Organic Chemistry

Paula Yurkanis Bruice

Chapter 17

Carbonyl Compounds I - all with Video Answers

Educators

Chapter Questions

Problem 1

The word "lactone" has its origin in lactic acid, a three-carbon carboxylic acid with an OH group on the $\alpha$ -carbon. Ironically, lactic acid cannot form a lactone. Why not?

Temi Ajayi

Temi Ajayi

Numerade Educator

Problem 2

Name the following compounds:

Lottie Adams

Numerade Educator

Problem 3

Write a structure for each of the following compounds:
a. phenyl acetate
b. $\gamma$ -caprolactam
c. butanenitrile
d. $N$ -benzylethanamide
e. $\gamma$ -caproic acid
f. ethyl 2-chloropentanoate
g. $\beta$ -bromobutyramide
h. propanoic anhydride
i. cyclohexanecarbonyl chloride

Temi Ajayi

Numerade Educator

Problem 4

Which is longer, the carbon-oxygen single bond in a carboxylic acid or the carbon-oxygen bond in an alcohol? Why?

Sherry Tsui

Numerade Educator

Problem 5

There are three carbon-oxygen bonds in methyl acetate.
a. What are their relative lengths?
b. What are the relative infrared (IR) stretching frequencies of these bonds?

Temi Ajayi

Numerade Educator

Problem 6

Match the compound with the appropriate carbonyl IR absorption band:

\begin{array}{ll} \text { acyl chloride } & \sim 1800\ \mathrm {and}\ 1750 \mathrm{cm}^{-1} \\\end{array}
\begin{array}{ll} \text {acid anhydride } & \sim 1640\ \mathrm{cm}^{-1} \\\end{array}
\begin{array}{ll} \text { ester } & \sim 1730\ \mathrm{cm}^{-1} \\\end{array}
\begin{array}{ll} \text { amide } & \sim 1800\ \mathrm{cm}^{-1} \\\end{array}

Temi Ajayi

Numerade Educator

Problem 7

Using the $\mathrm{p} K_{\mathrm{a}}$ values in Table $17.1,$ predict the products of the following reactions:

Temi Ajayi

Numerade Educator

Problem 8

Is the following statement true or false?
If the newly added group in the tetrahedral intermediate is a stronger base than the group attached to the acyl group in the reactant, formation of the tetrahedral intermediate is the rate-limiting step of a nucleophilic acyl substitution reaction.

Tom Rutherford

Numerade Educator

Problem 9

What will be the product of a nucleophilic acyl substitution reaction $-$ a new carboxylic acid derivative, a mixture of two carboxylic acid derivatives, or no reaction $-$ if the new group in the tetrahedral intermediate is the following?
a. a stronger base than the group that was already there
b. a weaker base than the group that was already there
c. similar in basicity to the group that was already there

Temi Ajayi

Numerade Educator

Problem 10

a. Two amides are obtained from the reaction of acetyl chloride with a mixture of ethylamine and propylamine. Identify the amides.
b. Only one amide is obtained from the reaction of acetyl chloride with a mixture of ethylamine and pyridine. Why is only one amide obtained?

Nicholas Sacco

Numerade Educator

Problem 11

Although excess amine is necessary in the reaction of an acyl chloride with an amine, explain why it is not necessary to use excess alcohol in the reaction of an acyl chloride with an alcohol.

Nicholas Sacco

Numerade Educator

Problem 12

Write the mechanism for the following reactions:
a. the reaction of acetyl chloride with water to form acetic acid
b. the reaction of acetyl bromide with methylamine to form $N$ -methylacetamide

Nicholas Sacco

Numerade Educator

Problem 13

Starting with acetyl chloride, what nucleophile would you use to make each of the following compounds?

Nicholas Sacco

Numerade Educator

Problem 14

a. Propose a mechanism for the reaction of acetic anhydride with water.
b. How does this mechanism differ from the mechanism for the reaction of acetic anhydride with an alcohol?

Arun Bana

Numerade Educator

Problem 15

We have seen that acid anhydrides react with alcohols, water, and amines. In which one of these three reactions does the tetrahedral intermediate not have to lose a proton before it eliminates the carboxylate ion? Explain.

Megan Schrage

Numerade Educator

Problem 16

Write a mechanism for the following reactions:
a. the noncatalyzed hydrolysis of methyl propionate
b. the aminolysis of phenyl formate, using methylamine

Nicholas Sacco

Numerade Educator

Problem 17

a. State three factors that contribute to the fact that the noncatalyzed hydrolysis of an ester is a slow reaction.
b. Which is faster, hydrolysis of an ester or aminolysis of the same ester?

