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Organic Chemistry

Marc Loudon, Jim Parise

Chapter 11

The Chemistry of Ethers, Epoxides, Glycols, and Sulfides - all with Video Answers

Educators

Chapter Questions

06:55

Problem 1

Arrange the ions in the following list in order of increasing acidity, and explain your reasoning.
a
b
c
d

Ian Kaigh
Ian Kaigh
Numerade Educator
02:12

Problem 2

Complete the following reactions. If no reaction is likely, explain why.
(a) $\left(\mathrm{CH}_{3}\right)_{2} \mathrm{CH}-\mathrm{OH}+\mathrm{Na} \longrightarrow \stackrel{\mathrm{CH}_{3} \mathrm{I}}{\longrightarrow}$
(b) $\mathrm{CH}_{3} \mathrm{SH}+\mathrm{NaOH}_{(1 \text { equiv. })} \longrightarrow$
(c) $\mathrm{CH}_{3} \mathrm{O}^{-} \mathrm{Na}^{+}+\left(\mathrm{CH}_{3}\right)_{3} \mathrm{C}-\mathrm{Br} \underset{\mathrm{CH}_{3} \mathrm{OH}}{\longrightarrow}$
(d) $\mathrm{EtO}^{-} \mathrm{K}^{+}+\left(\mathrm{CH}_{3}\right)_{3} \mathrm{CCH}_{2}-\mathrm{OTs} \underset{\mathrm{EtOH}}{\frac{25^{\circ} \mathrm{C}}{25}}$

Nadir Iqbal
Nadir Iqbal
Numerade Educator
05:24

Problem 3

Suggest a Williamson ether synthesis, if one is possible, for each of the following compounds. If no Williamson ether synthesis is possible, explain why.
a.
(b) $\left(\mathrm{CH}_{3}\right)_{2} \mathrm{CH}-\mathrm{S}-\mathrm{CH}_{3}$
(c) $\left(\mathrm{CH}_{3}\right)_{3} \mathrm{C}-\mathrm{O}-\mathrm{C}\left(\mathrm{CH}_{3}\right)_{3}$

Preeti Kumari
Preeti Kumari
Numerade Educator
05:42

Problem 4

(a) Write the mechanism of Eq. $11.8 \mathrm{a}$ and account for the regioselectivity of the reaction.
(b) Explain what would happen in an attempt to synthesize the ether product of Eq. $11.8 \mathrm{~b}$ by a Williamson ether synthesis.

Lottie Adams
Lottie Adams
Numerade Educator
01:02

Problem 5

Complete the following reaction:
$$
\left(\mathrm{CH}_{3}\right)_{2} \mathrm{CH}-\mathrm{CH}=\mathrm{CH}_{2}+\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OH}+\mathrm{Hg}(\mathrm{OAc})_{2} \longrightarrow \stackrel{\mathrm{NaBH}_{4}}{\longrightarrow}
$$

Narayan Hari
Narayan Hari
Numerade Educator
02:50

Problem 6

Explain why a mixture of two isomeric ethers is formed in the following reaction.
$$
\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}=\mathrm{CHCH}_{3}+\mathrm{MeOH}+\mathrm{Hg}(\mathrm{OAc})_{2} \longrightarrow \stackrel{\mathrm{NaBH}_{4}}{\longrightarrow}
$$

Susan Hallstrom
Susan Hallstrom
Numerade Educator
02:46

Problem 7

Outline a synthesis of each of the following ethers using alkoxymercuration-reduction:
(a) dicyclohexyl ether
(b) tert-butyl isobutyl ether

Kaitlynn Wade
Kaitlynn Wade
Numerade Educator
11:44

Problem 8

Explain why the dehydration of primary alcohols can only be used for preparing symmetrical ethers. What would happen if a mixture of two different alcohols were used as the starting material in this reaction?

JC
Jared Cellini
Numerade Educator
01:12

Problem 9

Complete the following reaction by giving the major organic product.

Narayan Hari
Narayan Hari
Numerade Educator
01:58

Problem 10

Draw the structure of two alkenes, either of which when treated with dilute $\mathrm{H}_{2} \mathrm{SO}_{4}$ and ethanol will give the same ether product as the reaction in Problem $11.9 .$

Nicholas Sacco
Nicholas Sacco
Numerade Educator
02:27

Problem 11

Outline a synthesis of each ether using either alcohol dehydration or alkene addition, as appropriate.
(a) $\mathrm{ClCH}_{2} \mathrm{CH}_{2} \mathrm{OCH}_{2} \mathrm{CH}_{2} \mathrm{Cl}$
(b) 2 -methoxy-2-methylbutane
(c) tert-butyl isopropyl ether
(d) dibutyl ether

Lottie Adams
Lottie Adams
Numerade Educator
04:02

Problem 12

Give the structure of the alkene that would react with mCPBA to give each of the following epoxides.

