___.

Consider the expected 1H NMR spectrum of 2,4-dimethyl-1,4-pentadiene.Which of the following is likely to be observed?

Which of these compounds will not be represented by a singlet only in the 1H NMR spectrum?

A bromodichlorobenzene which gives four signals in the broadband proton-decoupled 13C spectrum could be:

Explain the key differences in the 2-dimensional NMR techniques known as COSY and heteronuclear correlations.

In 13C NMR spectroscopy,the signal due to this type of carbon occurs furthest downfield.

The 1H NMR signal for which of the indicated protons will occur at the lowest frequency (most upfield signal)?

In NMR terminology,protons Ha and Hb are said to be:

Consider the expected splitting of signal "b" in the 1H NMR spectrum of N-methyl-1-propanamine,shown below.Presuming that Jab is sufficiently different from Jbc and that the instrument has sufficient resolving power,what is the theoretical multiplicity of signal "b"?

For the C2 methylene group in 1-bromopropane, the theoretical multiplicity in the 1H NMR spectrum,presuming that Jab is sufficiently different from Jbc and that the instrument has sufficient resolving power,is which of these?

Draw the structure for a compound that has the chemical formula C4H8O2 and shows one singlet,one triplet and one quartet in the proton NMR.

What is the structure of the compound in the following 1H-NMR spectrum with the molecular formula C6H12? Relative integration is shown.

What is the structure of the compound in the following 1H-NMR spectrum with the molecular formula C5H10O? The IR spectrum does not show any characteristic stretches around 1700 cm-1.Relative integration is shown.

The Basics

Families of Carbon

Acids and Bases

Nomenclature and Conformations of Alkanes and Cycloalkanes

Stereochemistry

Nucleophilic Reactions

Alkenes and Alkynes I

Alkenes and Alkynes II

Radical Reactions

Alcohols and Ethers

Alcohols From Carbonyl Compounds

Conjugated Unsaturated Systems

Aromatic Compounds

Reactions of Aromatic Compounds

Aldehydes and Ketones

Carboxylic Acids and Their Derivatives

Reactions at the Α Carbon of Carbonyl Compounds

Condensation and Conjugate Addition Reactions of Carbonyl Compounds

Amines

Transition Metal Complexes

Carbohydrates

Lipids

Amino Acids and Proteins

Nucleic Acids and Protein Synthesis

Filters

An unknown compound,A,has the formula C₇H₁₄O.Elucidate the structure of A by scrutinizing its IR and¹H NMR spectra,shown below.

In the structure shown,H_a and H_b are classified as:

What is the structure of the compound in the following ¹H-NMR spectrum with the molecular formula C₁₀H₂₀? Relative integration is shown.

Consider the expected ¹H NMR spectrum of 2,4-dimethyl-1,4-pentadiene.Which of the following is likely to be observed?

Which of these compounds will not be represented by a singlet only in the ¹H NMR spectrum?

A bromodichlorobenzene which gives four signals in the broadband proton-decoupled ¹³C spectrum could be:

In ¹³C NMR spectroscopy,the signal due to this type of carbon occurs furthest downfield.

The ¹H NMR signal for which of the indicated protons will occur at the lowest frequency (most upfield signal)?

In NMR terminology,protons H_a and H_b are said to be:

Consider the expected splitting of signal "b" in the ¹H NMR spectrum of N-methyl-1-propanamine,shown below.Presuming that J_ab is sufficiently different from J_bc and that the instrument has sufficient resolving power,what is the theoretical multiplicity of signal "b"?

For the C2 methylene group in 1-bromopropane, the theoretical multiplicity in the ¹H NMR spectrum,presuming that J_ab is sufficiently different from J_bc and that the instrument has sufficient resolving power,is which of these?

Draw the structure for a compound that has the chemical formula C₄H₈O₂ and shows one singlet,one triplet and one quartet in the proton NMR.

What is the structure of the compound in the following ¹H-NMR spectrum with the molecular formula C₆H₁₂? Relative integration is shown.

What is the structure of the compound in the following ¹H-NMR spectrum with the molecular formula C₅H₁₀O? The IR spectrum does not show any characteristic stretches around 1700 cm^-1.Relative integration is shown.