Nicholas Sacco

Numerade Educator

Problem 18

a. List the following esters in order of decreasing reactivity toward hydrolysis:
b. How would the rate of hydrolysis of the para-methylphenyl ester compare with the rate
of hydrolysis of these three esters?

Nicholas Sacco

Numerade Educator

Problem 19

Referring to the mechanism for the acid-catalyzed hydrolysis of methyl acetate:
a. What species could be represented by HB $^{+} ?$
b. What species could be represented by :B?
c. What species is $\mathrm{HB}^{+}$ most likely to be in a hydrolysis reaction?
d. What species is $\mathrm{HB}^{+}$ most likely to be in the reverse reaction?

Temi Ajayi

Numerade Educator

Problem 20

Referring to the mechanism for the acid-catalyzed hydrolysis of methyl acetate, write the mechanism-showing all the curved arrows- -for the acid-catalyzed reaction of acetic acid and methanol to form methyl acetate. Use $\mathrm{HB}^{+}$ and : $\mathrm{B}$ to represent proton-donating and proton-removing species, respectively.

Nicholas Sacco

Numerade Educator

Problem 21

Write the mechanism for the acid-catalyzed transesterification reaction of methyl acetate with ethanol.

Grigoriy Sereda

Grigoriy Sereda

Numerade Educator

Problem 22

a. What species other than an acid can be used to increase the rate of a transesterification reaction that converts methyl acetate to propyl acetate?
b. Explain why the rate of aminolysis of an ester cannot be increased by $\mathrm{H}^{+}, \mathrm{HO}^{-}$, or $\mathrm{RO}^{-}$

Tom Rutherford

Numerade Educator

Problem 23

If butanoic acid and $^{18} \mathrm{O}$ labeled methanol are allowed to react under acidic conditions, what compounds will be labeled when the reaction has reached equilibrium?

Nicholas Sacco

Numerade Educator

Problem 24

D. N. Kursanov, a Russian chemist, proved that the bond that is broken in the hydroxideion-promoted hydrolysis of an ester is the acyl $\mathrm{C}-\mathrm{O}$ bond, rather than the alkyl $\mathrm{C}-\mathrm{O}$ bond, by studying the reaction of the following ester with $\mathrm{HO}^{-} / \mathrm{H}_{2} \mathrm{O}$ :
a. Which of the products contained the $^{18}$ O label?
b. What product would have contained the $^{18} \mathrm{O}$ label if the alkyl $\mathrm{C}-$ O bond had broken?

Megan Schrage

Numerade Educator

Problem 25

Early chemists could envision several possible mechanisms for hydroxide-ion-promoted ester hydrolysis:
1. a nucleophilic acyl substitution reaction
2. an $S_{\mathrm{N}} 2$ reaction
3. an $\mathrm{S}_{\mathrm{N}} 1$ reaction

Temi Ajayi

Numerade Educator

Problem 26

An oil obtained from coconuts is unusual in that all three fatty acid components are identical. The molecular formula of the oil is $\mathrm{C}_{45} \mathrm{H}_{86} \mathrm{O}_{6} .$ What is the molecular formula of the carboxylate ion obtained when the oil is saponified?

Grigoriy Sereda

Grigoriy Sereda

Numerade Educator

Problem 27

Using an alcohol for one method and an alkyl halide for the other, show two ways to make each of the following esters:
a. methyl butyrate (odor of apples)
b. propyl acetate (odor of pears)
c. ethyl butyrate (odor of pineapple)
d. octyl acetate (odor of oranges)
e. isopentyl acetate (odor of bananas)
f. methyl phenylethanoate (odor of honey)

Nicholas Sacco

Numerade Educator

Problem 28

Propose a mechanism for the following reaction. (Hint: Number the carbons to help you see where they end up in the product.)

Tom Rutherford

Numerade Educator

Problem 29

a. Which of the following reactions would lead to the formation of an amide?
b. For those reactions that do form amides, what could you do to improve either the rate of amide formation or the yield of the amide product?

Nicholas Sacco

Numerade Educator

Problem 30

Propose a mechanism for the reaction of an amide with thionyl chloride to form a nitrile. (Hint: In the first step of the reaction, the amide is the nucleophile and thionyl chloride is the electrophile.)

Nicholas Sacco

Numerade Educator

Problem 31

List the following amides in order of decreasing reactivity toward acid-catalyzed hydrolysis:

Temi Ajayi

Numerade Educator

Problem 32

What alkyl bromide would you use in a Gabriel synthesis to prepare each of the following amines?
a. pentylamine
b. isohexylamine
c. benzylamine
d. cyclohexylamine

Aadit Sharma

Numerade Educator

Problem 33

Primary amines can also be prepared by the reaction of an alkyl halide with azide ion, followed by catalytic hydrogenation. What advantage do this method and the Gabriel synthesis have over the synthesis of a primary amine using an alkyl halide and ammonia?

