a. Identify the two products obtained from the following reaction: b. A student carried

The aromas of many flowers and fruits are due to esters such as those shown in this problem. What are the common names of these esters? (Also see Problem 57.)

Name the following:

Draw the structure for each of the following: a. phenyl acetate b. g-caprolactam c. sodium formate d. N-benzylethanamide e. g-methylcaproic acid f. b-bromobutyramide g. ethyl 2-chloropentanoate h. cyclohexanecarbonyl chloride i. a-chlorovaleric acid

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

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

Which is a correct statement? A. The delocalization energy of an ester is about 18 kcal/mol, and the delocalization energy of an amide is about 10 kcal/mol. B. The delocalization energy of an ester is about 10 kcal/mol, and the delocalization energy of an amide is about 18 kcal/mol.

a. What is the product of the reaction of acetyl chloride with HO-? The pKa of HCl is -7; the pKa of H2O is 15.7. b. What is the product of the reaction of acetamide with HO-? The pKa of NH3 is 36; the pKa of H2O is 15.7.

What is the product of an acyl substitution reactiona new carboxylic acid derivative, a mixture of two carboxylic acid derivatives, or no reactionif the new group in the tetrahedral intermediate is the following? a. a stronger base than the substituent that is attached to the acyl group b. a weaker base than the substituent that is attached to the acyl group c. similar in basicity to the substituent that is attached to the acyl group

a. Which compound has the stretching vibration for its carbonyl group at the highest frequency: acetyl chloride, methyl acetate, or acetamide? b. Which one has the stretching vibration for its carbonyl group at the lowest frequency?

Using the pKa values listed in Table 15.1, predict the products of the following reactions:

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, then formation of the tetrahedral intermediate is the rate-limiting step of a nucleophilic acyl substitution reaction.

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

Write the mechanism for each of the following reactions: a. the reaction of acetyl chloride with water to form acetic acid b. the reaction of benzoyl chloride with excess methylamine to form N-methylbenzamide

a. What two amides are obtained from the reaction of acetyl chloride with an equivalent of ethylamine and an equivalent of propylamine? b. Why is only one amide obtained from the reaction of acetyl chloride with an equivalent of ethylamine and an equivalent of triethylamine?

Starting with methyl acetate, what neutral nucleophile would you use to synthesize each of the following compounds? a. ethyl acetate b. acetamide c. phenyl acetate d. benzyl acetate

We saw that it is necessary to use excess amine 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.

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

Rank the following esters from most reactive to least reactive toward hydrolysis

Which ester hydrolyzes more rapidly? a. methyl acetate or phenyl acetate? b. phenyl acetate or benzyl acetate?

a. State three factors that cause the uncatalyzed hydrolysis of an ester to be a slow reaction. b. Which is faster, the hydrolysis of an ester or the aminolysis of the same ester? Explain.

In the mechanism for the acid-catalyzed hydrolysis of an ester, a. what species could be represented by HB+? b. what species could be represented by B? c. what species is HB+ most likely to be in the hydrolysis reaction? d. what species is HB+ most likely to be in the reverse reaction?

Using the mechanism for the acid-catalyzed hydrolysis of an ester as your guide, write the mechanism showing all the curved arrowsfor the acid-catalyzed reaction of acetic acid and methanol to form methyl acetate. Use HB+ and B to represent the proton-donating and proton-removing species, respectively.

What products are formed from the acid-catalyzed hydrolysis of the following esters?

Show the mechanism for the acid-catalyzed formation of 23c starting with the product obtained from its hydrolysis.

What products are obtained from the following reactions? a. ethyl benzoate + excess isopropanol + HCl b. phenyl acetate + excess ethanol + HCl

Write the mechanism for the acid-catalyzed transesterification of ethyl acetate with methanol.

Write the mechanism for the acid-catalyzed reaction of tert-butyl acetate with methanol.

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

D. N. Kursanov, a Russian chemist, proved that the bond that is broken in the hydroxide-ion-promoted hydrolysis of an ester is the acyl CO bond, rather than the alkyl CO bond, by studying the hydrolysis of the following ester under basic conditions:a. What products contained the 18O label? b. What product would have contained the 18O label if the alkyl CO bond had broken?

