Organic Chemistry—reactions 506 Test Bank Olmsted Ch.11

CHAPTER 11

ORGANIC CHEMISTRY – REACTIONS

CHAPTER STUDY OBJECTIVES

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

SKILLS TO MASTER: Recognizing substitution, elimination, and addition reactions; recognizing electrophilic and nucleophilic centres; drawing curved arrows

KEY CONCEPTS: 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.

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

SKILLS TO MASTER: Recognizing the nucleophile, substrate, product, and leaving group in a nucleophilic substitution reaction; stating the factors that make a good nucleophile and a good leaving group; drawing the flow of electrons in substitution reactions using curved arrows; predicting the stereochemistry of the product of a substitution reaction involving a chiral substrate; predicting the effects of different substrates on the rates of substitution reactions; predicting whether the SN1 or SN2 reaction will occur for a given reaction.

KEY CONCEPTS: 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.

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

SKILLS TO MASTER: Predicting the major and minor products of elimination reactions; predicting whether the E1 or E2 mechanism will occur for a given reaction

KEY CONCEPTS: 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.

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

SKILLS TO MASTER: Applying Markovnikov’s rule

KEY CONCEPTS: Addition reactions convert a double bond to a single bond and add an atom or group of atoms to each of the carbons. Markovnikov’s rule: In the addition of HX to an alkene, the hydrogen atom adds to the carbon atom of the double bond that already has the greater number of hydrogen atoms.

Multiple Choice QUESTIONS

1. Which of the following does not contain a nucleophile?

a) propanol

b) propane

c) n-propylamide

d) propene

e) propoxide ion

Difficulty: Easy

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

Section Reference: 11.1 An Introduction to Organic Reactions

2. Which of the following is NOT a nucleophile?

a) H₂O

b) CH₃O^-

c) NH₃

d) NH₄⁺

e) All are nucleophiles.

Difficulty: Easy

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

Section Reference: 11.1 An Introduction to Organic Reactions

3. Which of the following is an electrophile?

a) H₂O

b) CH₃O^-

c) NH₃

d) NH₄⁺

e) All are nucleophiles.

Difficulty: Easy

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

Section Reference: 11.1 An Introduction to Organic Reactions

4. The hybridization state of the charged carbon in a carbocation is

a) sp⁴

b) sp³

c) sp²

d) sp

e) s

Difficulty: Easy

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

Section Reference: 11.1 An Introduction to Organic Reactions

Feedback: Draw structure.

5. 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

Difficulty: Easy

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

Section Reference: 11.1 An Introduction to Organic Reactions

6. Identify the nucleophile in the following reaction:

2 H₂O + RX 🡪 ROH + H₃O⁺ + X^–

a) X^-

b) H₃O⁺

c) ROH

d) H₂O

e) RX

Difficulty: Medium

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

Section Reference: 11.1 An Introduction to Organic Reactions

7. Which is the strongest nucleophile?

a) OH^-

b) CH₃CH₂O^-

c) CH₃COO^-

d) CH₃CH₂OH

e) H₂O

Difficulty: Medium

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

Section Reference: 11.1 An Introduction to Organic Reactions

Feedback: Recognize that CH₃CH₂ is electron donating.

8. Which of the following is a nucleophile?

a) hexane

b) cyclohexane

c) 1-chlorohexane

d) cyclohexene

e) none of the above

Difficulty: Easy

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

Section Reference: 11.1 An Introduction to Organic Reactions

9. Consider the S_N2 reaction of butyl bromide with OH^- ion.

CH₃CH₂CH₂CH₂Br + OH-  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

Difficulty: Medium

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

Section Reference: 11.2 Substitution Reactions

10. 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

Difficulty: Medium

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

Section Reference: 11.2 Substitution Reactions

11. Select the rate law for the following reaction, e.g.,

CH₃CH₂CH₂CHBrCH₃ + OH^–  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

Difficulty: Easy

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

Section Reference: 11.2 Substitution Reactions

12. 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

Difficulty: Easy

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

Section Reference: 11.2 Substitution Reactions

13. 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

Difficulty: Easy

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

Section Reference: 11.2 Substitution Reactions

14. 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

Difficulty: Medium

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

Section Reference: 11.2 Substitution Reactions

15. 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

Difficulty: Hard

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

Section Reference: 11.2 Substitution Reactions

16. The major product of the following reaction would be

a) I

b) II

c) III

d) IV

e) equimolar mixture of I and II

Difficulty: Hard

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

Section Reference: 11.2 Substitution Reactions

17. 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

Difficulty: Hard

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

Section Reference: 11.2 Substitution Reactions

18. What would be the major product of the following reaction?

a) I

b) II

c) III

d) IV

e) V

Difficulty: Hard

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

Section Reference: 11.2 Substitution Reactions

19. 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

Difficulty: Hard

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

Section Reference: 11.2 Substitution Reactions

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

a) The rate of an S_N1 reaction depends on the concentration of the alkyl halide.

