Question 1

Consider the molecular orbital model of benzene.In the ground state how many molecular orbitals are filled with electrons?

Accepted Answer

A)  1 
B)  2 
C)  3 
D)  4 
E)  5 
A)  1 
B)  2 
C)  3 
D)  4 
E)  5

Question 2

The heats of hydrogenation for cyclohexene and benzene are given below.Calculate the resonance stabilization energy of benzene.
C6H10 + H2 $\rightarrow$ C6H12 $\Delta$Ho = -120 kJ/mol
C6H6 + 3H2 $\rightarrow$ C6H12 $\Delta$Ho = -208 kJ/mol

Accepted Answer

The resonance stabilization energy of be

Question 3

In the molecular orbital model of cyclobutadiene,how many pairs of degenerate  $\pi$-antibonding molecular orbitals are there?

Accepted Answer

A)  1 
B)  2 
C)  3 
D)  4 
E)  0 
A)  1 
B)  2 
C)  3 
D)  4 
E)  0

Question 4

Which reagent(s)would serve as the basis for a simple chemical test that would distinguish between benzene and cyclohexene?

Accepted Answer

A)  NaOH in H2O 
B)  Br2 in CCl4 
C)  AgNO3 in C2H5OH 
D)  NaHSO3 in H2O 
E)  None of these 
A)  NaOH in H2O 
B)  Br2 in CCl4 
C)  AgNO3 in C2H5OH 
D)  NaHSO3 in H2O 
E)  None of these

Question 5

If thiophene is an aromatic molecule and reacts similarly to benzene,how many (neutral)monobromothiophenes could be obtained in the following reaction?

Accepted Answer

A)  1 
B)  2 
C)  3 
D)  4 
E)  5 
A)  1 
B)  2 
C)  3 
D)  4 
E)  5

Question 6

How many resonances would be expected in the broad-band decoupled C-13 spectra of:

Accepted Answer

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

Question 7

Which of the following is true of benzene?

Accepted Answer

A)  Benzene tends to undergo addition rather than substitution reactions. 
B)  All of the hydrogen atoms of benzene are equivalent. 
C)  The carbon-carbon bonds of benzene are alternately short and long around the ring. 
D)  The benzene ring is a distorted hexagon. 
E)  Benzene has the stability expected for cyclohexatriene. 
A)  Benzene tends to undergo addition rather than substitution reactions. 
B)  All of the hydrogen atoms of benzene are equivalent. 
C)  The carbon-carbon bonds of benzene are alternately short and long around the ring. 
D)  The benzene ring is a distorted hexagon. 
E)  Benzene has the stability expected for cyclohexatriene.

Question 8

The carbon-carbon bonds in benzene are:

Accepted Answer

A)  of equal length and are shorter than the double bond of ethene. 
B)  of equal length and are intermediate between a double bond and a single bond. 
C)  of unequal length and are alternately short and long around the ring. 
D)  due only to p-orbital overlap. 
E)  of equal length and intermediate between the carbon-carbon bond lengths in ethene and ethyne. 
A)  of equal length and are shorter than the double bond of ethene. 
B)  of equal length and are intermediate between a double bond and a single bond. 
C)  of unequal length and are alternately short and long around the ring. 
D)  due only to p-orbital overlap. 
E)  of equal length and intermediate between the carbon-carbon bond lengths in ethene and ethyne.

Question 9

A compound has the formula C8H9Br.Its 1H NMR spectrum consists of: doublet,$\delta$ 2.0
Quartet,$\delta$ 5.15
Multiplet,$\delta$ 7.35
The IR spectrum shows two peaks in the 680-840 cm-1 region;one is between 690 and 710 cm-1 and the other is between 730 and 770 cm-1.Which is a possible structure for the compound?

