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Organic Chemistry

Janice Gorzynski Smith

Chapter 7

Alkyl Halides and Nucleophilic Substitution - all with Video Answers

Educators

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Chapter Questions

02:19

Problem 1

Classify each alkyl halide as 1$^\circ$, 2$^\circ$, or 3$^\circ$.

Anupa Sharad Medhekar
Anupa Sharad Medhekar
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03:48

Problem 2

Telfairine, a naturally occurring insecticide, and halomon, an antitumor agent, are two polyhalogenated compounds isolated from red algae. (a) Classify each halide bonded to an $sp^3$ hybridized carbon as 1$^\circ$, 2$^\circ$, or 3$^\circ$. (b) Label each halide as vinyl, allylic, or neither.

Catherine Smith
Catherine Smith
Missouri State University
06:28

Problem 3

Draw the structure of an alkyl bromide with molecular formula $C_6H_{13}Br$ that fits each description: (a) a 1$^\circ$ alkyl bromide with one stereogenic center; (b) a 2$^\circ$ alkyl bromide with two stereogenic centers; (c) an achiral 3$^\circ$ alkyl bromide.

Anupa Sharad Medhekar
Anupa Sharad Medhekar
Numerade Educator
03:18

Problem 4

Give the IUPAC name for each compound.

Catherine Smith
Catherine Smith
Missouri State University
04:48

Problem 5

Give the structure corresponding to each name.
a. 3-chloro-2-methylhexane
b. 4-ethyl-5-iodo-2,2-dimethyloctane
c. $cis$-1,3-dichlorocyclopentane
d. 1, 1,3-tribromocyclohexane
e. propyl chloride
f. sec-butyl bromide

Ronald Prasad
Ronald Prasad
Numerade Educator
03:22

Problem 6

An $sp^3$ hybridized C - Cl bond is more polar than an $sp^2$ hybridized C- Cl bond. (a) Explain why this phenomenon arises. (b) Rank the following compounds in order of increasing boiling point.

Catherine Smith
Catherine Smith
Missouri State University
06:01

Problem 7

Chondrocole $A$ is a marine natural product isolated from red seaweed that grows in regions of heavy surf in the Pacific Ocean. (a) Predict the solubility of chondrocole A in water and $CH_2Cl_2$ . (b) Locate the stereogenic centers and label each as $R$ or $S$. (c) Draw a stereoisomer and a
constitutional isomer of chondrocole $A$.

Anupa Sharad Medhekar
Anupa Sharad Medhekar
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04:19

Problem 8

Identify the nucleophile and leaving group and draw the products of each substitution reaction.

Catherine Smith
Catherine Smith
Missouri State University
03:58

Problem 9

Draw the product of nucleophilic substitution with each neutral nucleophile. When the initial substitution product can lose a proton to form a neutral product, draw the product after proton transfer.

Anupa Sharad Medhekar
Anupa Sharad Medhekar
Numerade Educator
01:10

Problem 10

CPC (cetylpyridinium chloride), an antiseptic found in throat lozenges and mouthwash, is synthesized by the following reaction. Draw the structure of CPC.

Catherine Smith
Catherine Smith
Missouri State University
03:27

Problem 11

Which is the better leaving group in each pair?
a. Cl$^-, 1^-$ b. $NH_3, ^-NH_2$ c. $H_2O, H_2S$

Anupa Sharad Medhekar
Anupa Sharad Medhekar
Numerade Educator
02:03

Problem 12

Which molecules contain good leaving groups?
a. $CH_3CH_2CH_2Br$ b. $CH_3CH_2CH_2OH$ c.$CH_3CH_2+OH_2$ d. $CH_3CH_3$

Catherine Smith
Catherine Smith
Missouri State University
02:26

Problem 13

Does the equilibrium favor the reactants or products in each substitution reaction?

Anupa Sharad Medhekar
Anupa Sharad Medhekar
Numerade Educator
00:41

Problem 14

Should it be possible to convert $CH_3CH_2CH_2OH$ to $CH_3CH_2CH_2CI$ by a nucleophilic substitution reaction with NaCl? Explain why or why not.

