Deck 10: Alkynes

Question 1

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

A)It contains 3 sigma bonds.
B)It contains 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 1

The C≡C-C bond angle is 180°.

Question 2

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 2

sp²,sp

Question 3

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

Answer 3

sp-sp

Question 4

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

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

Question 5

What is the correct 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 6

What is the correct 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 7

Provide the systematic 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 8

What is the correct 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 9

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 10

What is the correct 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 11

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

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

Question 12

Which of 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 13

What is the correct IUPAC name for the molecule shown below?

A)5,6,6-Trimethyl-1-heptyne
B)5-tert-Tutyl-1-hexyne
C)2,2,3-Trimethyl-6-heptyne
D)2,2,3-(3-Butynyl)butane
E)sec-Butyl-tert-butylacetylene

Question 14

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

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

Question 15

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 16

Provide the systematic 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 17

What is the correct 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 18

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

Question 19

Provide the systematic IUPAC name for HC≡CCH₂CH₂CH₃.

A)Pentyne
B)1-Pentyne
C)Butyne
D)1-Butyne
E)2-Butyne

Question 20

What is the correct IUPAC name for the molecule shown below?

A)4,4-Dimethyl-2-pentyne
B)2,2-Dimethyl-4-heptyne
C)1-tertButyl-3-heptyne
D)6,6-Dimethyl-3-heptyne
E)6,6,6-Trimethyl-3-hexyne

Question 21

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 22

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 23

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

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

Question 24

What is the correct IUPAC name for the molecule shown below?

A)3-Bromo-4-acetylenyl-heptane
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 25

What is the correct 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 26

What is the correct 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 27

Rank the following carbanions,with the weakest base first,then by increasing base strength.

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

Question 28

Which of the circled hydrogen atoms is the most acidic?

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

Question 29

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

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

Question 30

What is the correct 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 31

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

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

Question 32

What is the correct IUPAC name for the molecule shown below?

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

Question 33

Provide the systematic IUPAC name for the molecule below: CH₃C(CH₃)₂CH₂C≡CCH₂CH(CH₂CH₃)CH₃

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 34

Which of the following is an acceptable 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 35

Provide the systematic 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 36

What is the correct systematic 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 37

Rank the following acids,with the strongest acid first,then by 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 38

Provide the systematic 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 39

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

A)(CH₃CH₂)CH(CH₃)C≡CCH₂CH(CH₃)₂
B)(CH₃CH₂)C(CH₃)₂C≡CCH(CH₃)₂
C)(CH₃CH₂)₂C(CH₃)C≡CCH₂CH₃
D)CH₃CH₂C(CH₃)₂C≡CC(CH₃)₃
E)(CH₃CH₂CH₂)CH(CH₃)C≡CC(CH₃)₃

Question 40

Rank the following bases,with the strongest base first,then by 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 41

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

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

Question 42

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 43

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 44

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 45

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 46

Which statement below best explains acetylene's K_a being greater than ethylene's?

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 being greater than sp² carbons.
D)The electronegativity of sp carbons being less than sp² carbons.
E)Acetylene has only two hydrogen atoms while ethylene has four.

Question 47

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 48

Which of the bases below would result in the greatest 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 49

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 50

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 51

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

A)the production of the sodium acetylide.
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.

Question 52

Which of the circled hydrogen atoms is the least acidic?

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

Question 53

Treatment of 2,2-dibromobutane with molten KOH at 200°C would be expected to produce which of the following:

A)(E)-2-bromo-2-butene
B)(Z)-2-bromo-2-butyne
C)1,2-butadiene
D)1-butyne
E)2-butyne

Question 54

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

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

Question 55

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

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

Question 56

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

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

Question 57

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

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

Question 58

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 59

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 60

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

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

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

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 63

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

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

Question 64

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-Bethyl-1,3,5-heptatriene

Question 65

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 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

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 68

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 69

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 70

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 71

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 72

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 73

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 74

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

Question 75

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)Xs HCl
E)HgSO₄,H₂O

Question 76

The expected major product from treatment of 1-pentyne with excess HBr in the presence of peroxides is:

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

Question 77

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 78

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

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

Question 79

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 80

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 and B
E)B and C