b) The rate of an S_N1 reaction depends on the concentration of the nucleophile.

c) S_N1 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.

Difficulty: Easy

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

Section Reference: 11.2 Substitution Reactions

21. S_N2 reactions of the type, Nu^- + RL  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)

Difficulty: Easy

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

Section Reference: 11.2 Substitution Reactions

22. Which would be the major product of the following reaction?

a) I

b) II

c) III

d) IV

e) II and III

Difficulty: Hard

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

Section Reference: 11.3 Elimination Reactions

23. 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

Difficulty: Hard

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

Section Reference: 11.3 Elimination Reactions

24. 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

Difficulty: Hard

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

Section Reference: 11.3 Elimination Reactions

25. 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

Difficulty: Hard

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

Section Reference: 11.3 Elimination Reactions

26. Which compound would be the major product?

I II III

IV V

a) I

b) II

c) III

d) IV

e) V

Difficulty: Hard

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

Section Reference: 11.3 Elimination Reactions

27. 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.

Difficulty: Medium

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

Section Reference: 11.3 Elimination Reactions

28. 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

Difficulty: Hard

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

Section Reference: 11.3 Elimination Reactions

29. 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.

Difficulty: Easy

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

Section Reference: 11.3 Elimination Reactions

30. 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.

Difficulty: Easy

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

Section Reference: 11.3 Elimination Reactions

31. 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.

Difficulty: Easy

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

Section Reference: 11.3 Elimination Reactions

32. What would be the major product of the following reaction?

a) I

b) II

c) III

d) IV

e) V

Difficulty: Medium

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

Section Reference: 11.4 Addition Reactions

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

a) I

b) II

c) III

d) IV

e) V

Difficulty: Medium

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

Section Reference: 11.4 Addition Reactions

34. What is the chief product of the reaction of IBr with 2-methyl-2-pentene?

a) 2-bromo-3-iodo-2-methylpentane

b) 3-bromo-2-iodo-2-methylpentane

c) 1-bromo-2-iodo-2-methylpentane

d) 2-bromo-1-iodo-2-methylpentane

e) a mix of 2-bromo-3-iodo-2-methylpentane and 3-bromo-2-iodo-2-methylpentane

Difficulty: Hard

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

Section Reference: 11.4 Addition Reactions

35. What is the chief product of the acid-catalyzed hydration of 2,5-dimethyl-2-hexene?

a) 2,5-dimethyl-1-hexanol

b) 2,5-dimethyl-2-hexanol

c) 2,5-dimethyl-3-hexanol

d) 2,5-dimethyl-2,3-hexanediol

e) 2,5-dimethyl-3,4-hexanediol

Difficulty: Medium

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

Section Reference: 11.4 Addition Reactions

36. 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

Difficulty: Medium

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

Section Reference: 11.4 Addition Reactions

37. 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

Difficulty: Hard

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

Section Reference: 11.4 Addition Reactions

38. 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

Difficulty: Hard

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

Section Reference: 11.4 Addition Reactions

39. 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

Difficulty: Hard

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

Section Reference: 11.4 Addition Reactions

40. Markovnikov addition of HI to 2-methyl-2-butene involves

a) initial attack by an iodide ion.

b) initial attack by an iodine atom.

c) isomerization of 2-iodo-2-methylbutene.

d) formation of a carbocation at C-2.

e) formation of a carbocation at C-3.

Difficulty: Medium

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

Section Reference: 11.4 Addition Reactions

ESSAY QUESTIONS

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

Difficulty: Easy

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

Section Reference: 11.1 An Introduction to Organic Reactions

42.  bonds often react with electron-seeking reagents, also referred to as ______.

Difficulty: Easy

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

Section Reference: 11.1 An Introduction to Organic Reactions

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