Catherine Smith
Catherine Smith
Missouri State University
03:11

Problem 15

Identify the stronger nucleophile in each pair.
a.$ NH_3, ^-NH_2$ b. $CH_3NH_2, CH_30H$ c. $CH_3C00^-, CH_3CH_20^-$

Anupa Sharad Medhekar
Anupa Sharad Medhekar
Numerade Educator
01:10

Problem 16

Classify each solvent as protic or aprotic.
a. $HOCH_2CH_2OH$ b. $CH_3CH_2OCH_2CH_3$ c.$CH_3COOCH_2CH_3$

Catherine Smith
Catherine Smith
Missouri State University
04:04

Problem 17

Identify the stronger nucleophile in each pair of anions.
a. Br$^-$ or CI$^-$ in a polar protic solvent
b. HO$^-$ or CI$^-$ in a polar aprotic solvent
c. HS$^-$ or F$^-$ in a polar protic solvent

Anupa Sharad Medhekar
Anupa Sharad Medhekar
Numerade Educator
06:37

Problem 18

Rank the nucleophiles in each group in order of increasing nucleophilicity.
a. $^-OH, ^-NH_2, H_2O$
b. $^-OH, Br^-, F^-$ (polar aprotic solvent)
c. $H_2O, ^-OH, CH_3COO$

Catherine Smith
Catherine Smith
Missouri State University
02:14

Problem 19

What nucleophile is needed to convert (CH3hCHCH2CH2-Br to each product?
a. $(CH_3)_2CHCH_2CH_2 - SH$
b. $(CH_3)_2CHCH_2CH_2 - OCH_2CH_3$
c. $(CH3)_2CHCH_2CH_2 - OCOCH_3$
d. $(CH_3)_2CHCH_2CH_2 - C = CH$

Anupa Sharad Medhekar
Anupa Sharad Medhekar
Numerade Educator
02:21

Problem 20

What happens to the rate of an S$_N$2 reaction under each of the following conditions?
a. [RX] is tripled, and [:Nu$^-$] stays the same.
b. Both [RX] and [:Nu$^-$] are tripled.
c. [RX] is halved, and [:Nu$^-$] stays the same.
d. [RX] is halved, and [:Nu$^-$] is doubled.

Catherine Smith
Catherine Smith
Missouri State University
03:35

Problem 21

Draw the structure of the transition state in each of the following S$_N$2 reactions.

Anupa Sharad Medhekar
Anupa Sharad Medhekar
Numerade Educator
02:03

Problem 22

Draw an energy diagram for the reaction in Problem 7.21a. Label the axes, the starting material, the product, and the transition state. Assume the reaction is exothermic. Label $\Delta H^\circ$ and $E_a$.

Catherine Smith
Catherine Smith
Missouri State University
05:12

Problem 23

Draw the product of each S$_N$2 reaction and indicate stereochemistry.

Anupa Sharad Medhekar
Anupa Sharad Medhekar
Numerade Educator
01:23

Problem 24

Which compound in each pair undergoes a faster S$_N$2 reaction?

Catherine Smith
Catherine Smith
Missouri State University
02:26

Problem 25

Nicotine, a toxic and addictive component of tobacco, is synthesized from $A$ using SAM. Write out
the reaction that converts $A$ into nicotine.

Anupa Sharad Medhekar
Anupa Sharad Medhekar
Numerade Educator
01:39

Problem 26

What happens to the rate of an S$_N$1 reaction under each of the following conditions?
a. [RX] is tripled, and [:Nu$^-$] stays the same.
b. Both [RX] and [:Nu$^-$] are tripled.
c. [RX] is halved, and [:Nu$^-$] stays the same.
d. [RX] is halved, and [:Nu$^-$] is doubled.

Catherine Smith
Catherine Smith
Missouri State University
07:35

Problem 27

Draw the products of each S$_N$1 reaction and indicate the stereochemistry of any stereogenic
centers.

Anupa Sharad Medhekar
Anupa Sharad Medhekar
Numerade Educator
01:03

Problem 28

Classify each carbocation as 1$^\circ$, 2$^\circ$, or 3$^\circ$.

Catherine Smith
Catherine Smith
Missouri State University
02:21

Problem 29

Draw the structure of a 1$^\circ$, 2$^\circ$, and 3$^\circ$ carbocation, each having molecular formula $C_4H_9^+$. Rank the three carbocations in order of increasing stability.

