Deck 10: Alkynes

Question 1

Provide the IUPAC name for BrCH₂CH₂C≡CCH₂CH₃.

A) 1-bromo-3-hexyne
B) 6-bromo-3-hexyne
C) 1-bromo-2-hexyne
D) 6-bromo-4-hexyne
E) 1-bromo-4-hexyne

Answer 1

1-bromo-3-hexyne

Question 2

Which of the following statements is true about propyne, H-C≡C-CH₃?

A) It contains a total of three sigma bonds.
B) It contains a total of three pi bonds.
C) The H-C≡C bond angle is about 109.5°.
D) The C≡C-C bond angle is 180°.
E) All carbon-carbon bonds are of equal length.

Answer 2

The C≡C-C bond angle is 180°.

Question 3

For the molecule below, known as 2-pentyne, which of the following describes the orbital overlap of the C2-C3 sigma bond?

A) sp-sp
B) sp²-sp²
C) sp³-sp³
D) p-p
E) sp³-sp

Answer 3

sp-sp

Question 4

Which of the following is a structure for hepta-3,6-dien-1-yne?

A) I
B) II
C) III
D) IV
E) V

Question 5

Provide the IUPAC name for HC≡CCH₂CH₂CH₃.

A) pentyne
B) 1-pentyne
C) butyne
D) 1-butyne
E) 2-butyne

Question 6

Which of the following is the structure for 3-sec-butyl-1-heptyne?

A) I
B) II
C) III
D) IV
E) V

Question 7

What is the IUPAC name for the molecule shown below?

A) 4-ethyl-2-pentyne
B) 2-ethyl-3-pentyne
C) 3-methyl-4-hexyne
D) 4-methyl-2-hexyne
E) sec-Butylpropyne

Question 8

What is the IUPAC name for the molecule shown below?

A) 2-methyl-5-propyl-3-heptyne
B) 5-ethyl-2-methyl-3-octyne
C) 1-isopropyl-3-ethyl-1-hexyne
D) 6-methyl-3-propyl-4-heptyne
E) 4-ethyl-7-methyl-5-octyne

Question 9

For the molecule below, known as 2,4-hexadiyne, which of the following describes the orbital overlap of the C3-C4 sigma bond?

A) sp-sp
B) sp²-sp²
C) sp³-sp³
D) p-p
E) sp³-sp

Question 10

Which of the following statements best describes the general reactivity of alkynes?

A) An alkyne reacts as a nucleophile and is therefore electron rich.
B) An alkyne reacts as a nucleophile and is therefore electron poor.
C) Alkynes fail to undergo electrophilic addition reactions, unlike alkenes.
D) An alkyne reacts as an electrophile and is therefore electron rich.
E) An alkyne reacts as an electrophile and is therefore electron poor.

Question 11

Which of the following is the structure for 2-hexyne?

A) I
B) II
C) III
D) IV

Question 12

What is the IUPAC name for the molecule shown below?

A) 2,2,3-trimethyl-4-hexyne
B) 4-tert-butyl-2-pentyne
C) 4,5,5-trimethyl-2-hexyne
D) 4,5,5,5-tetramethyl-2-pentyne
E) 2,2-dimethyl-3-(1-propynyl)butane

Question 13

What is the IUPAC name for the molecule shown below?

A) 1,1-diethyl-2-pentyne
B) 3-(1-butynyl)pentane
C) 5-ethyl-3-octyne
D) 3-ethyl-4-heptyne
E) 5-ethyl-3-heptyne

Question 14

What is the IUPAC name for the molecule shown below?

A) 4,4-dimethyl-2-pentyne
B) 2,2-dimethyl-4-heptyne
C) 1-tert-butyl-3-heptyne
D) 6,6-dimethyl-3-heptyne
E) 6,6,6-trimethyl-3-hexyne

Question 15

What is the IUPAC name for the molecule shown below?

A) 5,6,6-trimethyl-1-heptyne
B) 5-tert-butyl-1-hexyne
C) 2,2,3-trimethyl-6-heptyne
D) 2,2,3-(3-butynyl)butane
E) sec-butyl-tert-butylacetylene

Question 16

What is the IUPAC name for the molecule shown below?

