Chapter 7 Flashcards
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
How many distinct terminal alkynes exist with a molecular formula of C5H8?
A) 1
B) 2
C) 3
D) 4
E) 5
Answer: B
How many distinct internal alkynes exist with a molecular formula of C6H10?
A) 1
B) 2
C) 3
D) 4
E) 5
Answer: C
What is the common name for the following alkyne?
A) neohexyne
B) trimethylpropyne
C) trimethylacetylene
D) tert-butylacetylene
E) isopropylacetylene
Answer: D
Write structures and give IUPAC names for all alkynes with molecular formula C5H8.
Give the IUPAC name for (CH3)2C(CH2CH3)CCCH(CH3)2.
Answer: 2,5,5-trimethyl-3-heptyne
Give the IUPAC name for HCCCH2CH2CH3.
Answer: 1-pentyne
Give the IUPAC name for BrCH2CH2CCCH2CH3.
Answer: 1-bromo-3-hexyne
Draw an acceptable structure for acetylene.
Answer: H–C C–H
Draw an acceptable structure for 3-sec-butyl-1-heptyne.
Draw an acceptable structure for 2-hexyne.
Provide the systematic name of the compound shown.
Answer: 5,6,6-trimethyl-1-heptyne
Give the systematic name for the alkyne Cl3CCH2CH2CCCH3.
Answer: 6,6,6-trichloro-2-hexyne
Provide the structure of all distinct terminal alkynes with a molecular formula of C6H10.
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
Name the following compound.
Answer: cis-4,5-dimethyl-4-hepten-2-yne
or (Z)-4,5-dimethyl-4-hepten-2-yne
Provide an acceptable name for the compound shown.
Answer: 7,7-dichloro-5,5-dimethyl-3-heptyne
or
7,7-dichloro-5,5-dimethylhept-3-yne
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
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
Give the systematic name of the compound shown below.
Answer: 1,7-dimethyl-1,3-cycloheptadiene
Give the systematic name of the compound shown below.
Answer: (S)-5-methyl-5-hexen-2-ol
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
Provide the structure of (2E,4E)-2-chloro-2,4-octadiene.
Provide the systematic name of the compound shown.
Answer: (E)-5-methyl-5-hepten-1-yne
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 structure of the major organic product of the following reaction.
Provide the major organic product in the reaction below.
Provide the major organic product in the reaction below.
Provide the major organic product in the reaction below.
Provide the major organic product in the reaction below.
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) K2Cr2O7, 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.
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.
Provide the structure of the major organic product of the following reaction.
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
- CH3CH2I
- H2, Lindlar catalyst
Provide the sequence of reagents that are needed to accomplish the multistep synthesis below.
Answer: 1. NaNH2
- CH3CH2I
- 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
- O3
- Me2S
Reaction Conditions:
B 9-BBN, THF
NaOH, H2O2, H2O
