Deck 11: Organic Chemistryreactions

Question 1

Recognize nucleophiles and electrophiles. Show electron movement in a reaction using curved arrows.

Answer 1

All chemical reactions happen as a result of the movement of electrons. Substitution as well as elimination and addition reactions involve the attraction of an electrophile to a nucleophile.

Question 2

Predict the products from SN2 and SN1 reactions. Write and explain the mechanisms of SN2 and SN1 reactions.

Answer 2

SN2 reactions occur in a single step. SN1 reactions occur via the formation of a carbocation, followed by its reaction with a nucleophile. Rates of substitution reactions are sensitive to the type of substrate, nucleophile, and leaving group.

Question 3

Predict the products from E2 and E1 reactions. Write and explain the mechanisms of E2 and E1 reactions.

Answer 3

Elimination reactions convert a single bond into a double bond. E2 reactions occur in a single step. E1 reactions occur via the formation of a carbocation, followed by its reaction with a nucleophile.

Question 4

Predict the products of addition reactions. Write the mechanisms of electrophilic addition of hydrogen halides, water, or halogens to alkenes.

Question 5

Which of the following does not contain a nucleophile?

A) propanol
B) propane
C) n-propylamide
D) propene
E) propoxide ion

Question 6

Which of the following is an electrophile?

A) H₂O
B) CH₃O^-
C) NH₃
D) NH₄⁺
E) All are nucleophiles.

Question 7

Ambident nucleophiles are ones which can react with a substrate at either of two nucleophilic sites. Which of the following is NOT an ambident nucleophile?

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

Question 8

Identify the nucleophile in the following reaction:
2 H₂O + RX $\rarr$ ROH + H₃O⁺ + X^-

A) X^-
B) H₃O⁺
C) ROH
D) H₂O
E) RX

Question 9

Which of the following is a nucleophile?

A) hexane
B) cyclohexane
C) 1-chlorohexane
D) cyclohexene
E) none of the above

Question 10

Consider the S_N2 reaction of butyl bromide with OH^- ion.
CH₃CH₂CH₂CH₂Br + OH- $\rarr$ CH₃CH₂CH₂CH₂OH + Br^-

A) no effect
B) double the rate
C) triple the rate
D) rate would increase by four times
E) rate would increase by six times

Question 11

Consider the S_N2 reaction of 2-iodopentane with CH₃CO₂^- ion. Assuming no other changes, what effect on the rate would result from simultaneously doubling the concentrations of both 2-iodopentane and CH₃CO₂^- ion?

A) no effect
B) double the rate
C) triple the rate
D) rate would increase by four times
E) rate would increase by six times

Question 12

Select the rate law for the following reaction, e.g.,
CH₃CH₂CH₂CHBrCH₃ + OH^- $\rarr$ CH₃CH₂CH₂CHOHCH₃ + X^-(RBr)

A) Rate = k [RBr]
B) Rate = k [RBr] [OH^-]
C) Rate = k [RBr]² [OH^-]
D) Rate = k [RBr] [OH^-]²
E) Rate = k [RBr]² [OH^-]²

Question 13

The rate equation for a nucleophilic substitution reaction of a tertiary alkyl bromide (R-Br) with I^- ion would be

A) Rate = k [RBr]
B) Rate = k [I^-]
C) Rate = k [RBr][I^-]
D) k [RBr]²[I^-]
E) Rate = k [RBr][I^-]²

Question 14

The rate equation for a nucleophilic substitution reaction of a secondary alkyl chloride (R-Cl) with I^- ion would be

A) Rate = k [RCl]
B) Rate = k [I^-]
C) Rate = k [RCl][I^-]
D) Rate = k [RCl]²[I^-]
E) Rate = k [RCl][I^-]²

Question 15

Consider the reaction of 2-chloro-2-methylpentane with sodium iodide: Assuming no other changes, how would it affect the rate if one simultaneously doubled the concentration of 2-chloro-2-methylpentane and sodium iodide?

A) no effect
B) double the rate
C) triple the rate
D) rate would increase by four times
E) rate would increase by six times

Question 16

What product(s) would you expect to obtain from the following S_N2 reaction?