Kaitlynn Wade
Kaitlynn Wade
Numerade Educator
04:28

Problem 13

Give the product expected when each of the following alkenes is treated with MMPP.
a.
b.

Nicholas Sacco
Nicholas Sacco
Numerade Educator
02:00

Problem 14

From models of the transition states for their reactions, predict which of the following two diastereomers of 3 -bromo-2-butanol should form an epoxide at the greater rate when treated with base, and explain your reasoning. (Hint: Draw the conformations required for reaction and consider their relative energies.)

Grigoriy Sereda
Grigoriy Sereda
Numerade Educator
02:51

Problem 15

The chlorohydrin trans-2-chlorocyclohexanol reacts rapidly in base to form an epoxide. The cis stereoisomer, however, is relatively unreactive and does not give an epoxide. Explain why the two stereoisomers behave so differently.

Madeline Currie
Madeline Currie
Numerade Educator
01:48

Problem 16

Explain each of the following facts with a mechanistic argument.
(a) When butyl methyl ether (1-methoxybutane) is treated with HI and heat, the initially formed products are mainly methyl iodide and 1 -butanol; little or no methanol and 1-iodobutane are formed.
(b) When the reaction mixture in part (a) is heated for longer times, 1 -iodobutane is also formed.
(c) When tert-butyl methyl ether is treated with HI, the products formed are tert-butyl iodide and methanol.
(d) Tert-butyl methyl ether cleaves much faster in HBr than its sulfur analog, tert-butyl methyl sulfide. (Hint: See Sec. 11.1.)
(e) When enantiomerically pure $(S)-2$ -methoxybutane is treated with $\mathrm{HBr}$, the products are enantiomerically pure $(S)-2$ -butanol and methyl bromide.

Lottie Adams
Lottie Adams
Numerade Educator
01:52

Problem 17

What products are formed when each of the following ethers reacts with concentrated aqueous HI?
(a) diisopropyl ether
(b) 2 -ethoxy-2,3-dimethylbutane

Shahina -
Shahina -
Numerade Educator
03:53

Problem 18

Predict the products of the following reactions by drawing a curved-arrow mechanism for each.
a
b.

Nima Gharibi
Nima Gharibi
Numerade Educator
06:04

Problem 19

From what epoxide and what nucleophile could each of the following compounds be prepared? (Assume each is racemic.)
a.
b.

Nicholas Sacco
Nicholas Sacco
Numerade Educator
00:50

Problem 20

Predict the major product(s) of each of the following transformations.
a.
b.

Alkendra Singh
Alkendra Singh
Numerade Educator
05:53

Problem 21

(a) Suppose 2,2 -dimethyloxirane reacts with water that has been enriched with the oxygen isotope ${ }^{18} \mathrm{O}$. Indicate how the hydrolysis product would differ under acidic and basic conditions.
(b) Show how the stereochemistry of the products will differ (if at all) when the following enantiomerically pure epoxide reacts with water under acidic and basic conditions.

Kim Trang Nguyen
Kim Trang Nguyen
Numerade Educator
05:17

Problem 22

(a) From what Grignard reagent can 3 -methyl-1-pentanol be prepared by reaction with ethylene oxide, then aqueous acid?
(b) From what epoxide and what higher-order cuprate reagent can 3 -ethyl-3-heptanol be prepared?

Ian Kaigh
Ian Kaigh
Numerade Educator
03:35

Problem 23

Complete the following reactions by giving the structures of the alcohol products. In part (b), show the stereochemistry of the product as well.
a.
b.

Madi Sousa
Madi Sousa
Numerade Educator
09:13

Problem 24

What organic product is formed (including its stereochemistry) when each of the following alkenes is treated with NMMO in the presence of $\mathrm{H}_{2} \mathrm{O}$ and a catalytic amount of $\mathrm{OsO}_{4} ?$
(a) 1-methylcyclopentene
(b) trans-2-butene

Tom Rutherford
Tom Rutherford
Numerade Educator
06:01

Problem 25

From what alkene could each of the following glycols be prepared by the $\mathrm{OsO}_{4}$ or $\mathrm{KMnO}_{4}$ method?
a.
b.
c.
d.

Brittany Carnathan
Brittany Carnathan
Numerade Educator
02:41

Problem 26

Show a curved-arrow mechanism for the first step, and the structure of the cyclic intermediate formed, when an alkene is treated with $\mathrm{KMnO}_{4}$. A Lewis structure for the permanganate ion is as follows:

Niamat Khuda
Niamat Khuda
Numerade Educator
01:40

Problem 27

Give the product(s) expected when each of the following compounds is treated with periodic acid.
a.
b.
c.