Accepted Answer

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

Question 10

We now know that the two Kekule structures for benzene are related in the following way:

Accepted Answer

A)  They are each equally correct as a structure for benzene. 
B)  Benzene is sometimes one structure and sometimes the other. 
C)  The two structures are in a state of rapid equilibrium. 
D)  Neither of the two structures adequately describes benzene;benzene is a resonance hybrid of the two. 
E)  None of the above 
A)  They are each equally correct as a structure for benzene. 
B)  Benzene is sometimes one structure and sometimes the other. 
C)  The two structures are in a state of rapid equilibrium. 
D)  Neither of the two structures adequately describes benzene;benzene is a resonance hybrid of the two. 
E)  None of the above

Question 11

In the molecular orbital model of cyclobutadiene,how many  $\pi$-bonding molecular orbitals are there?

Accepted Answer

A)  1 
B)  2 
C)  3 
D)  4 
E)  5 
A)  1 
B)  2 
C)  3 
D)  4 
E)  5

Question 12

In the molecular orbital model of the cyclobutadiene,how many pairs of degenerate $\pi$-bonding molecular orbitals are there?

Accepted Answer

A)  1 
B)  2 
C)  3 
D)  4 
E)  0 
A)  1 
B)  2 
C)  3 
D)  4 
E)  0

Question 13

How many resonances would be expected in the broad-band decoupled C-13 spectra of:

Accepted Answer

A)  1 
B)  2 
C)  3 
D)  4 
E)  5 
A)  1 
B)  2 
C)  3 
D)  4 
E)  5

Question 14

In which of the following compounds would the shortest carbon-carbon bond(s)be found?

Accepted Answer

A)  Toluene 
B)  2-Ethylcyclopentene 
C)  4-Methyl-1,3-cyclohexadiene 
D)  3-Methyl-1-hexyne 
E)  3-Methyl-1,3-hexadiene 
A)  Toluene 
B)  2-Ethylcyclopentene 
C)  4-Methyl-1,3-cyclohexadiene 
D)  3-Methyl-1-hexyne 
E)  3-Methyl-1,3-hexadiene

Question 15

How many resonances would be expected in the broad-band decoupled C-13 spectra of:

Accepted Answer

A)  4 
B)  5 
C)  6 
D)  7 
E)  8 
A)  4 
B)  5 
C)  6 
D)  7 
E)  8

Question 16

Use the "polygon-in-circle" method to draw an MO diagram showing the pi-electron distribution pattern in the cyclopentadienyl anion.How is this diagram useful in explaining the aromatic properties of this anion?

Accepted Answer

The following MO diagram can be generate

Question 17

On the basis of molecular orbital theory and Hückel's rule,which molecules and/or ions should be aromatic?

Accepted Answer

A)  I and V 
B)  III and VIII 
C)  IV,VII and IX 
D)  IV,VI,VII and IX 
E)  All of the structures,I-IX 
A)  I and V 
B)  III and VIII 
C)  IV,VII and IX 
D)  IV,VI,VII and IX 
E)  All of the structures,I-IX

Question 18

Which dibromobenzene can,in theory,yield three mononitro derivatives?

Accepted Answer

A)  o-Dibromobenzene 
B)  m-Dibromobenzene 
C)  p-Dibromobenzene 
D)  All of these 
E)  None of these 
A)  o-Dibromobenzene 
B)  m-Dibromobenzene 
C)  p-Dibromobenzene 
D)  All of these 
E)  None of these

Question 19

Which of the following statements regarding the cyclopentadienyl radical is correct?

Accepted Answer

A)  It is aromatic. 
B)  It is not aromatic. 
C)  It obeys Huckel's rule. 
D)  It undergoes reactions characteristic of benzene. 
E)  It has a closed shell of 6 pi-electrons. 
A)  It is aromatic. 
B)  It is not aromatic. 
C)  It obeys Huckel's rule. 
D)  It undergoes reactions characteristic of benzene. 
E)  It has a closed shell of 6 pi-electrons.

Question 20

Which of the following structures would be aromatic?

Accepted Answer

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

Exam 14: Aromatic Compounds

Consider the molecular orbital model of benzene.In the ground state how many molecular orbitals are filled with electrons?