Aadit Sharma

Numerade Educator

Problem 34

Which alkyl halides form the following carboxylic acids after reacting with sodium cyanide and the product heated in an acidic aqueous solution?
a. butyric acid
b. isovaleric acid
c. cyclohexanecarboxylic acid

Temi Ajayi

Numerade Educator

Problem 35

Design a synthesis for each of the following compounds, using an intramolecular reaction:

Nicholas Sacco

Numerade Educator

Problem 36

a. Propose a mechanism for the formation of succinic anhydride in the presence of acetic anhydride.
b. How does acetic anhydride help in the formation of succinic anhydride?

Temi Ajayi

Numerade Educator

Problem 37

What products would you expect to obtain from the following reactions?
a. phosgene $+$ excess diethylamine
b. malonic acid +2 acetyl chloride
c. methyl carbamate $+$ methylamine
d. urea + water
e. urea $+$ water $+\mathrm{H}^{+}$
f. $\beta$ -ethylglutaric acid $+$ acetyl chloride $+\Delta$

Nicholas Sacco

Numerade Educator

Problem 38

Write a structure for each of the following compounds:
a. $N, N$ -dimethylhexanamide
b. 3,3-dimethylhexanamide
c. cyclohexanecarbonyl chloride
d. propanenitrile
e. propionyl bromide
f. sodium acetate
g. benzoic anhydride
h. $\beta$ -valerolactone
i. 3 -methylbutanenitrile
j. cycloheptanecarboxylic acid

Temi Ajayi

Numerade Educator

Problem 39

Name the following compounds:

Lottie Adams

Numerade Educator

Problem 40

What products would be formed from the reaction of benzoyl chloride with the following reagents? a. sodium acetate
b. water
c. dimethylamine
d. aqueous HCl
e. aqueous $\mathrm{NaOH}$
f. cyclohexanol
g. benzylamine
h. 4-chlorophenol
i. isopropyl alcohol
j. aniline

Nicholas Sacco

Numerade Educator

Problem 41

a. List the following esters in order of decreasing reactivity in the first step of a nucleophilic acyl substitution reaction (formation of the tetrahedral intermediate):
b. List the same esters in order of decreasing reactivity in the second step of a nucleophilic acyl substitution reaction (collapse of the tetrahedral intermediate).

Temi Ajayi

Numerade Educator

Problem 42

a. Which compound would you expect to have a higher dipole moment, methyl acetate or butanone?
b. Which would you expect to have a higher boiling point?

Megan Schrage

Numerade Educator

Problem 43

How could you use $^{1} \mathrm{H}$ NMR spectroscopy to distinguish among the following esters?

Temi Ajayi

Numerade Educator

Problem 44

If propionyl chloride is added to one equivalent of methylamine, only a $50 \%$ yield of $N$ -methylpropanamide is obtained. If, however, the acyl chloride is added to two equivalents of methylamine, the yield of $N$ -methylpropanamide is almost $100 \%$ Explain these observations.

Nicholas Sacco

Numerade Educator

Problem 45

a. When a carboxylic acid is dissolved in isotopically labeled water $\left(\mathrm{H}_{2} \mathrm{O}^{18}\right),$ the label is incorporated into both oxygens of the acid. Propose a mechanism to account for this.
b. If a carboxylic acid is dissolved in isotopically labeled methanol $\left(\mathrm{CH}_{3}^{18} \mathrm{OH}\right)$ and an acid catalyst is added, where will the label reside in the product?

Temi Ajayi

Numerade Educator

Problem 46

What reagents would you use to convert methyl propanoate into the following compounds?
a. isopropyl propanoate
b. sodium propanoate
c. $N$ -ethylpropanamide
d. propanoic acid

Aadit Sharma

Numerade Educator

Problem 47

A compound with molecular formula $\mathrm{C}_{5} \mathrm{H}_{10} \mathrm{O}_{2}$ gives the following IR spectrum. When it undergoes acid-catalyzed hydrolysis, the compound with the following 1 H NMR spectrum is formed. Identify the compounds.

Temi Ajayi

Numerade Educator

Problem 48

Aspartame, the sweetener used in the commercial products NutraSweet and Equal , is 160 times sweeter than sucrose. What products would be obtained if aspartame were hydrolyzed completely in an aqueous solution of HCl?