Sima Sarker
Sima Sarker
Numerade Educator
01:26

Problem 28

What glycol undergoes oxidation to give each of the following sets of products?
a.
b.

Narayan Hari
Narayan Hari
Numerade Educator
02:02

Problem 29

Explain why all attempts to isolate trimethyloxonium iodide lead instead to methyl iodide and dimethyl ether.

Tom Rutherford
Tom Rutherford
Numerade Educator
04:53

Problem 30

Complete the following reactions.
a.
b.

Nicholas Sacco
Nicholas Sacco
Numerade Educator
01:05

Problem 31

Using the abbreviations for lysine and SAM shown in Eq. 11.60a, write a curved-arrow mechanism for the formation of $N, N$ dimethyllysine. Assume that acids $\left({ }^{+} \mathrm{B} \mathrm{H}\right)$ and bases $(: \mathrm{B})$ are available as necessary. (Hint: A Brønsted acid-base reaction must precede each methylation; why?)

Aadit Sharma
Aadit Sharma
Numerade Educator
10:01

Problem 32

Give the structure of an intramolecular substitution product and an intermolecular substitution product that might be obtained from 4 -bromo-1-butanol on treatment with one equivalent of $\mathrm{NaOH}$. Which product do you think would be the major one? Why?

Shalini Tyagi
Shalini Tyagi
Numerade Educator
02:44

Problem 33

Two reactions, $A$ and $B$, have the same $\Delta H^{\circ \mp}$, but the $\Delta S^{\circ \neq}$ of reaction $A$ is $-30 \mathrm{~J} \mathrm{deg}^{-1} \mathrm{~mol}^{-1},$ and the $\Delta S^{\circ}{ }^{\circ}$ of reaction $B$ is $-180 \mathrm{~J} \mathrm{deg}^{-1} \mathrm{~mol}^{-1}$. At $25^{\circ} \mathrm{C}(298 \mathrm{~K})$, which reaction is faster and by what factor? (Hint: Apply Eq. 9.20b, p. 391.)

Preeti Kumari
Preeti Kumari
Numerade Educator
04:54

Problem 34

Indicate which reaction in each of the following pairs should have the greater (less negative, more positive) standard entropy of activation. Explain.
(a) Formation of product $A$ or formation of product $B$. (Hint: Remember that loss of internal rotations decreases freedom of motion and thus lowers entropy.)

Lara Gossage
Lara Gossage
Numerade Educator
03:21

Problem 35

The nucleophilic substitution reaction of sodium 2 -bromopropanoate with water and/or - $\mathrm{OH}$ can occur by both an $\mathrm{S}_{\mathrm{N}} 2$ (intermolecular) mechanism and a mechanism that involves neighboring-group participation.
(a) Give the curved-arrow notation for the $\mathrm{S}_{\mathrm{N}} 2$ mechanism with ${ }^{-} \mathrm{OH}$ as the nucleophile.
(b) Give the curved-arrow notation for an intramolecular mechanism. This mechanism should lead you to the structure of an unstable intermediate, which then reacts with - OH to give the product.
(c) The first-order rate constant $k_{1}$ for the intramolecular reaction is $1.2 \times 10^{-4} \mathrm{~s}^{-1}$. The second-order rate constant for the $\mathrm{S}_{\mathrm{N}}^{2}$ reaction is $6.4 \times 10^{-4} M^{-1} \mathrm{~s}^{-1} .$ Calculate the proximity effect for the intramolecular reaction.
(d) At what $\mathrm{NaOH}$ concentration does this reaction proceed by the two mechanisms at the same rate?
(e) What is the predominant mechanism in $1 M \mathrm{NaOH}$ ?
(f) Consider the structure of the intermediate you derived in part (b). The reason for the small proximity effect is that this intermediate is very unstable. Explain why this intermediate is more unstable than an ordinary epoxide. (Hint: Think about the preferred bond angles.)

Raghvendra Singh
Raghvendra Singh
Numerade Educator
View

Problem 36

Carry out an analysis similar to Study Problem 11.6 of the stereochemical result expected when the $(2 R, 3 R)$ -stereoisomer of the starting material is used.

Victor Salazar
Victor Salazar
Numerade Educator
03:15

Problem 37

The nucleophilic substitution reaction of sodium 2-bromopropanoate with water shown in Problem 11.35 occurs with retention of configuration at very low $\mathrm{NaOH}$ concentrations, but occurs with inversion of configuration at $1 \mathrm{M} \mathrm{NaOH}$. Relate this finding to your answers for Problem 11.35 .

