Chapter 7 Flashcards by Nina Klewin

What is the IUPAC name for the following alkyne?

A) 5-Bromo-2-heptyne

B) 3-Bromo-5-heptyne

C) 2-Bromo-2-methyl-4-hexyne

D) 5-Bromo-5,5-dimethylhexyne

E) 5-Bromo-5-methyl-2-hexyne

Answer: E

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How many distinct terminal alkynes exist with a molecular formula of C5H8?

A) 1

B) 2

C) 3

D) 4

E) 5

Answer: B

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How many distinct internal alkynes exist with a molecular formula of C6H10?

A) 1

B) 2

C) 3

D) 4

E) 5

Answer: C

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What is the common name for the following alkyne?

A) neohexyne

B) trimethylpropyne

C) trimethylacetylene

D) tert-butylacetylene

E) isopropylacetylene

Answer: D

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Write structures and give IUPAC names for all alkynes with molecular formula C5H8.

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Give the IUPAC name for (CH₃)₂C(CH₂CH₃)CCCH(CH₃)₂.

Answer: 2,5,5-trimethyl-3-heptyne

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Give the IUPAC name for HCCCH₂CH₂CH₃.

Answer: 1-pentyne

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Give the IUPAC name for BrCH₂CH₂CCCH₂CH₃.

Answer: 1-bromo-3-hexyne

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Draw an acceptable structure for acetylene.

Answer: H–C C–H

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Draw an acceptable structure for 3-sec-butyl-1-heptyne.

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Draw an acceptable structure for 2-hexyne.

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Provide the systematic name of the compound shown.

Answer: 5,6,6-trimethyl-1-heptyne

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Give the systematic name for the alkyne Cl₃CCH₂CH₂CCCH₃.

Answer: 6,6,6-trichloro-2-hexyne

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Provide the structure of all distinct terminal alkynes with a molecular formula of C₆H₁₀.

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Name the following compound.

A) 3-heptyn-6-ol

B) 3-hepten-6-ol

C) 4-hepten-2-ol

D) 4-heptyn-2-ol

E) 4-heptan-2-ol

Answer: D

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Name the following compound.

Answer: cis-4,5-dimethyl-4-hepten-2-yne

or (Z)-4,5-dimethyl-4-hepten-2-yne

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Provide an acceptable name for the compound shown.

Answer: 7,7-dichloro-5,5-dimethyl-3-heptyne

7,7-dichloro-5,5-dimethylhept-3-yne

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Give the IUPAC name for the following compound.

A) isoprene
B) 3-methyl-1,3-butadiene

C) 2-methyl-1,3-butadiene

D) 2-methyl-2,3-butadiene

E) isobutadiene

Answer: C

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What is the IUPAC name for the following compound?

A) cis, trans-2, 4-heptadiene

B) 2Z,4Z-2, 4-heptadiene
C) cis, cis-2, 4-heptadiene
D) trans, trans-2, 4-heptadiene

E) 2E,4E-2, 4-heptadiene

Answer: A

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Give the systematic name of the compound shown below.

Answer: 1,7-dimethyl-1,3-cycloheptadiene

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Give the systematic name of the compound shown below.

Answer: (S)-5-methyl-5-hexen-2-ol

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Name the following compound.

Answer: (2E,4Z)-2,4-hexadiene

or trans, cis-2,4-hexadiene

or (2Z,4E)-2,4-hexadiene

or cis, trans-2,4-hexadiene

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Provide the structure of (2E,4E)-2-chloro-2,4-octadiene.

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Provide the systematic name of the compound shown.

Answer: (E)-5-methyl-5-hepten-1-yne

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Which of the following improperly describes the physical properties of an alkyne? A) relatively nonpolar B) nearly insoluble in water C) less dense than water D) insoluble in most organic solvents

Answer: D

What are the hybridizations 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: D

Which of the following statements is not true about propyne, HC C=-CH3? A) It contains six sigma bonds. B) It contains three pi bonds. C) The H—C—H bond angle is about 109.5°. D) The C—C—C bond angle is 180°. E) The pi bond is weaker than the sigma bond.

Answer: B

The carbon-carbon triple bond of an alkyne is composed of A) three σ bonds. B) two σ bonds and one π bond. C) one σ bond and two π bonds. D) three π bonds.

