Introduction to General, Organic and Biochemistry

Frederick A. Bettelheim, William H. Brown, Mary K. Campbell

Chapter 19

Carboxylic Anhydrides, Esters, and Amides - all with Video Answers

Educators

Chapter Questions

Problem 1

Draw a structural formula for each amide.
(a) $N$ -Cyclohexylacetamide
(b) Benzamide

Nicholas Sacco

Nicholas Sacco

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Problem 2

Complete the equation for each hydrolysis reaction. Draw all products as they are ionized under these experimental conditions.

Nicholas Sacco

Numerade Educator

Problem 3

Write a balanced equation for the hydrolysis of each amide in Example $19-3$ in concentrated aqueous NaOH. Draw all products as they exist in aqueous $\mathrm{NaOH}$

Nicholas Sacco

Numerade Educator

Problem 4

Draw a structural formula for each compound.
(a) Dimethyl carbonate
(b) $p$ -Nitrobenzamide
(c) Ethyl 3 -hydroxybutanoate
(d) Diethyl oxalate
(e) Ethyl trans-2-pentenoate
(f) Butanoic anhydride

Kamila Zakarian

Kamila Zakarian

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Problem 5

Write the IUPAC name for each compound

Susan Hallstrom

Susan Hallstrom

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Problem 6

When oil from the head of a sperm whale is cooled, spermaceti, a translucent wax with a white, pearly luster, crystallizes from the mixture. Spermaceti, which makes up $11 \%$ of sperm whale oil, is composed of mainly hexadecyl hexadecanoate (cetyl palmitate). At one time, spermaceti was widely used in the making of cosmetics, fragrant soaps, and candles. Draw the structural formula of spermaceti. (Hint: Hexadecane, the parent hydrocarbon, is $\mathrm{CH}_{3}\left(\mathrm{CH}_{2}\right)_{14} \mathrm{CH}_{3}$.)

Madeline Currie

Madeline Currie

Numerade Educator

Problem 7

What product forms when ethyl benzoate is treated with each of the following sets?
$(a) H_{2} O, N a O H,$ heat
(b) $\mathrm{H}_{2} \mathrm{O}, \mathrm{HCl}$, heat

Nicholas Sacco

Numerade Educator

Problem 8

What product forms when benzamide, $\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{CONH}_{2}$ is treated with each of the following sets?
(a) $\mathrm{H}_{2} \mathrm{O}, \mathrm{NaOH},$ heat
(b) $\mathrm{H}_{2} \mathrm{O}, \mathrm{HCl},$ heat

Madeline Currie

Madeline Currie

Numerade Educator

Problem 9

Which of these types of compounds will produce bubbles of $\mathrm{CO}_{2}$ when added to an aqueous solution of sodium bicarbonate?
(a) A carboxylic acid
(b) A carboxylic ester
(c) The sodium salt of a carboxylic acid

Sana Riaz

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Problem 10

Complete the equations for these reactions.

Ronald Prasad

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Problem 11

The analgesic phenacetin is synthesized by treating 4-ethoxyaniline with acetic anhydride. Draw a structural formula for phenacetin.

Madeline Currie

Madeline Currie

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Problem 12

Phenobarbital is a long-acting sedative, hypnotic, and anticonvulsant.
(a) Name all functional groups in this compound.
(b) Draw structural formulas for the products from complete hydrolysis of all amide groups in aqueous $\mathrm{NaOH}$

Madeline Currie

Madeline Currie

Numerade Educator

Problem 13

Following is a structural formula for aspartame, an artificial sweetener about 180 times as sweet as sucrose (table sugar).
(a) Is aspartame chiral? If so, how many stereoisomers are possible for it?
(b) Name each functional group in aspartame.
(c) Estimate the net charge on an aspartame molecule in aqueous solution at pH 7.0
(d) Would you expect aspartame to be soluble in water? Explain. (Chapter 5 )
(e) Draw structural formulas for the products of complete hydrolysis of aspartame in aqueous HCl. Show each product as it would be ionized in this solution.
(f) Draw structural formulas for the products of complete hydrolysis of aspartame in aqueous NaOH. Show each product as it would be ionized in this solution.

Madeline Currie

Madeline Currie

Numerade Educator

Problem 14

Why are nylon- 66 and Kevlar referred to as polyamides?

Madeline Currie

Madeline Currie

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Problem 15

Draw short sections of two parallel chains of nylon- 66 (each chain running in the same direction) and show how it is possible to align them such that there is hydrogen bonding between the $\mathrm{N}-\mathrm{H}$ groups of one chain and the $\mathrm{C}=\mathrm{O}$ groups of the parallel chain.

Madeline Currie

Madeline Currie

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Problem 16

Why are Dacron and Mylar referred to as polyesters?

Madeline Currie

Madeline Currie

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Problem 17

What type of structural feature do the anhydrides of phosphoric acid have in common with carboxylic acids?

Madeline Currie

Madeline Currie

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Problem 18

Draw structural formulas for the mono-, di-, and triethyl esters of phosphoric acid.

