Question 1

Which of the labeled hydrogens is most easily abstracted in a free radical bromination reaction?

Accepted Answer

A)  HS1U1B1aS1U1B0 
B)  HS1U1B1bS1U1B0 
C)  HS1U1B1cS1U1B0 
D)  HS1U1B1dS1U1B0 
A)  HS1U1B1aS1U1B0 
B)  HS1U1B1bS1U1B0 
C)  HS1U1B1cS1U1B0 
D)  HS1U1B1dS1U1B0

Question 2

Which of the following statements about radicals and radical reactions is not true?

Accepted Answer

A)  Most radicals are unstable. 
B)  A radical contains an atom that has an octet of electrons. 
C)  Half-headed arrows are used to show the movement of lone electrons. 
D)  A radical is formed by homolysis of a covalent bond. 
A)  Most radicals are unstable. 
B)  A radical contains an atom that has an octet of electrons. 
C)  Half-headed arrows are used to show the movement of lone electrons. 
D)  A radical is formed by homolysis of a covalent bond.

Question 3

Which of the following is a radical scavenger?

Accepted Answer

A)  O3 
B)  O2 
C)  Vitamin C 
D)  CO2 
A)  O3 
B)  O2 
C)  Vitamin C 
D)  CO2

Question 4

Rank the following radicals in order of decreasing stability, putting the most stable first. $\mathrm { CH } _ { 3 } \dot { \mathrm { C } } \mathrm { H } _ { 2 }\quad$ $\mathrm { H } _ { 2 } \mathrm { C } = \mathrm { C } \dot { \mathrm { C } } \mathrm { H } _ { 2 }\quad$ $\mathrm { CH } _ { 3 } \dot { \mathrm { C } } \mathrm { HCH } _ { 3 }\quad$ $\left( \mathrm { CH } _ { 3 } \right) _ { 3 } \dot { \mathrm { C } }$
I$\quad\quad\quad\quad\quad\quad\quad$II$\quad\quad\quad\quad\quad\quad\quad$III$\quad\quad\quad\quad\quad$IV

Accepted Answer

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

Question 5

Which of the following statements about radicals is true?

Accepted Answer

A)  Cleavage of a stronger bond forms the more stable radical. 
B)  The stability of a radical increases as the number of alkyl groups bonded to the radical carbon decreases. 
C)  The higher the bond dissociation energy for a C-H bond, the more stable the resulting carbon radical. 
D)  Less stable radicals generally do not rearrange to more stable radicals. 
A)  Cleavage of a stronger bond forms the more stable radical. 
B)  The stability of a radical increases as the number of alkyl groups bonded to the radical carbon decreases. 
C)  The higher the bond dissociation energy for a C-H bond, the more stable the resulting carbon radical. 
D)  Less stable radicals generally do not rearrange to more stable radicals.

Question 6

How many monochlorination products can be formed (constitutional isomers only) from the reaction of (CH3)2CHCH2CH3 with Cl2 and hF1F1F1S1F1F1F10?

Accepted Answer

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

Question 7

A possible reaction of ethane with chlorine is shown below. $$\mathrm { CH } _ { 3 } \mathrm { CH } _ { 3 } + \mathrm { Cl } _ { 2 } \longrightarrow \mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \mathrm { Cl } + \mathrm { HCl }$$ This reaction could conceivably occur by the following chain mechanisms [1], [2], and [3]. The chain propagating step(s) is (are) _______. $[ 1 ] \quad \mathrm { Cl } _ { 2 } \longrightarrow 2 \mathrm { Cl } \cdot$
[2] $\mathrm { Cl } \cdot + \mathrm { CH } _ { 3 } \mathrm { CH } _ { 3 } \stackrel { \text { slow } } { \longrightarrow } \mathrm { HCl } + \mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 }^ \cdot$
[3] $\mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } ^\cdot + \mathrm { Cl } _ { 2 } \stackrel { \text { fast } } { \longrightarrow } \mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \mathrm { Cl } + \mathrm { Cl }\cdot$.

Accepted Answer

A)  Only [1] and [2] 
B)  Only [2] and [3] 
C)  Only [1] and [3] 
D)  Only [3] 
A)  Only [1] and [2] 
B)  Only [2] and [3] 
C)  Only [1] and [3] 
D)  Only [3]

