Organic Chemistry

Paula Yurkanis Bruice

Chapter 12

Reactions of Alcohols, Ethers, Epoxides, and Sulfur-Containing Compounds - all with Video Answers

Educators

Chapter Questions

Problem 1

The observed relative reactivities of primary, secondary, and tertiary alcohols with a hydrogen halide are $3^{\circ}>2^{\circ}>1^{\circ} .$ If secondary alcohols underwent an $S_{\mathrm{N} 2}$ reaction rather than an $S_{N} 1$ reaction with a hydrogen halide, what would be the relative reactivities of the three classes of alcohols?

Joshua Gibson

Joshua Gibson

Numerade Educator

Problem 2

Give the major product of each of the following reactions:

Nicholas Sacco

Numerade Educator

Problem 3

Why can a halide ion such as $\mathrm{Br}^{-}$ react with a protonated primary alcohol, but not with a protonated primary amine?

Nicholas Sacco

Numerade Educator

Problem 4

Explain why the ether obtained by treating an optically active alcohol with $\mathrm{PBr}_{3}$ followed by sodium methoxide has the same configuration as the alcohol, whereas the ether obtained by treating the alcohol with tosyl chloride followed by sodium methoxide has a configuration opposite that of the alcohol. Conversion of the alcohol to the ether via the alkyl halide involves two successive $S_{\mathrm{N}} 2$ reactions: (1) attack of $\mathrm{Br}^{-}$ on the bromophosphite and (2) attack of $\mathrm{CH}_{3} \mathrm{O}^{-}$ on the alkyl halide. Each $\mathrm{S}_{\mathrm{N}} 2$ reaction takes place with inversion of configuration, so the final product has the same configuration as the starting material. In contrast, conversion of the alcohol to the ether via the alkyl tosylate involves only one $S_{N} 2$ reaction: attack of $\mathrm{CH}_{3} \mathrm{O}^{-}$ on the alkyl tosylate. Therefore, the final product and the starting material have opposite configurations.

Grigoriy Sereda

Grigoriy Sereda

Numerade Educator

Problem 5

Show how 1 -butanol can be converted into the following compounds: $$\text { a. } \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{Br}$$ $$\text { c. } \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{OCH}_{3}$$ $$\text { d. } \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{NHCH}_{2} \mathrm{CH}_{3}$$ e. $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{SH}$
f. $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{C} \equiv \mathrm{N}$

Nicholas Sacco

Numerade Educator

Problem 6

Explain why the acid-catalyzed dehydration of an alcohol is a reversible reaction, whereas the base-promoted dehydrohalogenation of an alkyl halide is an irreversible reaction.

Joshua Gibson

Numerade Educator

Problem 7

What product would be formed if the preceding alcohol were heated with an equivalent amount of HBr rather than with a catalytic amount of $\mathrm{H}_{2} \mathrm{SO}_{4} ?$

Nicholas Sacco

Numerade Educator

Problem 8

List the following alcohols in order of decreasing rate of dehydration in the presence
of acid:

Nicholas Sacco

Numerade Educator

Problem 9

Heating an alcohol with sulfuric acid is a good way to prepare a symmetrical ether such as dicthyl ether. It is not a good method for preparing an unsymmetrical ether such as ethyl propyl ether. a. Explain.
b. How would you synthesize ethyl propyl ether?

Joshua Gibson

Numerade Educator

Problem 10

What alcohol would you treat with phosphorus oxychloride and pyridine to form each of the following alkenes?

Tom Rutherford

Numerade Educator

Problem 11

Propose a mechanism for each of the following reactions:

Lottie Adams

Numerade Educator

Problem 12

Give the major product formed when each of the following alcohols is heated in the presence of $\mathrm{H}_{2} \mathrm{SO}_{4}:$

Nicholas Sacco

Numerade Educator

Problem 13

Explain why methyl propyl ether forms both methyl iodide and propyl iodide when it is heated with excess HI.

Tom Rutherford

Numerade Educator

Problem 14

Can HF be used to cleave ethers? Explain.