Madeline Currie

Madeline Currie

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Problem 19

1,3-Dihydroxy-2-propanone (dihydroxyacetone) and phosphoric acid form a monoester called dihydroxyacetone phosphate, which is an intermediate in glycolysis (Section 28-2). Draw a structural formula for this monophosphate ester

Sana Riaz

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Problem 20

Show how triphosphoric acid can form from three molecules of phosphoric acid. How many moles of $\mathrm{H}_{2} \mathrm{O}$ are produced per mole of triphosphoric acid?

Sana Riaz

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Problem 21

Write an equation for the hydrolysis of trimethyl phosphate to dimethyl phosphate and methanol in aqueous base. Show each product as it would be ionized in this solution.

Madeline Currie

Madeline Currie

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Problem 22

(Chemical Connections 19 A) Locate the ester group in pyrethrin I and draw a structural formula for chrysanthemic acid, the carboxylic acid from which this ester is derived.

Sana Riaz

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Problem 23

(Chemical Connections 19 A) What structural features do pyrethrin I (a natural insecticide) and permethrin (a synthetic pyrethrenoid) have in common?

Sana Riaz

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Problem 24

(Chemical Connections $19 \mathrm{A}$ ) A commercial Clothing \& Gear Insect Repellant gives the following information about permethrin, its active ingredient: Cis / trans ratio: Minimum $35 \%(+/-)$ cis and maxi$\operatorname{mum} 65 \%(+/-) \operatorname{trans}$
(a) To what does the cis$/$trans ratio refer?
(b) To what does the designation $^{u}(+/-) "$ refer?

Sana Riaz

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Problem 25

(Chemical Connections $19 \mathrm{B})$ (a) Identify the $\beta$ -lactam portion of amoxicillin and cenhalexin
(b) Penicillin-resistant organisms are able to synthesize $\beta$ -lactamase, an enzyme that catalyzes the hydrolysis of the $\beta$ -lactam ring of penicillin. The integrity of the $\beta$ -lactam ring is essential for antibacterial activity. Draw the structural formula of the molecule formed by the enzyme-catalyzed hydrolysis of the $\beta$ -lactam ring of penicillin $G$

Sana Riaz

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Problem 26

(Chemical Connections $19 \mathrm{C}$ ) What is the compound in willow bark that is responsible for its ability to relieve pain? How is this compound related to salicylic acid?

Sana Riaz

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Problem 27

(Chemical Connections $19 \mathrm{C}$ ) Name the two functional groups in aspirin.

Nicholas Sacco

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Problem 28

(Chemical Connections $19 \mathrm{C}$ ) Once it has been opened, and particularly if it has been left open to the air, a bottle of aspirin may develop a vinegar-like odor. Explain how this might happen.

Sana Riaz

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Problem 29

(Chemical Connections $19 \mathrm{C}$ ) What is the structural relationship between aspirin and ibuprofen? Between aspirin and naproxen?

Sana Riaz

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Problem 30

(Chemical Connections 19 D) What is the difference in meaning between sunblock and sunscreen?

Sana Riaz

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Problem 30

(Chemical Connections $19 \mathrm{D}$ ) What is the difference in meaning between sunblock and sunscreen?

Sana Riaz

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Problem 32

(Chemical Connections 19 D) What structural features do the three sunscreens given in this Chemical Connection have in common?

Sana Riaz

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Problem 33

(Chemical Connections $19 \mathrm{E}$ ) Barbiturates are derived from urea. Identify the portion of the structure of pentobarbital and phenobarbital that is derived from urea.

Sana Riaz

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Problem 34

(Chemical Connections $19 \mathrm{F}$ ) Why do Lactomer stitches dissolve within 2 to 3 weeks following surgery?

Sana Riaz

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Problem 35

Benzocaine, a topical anesthetic, is prepared by treating 4 -aminobenzoic acid with ethanol in the presence of an acid catalyst, followed by neutralization. Draw a structural formula for benzocaine.

Madeline Currie

Madeline Currie

Numerade Educator

Problem 36

The analgesic acetaminophen is synthesized by treating 4 -aminophenol with one equivalent of acetic anhydride. Write an equation for the formation of acetaminophen. (Hint: The $-\mathrm{NH}_{2}$ group is more reactive with acetic anhydride than the $-$ OH group.)

Madeline Currie

Madeline Currie

Numerade Educator

Problem 37

1,3-Diphosphoglycerate, an intermediate in glycolysis (Section $28-2$ ), contains a mixed anhydride (an anhydride of a carboxylic acid and phosphoric acid) and a phosphoric ester. Draw structural formulas for the products formed by hydrolysis of the anhydride and ester bonds in this molecule. Show each product as it would exist in solution at pH 7.4

Sana Riaz

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Problem 38

In Chapter $22,$ we will discuss a class of compounds called amino acids, so named because they contain both an amino group and a carboxyl group. Following is a structural formula for the amino acid alanine.

