Deck 11: Displacement Reactions on Saturated Carbons

Question 1

Which of the following is the stronger nucleophile and why?

A)Ethanol is stronger because oxygen is more electronegative than nitrogen.
B)Ethanamine is stronger because nitrogen is less electronegative than oxygen.
C)Ethanol is stronger because oxygen has a smaller atomic radius than nitrogen.
D)Ethanamine is stronger because nitrogen has a larger atomic radius than oxygen.

Answer 1

Ethanamine is stronger because nitrogen is less electronegative than oxygen.

Question 2

Which of the following best describes an S_N1 reaction?

A)It is unimolecular and occurs in a single step.
B)It is unimolecular and occurs in two steps.
C)It is bimolecular and occurs in a single step.
D)It is bimolecular and occurs in two steps.

Answer 2

It is unimolecular and occurs in two steps.

Question 3

Which of the following equations best describes the rate of an S_N2 reaction?

A)Rate = k[A]
B)Rate = k[A][B]
C)Rate = k[A]²
D)Rate = k

Answer 3

Rate = k[A][B]

Question 4

How do polar protic solvents improve the rate of S_N1 reactions?

A)They protonate the leaving group.
B)They stabilize the charge of the transition state.
C)They stabilize the charge of the nucleophile.
D)They stabilized the charge on the generated carbocation.

Question 5

Which of the following best describes an S_N2 reaction?

A)It is unimolecular and occurs in a single step.
B)It is unimolecular and occurs in two steps.
C)It is bimolecular and occurs in a single step.
D)It is bimolecular and occurs in two steps.

Question 6

Which of the following has the smallest effect on an S_N1 rate of reaction?

A)strength of the nucleophile
B)quality of leaving group
C)electrophile substituents
D)solvent

Question 7

Which of the following nucleophiles would have the greatest rate of reaction in an S_N2 reaction?

A)(^-NH₂)
B)(^-OH)
C)(^-F)
D)(H₂O)

Question 8

In an S_N2 reaction,what orbital of the electrophile is approached by the nucleophile?

A)ó
B)ó*
C)ð
D)ð*

Question 9

Which of the following electrophiles would have the greatest rate in an S_N2 reaction?

A)
B)
C)
D)

Question 10

Which of the following best describes the mechanism of an S_N2 reaction?

A)The nucleophile attacks and the leaving group leaves in a concerted fashion.
B)The nucleophile forms a bond with the electrophile first,followed by the loss of a leaving group.
C)The leaving group leaves first,followed by the attack of a nucleophile.
D)The electrophile attacks and the leaving group leaves in a concerted fashion.

Question 11

Which of the following best describes the mechanism of an S_N2 reaction?

A)The LUMO of a nucleophile interacts with the HOMO of an electrophile.
B)The LUMO of a nucleophile interacts with the LUMO of an electrophile.
C)The HOMO of a nucleophile interacts with the HOMO of an electrophile.
D)The HOMO of a nucleophile interacts with the LUMO of an electrophile.

Question 12

Which of the following conditions would most favour an S_N2 reaction with a secondary á-carbon?

A)strong nucleophile and protic solvent
B)weak nucleophile and protic solvent
C)strong nucleophile and aprotic solvent
D)weak nucleophile and aprotic solvent

Question 13

Given the conditions provided in the reaction scheme below,what would be the expected product?

A)
B)
C)
D)

Question 14

What is the predicted geometry of an S_N2 reaction transition state?

A)trigonal planar
B)tetrahedral
C)trigonal bipyramidal
D)trigonal pyramidal

Question 15

Which of the following would NOT form a stabilized carbocation in an S_N1 reaction mechanism?

A)
B)
C)
D)

Question 16

Which of the following statements best describes the nucleophilicity and leaving group capabilities of halogens?

A)I^- is both a worse nucleophile and leaving group compared to Cl^-.
B)I^- is a worse nucleophile and a better leaving group compared to Cl^-.
C)I^- is a better nucleophile and a worse leaving group compared to Cl^-.
D)I^- is both a better nucleophile and leaving group compared to Cl^-.

Question 17

Which of the following would act as the leaving group in the reaction shown below?

A)(^-OH)
B)(^-NH₂)
C)(^-CH₃)
D)(^-Cl)

Question 18

Which is the stronger nucleophile shown below and why?

A)Acetate is stronger because the charge is delocalized.
B)Ethanoate is stronger because the charge is not delocalized.
C)Ethanoate is stronger because it is less sterically hindered.
D)Both acetate and ethanoate are equally strong nucleophiles.

Question 19

In an S_N1 reaction,what sort of stereochemistry is observed in the product?

A)inversion of stereochemistry
B)retention of stereochemistry
C)a racemic mixture
D)Stereochemistry plays no role in S_N1 reactions.

Question 20

What is the predicted geometry of an S_N2 reaction intermediate?

A)trigonal planar
B)tetrahedral
C)trigonal bipyramidal
D)trigonal pyramidal

Question 21

Which of the following would be the most stable carbocation?

A)
B)
C)
D)

Question 22

Which of the following is considered a polar solvent?

A)dimethylsulfoxide
B)dimethylformamide
C)ethanol
D)acetonitrile

Question 23

Polar protic solvents increase the rate of S_N1 reactions.