Joshua Gibson

Numerade Educator

Problem 15

Give the major products that would be obtained from heating each of the following ethers with HI:

Nicholas Sacco

Numerade Educator

Problem 16

Draw the structure of the following compounds:
a. 2-propyloxirane
c. 2,2,3,3 -tetramethyloxirane
b. cyclohexene oxide
d. 2,3 -epoxy- 2 -methylpentane

Joshua Gibson

Numerade Educator

Problem 17

Why does the preceding reaction form two stereoisomers?

Joshua Gibson

Numerade Educator

Problem 18

Give the major product of each of the following reactions:

Nicholas Sacco

Numerade Educator

Problem 19

Would you expect the reactivity of a five-membered ring ether such as tetrahydrofuran (Table 12.2 ) to be more similar to an epoxide or to a noncyclic ether?

Joshua Gibson

Numerade Educator

Problem 20

Draw all possible resonance contributors for the two carbocations in the preceding reaction. Use the resonance contributors to explain why 1 -napthol is the major product of the reaction.

Grigoriy Sereda

Grigoriy Sereda

Numerade Educator

Problem 21

The existence of the NIH shift was established by determining the major product obtained from rearrangement of the following arene oxide, in which a hydrogen has been replaced by a deuterium: What would be the major product if the NIH shift did not occur?

Grigoriy Sereda

Grigoriy Sereda

Numerade Educator

Problem 22

How would the major products obtained from rearrangement of the following arene oxides differ?

Grigoriy Sereda

Grigoriy Sereda

Numerade Educator

Problem 23

Which compound is more likely to be carcinogenic?

Tom Rutherford

Numerade Educator

Problem 24

Explain why the two arene oxides in Problem 23 a open in opposite directions.

Grigoriy Sereda

Grigoriy Sereda

Numerade Educator

Problem 25

Three arene oxides can be obtained from phenanthrene. a. Give the structures of the three phenanthrene oxides.
b. What phenols can be obtained from each phenanthrene oxide?
c. If a phenanthrene oxide can lead to the formation of more than one phenol, which phenol will be obtained in greater yield?
d. Which of the three phenanthrene oxides is most likely to be carcinogenic?

Tom Rutherford

Numerade Educator

Problem 26

Using an alkyl halide and a thiol as starting materials, how would you prepare the following compounds?

Nicholas Sacco

Numerade Educator

Problem 27

Finding that mustard gas interfered with bone marrow development caused chemists to look for less reactive mustard gases that might be used clinically. The following three compounds were studied: One was found to be too reactive, one was found to be too unreactive, and one was found to be too insoluble in water to be injected intravenously. Which is which?

Grigoriy Sereda

Grigoriy Sereda

Numerade Educator

Problem 28

What alcohols would be formed from the reaction of ethylene oxide with the following Grignard reagents?

Nicholas Sacco

Numerade Educator

Problem 29

How could the following compounds be prepared, using cyclohexene oxide as a starting material?

Nicholas Sacco

Numerade Educator

Problem 30

Show, using any necessary reagents, how the following compounds could be prepared with ethylene oxide as one of the reactants: a. $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{OH}$
c. $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{D}$
b. $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{Br}$
d. $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{OH}$

Lottie Adams

Numerade Educator

Problem 31

Which of the following reactions will occur? (For the $\mathrm{p} K_{\mathrm{a}}$ values necessary to do this problem, see Appendix II.)

Carina Carlos

Numerade Educator

Problem 32

What organometallic compound will be formed from the reaction of methylmagnesium chloride and $\operatorname{SiCl}_{4}$ ?

Ian Kaigh

Numerade Educator

Problem 33

Explain why tertiary alkyl halides cannot be used in coupling reactions with Gilman reagents.

Ronald Prasad

Numerade Educator

Problem 34

Muscalure is the sex attractant of the common housefly. Flies are lured to traps by filling them with fly bait containing both muscalure and an insecticide. Eating the bait is fatal. How could you synthesize muscalure using the following reagents?

