Deck 14: Ethers, Epoxides, and Thioethers

Question 1

Give two properties of ethers which allow them to be commonly used as solvents in organic reactions.

Answer 1

(any two of the following)
1. Dissolve a wide variety of both polar and nonpolar compounds.
2. Tend to be unreactive under a large number of reaction conditions.
3. Have low boiling points; easily removed from product mixture.

Question 2

Provide the IUPAC name of the compound shown below.

Answer 2

1,1-diethoxycyclohexane

Question 3

Which of the following corresponds to the COC bond angle in dimethyl ether?

A) 60°
B) 94°
C) 110°
D) 122°
E) 180°

Answer 3

110°

Question 4

Provide the structure of 3-methoxyfuran.

Question 5

Provide a structural representation of 1,2-epoxybutane (also called 2-ethyloxirane).

Question 6

Provide a structural representation of isopropyl tert-butyl ether.

Question 7

What is the hybridization of the oxygen atom in dialkyl ethers?

A) sp³
B) sp²
C) sp
D) s
E) p

Question 8

What is the correct IUPAC name for the following compound?

A) 3-methyl-3,4-epoxypentan-1-ol
B) 5-hydroxy-3-methyl-2,3-epoxypentane
C) 1-(2-hydroxyethyl)-1,2-dimethyloxirane
D) 3,4-epoxy-3-methylpentan-1-ol

Question 9

Provide the structure of 4,4-dimethylpyran.

Question 10

What is the complete systematic IUPAC name for the following compound?

A) 4-(1-methylethoxy)-4-isopropyl-4-methylpent-2-ene
B) 4-isopropyl-2,4-dimethylhept-5-en-3-ol
C) isopropyl-(4-isopropyl-4-methylbut-2-enyl) ether
D) (E)-4-isopropoxy-4,5-dimethylhex-2-ene
E) 4-isopropyl-4-methylbut-2-en-isopropyl ether

Question 11

Which of the following is not a property of ethers which makes them good solvents in organic reactions?

A) They dissolve a wide range of polar substances.
B) They have relatively high boiling points for their molecular weights.
C) They are nonhydroxylic.
D) They dissolve a wide range of nonpolar substances.
E) They are normally unreactive toward strong bases.

Question 12

Anisole is known by two other names. Give either of them.

Question 13

Provide a structural representation of cis-3-ethyl-1,2-epoxycyclopentane.

Question 14

What complex results when BF₃ is dissolved in dimethyl ether?

Question 15

Which has the higher boiling point, diethyl ether or butan-1-ol? Briefly explain.

Question 16

Draw structures which show the hydrogen bonding interaction that exists between water and dimethyl ether.

Question 17

Provide a structural representation of 3-ethylfuran.

Question 18

Provide a structural representation of 2-ethoxypentane.

Question 19

Provide a structural representation of oxetane.

Question 20

Which of the following is not a true statement?

A) Dioxanes are six-membered ring ethers.
B) Furans are five-membered ring ethers.
C) Oxiranes are three-membered ring ethers.
D) Oxetanes are five-membered ring ethers.
E) Pyrans are six-membered-ring ethers.

Question 21

Provide the major organic product in the reaction below.
CH₃CH₂CH₂OH $\rightarrow$

Question 22

Provide the major organic product of the following.

Question 23

Which of the following is an acceptable way to synthesize t-butyl ethyl ether?

A) treatment of t-butyl bromide with sodium ethoxide
B) treatment of ethyl bromide with sodium t-butoxide
C) heating a mixture of ethanol and t-butanol in sulfuric acid
D) treating t-butyl bromide with Hg(OAc)₂
E) treating t-butanolwith Hg(OAc)₂

Question 24

Propose a structure for the ether of formula C₄H₁₀O with the following ¹H NMR signals:
δ 1.13 (doublet, 6H), 3.30 (singlet, 3H), 3.65 (septet, 1H) (ppm).

Question 25

Propose a structure for the ether of formula C₄H₁₀O with the following ¹H NMR signals:
δ 0.95 (triplet, 3H), 1.52 (multiplet, 2H), 3.30 (singlet, 3H), 3.40 (triplet, 2H) (ppm).

Question 26

Provide the major organic product of the following.

Question 27

Provide an acceptable name for the compound shown below.

Question 28

Provide an acceptable name for the compound shown below.
CH₃OCH₂CH(CH₃)₂

Question 29

Provide the major organic product of the following.

Question 30

Provide the structure of the fragment in the mass spectrum of dipropyl ether that results from a cleavage.

Question 31

The Williamson ether synthesis occurs by the ________ mechanistic pathway.

Question 32

In mass spectrometry, what is the most common fragmentation of ethers?

Question 33

Provide an acceptable name for the compound shown below.

Question 34

Provide the major organic product in the reaction below.

Question 35

What is the chemical shift of the carbon bound to oxygen in ethers in ¹³C NMR?

Question 36

Propose a structure for the ether of formula C₄H₁₀O with the following ¹H NMR signals:
δ 1.20 (triplet, 6H), δ 3.45 (quartet, 4H) (ppm).

Question 37

Which pair of reagents would produce the highest yield of (R)-2-ethoxybutane?