Anupa Sharad Medhekar
Anupa Sharad Medhekar
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00:58

Problem 30

Rank the following carbocations in order of increasing stability.

Catherine Smith
Catherine Smith
Missouri State University
03:03

Problem 31

Which alkyl halide in each pair reacts faster in an S$_N$1 reaction?

Anupa Sharad Medhekar
Anupa Sharad Medhekar
Numerade Educator
01:57

Problem 32

What is the likely mechanism of nucleophilic substitution for each alkyl halide?

Catherine Smith
Catherine Smith
Missouri State University
07:47

Problem 33

For each alkyl halide and nucleophile: [1] Draw the product of nucleophilic substitution;
[2] determine the likely mechanism (S$_N$1 or S$_N$2) for each reaction.

Anupa Sharad Medhekar
Anupa Sharad Medhekar
Numerade Educator
03:30

Problem 34

Draw the products (including stereochemistry) for each reaction.

Catherine Smith
Catherine Smith
Missouri State University
03:49

Problem 35

Which compound in each pair reacts faster in nucleophilic substitution?
a. $CH_3CH_2CH_2CI$ or $CH_3CH_2CH_2I$
b. $(CH_3)_3CBr$ or $(CH_3)_3CI$
c. $(CH_3)_3COH$ or $(CH_3)_3COH_2\,^ +$
d. $CH_3CH_2CH_2OH$ or $CH_3CH_2CH_2OCOCH_3$

Anupa Sharad Medhekar
Anupa Sharad Medhekar
Numerade Educator
01:01

Problem 36

Which solvents favor S$_N$1 reactions and which favor S$_N$2 reactions?
a. $CH_3CH_2OH$
b. $CH_3CN$
c. $CH_3COOH$
d. $CH_3CH_2OCH_2CH_3$

Catherine Smith
Catherine Smith
Missouri State University
07:29

Problem 37

For each reaction, use the identity of the alkyl halide and nucleophile to determine which
substitution mechanism occurs. Then determine which solvent affords the faster reaction.

Ronald Prasad
Ronald Prasad
Numerade Educator
06:24

Problem 38

Determine the mechanism and draw the products of each reaction. Include the stereochemistry at
all stereogenic centers.

Catherine Smith
Catherine Smith
Missouri State University
03:13

Problem 39

Rank the following carbocations in order of increasing stability.
a. $CH_3CH_2CH_2CH_2CH = CH$
b. $CH_3CH_2CH_2CH_2CHCH_3$
c. $CH_3CH_2CH_2CH_2CH_2CH_2$

Anupa Sharad Medhekar
Anupa Sharad Medhekar
Numerade Educator
02:49

Problem 40

What alkyl halide and nucleophile are needed to prepare each compound?

Catherine Smith
Catherine Smith
Missouri State University
02:52

Problem 41

The ether, $CH_3OCH_2CH_3$, can be prepared by two different nucleophilic substitution reactions, one using $CH_3O^-$ as nucleophile and the other using $CH_3CH_2O^-$ as nucleophile. Draw both routes.

Anupa Sharad Medhekar
Anupa Sharad Medhekar
Numerade Educator
04:54

Problem 42

Give the IUPAC name for each compound, including any $R$,$S$ designation.

Catherine Smith
Catherine Smith
Missouri State University
05:18

Problem 43

Draw the products formed when each alkyl halide is treated with NaCN.

Anupa Sharad Medhekar
Anupa Sharad Medhekar
Numerade Educator
07:03

Problem 44

Give the IUPAC name for each compound.

Catherine Smith
Catherine Smith
Missouri State University
14:06

Problem 45

Give the structure corresponding to each name.
a. isopropyl bromide
b. 3-bromo-4-ethylheptane f.
c. 1, 1-dichloro-2-methylcyclohexane
d. $trans$-1-chloro-3-iodocyclobutane
e. 1-bromo-4-ethyl-3-fluorooctane
f. ($3S$)-3-iodo-2-methylnonane
g. ($1 R,2R$)-trans-1-bromo-2-chlorocyclohexane
h. ($5R$)-4,4,5-trichloro-3,3-dimethyldecane

Anupa Sharad Medhekar
Anupa Sharad Medhekar
Numerade Educator
01:41

Problem 46

Classify each alkyl halide in Problem 7.44 as 1$^\circ$, 2$^\circ$, or 3$^\circ$. When a compound has more than one halogen, assign each separately.