Nicholas Sacco

Numerade Educator

Problem 35

What alkyl halides would you utilize to synthesize the following compounds, using the organoborane shown?

Grigoriy Sereda

Grigoriy Sereda

Numerade Educator

Problem 36

The organoborane used in a Suzuki reaction is prepared by the reaction of catecholborane with an alkene or an alkyne. What hydrocarbon would you use to prepare the organoborane of Problem $35 ?$

Grigoriy Sereda

Grigoriy Sereda

Numerade Educator

Problem 37

Give two sets of alkyl bromide and alkene that could be used in a Heck reaction to prepare the following compound:

Grigoriy Sereda

Grigoriy Sereda

Numerade Educator

Problem 38

Give the product of each of the following reactions:

Nicholas Sacco

Numerade Educator

Problem 39

Indicate which alcohol will undergo dehydration more rapidly when heated with $\mathrm{H}_{2} \mathrm{SO}_{4}$

Nicholas Sacco

Numerade Educator

Problem 40

Which of the following alkyl halides could be successfully used to form a Grignard reagent?

Lottie Adams

Numerade Educator

Problem 41

Starting with ( $R$ )-1-deuterio-1-propanol, how could you prepare: a. $\quad(S)-1$ -deuterio- 1 -propanol? b. $\quad(S)-1-$ deuterio- $1-$ methoxypropane? c. $\quad(R)-1$ -deuterio- 1 -methoxypropane?

Grigoriy Sereda

Grigoriy Sereda

Numerade Educator

Problem 42

What alkenes would you expect to be obtained from the acid-catalyzed dehydration of 1-hexanol?

Tom Rutherford

Numerade Educator

Problem 43

Give the product of each of the following reactions:

Temi Ajayi

Numerade Educator

Problem 44

When heated with $\mathrm{H}_{2} \mathrm{SO}_{4},$ both 3,3 -dimethyl- 2 -butanol and 2,3 -dimethyl- 2 -butanol are dehydrated to form 2,3 -dimethyl- 2 -butene. Which alcohol dehydrates more rapidly?

Nicholas Sacco

Numerade Educator

Problem 45

Using the given starting material, any necessary inorganic reagents, and any carbon-containing compounds with no more than two carbon atoms, indicate how the following syntheses could be carried out:

SK

Sara Kolms

Numerade Educator

Problem 46

Propose a mechanism for the following reaction:

Zubair Abdulla

Numerade Educator

Problem 47

When deuterated phenanthrene oxide undergoes an epoxide rearrangement in water, $81 \%$ of the deuterium is retained in the product. a. What percentage of the deuterium will be retained if an NIH shift occurs?
b. What percentage of the deuterium will be retained if an NIH shift does not occur?

Sima Sarker

Numerade Educator

Problem 48

When 3-methyl-2-butanol is heated with concentrated HBr, a rearranged product is obtained. When 2-methyl-1-propanol reacts under the same conditions, a rearranged product is not obtained. Explain.

Nicholas Sacco

Numerade Educator

Problem 49

When the following seven-membered ring alcohol is dehydrated, three alkenes are formed:

Grigoriy Sereda

Grigoriy Sereda

Numerade Educator

Problem 50

How could you synthesize isopropyl propyl ether, using isopropyl alcohol as the only carbon-containing reagent?

Nicholas Sacco

Numerade Educator

Problem 51

Ethylene oxide reacts readily with $\mathrm{HO}^{-}$ because of the strain in the three-membered ring. Cyclopropane has approximately the same amount of strain, but does not react with HO'. Explain.

Nicholas Sacco

Numerade Educator

Problem 52

Which of the following ethers would be obtained in greatest yield directly from alcohols?

Tom Rutherford

Numerade Educator

Problem 53

Propose a mechanism for each of the following reactions:

Lottie Adams

Numerade Educator

Problem 54

Indicate how each of the following compounds could be prepared, using the given starting material:

Zubair Abdulla

Numerade Educator

Problem 55

Triethylene glycol is one of the products obtained from the reaction of ethylene oxide and hydroxide ion. Propose a mechanism for
its formation.