A) sodium (S)-2-butoxide + iodoethane
B) sodium (R)-2-butoxide + iodoethane
C) sodium ethoxide + (S)-2-iodobutane
D) sodium ethoxide + (R)-2-iodobutane
E) Both B and C would work equally well.

Question 38

Show the best method for preparing methoxycyclopentane via the Williamson ether synthesis.

Question 39

Provide the major organic product of the following.

Question 40

Provide an acceptable name for the compound shown below.

Question 41

Provide the major organic product of the reaction shown below.

Question 42

Provide the major organic product of the following.

Question 43

Provide the major organic product of the following.

Question 44

Provide the sequence of reactions by which propoxycyclohexane can be prepared through a Williamson ether synthesis.

Question 45

Show the reagents necessary to prepare 1-ethoxy-1-methylcyclopentane from 1-methylcyclopentene.

Question 46

Show the reagents necessary for the conversion of 1-bromo-1-methylcyclopentane to
1-ethoxy-1-methylcyclopentane.

Question 47

Show the best Williamson ether synthesis for the following target molecule.

Question 48

Provide the major organic product of the following reactions.

Question 49

Complete the following reaction by drawing a structure for the expected product.

Question 50

Provide the major organic product of the following reactions.

Question 51

Provide the major organic product of the reaction shown below.

Question 52

Provide the necessary reagents to complete the following reaction.

Question 53

Which of the following reactions is classified as a Williamson ether synthesis?

A)

B)

C)

D)

E)

Question 54

Which of the following reactions or series of reactions will lead to the formation of methoxycyclohexane?

A)

B)

C)

D)

E)

Question 55

Provide the major organic product in the reaction below.
CH₃CH₂CH=CH<sub>2

→</sub>

Question 56

When cyclohexene is subjected to mercuration in methanol and the resulting mixture is reduced with sodium borohydride, the major organic product is:

A) a meso ether.
B) a 1:1 mixture of enantiomeric ethers.
C) a meso diol.
D) a 1:1 mixture of enantiomeric diols.
E) methoxycyclohexane.

Question 57

Show the best method for preparing 4-propoxytoluene via the Williamson ether synthesis.

Question 58

Provide the major organic product of the following reactions.

Question 59

Show how propyl cyclopentyl ether can be prepared starting with cyclopentene and using an alkoxymercuration-demercuration route.

Question 60

When pent-1-ene is treated with mercury(II) acetate in methanol and the resulting product is reacted with NaBH₄, what is the primary organic compound which results?

A) 3-ethoxypentane
B) 1-methoxypentane
C) 1-ethoxypentane
D) 2-ethoxypentane
E) 2-methoxypentane

Question 61

When hexan-1-ol is treated with conc. H₂SO₄ at moderate temperatures, ________ is formed via a(n) ________ mechanism.

A) di-n-hexyl ether, S_N2
B) di-n-hexyl ether, S_N1
C) di-n-hexyl ether, E2
D) di-n-propyl ether, E1
E) hex-1-ene, S_N1

Question 62

Can one prepare di-sec-butyl ether in good yield by heating butan-2-ol in the presence of sulfuric acid? Explain.

Question 63

Treatment of tetrahydrofuran with excess HBr results in the formation of what major organic product?

A) 1-bromobutane
B) 1,2-dibromobutane
C) 1,4-dibromobutane
D) 1-bromopentane
E) 1,5-dibromopentane

Question 64

Which of the following compounds would undergo autoxidation most readily?

A) dibenzyl ether
B) MTBE
C) diethyl ether
D) isobutyl phenyl ether

Question 65

Di-n-pentyl ether can be converted to 1-bromopentane by treatment with HBr through essentially a(n) ________ mechanism.

A) S_N2
B) S_N1
C) E2
D) E1
E) ring opening

Question 66

Provide the major organic product of the reaction shown below.

Question 67

What are the expected products of the reaction of PhOCH₃ with concentrated HI?

A) phenol and methanol
B) phenol and iodomethane
C) iodobenzene and methanol
D) iodobenzene and iodomethane

Question 68

Provide the major organic product in the reaction below.

Question 69

When ethers are stored in the presence of oxygen, what explosive materials can result from autoxidation of the ether?

Question 70

Provide the major organic product of the following reactions.

Question 71

Provide the major organic product of the reaction shown below.

Question 72

Provide two reasons why it would be difficult to prepare ethoxycyclopentane via an intermolecular dehydration route from ethanol and cyclopentanol.

Question 73

Provide the major organic product(s) in the reaction below.

Question 74

Predict the products of the following reaction and give a reasonable mechanism for their formation.

Question 75

What is the major organic product which results when tetrahydrofuran is reacted with excess HBr?

A) 1,2-dibromobutane
B) 1,3-dibromobutane
C) 1,4-dibromobutane
D) 4-bromobutan-1-ol
E) 3-bromobutan-1-ol

Question 76

Some ethers can be prepared by heating the appropriate alcohol in the presence of sulfuric acid. Can di-sec-butyl ether be prepared from sec-butanol by this route? Explain your answer.

Question 77

Provide the major organic product of the following.

Question 78

Suggest a reasonable mechanism for the reaction shown below.

Question 79

Provide the major organic product in the reaction below.

Question 80

The presence of what product of the autooxidation of ethers makes the distillation of ethers dangerous?