Sana Riaz

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Problem 39

We have seen that an amide can be formed from a carboxylic acid and an amine. Suppose that you start instead with an amino acid such as alanine. Show how amide formation in this case can lead to a macromolecule of molecular weight several thousands of times that of the starting materials. We will study these polyamides in Chapter 22 (proteins).

Sana Riaz

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Problem 40

We will encounter the following molecule in our discussion of glycolysis, the biochemical pathway that converts glucose to pyruvic acid (Section $28-2$ ).
(a) Draw structural formulas for the products of hydrolysis of the ester bond in phosphoenolpyruvate.
(b) Why are the letters enol a part of the name of this compound?

Sana Riaz

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Problem 41

Starting with ethylene as the only source of carbon atoms, show how you could synthesize ethyl acetate.

Madeline Currie

Madeline Currie

Numerade Educator

Problem 42

From what carboxylic acid and amine or ammonia can each amide be synthesized?

Madeline Currie

Madeline Currie

Numerade Educator

Problem 43

$N, N$ -Diethyl $m$ -toluamide (DEET) is the active ingredient in several common insect repellents. From what acid and amine can DEET be synthesized?

Madeline Currie

Madeline Currie

Numerade Educator

Problem 44

Following are structural formulas for two local anesthetics used in dentistry. Lidocaine was introduced in 1948 and is now the most widely used local anesthetic for infiltration and regional anesthesia. Its hydrochloride salt is marketed under the name Xylocaine. Mepivacaine is faster-acting and somewhat longer lasting than lidocaine. Its hydrochloride salt is marketed under the name Carbocaine.
(a) Name the functional groups in each anesthetic.
(b) Which of these anesthetics are chiral?
(c) Which nitrogen atom in each is the more basic?
(d) What similarities in structure do you find between these compounds?

Madeline Currie

Madeline Currie

Numerade Educator

Problem 45

Barbiturates are prepared by treating diethyl malonate or a derivative of diethyl malonate with urea in the presence of sodium ethoxide as a catalyst. Following is an equation for the preparation of barbital from a substituted diethyl malonate and urea. Barbital, a long-duration hypnotic and sedative, is prescribed under a dozen or more names. Draw the structural formula of barbital. $$\frac{1 . \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{O}^{-} \mathrm{Na}^{+}}{2 . \mathrm{H}_{2} \mathrm{O}} \text { Barbital }+2 \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OH}$$

Madeline Currie

Madeline Currie

Numerade Educator

Problem 46

Consider the experimental antiviral drug Peramivir, shown below, a neuraminidase inhibitor recently supported by the U.S. Department of Health and Human Services as a treatment for Influenza A (H1N1), "Swine Flu."
(a) What is the molecular formula of Peramivir?
(b) Identify the functional groups labeled with arrows in the structure above. If any alcohols or amines are present, determine if they are primary, secondary, or tertiary.
(c) How many stereocenters are present in Peramivir?
(d) Determine the maximum number of stereoisomers possible for this molecule.
(e) Fill in the blanks: There is/are ______ enantiomer(s) and _______ diastereomer(s) of Peramivir.

Sana Riaz

Numerade Educator

Problem 47

In pharmaceutical research, structural analogs (or derivatives) of drugs are often made in order to see if they have similar biological properties. Following is a structural analog of Peramivir (Problem $19-46$ ) called $\mathbf{A}$
(a) Complete the drawings of the alternative chair conformations of $\mathbf{A},$ making sure to note the numbering of the ring atoms. Which of the alternative chair conformations is more stable? (Chapter 11 )
(b) A is formed from the cyclization of B. Which two functional groups in B react to form A? What is the name of the new functional group formed when these two groups react to close the ring?

Sana Riaz

Numerade Educator

Problem 48

Following is an example of how a moth uses a plant-derived chemical as a raw material from which to synthesize a compound that impacts its species' survival.
When the hawk moth caterpillar munches on certain plant leaves, it ingests compound (A), and an enzyme in its saliva catalyzes the isomerization of $(\mathrm{A})$ to $(\mathrm{B}) .$ Bugs of the insect family Geocoris are attracted by the volatile odor of Compound (B) and come to dine on both the caterpillars and unhatched eggs. Studies have shown that female hawk moths can detect compound (B) on leaves chewed by these caterpillars and will avoid laying eggs on the same leaves, thus reducing competition for food among different clusters of hatched larva and also reducing the risk of eggs being eaten by predators. Write the IUPAC name of each ester.

Madeline Currie

Madeline Currie

Numerade Educator

Problem 49

Only certain types of polymers are readily biodegradable; that is, only certain types of chemical bonds are easily broken in the process of composting. Chief among these polymers are those that contain ester bonds, which are readily broken by esterases, microbial enzymes that catalyze the hydrolysis of esters. Following are structural formulas for two such biodegradable polyesters. For each, draw the structural formulas and write names for the monomer units present in each.

Madeline Currie

Madeline Currie

Numerade Educator