Early chemists could envision three possible mechanisms for hydroxide-ion-promoted ester hydrolysis. Devise an experiment that would show which of the three is the actual mechanism. 1. a nucleophilic acyl substitution reaction

Show how each of the following esters could be prepared using a carboxylic acid as one of the starting materials: a. methyl butyrate (odor of apples) b. octyl acetate (odor of oranges)

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

What acyl chloride and amine are required to synthesize the following amides? a. N-ethylbutanamide b. N,N-dimethylbenzamide

Which of the following reactions lead to the formation of an amide?

Write the mechanism for the acid-catalyzed reaction of an amide with an alcohol to form an ester.

Rank the following amides from greatest reactivity to least reactivity toward acid-catalyzed hydrolysis:

Why, in the last step of the mechanism for hydroxide-ion promoted hydrolysis of an amide, is the amide ion protonated?

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

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?

Give two names for each of the following nitriles: a. CH3CH2CH2CN b. CH3CHCH2CH2C N CH3

Which alkyl halides form the carboxylic acids listed here after reaction with sodium cyanide followed by heating the product in an acidic aqueous solution? a. butyric acid b. isovaleric acid c. cyclohexanecarboxylic acid

An amide with an NH2 group can be dehydrated to a nitrile with thionyl chloride (SOCl2). Propose a mechanism for this reaction.

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?

Propose a mechanism for the reaction of an acyl chloride with acetate ion to form an acid anhydride.

We saw that acid anhydrides react with alcohols, water, and amines. In which of these reactions can the tetrahedral intermediate eliminate the carboxylate ion even if it does not lose a proton before the elimination step? Explain.

a. Propose a mechanism for the formation of succinic anhydride in the presence of acetic anhydride. b. How does acetic anhydride make it easier to form the anhydride?

How could you synthesize the following compounds starting with a carboxylic acid?

Draw a structure for each of the following: a. N,N-dimethylhexanamide b. 3,3-dimethylhexanamide c. cyclohexanecarbonyl chloride d. propanenitrile e. propionamide f. sodium acetate g. benzoic anhydride h. b-valerolactone i. 3-methylbutanenitrile j. cycloheptanecarboxylic acid k. benzoyl chloride

Name the following:

What compounds are formed from the reaction of benzoyl chloride with the following reagents? a. sodium acetate b. water c. excess dimethylamine d. aqueous HCl e. aqueous NaOH f. cyclohexanol g. excess benzylamine h. 4-chlorophenol i. isopropyl alcohol j. excess aniline k. potassium formate

What compounds are obtained from the following hydrolysis reactions?

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

Because bromocyclohexane is a secondary alkyl halide, both cyclohexanol and cyclohexene are formed when the alkyl halide reacts with hydroxide ion. Suggest a method to synthesize cyclohexanol from bromocyclohexane that forms little or no cyclohexene.

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

How could you use 1H NMR spectroscopy to distinguish the following esters?

Rank the following compounds in order of decreasing frequency of the carbonoxygen double-bond stretch:

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

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

What products would you expect to obtain from the following reactions? a. malonic acid + 2 acetyl chloride b. methyl carbamate + methylamine c. urea + water d. b-ethylglutaric acid + acetyl chloride + 

A compound with molecular formula C5H10O2 gives the following IR spectrum. When it undergoes acid-catalyzed hydrolysis, the compound with the 1H NMR spectrum shown below is formed. Identify the compounds.

Aspartame, the sweetener used in the commercial products NutraSweet and Equal, is 200 times sweeter than sucrose. What products will be obtained if aspartame is hydrolyzed completely in an aqueous solution of HCl?

To prove that the reaction of an ester with hydroxide ion is not an SN2 reaction but, instead, forms a tetrahedral intermediate that subsequently collapses, the products obtained after allowing hydroxide ion to react with an ester containing an isotopically labeled carbonyl oxygen (18O) were isolated. One of the products was isotopically labeled hydroxide ion. Explain how obtaining this product proves that a tetrahedral intermediate was formed.

a. Which of the following reactions does 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?

Describe how the target molecule (butanone) can be synthesized in a high yield from butane.

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

a. If the equilibrium constant for the reaction of acetic acid and ethanol to form ethyl acetate is 4.02, what is the concentration of ethyl acetate at equilibrium if the reaction is carried out with equal amounts of acetic acid and ethanol? b. What is 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 ax2 + bx + c = 0, x = -b { 1b2 - 4ac21>2 2a c. What is the concentration of ethyl acetate at equilibrium if the reaction is carried out with 100 times more ethanol than acetic acid?