Catherine Smith
Catherine Smith
Missouri State University
15:34

Problem 47

Draw the eight constitutional isomers having the molecular formula $C_5H_{11} CI$.
a. Give the IUPAC name for each compound (ignoring $R$ and $S$ designations).
b. Label any stereogenic centers.
c. For each constitutional isomer that contains a stereogenic center, draw all possible stereoisomers, and label each stereogenic center as $R$ or $S$.

Molly Cary
Molly Cary
Numerade Educator
00:56

Problem 48

Which compound in each pair has the higher boiling point?

Catherine Smith
Catherine Smith
Missouri State University
07:21

Problem 49

Draw the substitution product that results when $CH_3CH_2CH_2CH_2Br$ reacts with each nucleophile.
a. $^-OH$
b. $^-SH$
c. $^-CN$
d. $^-OCH(CH_3)_2$
e. $^-C \equiv CH$
f. $H_2O$
g. $NH_3$
h. $Nal$
i. $NaN_3$

Ronald Prasad
Ronald Prasad
Numerade Educator
05:17

Problem 50

Draw the products of each nucleophilic substitution reaction.

Catherine Smith
Catherine Smith
Missouri State University
03:22

Problem 51

Which of the following molecules contain a good leaving group?

Anupa Sharad Medhekar
Anupa Sharad Medhekar
Numerade Educator
03:17

Problem 52

Rank the species in each group in order of increasing leaving group ability.
a. $^-OH, F^-, ^-NH_2$
b. $H_2O, ^-NH_2, ^-OH$
c. $Br^-, CI^-, I^-$
d. $NH_3, H_2S, H_2O$

Catherine Smith
Catherine Smith
Missouri State University
02:24

Problem 53

Which of the following nucleophilic substitution reactions will take place?

Anupa Sharad Medhekar
Anupa Sharad Medhekar
Numerade Educator
05:48

Problem 54

Rank the species in each group in order of increasing nucleophilicity.
a. $CH3^-, ^-OH, ^-NH_2$
b. $H_2O, ^-OH, ^-SH$ in $CH_3OH$
c. $CH_3CH_2S^-, CH_3CH_2O^-, CH_3COO^-$ in $CH_3OH$
d. $CH_3NH_2, CH_3SH, CH_3OH$ in acetone
e. $^-OH, F^-, CI^-$ in acetone
f. $HS^-, F^-, CI^-$ in $CH_3OH$

Catherine Smith
Catherine Smith
Missouri State University
03:35

Problem 55

Classify each solvent as protic or aprotic.
a. $(CH_3)_2CHOH$
b. $CH_3NO_2$
c. $CH_2CI_2$
d. $NH_3$
e. $N(CH_3)_3$
f. $HCONH_2$

Anupa Sharad Medhekar
Anupa Sharad Medhekar
Numerade Educator
00:43

Problem 56

Why is the amine $N$ atom more nucleophilic than the amide $N$ atom in $CH_3CONHCH_2CH_2CH_2NHCH_3$?

Catherine Smith
Catherine Smith
Missouri State University
12:30

Problem 57

Consider the following S$_N$2 reaction:
a. Draw a mechanism using curved arrows.
b. Draw an energy diagram. Label the axes, the reactants, products, $E_a$, and $\Delta H^\circ$. Assume that the reaction is exothermic.
c. Draw the structure of the transition state.
d. What is the rate equation?
e. What happens to the reaction rate in each of the following instances? [1] The leaving group is changed from $Br^-$ to $I^-$; [2] The solvent is changed from acetone to $CH_3CH_2OH$; [3] The alkyl halide is changed from $CH_3(CH_2)_4$$Br$ to $CH_3CH_2CH_2CH(Br)CH_3$; [4] The concentration of $^-CN$ is increased by a factor of five; and [5] The concentrations of both the alkyl halide and $^-CN$ are increased by a factor of five.

Molly Cary
Molly Cary
Numerade Educator
01:08

Problem 58

Rank the organic halides in each group in order of increasing S$_N$2 reactivity.

