Deck 9: An Overview of the Most Common Elementary Steps

Question 1

Which of the following can behave as an electrophile?

A)CH₃O^-
B)Cl^-
C)HBr
D)CH₃CH₂CH₂CH₃
E)None of the above

Answer 1

HBr

Question 2

Which of the following is true of S_N2 reactions?

A)They require two mechanism steps.
B)They involve two nucleophiles.
C)They do not require a leaving group.
D)They require one atom or group of atoms to be replaced by another atom or group of atoms.
E)They require two electron-poor species to react.

Answer 2

They require one atom or group of atoms to be replaced by another atom or group of atoms.

Question 3

Which of the following is not true about Lewis bases?

A)They donate electron density.
B)They often bear a negative charge.
C)They attack electron-poor sites.
D)They tend to be electron rich.
E)They tend to be electrophiles.

Answer 3

They tend to be electrophiles.

Question 4

Which of the following is a coordination step?

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

Question 5

Which of the following is an E2 step?

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

Question 6

Which of the following is not true about a nucleophile elimination step?

A)A leaving group leaves.
B)A multiple bond is formed.
C)Only one product is formed.
D)Electrons move from electron-rich to electron-poor parts of a molecule.
E)Two mechanism arrows are used.

Question 7

What type of mechanism step is shown below?

A)S_N2
B)Nucleophilic addition
C)E2
D)Electrophile elimination
E)Nucleophile elimination

Question 8

Which of the following is an S_N2 step?

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

Question 9

Which of the following is a coordination step?

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

Question 10

What is the most likely mechanism for the following reaction?

A)S_N2
B)E2
C)Electrophilic addition
D)1,2 methyl shift
E)Nucleophilic addition

Question 11

Which of the following is true about Lewis acids?

A)They accept electrons.
B)They often have a negative charge.
C)They tend to be electron rich.
D)They attract electron-poor sites.
E)They only attract protons.

Question 12

Which of the following is an acceptable mechanism step?

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

Question 13

Which of the following is considered heterolysis?

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

Question 14

Which of the following is not true about Grignard reagents?

A)They include a metal directly bonded to a carbon.
B)They tend to be electrophiles.
C)They are useful for forming new carbon-carbon bonds.
D)They consist of a highly polar bond.
E)They are organometallic compounds.

Question 15

The following mechanism step is ________.

A)Heterolysis
B)Coordination
C)Nucleophile elimination
D)E2
E)Electrophile elimination

Question 16

Which of the following is true of curved arrow notation showing reaction mechanisms?

A)Arrows begin at the electrophile.
B)Arrows point to nucleophiles.
C)Arrows show electrons flowing from nucleophiles to electrophiles.
D)Only one arrow is required.
E)Arrows never begin at the middle of a multiple bond.

Question 17

Which of the following is an acceptable mechanism step?

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

Question 18

What type of mechanism step is shown below?

A)S_N2
B)Nucleophilic addition
C)Electrophilic addition
D)Electrophile elimination
E)Nucleophile elimination

Question 19

Which of the following can behave as a nucleophile?

A)CH₃CH₂CH₃
B)N(CH₃)₄⁺
C)SiH₄
D)CH₃OH
E)None of the above

Question 20

Which of the following is true about spectator ions?

A)They can be disregarded when drawing mechanisms.
B)They are located in group 4A.
C)They are highly insoluble.
D)They are great targets for nucleophiles.
E)They are highly reactive species.

Question 21

The two following molecules can react via a coordination step.Draw the mechanism for this step and the resulting product.Also label the nucleophile and the electrophile.

Question 22

Which of the following is the carbocation most likely formed after a 1,2-hydride shift?

A)I
B)II
C)III
D)IV
E)None of these

Question 23

Which of the following mechanism steps is most energetically favorable?

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

Question 24

For the following reaction,label which reactant is the Lewis base,and supply the missing mechanism arrows.

Question 25

The two following species can react via an S_N2 mechanism.Fill in the mechanism arrows,and supply the expected products.