Benjamin Angeles
Benjamin Angeles
Numerade Educator
05:18

Problem 38

In the nucleophilic substitution reaction of the following radioactively labeled compound with water, what labeling pattern should be observed in the product (a) if the neighboring-group participation does not occur and (b) if neighboring-group participation does occur?

Nicholas Sacco
Nicholas Sacco
Numerade Educator
04:56

Problem 39

Explain why the following two alcohols each react with $\mathrm{HCl}$ to give the same alkyl chloride.

Tom Rutherford
Tom Rutherford
Numerade Educator
03:25

Problem 40

Outline a synthesis for each of the following compounds from the indicated starting materials and any other reagents:
(a) $\left(\mathrm{CH}_{3}\right)_{2} \mathrm{CHCH}_{2} \mathrm{CH}_{2} \mathrm{CO}_{2} \mathrm{H}$ from $\left(\mathrm{CH}_{3}\right)_{2} \mathrm{C}=\mathrm{CH}_{2}$ (2-methylpropene)
(b) $\left(\mathrm{CH}_{3}\right)_{2} \mathrm{CHCO}_{2} \mathrm{H}$ from 2 -methylpropene
(c) dibutyl sulfone from 1-butanethiol
(d) (\pm)-trans-1-ethoxy-2-methylcyclopentane from cyclopentene

Lottie Adams
Lottie Adams
Numerade Educator
01:56

Problem 41

Give the product and its stereochemistry when each of the following alcohols is subjected to asymmetric epoxidation with tert-butyl hydroperoxide, $\mathrm{Ti}(\mathrm{O} i \mathrm{Pr})_{4},$ and the stereoisomer of diethyl tartrate (DET) indicated.
a.
b.
c.

Aadit Sharma
Aadit Sharma
Numerade Educator
09:39

Problem 42

Propose a synthesis for each of the following compounds in enantiomerically pure form. Use an asymmetric epoxidation ir each synthesis.
a.
b.

Nicholas Sacco
Nicholas Sacco
Numerade Educator
View

Problem 43

(a) Use the picture of the catalyst complex in Fig. 11.3a to explain why most $E$ allylic alcohols undergo asymmetric epoxidation more rapidly than their $Z$ isomers.
(b) Would the same phenomenon be observed with (-)-DET, the enantiomer of the DET used in Fig. 11.3? Explain.

Lainey Roebuck
Lainey Roebuck
Numerade Educator
02:29

Problem 45

Give the major organic product of each of the following reactions. Include stereochemistry where relevant.
(a) dibutyl sulfide with 1 equivalent of $\mathrm{H}_{2} \mathrm{O}_{2}$ at $25^{\circ} \mathrm{C}$
(b) dibutyl sulfide with 2 or more equivalents of $\mathrm{H}_{2} \mathrm{O}_{2}$ and heat
(c) cis-3-hexene with magnesium monoperoxyphthalate (MMPP)
(d) the product of
(c) with $\left(\mathrm{CH}_{3}\right)_{2} \mathrm{CuCNLi}_{2},$ then $\mathrm{H}_{3} \mathrm{O}^{+}$
(e) the product of
(c) with solvent $\mathrm{H}_{2} \mathrm{O}$ in acidic solution
(f) the product of
(e) with periodic acid
(g) the product of (d) with $\mathrm{NaH}$ in THF followed by $\mathrm{CH}_{3} \mathrm{I}$
(h) $(E)-3$ -methyl-3-hexene with $\mathrm{Hg}(\mathrm{OAc})_{2}$ in ethanol solvent followed by $\mathrm{NaBH}_{4}$
(i) the product of (h) with acidic methanol
(j) $(R)$ -3-Methyl-1-bromopentane with $\mathrm{Mg}$ in ether, then with ethylene oxide, then with $\mathrm{CH}_{3} \mathrm{I}$

Raghvendra Singh
Raghvendra Singh
Numerade Educator
View

Problem 45

Draw the structure of each of the following. (Some parts may have more than one correct answer.)
(a) a nine-carbon ether that cannot be prepared by the Williamson synthesis
(b) a nine-carbon ether that $c a n$ be prepared by the Williamson synthesis
(c) a four-carbon ether that would yield 1,4 -diiodobutane after heating with an excess of HI
(d) an ether that would react with HBr to give propyl bromide as the only alkyl halide
(e) a four-carbon alkene that would give different glycols after treatment with alkaline $\mathrm{KMnO}_{4}$ or treatment with meta-chloroperoxybenzoic acid followed by dilute aqueous acid
(f) a four-carbon alkene that would give the same glycol as a result of the different reaction conditions in (e)
(g) a diene (a compound with two double bonds) $\mathrm{C}_{6} \mathrm{H}_{8}$ that can form only one mono-epoxide and two di-epoxides (counting stereoisomers)
(h) an alkene $\mathrm{C}_{6} \mathrm{H}_{12}$ that would give the same glycol either from treatment with a peroxycarboxylic acid, followed by acid catalyzed hydrolysis, or from glycol formation with $\mathrm{OsO}_{4}$