A) 1,1,1-trichloro-4-hexyne
B) 4,4,4-trichloro-1-butyne
C) 1,1,1-trichloro-2-butyne
D) 5,5,5-trichloro-2-pentyne
E) 6,6,6-trichloro-2-hexyne

Question 17

What is the IUPAC name for the molecule shown below?

A) 6-bromo-3-octyne
B) 6-bromo-6-methyl-3-heptyne
C) 2-bromo-2-methyl-4-heptyne
D) 6-bromo-6,6-dimethyl-3-hexyne
E) 2-bromo-4-octyne

Question 18

What is the hybridization of the carbon atoms numbered 1 and 2 respectively in the following structure?

A) sp³, sp²
B) sp², sp²
C) sp, sp
D) sp², sp
E) sp, sp²

Question 19

The C≡C bond of an alkyne is composed of which bond types?

A) three anti-bonds
B) three σ bonds
C) two σ bonds and one π bond
D) one σ bond and two π bonds
E) three π bonds

Question 20

The sigma bond of an alkyne is formed from the overlap of which orbitals?

A) sp³-sp³
B) p-p
C) sp²-sp²
D) s-s
E) sp-sp

Question 21

Provide the IUPAC name for Cl₃CCH₂CH₂CH₂C≡CH.

A) 6,6,6-trichloro-1-hexyne
B) 1,1,1-trichloro-5-hexyne
C) 5,5,5-trichloro-1-pentyne
D) 1-heptyne
E) trichlorobutylacetylene

Question 22

What is the IUPAC name for the molecule shown below?

A) (E)-5-methyl-5-hepten-1-yne
B) (Z)-5-methyl-5-hepten-1-yne
C) (E)-3-methyl-2-hepten-6-yne
D) (Z)-3-methyl-2-hepten-6-yne
E) (E)-2-butynyl-2-butene

Question 23

What is the IUPAC name for the molecule shown below?

A) (4R,5Z)-4-chlorohept-5-en-2-yne
B) (4S,5E)-4-chlorohept-5-en-2-yne
C) (2E,4S)-4-chlorohept-2-en-5-yne
D) (2E,4R)-4-chlorohept-2-en-5-yne

Question 24

What is the IUPAC name for diisobutylacetylene?

A) diisopropylbutyne
B) 2,7-dimethyl-4-octyne
C) 3,6-dimethyl-4-octyne
D) 2,5-diethyl-3-hexyne
E) 2,2,5,5-tetramethyl-3-hexyne

Question 25

Which of the circled hydrogen atoms is the most acidic?

A) I
B) II
C) III
D) IV
E) V

Question 26

Which of the following is the structure for (2E,4E)-octa-2,4-dien-6-yne?

A) I
B) II
C) III
D) IV
E) V

Question 27

Which of the following is the structure for 2,5,5?trimethylhept?3?yne?

A) CH₃CH₂CH(CH₃)C≡CCH₂CH(CH₃)₂
B) CH₃CH₂C(CH₃)₂C≡CCH(CH₃)₂
C) (CH₃CH₂)₂C(CH₃)C≡CCH₂CH₃
D) CH₃CH₂C(CH₃)₂C≡CC(CH₃)₃
E) CH₃CH₂CH₂CH(CH₃)C≡CC(CH₃)₃

Question 28

Which of the following is a structure for octa-3,6-dien-1-yne?

A) HC≡CCH=CHCH=CHCH₂CH₃
B) CH₃CH=CHCH₂C≡CC≡CH
C) CH₃CH=CHCH₂CH=CHC≡CH
D) CH₃C≡CCH=CHCH=CHCH₃
E) H₂C=CHC≡CCH₂CH=CHCH₃

Question 29

What is the IUPAC name for the molecule shown below?

A) 3-bromo-4-acetylenylheptane
B) 3-(1-bromopropyl)-1-hexyne
C) 3-bromo-4-propyl-5-hexyne
D) 4-bromo-3-propyl-1-hexyne
E) 4-ethynyl-5-bromo-heptane

Question 30

Provide the IUPAC name for (CH₃)₂CHC≡CCH₂C(CH₃)₃.

A) 1,1,5,5,5-pentamethyl-2-pentyne
B) 1,1,1,5,5-pentamethyl-3-pentyne
C) 2,2,6-trimethyl-4-heptyne
D) 2,6,6-trimethyl-3-heptyne
E) tert-butylisopropylacetylene

Question 31

Which of the following is the acceptable structure for (R)-5-bromohept-2-yne?