Answer: C

What are the hybridizations of the carbon atoms numbered 1 and 2 in the structure below? A) sp3, sp2 B) sp2, sp2 C) sp2, sp D) sp, sp

Answer: D

What two atomic orbitals or hybrid atomic orbitals overlap to form the carbon-carbon σ bond in ethyne? A) sp3—sp3 B) p—p C) sp2—sp2 D) s—s E) sp—sp

Answer: E

Which of the following statements correctly describes the general reactivity of alkynes? A) An alkyne is an electron-rich molecule and therefore reacts as a nucleophile. B) The σ bonds of alkynes are higher in energy than the π bonds and are thus more reactive. C) Unlike alkenes, alkynes fail to undergo electrophilic addition reactions. D) Alkynes are generally more reactive than alkenes. E) Alkynes react as electrophiles, whereas alkenes reacts as nucleophiles.

Answer: A

Although you might expect 1-propyne to be more reactive than 1-propene in electrophilic addition reactions, the reverse is true. Explain this using your knowledge of the mechanism of electrophilic additions to both alkynes and alkenes.

What is the major product of the following reaction?

Answer: B

Which of the following is the best synthesis of 2, 2-dibromopropane?

Answer: C

In the addition of hydrogen bromide to alkynes in the absence of peroxides, which of the following species is believed to be an intermediate? A) vinyl anion B) vinyl cation C) vinyl radical D) carbene E) bromonium ion

Answer: B

\_\_\_\_\_\_\_\_ is produced when 1 equivalent of HBr is added to 1-hexyne. A) 2-bromo-1-hexene B) *E*-1-bromo-1-hexene C) *Z*-1-bromo-1-hexene D) A mixture of *E* and *Z* isomers of 1-bromo-1-hexene E) *E*-2-bromo-2-hexene

Answer: A

Which of the following compounds is the major product when 1-hexyne is treated with excess HBr? A) 1,1-dibromohexane B) 1,1-dibromohexene C) 1,2-dibromohexene D) 1,2-dibromohexane E) 2,2-dibromohexane

Answer: E

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

Provide the structure of the major organic product of the following reaction.

Provide the major organic product in the reaction below.

Give the major organic product for the reaction.

Answer: D

Give the major organic product for the reaction.

Answer: E

Provide the structure of the major organic product that results when 2-butyne is treated with 1 equivalent of HCl.

Provide the structure of the major organic product that results when 2-butyne is treated with 2 equivalents of HCl.

Answer: CH3CH2CCl2CH3

Provide the structure of the major organic product that results when 2-butyne is treated with 1 equivalent of Br2.

Which of the following are enol forms of 2-butanone?

Answer: E

Which of the following is the final and major product of this reaction? A) I B) II C) III D) IV E) V

Answer: A

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

For the reaction below indicate whether the equilibrium constant will be greater than 1 or less than 1.

Answer: less than 1

Provide the structure of the intermediate which forms in the first step of the reaction of 1- butyne with water in the presence of H2SO4/HgSO4.

Provide the structure of the major organic product of the following reaction.

Provide the major organic product in the reaction below.

Give the major organic product for the reaction.

Answer: A

Give the best reagents for the reaction. A) H₂SO₄, HgSO₄, HgSO₄ B) 1. disiamylborane, 2. HO-, H₂O, H₂O₂ C) K₂Cr₂O₇, H+ D) NaOCl E) H₂, Pd

Answer: A

Which of the following is the final and major product of this reaction? A) I B) II C) III D) IV E) V

Answer: C

Which of the alkyne addition reactions below involves an enol intermediate? A) hydroboration/oxidation B) treatment with HgSO₄ in dilute H₂SO₄ C) hydrogenation D) both A and B E) both A and C

Answer: D

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

Complete the following reaction.

Answer: ethynylcyclobutane

Provide the structure of the major organic product of the following reaction.

Provide the major organic product in the reaction below.

Give the major organic product for the reaction.

Answer: B

Give the best reagents for the reaction. A) H₂SO₄, HgSO₄, HgSO₄ B) 1. disiamylborane, 2. HO-, H₂O, H₂O₂ C) K₂Cr₂O_7, H+ D) NaOCl E) H₂, Pd

Answer: B

Provide the structure of the major organic product that results when 2-butyne is treated with HgSO₄/H₂SO₄ in water.

The reagent needed to convert 2-butyne to *cis*-2-butene is A) H₂/Pt. B) H₂/Lindlar's catalyst. C) Li/NH₃. D) Na/NH₃. E) H+/Zinc dust.