A) I
B) II
C) equimolar mixture of I and II
D) III
E) mixture of II and III

Question 17

The major product of the following reaction would be

A) I
B) II
C) III
D) IV
E) equimolar mixture of I and II

Question 18

The major product(s) of the following reaction is (are)

A) I
B) II
C) III
D) IV
E) equimolar mixture of I and II

Question 19

What would be the major product of the following reaction?

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

Question 20

What would be the major product of the following reaction?

A) I
B) II
C) III
D) IV
E) equimolar amounts of I and III

Question 21

Which of the following statements is (are) true of S_N1 reactions of alkyl halides in general?

A) The rate of an SN1 reaction depends on the concentration of the alkyl halide.
B) The rate of an SN1 reaction depends on the concentration of the nucleophile.
C) SN1 reactions of alkyl halides are favoured by polar solvents.
D) Answers a) and c) only are true.
E) Answers a, b, and c are true.

Question 22

S_N2 reactions of the type, Nu^- + RL $\rarr$ Nu-R + L^-, are favoured

A) when tertiary substrates are used.
B) by using a high concentration of the nucleophile.
C) by using a solvent of high polarity.
D) by the use of weak nucleophiles.
E) answers b and c

Question 23

Which would be the major product of the following reaction?

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

Question 24

What would be the major product(s) of the following reaction?

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

Question 25

Which product (or products) would be formed in appreciable amount(s) when trans-1-bromo-2-methylcyclohexane undergoes dehydrohalogenation upon treatment with sodium ethoxide in ethanol?

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

Question 26

What is the major product of this reaction?

A) (CH₃)₂C=C(CH₃)₂
B) (CH₃)₃C-CH=CH₂
C) (CH₃)₂C=CHCH₃
D) (CH₃)₂C=CHCH₂CH₃
E) (CH₃)₂C=C(CH₃)₂ and (CH₃)₃C-CH=CH₂

Question 27

Which compound would be the major product?

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

Question 28

A correct IUPAC name for the following compound is

A) 3,3,5-trimethyl-2-hexene.
B) 3-isobutyl-3-isopropyl-2-propene.
C) 3-isobutyl-4-methyl-2-pentene.
D) 3-(1-methylethyl)-5-methyl-2-hexene.
E) 3-ethene-2,5-methylhexane.

Question 29

Which compound listed below would you expect to be the major product when 2-bromo-2-methylbutane is refluxed with KOH/ethanol?
I
II
III
IV
V

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

Question 30

Elimination reactions

A) require an attacking group that is a Lewis acid.
B) require and attacking group that is a Lewis base.
C) always involve the formation of a carbocation.
D) do not involve the formation of a carboncation.
E) occur via a single step.

Question 31

E2 reactions

A) require a Lewis acid as a reactant.
B) occur via the formation of a carbocation.
C) occur in a single step.
D) occur via a two step process.
E) eliminate only the leaving group from the molecule.

Question 32

E1 reactions

A) require a Lewis acid as a reactant.
B) occur via the formation of a carbocation.
C) occur in a single step.
D) rate is determined by the removal of a proton from the carbocation.
E) eliminate only the leaving group from the molecule.

Question 33

What would be the major product of the following reaction?

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

Question 34

Treating 1-methylcyclohexene with HCl would yield primarily which of these?

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

Question 35

Acid-catalyzed hydration of 2-methyl-1-butene would yield which of the following?

A) (CH₃)₂C(OH)CH₂CH₃
B) CH₂OHCH(CH₃)CH₂CH₃
C) (CH₃)₂CHCHOHCH₃
D) (CH₃)₂CHCH₂CH₂OH
E) CH₃CH₂CH(CH₃)CH₂OH

Question 36

Which of these is NOT formed when cyclopentene reacts with an aqueous solution of bromine?

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

Question 37

Addition of hydrogen chloride to the following molecule would produce

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

Question 38

Reaction of trans-2-hexene with a solution of Br₂ in CCl₄ produces

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

Question 39

Reagents that seek to react with a proton or some other electron-deficient centre are called ______.

Question 40

$\pi$ bonds often react with electron-seeking reagents, also referred to as ______.