A) I
B) II
C) III
D) IV
E) V

Question 32

Rank the following carbanions in order of increasing base strength.

A) I < II < III
B) II < III < I
C) III < II < I
D) III < I < II
E) II < I < III

Question 33

Rank the following bases in order of decreasing basicity.

A) III > I > V > II > IV
B) III > V > IV > I> II
C) V > I > III > II > IV
D) III > IV > II > V > I
E) IV > II > I > III > V

Question 34

Which structure shown below represents (Z)-3,5-dichloro-3-hexen-1-yne?

A) I
B) II
C) III
D) IV
E) I and II are both correct

Question 35

What is the IUPAC name for the molecule shown below?

A) (E)-4-isopropyloct-3-en-5-yne
B) (Z)-4-isopropyloct-3-en-5-yne
C) (E)-5-isopropyloct-5-en-3-yne
D) (Z)-5-isopropyloct-5-en-3-yne
E) (E)-4-(2-methylethyl)oct-3-en-5-yne

Question 36

Provide the IUPAC name for Cl₃C(CH₂)₄C≡CH.

A) 4,4,4-trichloro-1-butyne
B) 1,1,1-trichloro-6-heptyne
C) 1,1,1-trichloro-5-heptyne
D) 6,6,6-trichloro-1-hexyne
E) 7,7,7-trichloro-1-heptyne

Question 37

Sodium amide (NaNH₂, sodamide) reacts with terminal alkynes in the role of the ____.

A) Brønsted acid.
B) Brønsted base.
C) reducing agent.
D) catalyst.
E) electrophile.

Question 38

What is the IUPAC name for di-sec-butylacetylene?

A) 2-ethyl-5-methyl-3-heptyne
B) 2,7-dimethyl-4-octyne
C) 3,6-dimethyl-4-octyne
D) 2,5-diethyl-3-hexyne
E) 2,2,5,5-tetramethyl-3-hexyne

Question 39

Provide the systematic IUPAC name for the molecule below: (CH₃)₃CCH₂C≡CCH₂CH(CH₃)CH₂CH₃

A) 2,7,7-trimethyl-5-nonyne
B) 2-ethyl-7,7-dimethyl-4-octyne
C) 2,2,7-trimethyl-4-nonyne
D) 7-ethyl-2,2-trimethyl-4-octyne
E) 6-undecyne

Question 40

Rank the following acids in order of decreasing acidity.

A) V > I > IV > II > III
B) III > IV > II > I > V
C) V > I > III > II > IV
D) I > IV > V > II > III
E) IV > I > V > II > III

Question 41

For the reaction shown, select the expected major organic product.

A) I
B) II
C) III
D) IV
E) V

Question 42

For the transformation shown below, select the expected major product.

A) I
B) II
C) III
D) IV
E) V

Question 43

Select the best reagent to convert 3-heptyne to trans-3-heptene?

A) Na/NH₃
B) 1 eq. NaNH₂, NH₃
C) xs NaNH₂, NH₃
D) H₂/Pt
E) H₂/Lindlar's catalyst

Question 44

Which of the bases below would quantitatively deprotonate a terminal alkyne?

A) BuLi
B) NH₃
C) NaOH
D) NaOCH₂CH₃
E) t-BuOK

Question 45

For the reaction sequence below, select the expected major product.

A) 3-methylhexane
B) 1-bromo-3-methylhexene
C) 2-bromo-3-methylhexene
D) 3-methyl-1-hexyne
E) 3-methyl-2-hexyne

Question 46

Of the species listed below, select those less basic than acetylide.

A) BuLi
B) NaNH₂
C) NaOCH₃
D) both A and C
E) both B and C

Question 47

For the reaction shown, select the expected major organic product.

A) I
B) II
C) III
D) IV
E) V

Question 48

Select the reagent(s) expected to accomplish the transformation shown below.

A) H₂, Pd
B) H₂, Lindlar's catalyst
C) Na, NH₃(l)
D) A or B
E) B or C

Question 49

Which of the circled hydrogen atoms is the least acidic?