Question 8

A possible reaction of ethane with chlorine is shown below. $$\mathrm { CH } _ { 3 } \mathrm { CH } _ { 3 } + \mathrm { Cl } _ { 2 } \longrightarrow \mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \mathrm { Cl } + \mathrm { HCl }$$ This reaction could conceivably occur by the following chain mechanisms [1], [2], and [3]. Determine F1F1F1S1?F1F1F10H for step [1]. [1] $\mathrm { Cl } _ { 2 } \longrightarrow 2 \mathrm { Cl } \cdot$
[2] $\mathrm { Cl } \cdot + \mathrm { CH } _ { 3 } \mathrm { CH } _ { 3 } \stackrel { \text { slow } } { \longrightarrow } \mathrm { HCl } + \mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } ^ \cdot$
[3] $\mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } ^ \cdot+ \mathrm { Cl } _ { 2 } \stackrel { \text { fast } } { \longrightarrow } \mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \mathrm { Cl } + \mathrm { Cl }\cdot$. Bond dissociation energies (kcal/mol): $$\begin{array} { | l | l | } 
\hline \text { Bond A-B } & \Delta \mathrm { H } \
\hline \mathrm { Cl } - \mathrm { Cl } & 58 \
\mathrm { CH } _ { 3 } - \mathrm { H } & 104 \
\mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } - \mathrm { H } & 98 \
\mathrm { CH } _ { 3 } - \mathrm { CH } _ { 3 } & 88 \
\mathrm { CH } _ { 3 } - \mathrm { Cl } & 84 \
\mathrm { H } - \mathrm { Cl } & 103 \
\hline
\end{array}$$

Accepted Answer

A)  -5 kcal/mol 
B)  +58 kcal/mol 
C)  -28 kcal/mol 
D)  None of the choices are correct. 
A)  -5 kcal/mol 
B)  +58 kcal/mol 
C)  -28 kcal/mol 
D)  None of the choices are correct.

Question 9

Which of the following statements about the stereochemistry of halogenation reactions is true?

Accepted Answer

A)  An achiral starting material always gives an achiral product only. 
B)  An achiral starting material always gives a racemic product only. 
C)  The configuration at a stereogenic center of a product must change even if a reaction does not occur at a stereogenic center. 
D)  An achiral starting material always gives either an achiral or a racemic product. 
A)  An achiral starting material always gives an achiral product only. 
B)  An achiral starting material always gives a racemic product only. 
C)  The configuration at a stereogenic center of a product must change even if a reaction does not occur at a stereogenic center. 
D)  An achiral starting material always gives either an achiral or a racemic product.

Question 10

A possible reaction of ethane with chlorine is shown below. $$\mathrm { CH } _ { 3 } \mathrm { CH } _ { 3 } + \mathrm { Cl } _ { 2 } \longrightarrow \mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \mathrm { Cl } + \mathrm { HCl }$$ This reaction could conceivably occur by the following chain mechanisms [1], [2], and [3]. Determine F1F1F1S1?F1F1F10H for step [2]. [1] $\quad \mathrm { Cl } _ { 2 } \longrightarrow 2 \mathrm { Cl } \cdot$
[2] $\mathrm { Cl } ^ { \cdot } + \mathrm { CH } _ { 3 } \mathrm { CH } _ { 3 } \stackrel { \text { slow } } { \longrightarrow } \mathrm { HCl } + \mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } ^ \cdot$
$[ 3 ] \mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } ^ \cdot + \mathrm { Cl } _ { 2 } \stackrel { \text { fast } } { \longrightarrow } \mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \mathrm { Cl } + \mathrm { Cl } ^\cdot$ Bond dissociation energies (kcal/mol): $$\begin{array} { | l l | } 
\hline \text { Bond A-B } & \Delta \mathrm { H } \
\hline \mathrm { Cl } - \mathrm { Cl } & 58 \
\mathrm { CH } _ { 3 } - \mathrm { H } & 104 \
\mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } - \mathrm { H } & 98 \
\mathrm { CH } _ { 3 } \mathrm { CH } _ { 3 } & 88 \
\mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } - \mathrm { Cl } & 81 \
\mathrm { H } - \mathrm { Cl } & 103 \
\hline
\end{array}$$

Accepted Answer

A)  -5 kcal/mol 
B)  +58 kcal/mol 
C)  -28 kcal/mol 
D)  None of the choices are correct. 
A)  -5 kcal/mol 
B)  +58 kcal/mol 
C)  -28 kcal/mol 
D)  None of the choices are correct.

Question 11

Determine the product(s) of the following reaction.

Accepted Answer

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

Question 12

Which of the following statements is (are) true about free radical halogenation of alkanes?

Accepted Answer

A)  The first of the chain-propagating steps is rate-determining. 
B)  The reaction proceeds by way of a flat sp2 hybridized free radical. 
C)  The chain-initiating step involves cleavage of a carbon-hydrogen bond to afford a carbon radical and a hydrogen atom. 
D)  Statements (The first of the chain-propagating steps is rate-determining) and (The reaction proceeds by way of a flat sp2 hybridized free radical) are both true. 
A)  The first of the chain-propagating steps is rate-determining. 
B)  The reaction proceeds by way of a flat sp2 hybridized free radical. 
C)  The chain-initiating step involves cleavage of a carbon-hydrogen bond to afford a carbon radical and a hydrogen atom. 
D)  Statements (The first of the chain-propagating steps is rate-determining) and (The reaction proceeds by way of a flat sp2 hybridized free radical) are both true.