Lainey Roebuck
Lainey Roebuck
Numerade Educator
03:00

Problem 46

Give the products of the reaction of 2 -ethyl2 -methyloxirane (or other compound indicated) with each of the following reagents.
(a) water, $\mathrm{H}_{3} \mathrm{O}^{+}$
(b) water, $\mathrm{NaOH}$, heat
(c) $\mathrm{Na}^{+} \mathrm{CH}_{3} \mathrm{O}^{-}$ in $\mathrm{CH}_{3} \mathrm{OH}$
(d) $\mathrm{CH}_{3} \mathrm{OH}$ and a catalytic amount of $\mathrm{H}_{2} \mathrm{SO}_{4}$
(e) dilithium dimethylcyanocuprate, then $\mathrm{H}_{3} \mathrm{O}^{+}$
(f) product of part (c) $+\mathrm{HBr}, 25^{\circ} \mathrm{C}$
(g) product of part (d) $+\mathrm{HBr}, 25^{\circ} \mathrm{C}$
(h) product of part (c) $+\mathrm{NaH}$, then $\mathrm{CH}_{3} \mathrm{I}$
(i) product of part (d) $+\mathrm{NaH},$ then $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{I}$
(j) product of part (a) $+$ periodic acid
(k) product of part (f) $+\mathrm{Mg}$ in dry ether
(1) product of part $(\mathrm{k})+$ ethylene oxide, then $\mathrm{H}_{3} \mathrm{O}^{+}$

Ian Kaigh
Ian Kaigh
Numerade Educator
00:55

Problem 47

Which of the ring-opening reactions given in Fig. P11.47 should occur most readily? Explain.

Grigoriy Sereda
Grigoriy Sereda
Numerade Educator
00:55

Problem 48

Which of the ring-opening reactions given in Fig. $\mathrm{P} 11.48$ should occur most readily? Explain.

Grigoriy Sereda
Grigoriy Sereda
Numerade Educator
01:25

Problem 49

Explain how you could differentiate between the compounds in each of the following pairs by using simple physical or chemical tests that give readily observable results, such as obvious solubility differences, color changes, evolution of gases, or formation of precipitates.
(a) 3 -ethoxypropene and 1 -ethoxypropane
(b) 1 -pentanol and 1 -methoxybutane
(c) 1-methoxy-2-methylpropane and 2 -chloro-1methoxy-2-methylpropane

Joanna Quigley
Joanna Quigley
Numerade Educator
01:38

Problem 50

When $\mathrm{HCl}$ is formed as a by-product in reactions, it is usually removed from reaction mixtures by neutralization with aqueous base. At times, however, the use of base is not compatible with the products or conditions of a reaction. It has been found that propylene oxide (2-methyloxirane) can be used to remove HCl quantitatively. Explain why this procedure works.

Shazia Naz
Shazia Naz
Numerade Educator
07:24

Problem 51

A student has run the reactions shown in Fig. $\mathrm{P} 11.51$ on p. 562 and is disappointed to find that each has given none of the desired product. Explain why each reaction failed.

Tom Rutherford
Tom Rutherford
Numerade Educator
02:33

Problem 52

Tell whether each of the following compounds can be prepared by the reaction of a Grignard reagent with ethylene oxide. If so, show the reaction; if not, explain why and give a different synthesis that uses a different epoxide starting material.
(a) 2 -pentanol
(b) 1-pentanol

Shazia Naz
Shazia Naz
Numerade Educator
09:13

Problem 53

For each of the following alkenes, state whether a reaction with $\mathrm{OsO}_{4}$ followed by aqueous $\mathrm{NaHSO}_{3}$ will give a racemic mixture of products that can (in principle) be resolved into enantiomers under ordinary conditions.
(a) ethylene
(b) $c i s-2$ -butene
(c) trans-2-butene
(d) $c i s-2$ -pentene

Tom Rutherford
Tom Rutherford
Numerade Educator
09:15

Problem 54

The (+)-stereoisomer of 2 -methyloxirane reacts with aqueous $\mathrm{NaOH}$ to give the $(R)-(-)$ -stereoisomer of 1,2 propanediol. Use this observation to propose the absolute stereochemical configuration of $(+)-2$ -methyloxirane.