Question 26

The following compounds can react via an E2 step.Draw this mechanism,give the expected products,and label which of the starting materials is the nucleophile and which is the electrophile.

Question 27

Which of the following molecules can tautomerize?

A)I
B)II
C)III
D)IV
E)All of these

Question 28

For the following reaction,label which reactant is the Lewis acid,and supply the missing mechanism arrows.

Question 29

Which of the following is an example of electrophile elimination?

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

Question 30

The following molecule can undergo heterolysis.Draw the mechanism for this step,and give the most likely products.

Question 31

The two following molecules can react via a coordination step.Draw the mechanism for this step and the resulting product.Also label the nucleophile and the electrophile.

Question 32

In the following reaction,identify all electron-rich and electron-poor sites in the starting materials,and supply the missing mechanism arrows required to form the given product.

Question 33

In the following reaction,identify all electron-rich and electron-poor sites in the starting materials,and supply the missing mechanism arrows required to form the given product.

Question 34

Add mechanism arrows for the following reactions.Also supply missing electrons in the starting materials and products to complete the mechanism.

Question 35

Which of the following is an example of electrophilic addition?

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

Question 36

The two following species can react via an S_N2 mechanism.Fill in the mechanism arrows,and supply the expected products.

Question 37

Which of the following 1,2-hydride shift rearrangements is most likely?

A)I
B)II
C)III
D)IV
E)None of these

Question 38

Which of the following is a nucleophilic addition step?

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

Question 39

Explain what is wrong with the following mechanism step,and provide an alternative way in which the two species could react.

Question 40

Explain what is wrong with the following mechanism step,and provide an alternative way in which the two species could react.

Question 41

There are two possible nucleophile elimination products for the molecule below.Give these products,and draw the nucleophile elimination step that leads to each one.

Question 42

The following carbocation undergoes a 1,2-alkyl shift.Draw the mechanism,and give the products of this shift.

Question 43

The two following species can react via an electrophilic addition step.Draw the mechanism arrows for this step,give the expected product,and label the nucleophile and the electrophile.

Question 44

The following compounds can react via an E2 step.Draw this mechanism,give the expected products,and label which of the starting materials is the nucleophile and which is the electrophile.

Question 45

The following molecule can undergo heterolysis.Draw the mechanism for this step,and give the most likely products.

Question 46

Butyl lithium reacts with the following acetyl bromide via a nucleophilic addition step.Provide the omitted mechanism arrows,and draw the missing product in the box.

Question 47

Draw the keto tautomer for the following compound.

Question 48

For the following reaction scheme,name what type of elementary mechanism step is occurring in Step 1 and Step 2.Choose from the following: S_N2,coordination,heterolysis,E2,nucleophilic addition,nucleophile elimination,electrophilic addition,electrophile elimination,carbocation rearrangement,or none of the above.

Question 49

The two following species can react via an electrophile elimination step.Draw the mechanism arrows for this step,give the expected product,and label the nucleophile and the electrophile.

Question 50

For each of the five following mechanism steps,name the step being shown.Choose from the following: proton transfer,S_N2,coordination,heterolysis,E2,nucleophilic addition,nucleophile elimination,electrophilic addition,electrophile elimination,carbocation rearrangement,or none of the above.

Question 51

The following carbocation undergoes a 1,2-hydride shift.Draw the mechanism,and give the products of this shift.

Question 52

Draw the enol tautomer for the following compound.

Question 53

The two following species can react via an electrophile elimination step.Draw the mechanism arrows for this step,give the expected product,and label the nucleophile and the electrophile.

Question 54

Suppose that the two following molecules undergo an electrophilic addition step.Draw the mechanism and the product,and label the nucleophile and the electrophile.

Question 55

Explain why the products are favored in the following reaction.

Question 56

The following mechanism proceeds through nucleophile elimination.Fill in the omitted mechanism arrows,and draw the missing product in the box.

Question 57

Indicate which mechanism step is shown below,and draw the expected product(s).

Question 58

The two following molecules can react via a nucleophilic addition.Draw the mechanism arrows for this step,and give the products.