A) I
B) II
C) III
D) IV
E) V

Question 50

When preparing terminal alkynes by an elimination reaction, sodium amide (NaNH₂) dissolved in liquid ammonia (NH₃) is used most frequently. Which of the following statements offers the best explanation for the above statement?

A) The above statement is false; terminal alkynes are not produced under the given conditions.
B) Sodium amide deprotonates the terminal alkyne, driving formation of the alkynide ion.
C) Only sodium amide is a strong enough base to deprotonate a carbon.
D) Terminal alkynes are more stable than the internal alkynes, and are always the favored product.
E) Steric hindrance favors preparation of the less substituted terminal alkyne.

Question 51

Select the best explanation for why methanol, CH₃OH, cannot be used as a solvent for the deprotonation of a terminal alkyne by sodium amide, NaNH₂.

A) Sodium amide is not a strong enough base to deprotonate the alkyne.
B) Sodium amide in methanol reduces alkynes to alkenes.
C) Methanol is a poor solvent for dissolving alkynes.
D) Methanol is more acidic than the alkyne and will be deprotonated instead.
E) Methanol is toxic, and should be avoided when possible.

Question 52

Which of the bases below would result in the most complete deprotonation of the alkyne, shown in the reaction below?

A) NaOCH₂CH₃ (sodium ethoxide)
B) t-BuONa (sodium tert-butoxide)
C) NaH (sodium hydride)
D) NaHCO₃ (sodium bicarbonate)
E) NaOH (sodium hydroxide)

Question 53

The major result of treating 1-butyne with 6M aqueous NaOH would be:

A) the production of the sodium alkynide.
B) the production of an alkene.
C) the production of an alkane.
D) the production of an enol.
E) nothing, as the alkyne would not react to an appreciable extent.

Question 54

Which of the reagents below would convert 2-pentyne to trans-2-pentene?

A) NaNH₂, NH₃
B) Na, NH₃
C) H₂, Lindlar's catalyst
D) H₂, Pd/C
E) H₂O, HgSO₄/H₂SO₄

Question 55

What are the products of the reaction shown below? CH₃OH + CH₃C≡C^-Na⁺ → ?

A) CH₃C≡CCH₃ + Na⁺OH^-
B) CH₃C≡CH + CH₃O^-Na⁺
C) CH₃C≡COCH₃ + Na⁺OH^-
D) CH₃OC≡CH + Na⁺CH₃^-
E) no reaction

Question 56

Complete reduction of 1 mole of (3E,5Z)-3-methylhepta-3,5-dien-1-yne will require how many moles of hydrogen (H₂)?

A) 1
B) 2
C) 3
D) 4
E) 5

Question 57

Select the reagent(s) expected to accomplish the transformation shown below.

A) H₂, Ni
B) H₂, Ni₂B
C) Na, NH₃(l)
D) A or B
E) B or C

Question 58

For the reaction shown, select the expected major organic product.

A) I
B) II
C) III
D) IV
E) V

Question 59

Which statement below best explains why the K_a of acetylene is greater than that of ethylene?

A) Acetylide anions are resonance stabilized.
B) The 4 $\pi$ electrons of the acetylide anion better stabilize a negative charge.
C) The electronegativity of sp carbons is greater than that of sp² carbons.
D) The electronegativity of sp carbons is less than that of sp² carbons.
E) Acetylene has only two hydrogen atoms while ethylene has four.

Question 60

Select the best reagent expected to convert 3-heptyne to cis-3-heptene.

A) NaNH₂, NH₃
B) Na, NH₃
C) H₂, Lindlar's catalyst
D) Both A and C
E) Both B and C

Question 61

For the reaction shown below, what is the IUPAC name of the expected product?

A) 2-methylhexane
B) (Z)-2-methyl-4-hexene
C) (E)-2-methyl-4-hexene
D) (Z)-5-methyl-2-hexene
E) (E)-5-methyl-2-hexene

Question 62

Which of the compounds shown below would be the most likely product expected from the reaction scheme shown?

A) I
B) II
C) III
D) IV
E) V

Question 63

For the reaction shown, select the expected major organic product.

A) I
B) II
C) III
D) IV
E) V

Question 64

Of the reaction conditions provided below, which would be expected to convert 1 mole of 4-methyl-1-pentyne into 2-methylpentane?