Evelyn Clay
Evelyn Clay
Numerade Educator
01:49

Problem 55

Predict the absolute configuration of the major diol product formed by treatment of $(S)-2$ -ethyl-2-methyloxirane with water in the presence of an acid catalyst.

Kaitlynn Wade
Kaitlynn Wade
Numerade Educator
10:28

Problem 56

Keeping in mind that many intramolecular reactions that form six-membered rings are faster than competing intermolecular reactions (Sec. 11.8 ), predict the product of the reaction given in Fig. $\mathrm{P} 11.56 .$

Anupa Sharad Medhekar
Anupa Sharad Medhekar
Numerade Educator
01:15

Problem 57

When $(3 S, 4 S)-4$ -methoxy-3-methyl-1-pentene is treated with mercuric acetate in methanol solvent, then with $\mathrm{NaBH}_{4}$, two isomeric compounds with the formula $\mathrm{C}_{8} \mathrm{H}_{18} \mathrm{O}_{2}$ are isolated. One, compound $A$, is optically inactive, but the other, compound $B$, is optically active. Give the structures and absolute configurations of both compounds. (See Study Guide Link 7.2.)

Lottie Adams
Lottie Adams
Numerade Educator
02:33

Problem 58

You are a manager for a company, Weighty Matters, that specializes in the manufacture of organic compounds containing ${ }^{18} \mathrm{O}$, a heavy isotope of oxygen. You have assigned the task of preparing ether $B$ to a team of two staff experts, and you have stipulated that alcohol $A$ must be used as a starting material $\left({ }^{*} \mathrm{O}={ }^{18} \mathrm{O}\right)$ :
1.
2.
A member of your staff, Homer Flaskclamper, has proposed the following two possible syntheses and has come to you for advice.
Which synthesis would you advise Flaskelamper to use and why?

Shazia Naz
Shazia Naz
Numerade Educator
03:32

Problem 59

Match each of the following four compounds with one of the compounds $A-D$ on the basis of the following experimental facts. Compounds $A, B,$ and $C$ are optically active, but compound $D$ is not. Compound $C$ gives the same products as compound $D$ on treatment with periodic acid, but compound $B$ gives a different product. Compound $A$ does not react with periodic acid.
(1) $(2 S, 3 S)-2,4$ -dimethoxy-1,3-butanediol
(2) meso-1,4-dimethoxy-2,3-butanediol
(3) $(+)-1,4$ -dimethoxy-2,3-butanediol
(4) $(2 R, 3 R)-3,4$ -dimethoxy-1,2-butanediol

Vasu Makani
Vasu Makani
Numerade Educator
03:11

Problem 60

Complete the reactions given in Fig. P11.60 by giving the principal organic products. Indicate the stereochemistry of the products in parts (d), $(\mathrm{g}),(\mathrm{h}),(\mathrm{i}),$ and $(\mathrm{k})$.

Catherine Lemar
Catherine Lemar
Numerade Educator
01:30

Problem 61

Outline a synthesis for each of the following compounds from the indicated starting material and any other reagents. [All chiral compounds should be prepared as racemates except in parts (1) and (m).]
(a) 2 -ethoxy-3-methylbutane from 3 -methyl-1-butene
(b) 2 -ethoxy-2-methylbutane from 2 -methyl-2-butanol
(c) 4,4 -dimethyl-1-pentanol from ethylene oxide
(d)

Grigoriy Sereda
Grigoriy Sereda
Numerade Educator
00:54

Problem 62

Outline a synthesis for each of the following compounds in enantiomerically pure form from enantiomerically pure $(2 R, 3 R)-2,3$ -dimethyloxirane:

Aadit Sharma
Aadit Sharma
Numerade Educator
03:13

Problem 63

Compound $A, C_{8} H_{16},$ undergoes catalytic hydrogenation to give octane. When treated with meta-chloroperoxybenzoic acid, $A$ gives an epoxide $B,$ which, when treated with aqueous acid, gives a compound $C, \mathrm{C}_{8} \mathrm{H}_{18} \mathrm{O}_{2},$ which can be resolved into enantiomers. When $A$ is treated with $\mathrm{OsO}_{4}$ followed by aqueous $\mathrm{NaHSO}_{3}$, an achiral compound $D$ (a stereoisomer of $C$ ) forms. Identify all compounds, including stereochemistry where appropriate.

Niamat Khuda
Niamat Khuda
Numerade Educator
01:16

Problem 64

An alternative to the ozonolysis of alkenes is to treat an alkene with $t w o$ molar equivalents of periodic acid and a catalytic amount of $\mathrm{OsO}_{4}$
(a) Explain the role of each reagent in the reaction shown in Fig. P11.64. Your explanation should account for the fact that $t w o$ molar equivalents of periodic acid are required.
(b) Complete the following reaction.