Answer: B

The reagent needed to convert 2-butyne to *trans*-2-butene is A) H₂/Pt. B) H₂/Lindlar's catalyst. C) Li/NH₃. D) Na/NH₃. E) C or D.

Answer: E

A mixture of 1-heptyne, 2-heptyne, and 3-heptyne was hydrogenated in the presence of a platinum catalyst until hydrogen uptake ceased. If one assumes that the hydrogenation went to completion, how many distinct seven-carbon hydrocarbons were produced? A) 1 B) 2 C) 3 D) 6 E) 8

Answer: A

In the reduction of alkynes using sodium in liquid ammonia, which of the species below is not an intermediate in the commonly accepted mechanism? A) vinyl anion B) vinyl radical C) radical anion D) vinyl cation

Answer: D

Provide the major organic product in the reaction below.

An optically active compound (A), C6H10, reacts with H2/Ni to produce compound (B), C6H14. (B) is optically inactive. Deduce the structures of (A) and (B).

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

Complete the following reaction.

Answer: *trans*-3-hexene

Provide the structure of the major organic product of the following reaction.

Give the major organic product for the reaction.

Answer: A

Give the major organic product for the reaction.

Answer: C

Give the major organic product for the reaction.

Answer: B

Give the best reagents for the reaction. A) H₂, Pd + B) 1. LiAlH₄, 2. H₃O C) 1. NaBH₄, 2. H₃O+ D) H₂, Lindlar catalyst E) Na, NH₃

Answer: A

Give the best reagents for the reaction. A) H₂, Pd B) 1. LiAlH₄, 2. H₃O+ C) 1. NaBH₄, 2. H₃O+ D) H₂, Lindlar catalyst E) Na, NH₃

Answer: D

Give the best reagents for the reaction. A) H₂, Pd + B) 1. LiAlH₄, 2. H₃O C) 1. NaBH₄, 2. H₃O+ D) H₂, Lindlar catalyst E) Na, NH₃

Answer: E

Provide the structure of the major organic product that results when 2-butyne is treated with H₂ in the presence of Lindlar's catalyst.

Which is the correct order of decreasing acidity in the following compounds? A) A \> E \> C \> D \> B B) A \> E \> D \> B \> C C) E \> A \> C \> B \> D D) A \> C \> E \> D \> B E) E \> D \> B \> A \> C

Answer: A

What are the products of the following reaction?

Answer: C

Which of the species below is less basic than acetylide? A) CH₃Li B) CH₃ONa C) NaOH D) both B and C E) all of the above

Answer: D

Among the compounds water, 1-butyne, 2-butyne, and ethane, which are stronger acids than ammonia? A) 1-butyne and ethane B) water and 1-butyne C) water and ethane D) 1-butyne and 2-butyne

Answer: B

What type of organic product results when 1-butyne is treated with 6M aqueous NaOH? A) a sodium acetylide B) an enol C) an alcohol D) an aldehyde E) Not much reaction; most of the alkyne remains unchanged.

Answer: E

Answer: Because nitrogen is more electronegative than carbon.

Which hydrogens are more acidic, those of benzene or those of cyclohexane? Why?

Answer: Benzene. The carbon hybridization of benzene is sp2 while that of cyclohexane is sp3. The more s character in benzene causes its hydrogens to be more acidic than those of cyclohexane.

Why are terminal alkynes more acidic than other hydrocarbons?

Answer: The carbanion which results upon deprotonation of a terminal alkyne has the lone pair of electrons in an sp hybrid orbital. The greater % s character of this orbital gives the orbital a significantly lower energy.

For the reaction below indicate whether the equilibrium constant will be greater than 1 or less than 1.

Answer: greater than 1

Provide the structure of the major organic product of the following reaction.

For the reaction below indicate whether the equilibrium constant will be greater than 1 or less than 1

Answer: less than 1

What is/are the major organic product(s) of the following reaction?

Answer: B

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

Provide the structure of the major organic product of the following reaction.

Give the major organic product for the reaction.

Answer: E

Give the reagents for the following reaction.

Answer: 1. NaNH₂, 2. CH₃CH₂Br, 3. H₂, Pd

Provide the major organic product of the following reaction sequence.

Suggest a plausible scheme for the following synthesis

Describe a sequence of reactions by which 3-heptyne can be straightforwardly prepared from acetylene.

Answer: 1) NaNH₂ 2) CH₃CH₂Br 3) NaNH₂ 4) CH₃CH₂CH₂Br

Describe a sequence of reactions by which *meso*-2,3-dibromobutane can be prepared from propyne.