Two products, A and B, are obtained from the reaction of 1-bromobutane with NH3. Compound A reacts with acetyl chloride to form C, and compound B reacts with acetyl chloride to form D. The IR spectra of C and D are shown. Identify A, B, C, and D.

What are the products of the following reactions?

Phosgene (COCl2) was used as a poison gas in World War I. What product would be formed from the reaction of phosgene with each of the following reagents? a. one equivalent of methanol b. excess methanol c. excess propylamine d. excess water

What reagent should be used to carry out the following reaction?

When a student 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.

When butanoic acid and 18O-labeled methanol react under acidic conditions, what compounds are labeled when the reaction has reached equilibrium?

When treated with an equivalent of methanol, compound A, with molecular formula C4H6Cl2O, forms the compound whose 1H NMR spectrum is shown here. Identify compound A.

a. Identify the two products obtained from the following reaction: b. A student 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?

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.

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.

a. When a carboxylic acid is dissolved in isotopically labeled water (H2 18O) and an acid catalyst is added, the label is incorporated into both oxygens of the acid. Propose a mechanism to account for this. + H2O CH3 OH 18 + H2O CH3 OH 18 18 C O C O HCl b. If a carboxylic acid is dissolved in isotopically labeled methanol (CH3 18OH) and an acid catalyst is added, where will the label reside in the product? c. If an ester is dissolved in isotopically labeled water (H2 18O) and an acid catalyst is added, where will the label reside in the product?

a. A student did not obtain any ester when he added 2,4,6-trimethylbenzoic acid to an acidic solution of ethanol. Why? (Hint: Build models.) b. Would he have encountered the same problem if he had tried to synthesize the methyl ester of 4-methylbenzoic acid in the same way?

Identify the major and minor products of the following reaction:

When a compound with molecular formula C11H14O2 undergoes acid-catalyzed hydrolysis, one of the products that is isolated gives the following 1H NMR spectrum. Identify the compound.

Cardura, a drug used to treat hypertension, is synthesized as shown here. a. Identify the intermediate (A) and show the mechanism for its formation. b. Show the mechanism for conversion of A to B. Which is formed more rapidly, A or B?

The reaction of a nitrile with an alcohol in the presence of a strong acid forms an N-substituted amide. This reaction, known as 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 an amide?

Some credit card sales slips have a top sheet of carbonless paper that transfers an imprint of a signature to a sheet lying underneath (the customer receipt). The paper contains tiny capsules filled with the following colorless compound. When you press on the paper, the capsules burst, and the colorless compound comes into contact with the acid-treated bottom sheet, forming a highly colored compound. What is the structure of the colored compound?

The 1H NMR spectra for two esters with molecular formula C8H8O2 are shown next. Which of the esters is hydrolyzed more rapidly in an aqueous solution with a pH of 10?

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

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

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

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

The following compound has been found to be an inhibitor of penicillinase. The enzyme can be reactivated by hydroxylamine (NH2OH). Propose a mechanism to account for the inhibition and for the reactivation.

Propose a mechanism that accounts for the formation of the product

Catalytic antibodies catalyze a reaction by forcing the conformation of the substrate in the direction of the transition state. The synthesis of the antibody is carried out in the presence of a transition state analoga stable molecule that structurally resembles the transition state. This causes an antibody to be generated that recognizes and binds to the transition state, thereby stabilizing it. 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 a possible 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. Draw the structure of an ester whose rate of hydrolysis would be increased by this catalytic antibody.c. Design a transition state analog that catalyzes amide hydrolysis at the amide group indicated.

Information about the mechanism of the reaction undergone by a series of substituted benzenes can be obtained by plotting the logarithm of the observed rate constant determined at a particular pH against the Hammett substituent constant (s) for the particular substituent. The s value for hydrogen is 0. Electron- donating substituents have negative s values; the more strongly electron donating the substituent, the more negative its s value. Electron-withdrawing substituents have positive s values; the more strongly electron withdrawing the substituent, the more positive its s value. The slope of a plot of the logarithm of the rate constant versus s is called the r (rho) value. The r value for the hydroxide-ion-promoted hydrolysis of a series of meta- and para-substituted ethyl benzoates is +2.46; the r 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 r value, whereas the other set of experiments gives a negative r value? b. Why were ortho-substituted compounds not included in the experiment? c. What do you predict the sign of the r value to be for the ionization of a series of meta- and para-substituted benzoic acids?