Temi Ajayi

Numerade Educator

Problem 49

a. Which of the following reactions will not give the carbonyl product shown?
b. Which of the reactions that do not occur can be made to occur if an acid catalyst is added to the reaction mixture?

Aadit Sharma

Numerade Educator

Problem 50

1,4-Diazabicyclo[2.2.2]octane (abbreviated DABCO) is a tertiary amine that catalyzes transesterification reactions. Propose a mechanism to show how it does this.

Temi Ajayi

Numerade Educator

Problem 51

Identify the major and minor products of the following reaction:

Arun Bana

Numerade Educator

Problem 52

Two products, A and $\mathrm{B}$, are obtained from the reaction of 1 -bromobutane with $\mathrm{NH}_{3}$. Compound $\mathrm{A}$ reacts with acetyl chloride to form $C,$ and $B$ reacts with acetyl chloride to form D. The IR spectra of $C$ and $D$ are shown. Identify $A, B, C,$ and $D$

Temi Ajayi

Numerade Educator

Problem 53

Phosgene (COCl $_{2}$ ) was used as a poison gas in World War I. Give the product that would be formed from the reaction of phosgene with each of the following reagents:
1. one equivalent of methanol
2. excess methanol
3. excess propylamine
4. one equivalent of ethanol followed by one equivalent of methylamine

Nicholas Sacco

Numerade Educator

Problem 54

When Ethyl Ester treated butanedioic acid with thionyl chloride, she was surprised to find that the product she obtained was an anhydride rather than an acyl chloride. Propose a mechanism to explain why she obtained an anhydride.

Temi Ajayi

Numerade Educator

Problem 55

Give the products of the following reactions:

Ricajoy Montero

Ricajoy Montero

Numerade Educator

Problem 56

When treated with an equivalent of methanol, compound A, with molecular formula $\mathrm{C}_{4} \mathrm{H}_{6} \mathrm{Cl}_{2} \mathrm{O},$ forms the compound whose $^{1}\mathrm {H}\ \mathrm {NMR}$ spectrum is shown below. Identify compound A.

Aadit Sharma

Numerade Educator

Problem 57

a. Identify the two products obtained from the following reaction:
b. Eddie Amine carried out the preceding reaction, but stopped it before it was half over, whereupon he isolated the major product. He was surprised to find that the product he isolated was neither of the products obtained when the reaction was allowed to go to completion. What product did he isolate?

Temi Ajayi

Numerade Educator

Problem 58

An aqueous solution of a primary or secondary amine reacts with an acyl chloride to form an amide as the major product. However, if the amine is tertiary, an amide is not formed. What product is formed? Explain.

Arun Bana

Numerade Educator

Problem 59

a. Ann Hydride did not obtain any ester when she added 2,4,6 -trimethylbenzoic acid to an acidic solution of methanol. Why? (Hint: Build models.)
b. Would Ann have encountered the same problem if she had tried to synthesize the methyl ester of $p$ -methylbenzoic acid in the same way?
c. How could she prepare the methyl ester of 2,4,6 -trimethylbenzoic acid? (Hint: See Section $16.12 .$ )

Grigoriy Sereda

Grigoriy Sereda

Numerade Educator

Problem 60

When a compound with molecular formula $\mathrm{C}_{11} \mathrm{H}_{14} \mathrm{O}_{2}$ undergoes acid-catalyzed hydrolysis, one of the products that is isolated gives the following $^{1} \mathrm{H}$ NMR spectrum. Identify the compound.

Arun Bana

Numerade Educator

Problem 61

List the following compounds in order of decreasing frequency of the carbon-oxygen double-bond stretch:

Temi Ajayi

Numerade Educator

Problem 62

a. If the equilibrium constant for the reaction of acetic acid and ethanol to form ethyl acetate is $4.02,$ what will be the concentration of ethyl acetate at equilibrium if the reaction is carried out with equal amounts of acetic acid and ethanol?
b. What will be the concentration of ethyl acetate at equilibrium if the reaction is carried out with 10 times more ethanol than acetic acid? Hint: Recall the quadratic equation: For $a x^{2}+b x+c=0$
$$x=\frac{-b \pm\left(b^{2}-4 a c\right)^{1 / 2}}{2 a}$$
c. What will be the concentration of ethyl acetate at equilibrium if the reaction is carried out with 100 times more ethanol than acetic acid?

Temi Ajayi

Numerade Educator

Problem 63

The $^{1} \mathrm{H}$ NMR spectra for two esters with molecular formula $\mathrm{C}_{8} \mathrm{H}_{8} \mathrm{O}_{2}$ are shown below. If each of the esters is added to an aqueous solution with a pH of $10,$ which of the esters will be hydrolyzed more completely when the hydrolysis reactions have reached equilibrium?