Grigoriy Sereda

Grigoriy Sereda

Numerade Educator

Problem 56

Give the major product expected from the reaction of 2 -ethyloxirane with each of the following reagents: a. $0.1 \mathrm{M} \mathrm{HCl}$
b. $\quad \mathrm{CH}_{3} \mathrm{OH} / \mathrm{H}^{+}$ c. ethyl magnesium bromide in ether, followed by $0.1 \mathrm{M} \mathrm{HCl}$
d. $0.1 \mathrm{M} \mathrm{NaOH}$

Grigoriy Sereda

Grigoriy Sereda

Numerade Educator

Problem 57

When ethyl ether is heated with excess HI for several hours, the only organic product obtained is ethyl iodide. Explain why ethyl alcohol is not obtained as a product.

Nicholas Sacco

Numerade Educator

Problem 58

a. Propose a mechanism for the following reaction: b. A small amount of a product containing a six-membered ring is also formed. Give the structure of that product.
c. Why is so little six-membered ring product formed?

Grigoriy Sereda

Grigoriy Sereda

Numerade Educator

Problem 59

Identify A through H.

Lottie Adams

Numerade Educator

Problem 60

Greg Nard added an equivalent of 3,4 -epoxy- 4 -methylcyclohexanol to an ether solution of methyl magnesium bromide and then added dilute hydrochloric acid. He expected that the product would be a diol. He did not get any of the expected product. What product did he get?

Grigoriy Sereda

Grigoriy Sereda

Numerade Educator

Problem 61

An ion with a positively charged nitrogen atom in a three-membered ring is called an aziridinium ion. The following aziridinium ion reacts with sodium methoxide to form A and B:

Grigoriy Sereda

Grigoriy Sereda

Numerade Educator

Problem 62

Dimerization is a side reaction that occurs during the preparation of a Grignard reagent. Propose a mechanism that accounts for the formation of the dimer.

Lottie Adams

Numerade Educator

Problem 63

Propose a mechanism for each of the following reactions:

Lottie Adams

Numerade Educator

Problem 64

One method used to synthesize an epoxide is to treat an alkene with an aqueous solution of $\mathrm{Br}_{2},$ followed by an aqueous solution
of sodium hydroxide.
a. Propose a mechanism for the conversion of cyclohexene into cyclohexene oxide by this method.
b. How many products are formed when cyclohexene oxide reacts with methoxide ion in methanol? Draw their structures.

Nicholas Sacco

Numerade Educator

Problem 65

Which of the following reactions occurs most rapidly? Why?

Tom Rutherford

Numerade Educator

Problem 66

When bromobenzene reacts with propene in a Heck reaction, two constitutional isomers are obtained as products. Give the structures of the products and explain why two products are obtained.

Grigoriy Sereda

Grigoriy Sereda

Numerade Educator

Problem 67

A vicinal diol has OH groups on adjacent carbons. The dehydration of a vicinal diol is accompanied by a rearrangement called the pinacol rearrangement. Propose a mechanism for this reaction.

Tom Rutherford

Numerade Educator

Problem 68

Although 2-methyl-1,2-propanediol is an asymmetrical vicinal diol, only one product is obtained when it is dehydrated in the presence of acid.
a. What is this product?
b. Why is only one product formed?

Nicholas Sacco

Numerade Educator

Problem 69

What product is obtained when the following vicinal diol is heated in an acidic solution?

Tom Rutherford

Numerade Educator

Problem 70

Two stereoisomers are obtained from the reaction of cyclopentene oxide and dimethylamine. The $R, R$ -isomer is used in the manufacture of eclanamine, an antidepressant. What other isomer is obtained?

Grigoriy Sereda

Grigoriy Sereda

Numerade Educator

Problem 71

Propose a mechanism for each of the following reactions:

Lottie Adams

Numerade Educator