Raghvendra Singh
Raghvendra Singh
Numerade Educator
04:35

Problem 65

Give the structures of all epoxides that could in principle be formed when each of the following alkenes reacts with meta-chloroperoxybenzoic acid (mCPBA). Which epoxide should predominate in each case? Why?
(a) cis-4,5-dimethylcyclohexene
(b) $\mathrm{CH}_{3}$

Vasu Makani
Vasu Makani
Numerade Educator
03:52

Problem 66

When $\mathrm{CH}_{3} \mathrm{CH}_{2} \ddot{\mathrm{S}} \mathrm{CH}_{2} \mathrm{CH}_{2} \ddot{\mathrm{S}} \mathrm{CH}_{2} \mathrm{CH}_{3}$ reacts with two equivalents of $\mathrm{CH}_{3} \mathrm{I},$ the following double sulfonium salt precipitates:
(a) Give a curved-arrow mechanism for the formation of this salt.
(b) Upon closer examination, this compound is found to be a mixture of two isomers with melting points of $123-124^{\circ} \mathrm{C}$ and $154^{\circ} \mathrm{C}$, respectively. Explain why two compounds of this structure are formed. What is the relationship between these isomers? (Hint: See Sec. $6.9 \mathrm{~B} .$ )

Grigoriy Sereda
Grigoriy Sereda
Numerade Educator
00:55

Problem 67

When $S$ -adenosylmethionine (Fig. 11.1, p. 537 ), isolated from natural sources, is allowed to stand in aqueous solution for several weeks at room temperature, a stereoisomeric contaminant appears in solution that can be separated by ordinary methods. Suggest a structure for this contaminant and a reason that it forms. (Hint: No covalent bonds are broken in this process.)

Anna Miller
Anna Miller
Numerade Educator
01:02

Problem 68

When the naturally occurring amino acid $(S)$ -methionine (see Eq. $11.78,$ p. 552 ) is converted into methionine sulfoxide, two isomers with different physical properties are formed. What are their structures and what is their stereochemical relationship?

Aadit Sharma
Aadit Sharma
Numerade Educator
01:43

Problem 69

One of the side reactions that occur when epoxides react with $^{-} \mathrm{OH}$ is the formation of polymers. Propose a mechanism for the following polymerization reaction, using the curved-arrow notation.

Grigoriy Sereda
Grigoriy Sereda
Numerade Educator
02:53

Problem 70

(a) Give a curved-arrow mechanism for the reaction shown in Fig. P11.70. Be sure your mechanism indicates the role of the weak acid ammonium chloride.
(b) Why does the reaction of an aziridine require this weak acid? (Hint: The $\mathrm{p} K_{\mathrm{a}}$ of an amine $\mathrm{RNH}_{2}$ is about 32.)
(c) The $\mathrm{p} K_{\mathrm{a}}$ of ammonium ion is $9.25 ;$ the conjugate-acid $\mathrm{p} K_{\mathrm{a}}$ of an aziridine is about 7 ; and the $\mathrm{p} K_{\mathrm{a}}$ of $\mathrm{HN}_{3}$ is 4.2. A student has suggested that dilute $(0.01 M)$ $\mathrm{HCl}$ should be an even better catalyst. Critique this suggestion.

ES
Eugene Schneider
University of Minnesota - Twin Cities
05:35

Problem 71

The drug mechlorethamine (mustine) has been used in antitumor therapy.
It is one of a family of compounds called nitrogen mustards, which also includes the antitumor drugs cyclophosphamide and chlorambucil.
(a) Mechlorethamine undergoes a nucleophilic substitution reaction with water that is several thousand times faster than the nucleophilic substitution reaction of 1,5 -dichloropentane. Give the product of the mechlorethamine reaction and the mechanism for its formation.
(b) The antitumor effects of mechlorethamine are due to the fact that it crosslinks DNA. (See the vignette on
p. $545,$ particularly Eqs. $11.70-11.71 .$ ) Show this crosslinking process with the curved-arrow notation, using $\mathrm{R}_{3} \mathrm{~N}$ : to represent a base on DNA.

Henry R
Henry R
Numerade Educator
01:17

Problem 72

In each of the following pairs, one of the glycols is virtually inert to periodate oxidation. Which glycol is inert? Explain why. (Hint: Consider the structure of the intermediate in the reaction.)
a.
b.
c.
d.