Temi Ajayi

Numerade Educator

Problem 64

Show how the following compounds could be prepared from the given starting materials. You can use any necessary organic or inorganic reagents.

Lottie Adams

Numerade Educator

Problem 65

Is the acid-catalyzed hydrolysis of acetamide a reversible or an irreversible reaction? Explain.

Arun Bana

Numerade Educator

Problem 66

The reaction of a nitrile with an alcohol in the presence of a strong acid forms a secondary amide. This reaction is known as the The Ritter reaction does not work with primary alcohols.a. Propose a mechanism for the Ritter reaction.
b. Why does the Ritter reaction not work with primary alcohols?
c. How does the Ritter reaction differ from the acid-catalyzed hydrolysis of a nitrile to form a primary amide?

Temi Ajayi

Numerade Educator

Problem 67

The intermediate shown here is formed during the hydroxide-ion-promoted hydrolysis of the ester group. Propose a mechanism for the reaction.

Aadit Sharma

Numerade Educator

Problem 68

What product would you expect to obtain from each of the following reactions?

Nicholas Sacco

Numerade Educator

Problem 69

Sulfonamides, the first antibiotics, were introduced clinically in 1934 (Sections 25.8 and 30.4 ). Show how a sulfonamide can be prepared from benzene.

Nicholas Sacco

Numerade Educator

Problem 70

a. How could aspirin be synthesized, starting with benzene?
b. Ibuprofen is the active ingredient in pain relievers such as Advil Motrin , and Nuprin . How could ibuprofen be synthesized, starting with benzene?

Nicholas Sacco

Numerade Educator

Problem 71

The following compound has been found to be an inhibitor of penicillinase. The enzyme can be reactivated by hydroxylamine $\left(\mathrm{NH}_{2} \mathrm{OH}\right) .$ Propose a mechanism to account for the inhibition and for the reactivation.

Temi Ajayi

Numerade Educator

Problem 72

For each of the following reactions, propose a mechanism that will account for the formation of the product:

Temi Ajayi

Numerade Educator

Problem 73

Show how Novocain a painkiller used frequently by dentists (Section 30.3 ), can be prepared from benzene.

Nicholas Sacco

Numerade Educator

Problem 74

Catalytic antibodies catalyze a reaction by binding to the transition state, thereby stabilizing it. As a result, the energy of activation is lowered and the reaction goes faster. The synthesis of the antibody is carried out in the presence of a transition state analog $-\mathrm{a}$ stable molecule that structurally resembles the transition state. This causes an antibody to be generated that will recognize and bind to the transition state. For example, the following transition state analog has been used to generate a catalytic antibody that catalyzes the hydrolysis of the structurally similar ester:
a. Draw the transition state for the hydrolysis reaction.
b. The following transition state analog is used to generate a catalytic antibody for the catalysis of ester hydrolysis. Give the structure of an ester whose rate of hydrolysis would be increased by this catalytic antibody.
c. Design a transition state analog that would catalyze amide hydrolysis at the amide group indicated.

Lottie Adams

Numerade Educator

Problem 75

Saccharin, an artificial sweetener, is about 300 times sweeter than sucrose. Describe how saccharin could be prepared, using benzene as the starting material.

Nicholas Sacco

Numerade Educator

Problem 76

Information about the mechanism of reaction of a series of substituted benzenes can be obtained by plotting the logarithm of the observed rate constant obtained at a particular pH against the Hammett substituent constant ( $\sigma$ ) for the particular substituent. The $\sigma$ value for hydrogen is $0 .$ Electron-donating substituents have negative $\sigma$ values; electron-withdrawing substituents have positive nore strongly electron donating ituent, the more negative its $\sigma$ value will be; the more strongly electron withdrawing the substituent, the more positive value its $\sigma$ value will be. The slope of a plot of the logarithm of the rate constant versus $\sigma$ is called the $\rho$ (rho) value. The $\rho$ value for the hydroxide-ion-promoted hydrolysis of a series of meta-and parasubstituted ethyl benzoates is $+2.46 ;$ the $\rho$ value for amide formation for the reaction of a series of meta-and para-substituted anilines with benzoyl chloride is $-2.78 .$ a. Why does one set of experiments give a positive $\rho$ value while the other set of experiments gives a negative $\rho$ value?
b. Why do you think that ortho-substituted compounds were not included in the experiment?
c. What would you predict the sign of the $\rho$ value to be for the ionization of a series of meta-and para-substituted benzoic acids?

Lottie Adams

Numerade Educator