Question 24

Which of the following would be the major product of the reaction shown below?

A)
B)
C)
D)

Question 25

How would you best describe the alkyl halide shown below?

A)primary
B)secondary
C)tertiary
D)quaternary

Question 26

Which of the following electrophiles would undergo the slowest rate of reaction?

A)
B)
C)
D)

Question 27

What is the product of the epoxide opening reaction under basic conditions shown below?

A)
B)
C)
D)

Question 28

Strength of a nucleophile has no effect in an S_N1 reaction.

Question 29

Which of the following is the strongest nucleophile?

A)
B)
C)
D)

Question 30

Which of the following mechanisms is preferred for the electrophile shown below?

A)S_N1
B)S_N2
C)Both S_N1 and S_N2
D)Neither S_N1 nor S_N2

Question 31

S_N2 reactions lead to an inversion of stereochemistry.

Question 32

Which of the following equations best describes the rate of an S_N2 reaction?

A)Rate = k[A]
B)Rate = k[A][B]
C)Rate = k[A]²
D)Rate = k

Question 33

Which of the following mechanisms is preferred for the electrophile shown below?

A)S_N1
B)S_N2
C)both S_N1 and S_N2
D)neither S_N1 nor S_N2

Question 34

Which of the following conditions would most favour an S_N1 reaction with a secondary á-carbon?

A)strong nucleophile and protic solvent
B)weak nucleophile and protic solvent
C)strong nucleophile and aprotic solvent
D)weak nucleophile and aprotic solvent

Question 35

Which of the following is the best electrophile?

A)
B)
C)
D)

Question 36

Which of the following mechanisms is preferred for the electrophile shown below?

A)S_N1
B)S_N2
C)both S_N1 and S_N2
D)neither S_N1 nor S_N2

Question 37

S_N2 reactions lead to a racemic mixture of products.

Question 38

Electrophiles act as electron donors.

Question 39

Which of the following electrophiles is most likely to go through an S_N1 reaction?

A)
B)
C)
D)

Question 40

Which of the following mechanisms is preferred for the electrophile shown below?

A)S_N1
B)S_N2
C)both S_N1 and S_N2
D)neither S_N1 nor S_N2

Question 41

Primary substrates react faster than secondary substrates through the S_N2 mechanism.

Question 42

Delocalization of electrons increases the nucleophilicity of a molecule.

Question 43

The more electronegative an atom is,the better a leaving group it is.

Question 44

Identity of the leaving group is important in S_N1 reactions but not S_N2.

Question 45

Amines are more nucleophilic than alcohols.

Question 46

A thiol is a stronger nucleophile than an alcohol.

Question 47

A benzylic halide is more electrophilic then an allylic halide.

Question 48

The higher the electronegativity of an atom,the more nucleophilic it is.

Question 49

The Gabriel synthesis involves the use of an azide to make an amine.

Question 50

Basic conditions promote nucleophillic attack on the more substituted position of an epoxide.

Question 51

Formation of a carbocation intermediate is the rate determining step in S_N1 reactions.

Question 52

In substitution reactions,the leaving group always takes a pair of electrons with it.

Question 53

Concerted reactions are those whereupon the steps of a reaction occur separately from each other.

Question 54

Increase in atomic size leads to decreased nucleophilicity.

Question 55

Cl^- is a better leaving group than I^-.

Question 56

Acetate is a stronger nucleophile than hydroxide.

Question 57

Weak nucleophiles will promote the S_N1 mechanism.

Question 58

An S_N1 reaction goes through a carbocation intermediate.

Question 59

Neighbouring inductive electron withdrawing groups can speed up an S_N2 reaction.

Question 60

Delocalization can stabilize a carbocation in S_N1 reactions.

Question 61

Another name for the electron donor in the substitution reaction is the _______________ .

Question 62

The Gabriel synthesis used _______________ as a source of nitrogen.

Question 63

DMSO is an example of a(n)_______________ solvent.

Question 64

Provide a mechanism for the transformation shown below.

Question 65

Provide a mechanism for the transformation shown below.

Question 66

Under the following reaction conditions,a mixture of three products were formed.Draw the three products.

Question 67

Propose a mechanism for the transformation shown below.

Question 68

S_N2 reactions lead to _______________ of stereochemistry.

Question 69

Nucleophilicity is _______________ in aprotic solvents.

Question 70

The transition state of an S_N2 reaction has a(n)_______________ geometry.

Question 71

Substitution reactions that go through the _______________ run the risk of carbocation rearrangements.

Question 72

Provide a mechanism for the following transformation.

Question 73

A tertiary á carbon structure will more likely undergo a(n)_______________ reaction mechanism.

Question 74

Neighbouring alkyl groups stabilize carbocations through _______________ .

Question 75

The intermediate of an S_N1 reaction has a(n)_______________ geometry.

Question 76

Draw two different sets of reactants that form the product in the following S_N1 reaction.One should contain an aromatic nucleophile and one should contain an aromatic electrophile.Which set is a better set of electrophiles and why?

Question 77

Predict the product of the following reaction under both S_N1 and S_N2 conditions.