Catherine Smith
Catherine Smith
Missouri State University
03:43

Problem 59

Which S$_N$2 reaction in each pair is faster?

Anupa Sharad Medhekar
Anupa Sharad Medhekar
Numerade Educator
01:42

Problem 60

Draw the products of each S$_N$2 reaction and indicate the stereochemistry where appropriate.

Catherine Smith
Catherine Smith
Missouri State University
01:51

Problem 61

Classify each carbocation as 1$^\circ$, 2$^\circ$, or 3$^\circ$.

Anupa Sharad Medhekar
Anupa Sharad Medhekar
Numerade Educator
00:55

Problem 62

Rank the carbocations in each group in order of increasing stability.

Catherine Smith
Catherine Smith
Missouri State University
02:25

Problem 63

Which of the following carbocations ($A$ or $B$) is more stable? Explain your choice.

Molly Cary
Molly Cary
Numerade Educator
07:01

Problem 64

Consider the following S$_N$1 reaction.
a. Draw a mechanism for this reaction using curved arrows.
b. Draw an energy diagram. Label the axes, starting material, product, $E_a$, and $\Delta H^\circ$. Assume that the starting material and product are equal in energy.
c. Draw the structure of any transition states.
d. What is the rate equation for this reaction?
e. What happens to the reaction rate in each of the following instances? [1] The leaving group is
changed from $I^-$ to $CI^-$; [2) The solvent is changed from $H_2O$ to DMF; [3] The alkyl halide is changed from $(CH_3)_2C(I)CH_2CH_3$ to $(CH_3)_2CHCH(I)CH_3$; [4] The concentration of $H_2O$ is increased by a factor of five; and [5] The concentrations of both the alkyl halide and $H_2O$ are increased by a factor of five.

Catherine Smith
Catherine Smith
Missouri State University
03:30

Problem 65

Rank the organic halides in each group in order of increasing S$_N$1 reactivity.

Anupa Sharad Medhekar
Anupa Sharad Medhekar
Numerade Educator
03:43

Problem 66

Which $S_N1$ reaction in each pair is faster?

Anupa Sharad Medhekar
Anupa Sharad Medhekar
Numerade Educator
06:48

Problem 67

Draw the products of each S$_N$1 reaction and indicate the stereochemistry when necessary.

Anupa Sharad Medhekar
Anupa Sharad Medhekar
Numerade Educator
10:50

Problem 68

Draw a stepwise mechanism for the following reaction that illustrates why two substitution products are formed. Explain why 1-bromo-2-hexene reacts rapidly with a weak nucleophile ($CH_3OH$) under S$_N$ 1 reaction conditions, even though it is a 1$^\circ$ alkyl halide

Dr. Satish Ingale
Dr. Satish Ingale
Numerade Educator
29:05

Problem 69

Determine the mechanism of nucleophilic substitution of each reaction and draw the products, including stereochemistry.

Dr. Satish Ingale
Dr. Satish Ingale
Numerade Educator
01:26

Problem 70

Diphenhydramine, the antihistamine in Benadryl, can be prepared by the following two-step sequence. What is the structure of diphenhydramine?

Ronald Prasad
Ronald Prasad
Numerade Educator
03:54

Problem 71

Text Unavailable

Draw a stepwise, detailed mechanism for the following reaction. Use curved arrows to show the movement of electrons.

Ronald Prasad
Ronald Prasad
Numerade Educator
08:37

Problem 72

Text Unavailable

When a single compound contains both a nucleophile and a leaving group, an $\textbf{intramolecular}$ reaction may occur. With this in mind, draw the product of the following reaction.

GY
Gabriela Young
Numerade Educator
05:39

Problem 73

Nicotine can be made when the following ammonium salt is treated with $Na_2CO_3$. Draw a stepwise mechanism for this reaction.

Susan Hallstrom
Susan Hallstrom
Numerade Educator
05:07

Problem 74

Quinapril (trade name Accupril) is a drug used to treat high blood pressure and congestive heart failure. One step in the synthesis of quinapril involves reaction of the racemic alkyl bromide $A$ with a single enantiomer of the amino ester $B$. (a) What two products are formed in this reaction? (b) Given the structure of quinapril, which one of these two products is needed to synthesize the drug?