Answer: 1) NaNH₂ 2) CH₃Br 3) Na, NH₃ 4) Br₂, CCl₄

Describe a sequence of reactions by which butylbenzene can be prepared from phenylacetylene.

Answer: 1) NaNH₂ 2) CH₃CH₂Br 3) H₂, Pt

Describe a sequence of reactions by which CH₃CH₂CH₂COCH₂CH₃ can be prepared from 1-butyne.

Answer: 1) NaNH₂ 2) CH₃CH₂Br 3) HgSO₄, H₂O, H₂SO4

Describe a sequence of reactions by which *trans*-2-pentene can be prepared from propyne.

Answer: 1) NaNH₂ 2) CH₃CH₂Br 3) Na, NH₃

Describe a sequence of reactions by which the aldehyde CH₃CH₂CH₂CH₂CHO could be prepared from acetylene.

Answer: 1) NaNH₂ 2) CH₃CH₂CH₂Br 3) disiamylborane 4) H₂O₂, -OH

Describe a sequence of reactions by which *cis*-2-pentene could be prepared from acetylene.

Answer: 1) NaNH₂ 2) CH₃CH₂Br 3) NaNH₂ 4) CH₃Br 5) H₂, Lindlar's catalyst

Complete the following tree of reactions by giving the major products.

Give the reagents for the following reaction.

Answer: 1. H₂, Lindlar catalyst or Na, NH₃; 2. Br₂

Give the reagents for the following reaction.

Answer: 1. NaNH₂, 2. CH₃CH₂Br, 3. disiamylborane, 4. HO-, H₂O₂, H₂O

Give the reagents for the following reaction.

Answer: 1. NaNH₂, 2. CH₃CH₂Br, 3. NaNH₂, 4. CH₃CH₂Br, 5. 2 Br₂

Provide the sequence of reagents that are needed to accomplish the multistep synthesis below.

Answer: 1. NaNH₂ 2. CH₃CH₂I 3. H₂, Lindlar catalyst

Provide the sequence of reagents that are needed to accomplish the multistep synthesis below.

Answer: 1. NaNH₂ 2. CH₃CH₂I 3. Na, NH₃

Provide the major organic product of the following reaction sequence.

2-butyne has higher boiling point than 2-butene because A) 2-butyne has stronger hydrogen bonds B) 2-butyne has stronger dipole dipole interactions C) 2-butyne has stronger london dispersion forces D) 2-butyne has triple bond which is harder to break E) 2-butyne has fewer hydrogens

Answer: C

The pi-bonds in ethyne is formed by A) end-to-end sp-sp overlap B) side-to-side sp-sp overlap C) end-to-end s-sp overlap D) end-to-end p-p overlap E) side-to-side p-p overlap

Answer: E

In the following molecule, how many bonds are formed by sp-s overlap? A) 0 B) 1 C) 2 D) 3 E) 4

Answer: B

Keto-enol forms are A) resonance structures B) enantiomers C) disatereomers D) constitutional isomers E) conformational isomers

Answer: D

Why are mercuric ions needed during the hydration of alkynes? A) They catalyze the reaction by reacting with the alkyne and making it more nucleophilic. B) They catalyze the reaction by reacting with the alkyne and making it more electrophilic. C) They make alkynes more soluble in water. D) They increase the rate of addition reaction. E) B and D

Answer: E

Draw both enol forms of the following molecule.

In the hydroboration-oxidation reaction of a terminal alkyne, the product is a(n) A) alkyne B) aldehyde C) ketone D) enol E) alcohol

Answer: B

Dissolving metal reduction involves A) addition of H₂O to a triple bond in the presence of Na in liquid NH₃ B) addition of H₂ to a triple bond in the presence of Na in liquid NH₃ C) addition of H₂O to a triple bond in the presence of NaNH₂ in liquid NH₃ D) addition of H₂ to a triple bond in the presence of NaNH₂ in liquid NH₃ E) both B and D

Answer: B

Fill in the missing reagents 2 and 4 and the compound 3.

What is the structure of the missing product A and reagent B of this reaction?

What is the structure of the missing reagents A and B below?

Answer: 1 equivalent of Br₂

Fill in the missing reagents A and B on both sides of the substrate.

Answer: Reaction conditions: A 1. H₂, Lindlar's 2. O₃ 3. Me₂S Reaction Conditions: B 9-BBN, THF NaOH, H₂O₂, H₂O