Deck 9: Addition Reactions of Alkenes

Question 1

For an addition reaction,why does the free energy term, $\Delta$ G,become more positive with increasing temperature?

A)The positive entropy term dominates at high temperature.
B)The negative entropy term dominates at high temperature.
C)The positive enthalpy term dominates at high temperature.
D)The negative enthalpy term dominates at high temperature.
E)The enthalpy and entropy terms cancel at high temperature.

Answer 1

The positive entropy term dominates at high temperature.

Question 2

What synthetic goal is achieved by subjecting an alkene to an oxymercuration-demercuration reaction sequence?

A)Markovnikov addition of H₂O,promoting skeletal rearrangement
B)Markovnikov addition of H₂O,preventing skeletal rearrangement
C)anti-Markovnikov addition of H₂O,promoting skeletal rearrangement
D)anti-Markovnikov addition of H₂O,preventing skeletal rearrangement
E)anti-Markovnikov addition of H₂O,syn-hydroxylation

Answer 2

Markovnikov addition of H₂O,preventing skeletal rearrangement

Question 3

The regioselectivity and stereospecificity in hydrohalogenation of an alkene is best described as:

A)Markovnikov orientation with syn-addition
B)Markovnikov orientation with anti-addition
C)anti-Markovnikov orientation with syn-addition
D)anti-Markovnikov orientation with anti-addition
E)Markonikov orientation with both syn- and anti-addition

Answer 3

Markonikov orientation with both syn- and anti-addition

Question 4

In the addition reaction of HI to 2-methyl-2-butene,the Markovnikov addition mechanism involves:

A)attack of 2-methyl-2-butene initiated by an iodide ion.
B)attack of 2-methyl-2-butene initiated by an iodine atom.
C)isomerization of 2-iodo-2-methylbutene.
D)formation of a carbocation at carbon two (C-2).
E)formation of carbocation at carbon three (C-3).

Question 5

Which of the reagents below are expected to convert cyclopentene into cyclopentane?

A)H₂ and Ni
B)H₂O
C)Heat
D)Zn,H₃O⁺
E)Light

Question 6

Addition reactions of alkenes are characterized by:

A)formation of a π bond
B)addition of two groups across a double bond
C)breaking of a π bond
D)A and B
E)B and C

Question 7

The expected Markovnikov addition product of HI to 2-methyl-2-butene is:

A)2-iodopentane
B)2-iodo-2-methylbutane
C)1-iodo-2-methylbutane
D)2-iodo-1-methylbutane
E)3-iodo-2-methylbutane

Question 8

The regioselectivity and stereospecificity in the hydroboration-oxidation of an alkene is best described as:

A)Markovnikov orientation with syn-addition
B)Markovnikov orientation with anti-addition
C)Anti-Markovnikov orientation with syn-addition
D)Anti-Markovnikov orientation with anti-addition
E)Markovnikov orientation with both syn- and anti-addition

Question 9

What product is formed when 5-chloro-1-methylcyclohexene is reduced with a Pt catalyst and H₂?

A)1-chloro-5-methylcyclohexane
B)1-chloro-3-methylcyclohexane
C)5-chloro-1-methylcyclohexane
D)3-chloro-1-methylcyclohexane
E)None of the above

Question 10

The decrease in entropy (the $\Delta$ S value is negative)observed for alkene addition reactions results from:

A)the breaking of a π and $\sigma$ bond.
B)the formation of two $\sigma$ bonds.
C)the reaction being exothermic.
D)two molecules reacting to form a single molecule.
E)the temperature dependence of the $\Delta$ S term.

Question 11

The regioselectivity and stereospecificity in the acid-catalyzed hydration of an alkene is best described as:

A)Markovnikov orientation with syn-addition
B)Markovnikov orientation with anti-addition
C)anti-Markovnikov orientation with syn-addition
D)anti-Markovnikov orientation with anti-addition
E)Markonikov orientation with both syn- and anti-addition

Question 12

In a reaction where addition and elimination reactions are in competition,which of the following statements is most correct?

A)Addition and elimination reactions are favored at low temperatures.
B)Addition and elimination reactions are favored at high temperatures.
C)Only addition reactions are favored at low temperatures.
D)Only elimination reactions are favored at low temperatures.
E)Addition and elimination reactions are disfavored at low temperatures.

Question 13

What product is formed when trans-1,2-dimethylcyclohexane is reacted with Pd/C and H₂?

A)No reaction
B)cis-1,2-dimethylcyclohexane
C)trans-3,4-dimethylhexane
D)trans-1,2-dimethylhexane
E)None of the above

Question 14

What is the expected major product for the hydrogenation of an alkene?

A)dihaloalkane
B)alkane
C)haloalkane
D)alcohol
E)ether

Question 15

Which statement is true about the temperature dependence of an addition reaction?

A)Addition reactions are thermodynamically favorable at all temperatures.
B)Addition reactions are thermodynamically disfavored at all temperatures.
C)Addition reactions are thermodynamically favorable at low temperatures.
D)Addition reactions are thermodynamically favorable at high temperatures.
E)Addition reactions are thermodynamically impossible.

Question 16

Addition reactions are favorable at low temperatures because:

A)the positive enthalpy term is larger than the negative entropy term.
B)the negative enthalpy term is larger than the positive entropy term.
C)the positive enthalpy term is smaller than the negative entropy term.
D)the negative enthalpy term is smaller than the positive entropy term.
E)the enthalpy and entropy terms are equal.

Question 17

When an alkene is subjected to treatment with Hg(OAc)₂ in alcohol,followed by reaction with NaBH₄,what functional group is formed?