Rashmi Sinha
Rashmi Sinha
Numerade Educator
07:59

Problem 75

Draw a stepwise, detailed mechanism for the following reaction.

Ian Kaigh
Ian Kaigh
Numerade Educator
10:42

Problem 76

When ($6R$)-6-bromo-2,6-dimethylnonane is dissolved in $CH_3OH$, nucleophilic substitution yields an optically inactive solution. When the isomeric halide ($5R$)-2-bromo-2,5-dimethylnonane is dissolved in $CH_3OH$ under the same conditions, nucleophilic substitution forms an optically active solution. Draw the products formed in each reaction, and explain why the difference in optical activity is observed.

Dr. Satish Ingale
Dr. Satish Ingale
Numerade Educator
03:46

Problem 77

Fill in the appropriate reagent or starting material in each of the following reactions .

Anupa Sharad Medhekar
Anupa Sharad Medhekar
Numerade Educator
03:29

Problem 78

Devise a synthesis of each compound from an alkyl halide using any other organic or inorganic reagents.

Ronald Prasad
Ronald Prasad
Numerade Educator
02:41

Problem 79

Benzalkonium chloride ($A$) is a weak germicide used in topical antiseptics and mouthwash. $A$ can be prepared from amines $B$ or $C$ by S$_N$2 reaction with an alkyl chloride. (a) What alkyl chloride is needed to prepare $A$ from $B$? (b) What alkyl chloride is needed to prepare $A$ from $C$?

Anupa Sharad Medhekar
Anupa Sharad Medhekar
Numerade Educator
01:20

Problem 80

Suppose you have compounds $A-D$ at your disposal. Using these compounds, devise two different ways to make $E$. Which one of these methods is preferred, and why?

David Collins
David Collins
Numerade Educator
07:47

Problem 81

Muscalure, the sex pheromone of the common housefly, can be prepared by a reaction sequence that uses two nucleophilic substitutions. Identify compounds $A-D$ in the following synthesis of muscalure.

Dr. Satish Ingale
Dr. Satish Ingale
Numerade Educator
00:42

Problem 82

We will return often to nucleophilic substitution, in particular the S$_N$2 reaction, in subsequent chapters. In each instance we will concentrate on the $nuceophile$, rather than the alkyl halide, as we have done in this chapter. By using different nucleophiles, nucleophilic substitution allows the synthesis of a wide variety of organic compounds with many different functional groups.

Aadit Sharma
Aadit Sharma
Numerade Educator
01:36

Problem 83

Explain why quinuclidine is a much more reactive nucleophile than triethylamine, even though both compounds have N atoms surrounded by three R groups.

Hailey Tomashek
Hailey Tomashek
Numerade Educator
06:10

Problem 84

Draw a stepwise mechanism for the following reaction sequence.

Susan Hallstrom
Susan Hallstrom
Numerade Educator
09:24

Problem 85

As we will learn in Chapter 9, an epoxide is an ether with an oxygen atom in a three-membered ring. Epoxides can be made by intramolecular S$_N$2 reactions of intermediates that contain a nucleophile and a leaving group on adjacent carbons, as shown.Assume that each of the following starting materials can be converted to an epoxide by this reaction. Draw the product formed
(including stereochemistry) from each starting material. Why might some of these reactions be more difficult than others in yielding nucleophilic substitution products?

Susan Hallstrom
Susan Hallstrom
Numerade Educator
06:55

Problem 86

When trichloride J is treated with $CH_3OH$, nucleophilic substitution forms the dihalide $K$. Draw a mechanism for this reaction and explain why one Cl is much more reactive than the other two Cl's so that a single substitution product is formed.

Susan Hallstrom
Susan Hallstrom
Numerade Educator
05:08

Problem 87

In some nucleophilic substitutions under S$_N$1 conditions, complete racemization does not occur and a small excess of one enantiomer is present. For example, treatment of optically pure 1-bromo-1 phenylpropane with water forms 1-phenyl-1-propanol. (a) Calculate how much of each enantiomer is present using the given optical rotation data. (b) Which product predominates$-$the product of inversion or the product of retention of configuration? (c) Suggest an explanation for this phenomenon.

Susan Hallstrom
Susan Hallstrom
Numerade Educator