Question 13

Which of the following statements about the propagation steps in the chlorination of ethane is true?

Accepted Answer

A)  Radical chlorination consists of two propagation steps. 
B)  The energy diagram for the propagation steps has three energy barriers. 
C)  The first of the propagation steps is rate-determining because its transition state is at lower energy. 
D)  The second of the propagation steps is rate-determining because its transition state is at higher energy. 
A)  Radical chlorination consists of two propagation steps. 
B)  The energy diagram for the propagation steps has three energy barriers. 
C)  The first of the propagation steps is rate-determining because its transition state is at lower energy. 
D)  The second of the propagation steps is rate-determining because its transition state is at higher energy.

Question 14

Identify the monomer used to make the following polymer.

Accepted Answer

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

Question 15

Which of the following compounds contain primary (1°) radical carbons?

Accepted Answer

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

Question 16

How many monochlorination products (constitutional isomers and stereoisomers) are formed from the reaction of pentane with Cl2 and hF1F1F1S1F1F1F10?

Accepted Answer

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

Question 17

What is the product of the following reaction?

Accepted Answer

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

Question 18

Which of the following statements about chlorination and bromination is true?

Accepted Answer

A)  Bromination is unselective, yielding a mixture of products. 
B)  Chlorination is often selective, yielding one major product. 
C)  Chlorination is faster than bromination. 
D)  Bromination is faster than chlorination. 
A)  Bromination is unselective, yielding a mixture of products. 
B)  Chlorination is often selective, yielding one major product. 
C)  Chlorination is faster than bromination. 
D)  Bromination is faster than chlorination.

Question 19

Which of the following statements about carbon radicals is not true?

Accepted Answer

A)  Carbon radicals are classified as primary, secondary, tertiary, or quaternary. 
B)  A carbon radical is sp2 hybridized. 
C)  The geometry of a carbon radical is trigonal planar. 
D)  The unhybridized p orbital in a carbon radical contains the unpaired electron. 
A)  Carbon radicals are classified as primary, secondary, tertiary, or quaternary. 
B)  A carbon radical is sp2 hybridized. 
C)  The geometry of a carbon radical is trigonal planar. 
D)  The unhybridized p orbital in a carbon radical contains the unpaired electron.

Question 20

Determine the monochlorination product(s)

Accepted Answer

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

Exam 15: Radical Reactions

Which of the labeled hydrogens is most easily abstracted in a free radical bromination reaction?

Which of the following statements about radicals and radical reactions is not true?

Which of the following is a radical scavenger?

Which of the following statements about radicals is true?

How many monochlorination products can be formed (constitutional isomers only) from the reaction of (CH3)2CHCH2CH3 with Cl2 and h?

Which of the following statements about the stereochemistry of halogenation reactions is true?

Determine the product(s) of the following reaction.

Which of the following statements is (are) true about free radical halogenation of alkanes?

Which of the following statements about the propagation steps in the chlorination of ethane is true?

Identify the monomer used to make the following polymer.

Which of the following compounds contain primary (1°) radical carbons?

How many monochlorination products (constitutional isomers and stereoisomers) are formed from the reaction of pentane with Cl2 and h?

What is the product of the following reaction?

Which of the following statements about chlorination and bromination is true?

Which of the following statements about carbon radicals is not true?

Determine the monochlorination product(s)

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 Epoxides

Alkenes

Alkynes

Oxidation and Reduction

Mass Spectrometry and Infrared Spectroscopy

Nuclear Magnetic Resonance Spectroscopy

Conjugation, Resonance, and Dienes

Benzene and Aromatic Compounds

Electrophilic Aromatic Substitution

Carboxylic Acids and the Acidity of the O-H Bond

Introduction to Carbonyl Chemistry; Organometallic Reagents; Oxidation and Reduction

Aldehydes and Ketones Nucleophilic Addition

Carboxylic Acids and Derivatives

Substitution Reactions of Carbonyl Compounds at the Alpha-Carbon

Carbonyl Condensation Reactions

Amines

Carbon-Carbon Bond Forming Reactions in Organic Synthesis

Pericyclic Reactions

Carbohydrates

Amino Acids and Proteins

Lipids

Synthetic Polymers

Filters

How many monochlorination products can be formed (constitutional isomers only) from the reaction of (CH₃)₂CHCH₂CH₃ with Cl₂ and h?

How many monochlorination products (constitutional isomers and stereoisomers) are formed from the reaction of pentane with Cl₂ and h?