Deck 9: Alkynes

Question 1

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

Answer 1

sp², sp

Question 2

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

Answer 2

5,6,6-trimethyl-1-heptyne

Question 3

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

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

Answer 3

sp-sp

Question 4

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 5

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 6

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 7

For 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 8

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

Question 9

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 10

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

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

Question 11

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 12

For 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

Question 13

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 14

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.

Question 15

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 16

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 17

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

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

Question 18

Describe the shape for acetylene.

Question 19

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 20

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 21

Provide the IUPAC name for HC≡CCH₂CH₂CH₃.

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

Question 22

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 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 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 25

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 26

Provide the IUPAC name for CH₃CHBrC≡C(CH₂)₃CH₃.

Question 27

Draw all of the constitutionally isomeric alkynes with molecular formula C₅H₈.

Question 28

Provide the IUPAC name for CH₃C≡CC(CH₃)₂CH(CH₂CH₃)₂.

Question 29

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 30

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 31

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 32

Provide the IUPAC name for CH₃CH(CH₃)C(CH₃)₂C≡CCH(CH₃)₂.

Question 33

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 34

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 35

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 36

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 37

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 38

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 39

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 40

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 41

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 42

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 43

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 44

Which of the circled hydrogen atoms is the least acidic?

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

Question 45

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 46

Provide the IUPAC name for the following compound.

Question 47

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 48

Provide the IUPAC name for the following compound.

Question 49

Provide the IUPAC name for the following compound:

Question 50

Provide the IUPAC name for the following compound.

Question 51

Provide the IUPAC name for the following compound.

Question 52

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 53

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 54

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

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

Question 55

Rank the following carbanions in order of increasing pKa.

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

Question 56

Which of the circled hydrogen atoms is the most acidic?

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

Question 57

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 58

Draw the line-bond structure for the compound with the IUPAC name 2,5,9-trimethyl-2-decen-7-yne.

Question 59

Sodium amide (NaNH₂, sodamide) reacts with terminal alkynes as a ____.

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

Question 60

Give the hybridization for the carbanion in the acetylide ion.

A) sp
B) sp²
C) sp³
D) s²p
E) s²p²

Question 61

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 62

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

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

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

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

Question 65

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

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

Question 66

A dihalide in which the halogens are attached on adjacent carbons is called a _______________ dihalide.

A) vicinal
B) geminal
C) vinylic
D) allylic
E) cis

Question 67

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 68

Identify the major product.

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

Question 69

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

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

Question 70

Identify the major product.

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

Question 71

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

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

Question 72

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

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

Question 73

Identify the product of the reaction of an alkyne with hydrogen and a metal catalyst.

A) cis alkene
B) trans alkene
C) diene
D) alkyne
E) alkane

Question 74

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

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

Question 75

Identify the product of the reaction of an alkyne with sodium and ammonia.

A) cis alkene
B) trans alkene
C) diene
D) alkyne
E) alkane

Question 76

A dihalide in which the halogens are attached on the same carbon is called a _______________ dihalide.

A) vicinal
B) geminal
C) vinylic
D) allylic
E) cis

Question 77

Identify the product of the reaction of an alkyne with hydrogen and Lindlar's catalyst.

A) cis alkene
B) trans alkene
C) diene
D) alkyne
E) alkane

Question 78

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

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

Question 79

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 80

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

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