The heats of hydrogenation for cyclohexene and benzene are given below.Calculate the resonance stabilization energy of benzene. C6H10 + H2 →\rightarrow→ C6H12 Δ\DeltaΔ Ho = -120 kJ/mol C6H6 + 3H2 →\rightarrow→ C6H12 Δ\DeltaΔ Ho = -208 kJ/mol

In the molecular orbital model of cyclobutadiene,how many pairs of degenerate π\piπ -antibonding molecular orbitals are there?

Which reagent(s)would serve as the basis for a simple chemical test that would distinguish between benzene and cyclohexene?

If thiophene is an aromatic molecule and reacts similarly to benzene,how many (neutral)monobromothiophenes could be obtained in the following reaction?

How many resonances would be expected in the broad-band decoupled C-13 spectra of:

Which of the following is true of benzene?

The carbon-carbon bonds in benzene are:

We now know that the two Kekule structures for benzene are related in the following way:

In the molecular orbital model of cyclobutadiene,how many π\piπ -bonding molecular orbitals are there?

In the molecular orbital model of the cyclobutadiene,how many pairs of degenerate π\piπ -bonding molecular orbitals are there?

How many resonances would be expected in the broad-band decoupled C-13 spectra of:

In which of the following compounds would the shortest carbon-carbon bond(s)be found?

How many resonances would be expected in the broad-band decoupled C-13 spectra of:

Use the "polygon-in-circle" method to draw an MO diagram showing the pi-electron distribution pattern in the cyclopentadienyl anion.How is this diagram useful in explaining the aromatic properties of this anion?

On the basis of molecular orbital theory and Hückel's rule,which molecules and/or ions should be aromatic?

Which dibromobenzene can,in theory,yield three mononitro derivatives?

Which of the following statements regarding the cyclopentadienyl radical is correct?

Which of the following structures would be aromatic?

Carbon Compounds and Chemical Bonds

Representative Carbon Compounds: Functional Groups, Intermolecular Forces, and Infrared Ir Spectroscopy

An Introduction to Organic Reactions: Acids and Bases

Alkanes: Nomenclature, Conformational Analysis, and an Introduction to Synthesis

Stereochemistry: Chiral Molecules

Ionic Reactions - Nucleophilic Substitution and Elimination Reactions of Alkyl Halides

Alkenes and Alkynes I: Properties and Synthesis, Elimination Reactions of Alkyl Halides

Alkenes and Alkynes Ii: Addition Reactions

Nuclear Magnetic Resonance and Mass Spectrometry: Tools for Structure Determination

Radical Reactions

Alcohols and Ethers

Alcohols From Carbonyl Compounds Oxidation-Reduction and Organometallic Compounds

Conjugated Unsaturated Systems

Reactions of Aromatic Compounds

Aldehydes and Ketones I Nucleophilic Addition to the Carbonyl Group

Aldehydes and Ketones Ii Aldol Reactions

Carboxylic Acids and Their Derivatives Nucleophilic Addition - Elimination at the Acyl Carbon

Synthesis and Reactions of Beta-Dicarbonyl Compounds: More Chemistry of Enolate Ions

Amines

Phenols and Aryl Halides: Nucleophilic Aromatic Substitution

Carbohydrates

Lipids

Amino Acids and Proteins

Nucleic Acids and Protein Synthesis

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The heats of hydrogenation for cyclohexene and benzene are given below.Calculate the resonance stabilization energy of benzene. C₆H₁₀ + H₂ $\rightarrow$ C₆H₁₂ $\Delta$ H^o = -120 kJ/mol C₆H₆ + 3H₂ $\rightarrow$ C₆H₁₂ $\Delta$ H^o = -208 kJ/mol

In the molecular orbital model of cyclobutadiene,how many pairs of degenerate $\pi$ -antibonding molecular orbitals are there?

In the molecular orbital model of cyclobutadiene,how many $\pi$ -bonding molecular orbitals are there?

In the molecular orbital model of the cyclobutadiene,how many pairs of degenerate $\pi$ -bonding molecular orbitals are there?