A) H₂, Lindlar's catalyst
B) Na, NH₃(l)
C) 2 moles of HCl
D) 2 moles H₂, Pt
E) 1 mole H₂, Pt

Question 65

For the reaction below, select the structure of the expected major organic product.

A) I
B) II
C) III
D) IV
E) V

Question 66

Complete hydrogenation of a mixture of 1-octyne, 2-octyne, and 3-octyne, in the presence of a palladium catalyst, would produce how many distinct eight-carbon hydrocarbon products?

A) 1
B) 2
C) 3
D) 6
E) 8

Question 67

Reaction of 3,4,5-trimethyl-4-hexen-1-yne with H₂ and Pd/C will produce which of the following compounds?

A) 2,3,4-trimethylhexane
B) 3,4,5-trimethylhexane
C) 2,3,4-trimethyl-1-hexene
D) 3,4,5-trimethyl-1-hexyne
E) 2,3,4-trimethyl-5-hexyne2

Question 68

For the reaction shown below, the resulting stereochemistry of the expected product is best described as:

A) only (S)
B) only (R)
C) racemic
D) meso
E) achiral

Question 69

Which reagents shown below would be expected to convert 2-pentyne to (Z)-2-pentene?

A) H₂, Pt
B) Na, NH₃
C) H₂, Lindlar's catalyst
D) excess HCl
E) HgSO₄, H₂O

Question 70

The expected major product from the treatment of 1-pentyne with 2 equivalents of HBr is:

A) 1-bromo-1-pentene
B) 2-bromo-1-pentene
C) 1,1-dibromopentane
D) 2,2-dibromopentane
E) 1,2-dibromopentane

Question 71

The expected major product from the treatment of 1-pentyne with 1 equivalent of HBr is:

A) 1-bromo-1-pentene
B) 2-bromo-1-pentene
C) 1,1-dibromopentane
D) 2,2-dibromopentane
E) 1,2-dibromopentane

Question 72

For the reaction shown below, the resulting stereochemistry of the expected product is best described as:

A) (R,E)
B) (S,E)
C) (R,Z)
D) (S,Z)
E) only (S)

Question 73

What is the expected major organic product from treatment of 4-methyl-2-pentyne with excess hydrogen in the presence of a platinum catalyst?

A) (E)-4-methyl-2-pentene
B) (Z)-4-methyl-2-pentene
C) 2-methylpentane
D) 4-methylpentane
E) Equal mixture of A and B

Question 74

What is the major expected product(s) of the reaction shown below?

A) 2,2-Dichloropentane
B) 3,3-Dichloropentane
C) 2,3-Dichloropentane
D) A and B
E) B and C

Question 75

What is the expected major organic product from treatment of 4-methyl-2-pentyne with sodium metal in liquid ammonia?

A) (E)-4-methyl-2-pentene
B) (Z)-4-methyl-2-pentene
C) (E)-2-methyl-2-pentene
D) (Z)-2-methyl-2-pentene
E) 2-methylpentane

Question 76

In a dissolving metal reduction of an alkyne, a postulated intermediate is the trans alkenyl radical, shown below. In which orbital type would the unpaired electron be located?

A) sp
B) sp²
C) sp³
D) p
E) s

Question 77

In the reaction between an alkyne and Na metal in liquid ammonia, the role of Na is:

A) Brønsted acid.
B) Brønsted base.
C) reducing agent.
D) catalyst.
E) electrophile.

Question 78

Select the reagent(s) expected to accomplish the transformation shown below.

A) H₂, Ni
B) H₂, Ni₂B
C) H₂, Lindlar's catalyst
D) A and B
E) B and C

Question 79

Reaction of (3E,5Z)-3-methylhepta-3,5-dien-1-yne with H₂ and Pd/C will produce which of the compounds below?

A) 1-sec-butylbutane
B) 2-butylbutane2
C) 3-methylheptane
D) 3-methyl-1-heptyne
E) (3E,5Z)-3-methyl-1,3,5-heptatriene

Question 80

What is the expected major organic product from treatment of 4-methyl-2-pentyne with hydrogen in the presence of Lindlar's catalyst?

A) (E)-4-methyl-2-pentene
B) (Z)-4-methyl-2-pentene
C) (E)-2-methyl-2-pentene
D) (Z)-2-methyl-2-pentene
E) 2-methylpentane