A)ether
B)epoxide
C)alkane
D)syn diol
E)alkyne

Question 18

What is the IUPAC name of the expected major product formed upon reaction of HCl with 3-methyl-1-butene?

A)1-Chloro-2-methylbutane
B)1-Chloro-3-methylbutane
C)2-Chloro-2-methylbutane
D)2-Chloro-3-methylbutane
E)1-Chloropentane

Question 19

The regioselectivity and stereospecificity in the oxymercuration-demercuration of an alkene is best described as:

A)Markovnikov orientation with syn-addition
B)Markovnikov orientation with anti-addition
C)anti-Markovnikov orientation with syn-addition
D)anti-Markovnikov orientation with anti-addition
E)Markonikov orientation with both syn- and anti-addition

Question 20

In an addition reaction to an alkene,the π bond plays the role of:

A)nucleophile
B)electrophile
C)leaving group
D)A and B
E)B and C

Question 21

Treating 2-methyl-2-pentene with Br₂ is expected to produce which of the following as the major product?

A)2,3-dibromo-2-methylpentane
B)2,2-dibromo-2-methylpentane
C)3,3-dibromo-2-methylpentane
D)2-bromo-2-methylpentane
E)3-dibromo-2-methylpentane

Question 22

The expected product(s)resulting from addition of Br₂ to (E)-3-hexene would be:

A)a meso dibromide.
B)a mixture of optically active enantiomeric dibromides.
C)a mixture of optically inactive enantiomeric dibromides.
D)(Z)-3,4-dibromo-3-hexene.
E)(E)-3,4-dibromo-3-hexene.

Question 23

Which of the following will yield 2-methylpentane upon catalytic hydrogenation?

A)2-methyl-1-pentene2
B)2-methyl-2-pentene
C)4-methyl-2-pentene
D)4-methyl-1-pentene
E)All of the above

Question 24

The Markovnikov product,resulting from an addition reaction to an unsymmetrical alkene,is formed because:

A)the product is statistically favored.
B)steric hindrance favors its formation.
C)the reaction proceeds via the more/most stable carbocation.
D)the reaction forms the more/most stable product.
E)All of the above are valid reasons

Question 25

To accomplish a Markovnikov addition of water to an unsymmetrical alkene,with minimal skeletal rearrangement,the best reagents would be:

A)water and dilute acid
B)water and concentrated acid
C)1)Hg(OAc)₂,H₂O 2.NaBH₄,NaOH
D)1)BH₃•THF 2.H₂O₂,NaOH
E)1)OsO₄,pyridine 2.NaHSO₃,H₂O

Question 26

In conducting a catalytic hydrogenation of an alkene,which catalyst listed is most likely soluble in the reaction medium?

A)Ni
B)Pt
C)Pd
D)Wilkinson
E)All of the above are soluble

Question 27

Any proper mechanism of hydroboration-oxidation must explain the observed _________ addition of the H and OH to the alkene as well as the _____________ regiochemistry.

Question 28

For the catalytic hydrogenation of alkenes,select from below those most likely to function as a homogenous catalyst?

A)Wilkinson
B)Ni
C)Pd
D)Pt
E)Au

Question 29

A reaction that could potentially yield two or more constitutional isomers,but as in hydroboration-oxidation produces only one isomer,is said to be _____________________.

Question 30

What is the expected major product upon reaction of 1-pentene with Cl₂?

A)1-chloropentane
B)2-chloropentane
C)1,1-dichloropentane
D)2,2-dichloropentane
E)1,2-dichloropentane

Question 31

How many moles of hydrogen (H₂)are required to completely reduce 1 mole of cis-2,3,3-trimethylhepta-1,5-diene?

A)02
B)1
C)2
D)3
E)4

Question 32

The rule that correctly predicts the regiochemistry of most ionic additions to alkenes is called ____________________.

Question 33

$\pi$ bonds are quite susceptible to reaction with electron-seeking reagents,also referred to as ____________________.

Question 34

How many moles of hydrogen (H₂)are consumed in the catalytic reduction of 1 mole of 1,3-dibromocyclohexa-1,4-diene?

A)12
B)2
C)3
D)4
E)None of the above

Question 35

The expected intermediate formed during a halohydrin reaction is:

A)a halonium ion.
B)the most stable carbocation with OH on the adjacent carbon.
C)the most stable carbocation with X on the adjacent carbon.
D)a cyclic oxonium ion.
E)the most stable carbanion.

Question 36

Which of the following alkene addition reactions occur(s)specifically in syn fashion?

A)dihydroxylation using OsO₄,H₂O₂
B)addition of H₂
C)hydroboration
D)addition of HCl
E)A,B,and C

Question 37

Wilkinson's catalyst accomplishes which of the listed molecular transformations?

A)syn addition of H₂ to an alkene
B)anti addition of H₂ to an alkene
C)syn dihydroxylation of an alkene
D)anti dihydroxylation of an alkene
E)oxidative cleavage of an alkene

Question 38

Which of the following alkene addition reactions occur(s)specifically in an anti fashion?

A)hydroboration-oxidation
B)addition of Br₂
C)addition of H₂
D)addition of H₂O in dilute acid
E)both A and B

Question 39

Which of the catalysts listed are used in the homogenous catalytic hydrogenation of alkenes? I)Ni II)Pt III)Wilkinson

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

Question 40

For the complete reduction of 1 mole of (3E,5E)-hepta-1,3,5-triene with H₂ using a Pd catalyst,how many moles of H₂ are consumed?

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