Alkendra Singh
Alkendra Singh
Numerade Educator
03:08

Problem 73

Account for the following observations with a mechanism. (Refer to Fig. P11.73.)
(1) In $80 \%$ aqueous ethanol, compound $A$ reacts to give compound $B$. Notice that trans- $B$ is the only stereoisomer of this compound that is formed.
(2) Optically active $A$ gives completely racemic $B$.
(3) The reaction of $A$ is about $10^{5}$ times faster than the analogous substitution reactions of both its stereoisomer $C$ and chlorocyclohexane.

Bobby Barnes
Bobby Barnes
University of North Texas
07:24

Problem 74

Provide a curved-arrow mechanism for each of the reactions in Fig. P11.74 on p. 566 that accounts for the stereochemical results. Show the structure of the unstable intermediate in each case and explain why it is unstable.

Kim Trang Nguyen
Kim Trang Nguyen
Numerade Educator
02:25

Problem 75

The reaction of $\delta$ -chlorobutyl phenyl sulfide in dioxane containing $20 \mathrm{M}$ water at $100{ }^{\circ} \mathrm{C}$ gives a cyclic compound $X$ that can be isolated. (See Fig. P11.75 on p. 566). This reaction is 21 times faster than the reaction of 1 -chlorohexane under the same conditions.
(a) Deduce the structure of $X$ and give the curved-arrow mechanism for its formation.
(b) Calculate the proximity effect for this reaction.
(c) Suggest a reason the proximity effect for this reaction is much smaller than the effect calculated for the similar reaction in Eq. $11.61 \mathrm{~b}$ (p. 539 ). (This proximity effect was calculated in Study Problem $11.5 .$ )

Aadit Sharma
Aadit Sharma
Numerade Educator
01:39

Problem 76

One of the reactions given in Fig. $\mathrm{P} 11.76$ is about 2000 times faster in pure water than it is in pure ethanol. Another is about 20,000 times faster in pure ethanol than it is in pure water. The rate of the third changes very little when the solvent composition is changed from ethanol to water. Which of the reactions is faster in ethanol, which is faster in water, and which has a rate that is solventinvariant? Explain. The solvent (ethanol, water, or a mixture of the two) in the following equations is indicated by ROH. (Hint: Notice the difference in dielectric constants for ethanol and water in Table 8.2 on p. $355 .$ )

Alexander Cheng
Alexander Cheng
Numerade Educator
00:36

Problem 77

Draw a curved-arrow mechanism for each of the conversions shown in Fig. P11.77 on p. 567 . Hint: The structure of the product in part (c) of Fig. P11.76 can also be redrawn as follows:

Aadit Sharma
Aadit Sharma
Numerade Educator
04:30

Problem 78

(a) As shown in Fig. P11.78(a) on p. 568 , 1,5 -cyclooctadiene undergoes an electrophilic addition with $\mathrm{SCl}_{2}$ to give compound $A$. (Notice the conformation of $A$, also shown.) Provide a curved-arrow mechanism for this transformation that accounts for the stereochemistry. (Hint: Start with a simple electrophilic addition of $\mathrm{SCl}_{2}$, to one double bond.)
(b) Suggest a mechanism that accounts for the reaction of $A$ shown in Fig. $\mathrm{P} 11.78(\mathrm{~b})$.

Benjamin Angeles
Benjamin Angeles
Numerade Educator
01:00

Problem 79

Each of three bottles, labeled respectively $A, B,$ and $C$ contains one of the compounds given in Fig. $\mathrm{P} 11.79$ on
p. 568. On treatment with $\mathrm{KOH}$ in methanol, compound A gives no epoxide, compound $B$ gives an epoxide $D$, and compound $C$ gives an epoxide $E$. Epoxides $D$ and $E$ are stereoisomers. Under identical conditions, $C$ gives $E$ much more slowly than $B$ gives $D$. Identify $A, B,$ and $C,$ and explain all observations.

Nikhil Choudhary
Nikhil Choudhary
Numerade Educator
01:49

Problem 80

Two of the compounds given in Fig. P11.80 on p. 568 form epoxides readily when treated with - OH, one forms an epoxide slowly, and one does not form an epoxide at all. Identify the compound(s) in each category and explain.

Lottie Adams
Lottie Adams
Numerade Educator
02:04

Problem 81

(a) Account for the stereochemical results in the reaction in Fig. $\mathrm{P} 11.81(\mathrm{a})$ on p. 568 with a mechanism. (Hint:
See Study Problem $11.6, \mathrm{p} .547 .)$
(b) What stereochemical result would you expect if the $2 S, 3 S$ -stereoisomer of 3 -bromo-2-butanol undergoes the same reaction?

Lottie Adams
Lottie Adams
Numerade Educator