Content check — Organic Chemistry, Chapter 6: An Overview of Organic Reactions

Every problem in the chapter beside the book’s answer, a chapter at a time as you scroll.

Chapter 6: An Overview of Organic Reactions

13 problems · 19 figures

6-1 §6.1 source ↗

Classify each of the following reactions as an addition, elimination, substitution, or rearrangement:

(a)

CH₃Br + KOH ⟶ CH₃OH + KBr

(b)

CH₃CH₂Br ⟶ H₂C = CH₂ + HBr

(c)

H₂C = CH₂ + H₂ ⟶ CH₃CH₃

Answer (3 parts)

(a)

Substitution

(b)

Elimination

(c)

Addition

6-2 §6.3 source ↗

Which of the following species are likely to be nucleophiles and which electrophiles? Which might be both?

(a)

CH₃Cl

(b)

CH₃S^–

(c)

(d)

Answer (4 parts)

(a)

Carbon is electrophilic.

(b)

Sulfur is nucleophilic.

(c)

Nitrogens are nucleophilic (for reasons that will be explained in Chapter 15).

(d)

Oxygen is nucleophilic; carbon is electrophilic.

6-3 §6.3 source ↗

An electrostatic potential map of boron trifluoride is shown. Is BF₃ likely to be a nucleophile or an electrophile? Draw a Lewis structure for BF₃, and explain your answer.

Answer

6-4 §6.4 source ↗

What product would you expect from reaction of cyclohexene with HBr? With HCl?

Answer

Bromocyclohexane; chlorocyclohexane

6-5 §6.4 source ↗

Reaction of HBr with 2-methylpropene yields 2-bromo-2-methylpropane. What is the structure of the carbocation formed during the reaction? Show the mechanism of the reaction.

Answer

The mechanism is shown in Figure 6.4

A 2-step reaction mechanism shows ethylene reacting with hydrogen bromide to form bromoethane via a carbocation intermediate. — Figure 6.4 in the book ↗

6-6 §6.5 source ↗

Add curved arrows to the following polar reactions to indicate the flow of electrons in each:

(a)

(b)

(c)

Answer (3 parts)

(a)

(b)

(c)

6-7 §6.5 source ↗

Predict the products of the following polar reaction, a step in the citric acid cycle for food metabolism, by interpreting the flow of electrons indicated by the curved arrows:

Answer

6-8 §6.6 source ↗

Radical chlorination of alkanes is not generally useful because mixtures of products often result when more than one kind of C−H bond is present in the substrate. Draw and name all monochloro substitution products C₆H₁₃Cl you might obtain by reaction of 2-methylpentane with Cl₂.

Answer

1-Chloro-2-methylpentane, 2-chloro-2-methylpentane, 3-chloro-2-methylpentane, 2-chloro-4-methylpentane, 1-chloro- 4-methylpentane

6-9 §6.6 source ↗

Using curved fishhook arrows, propose a mechanism for the formation of the cyclopentane ring of prostaglandin H₂.

Answer

6-10 §6.7 source ↗

Which reaction is more energetically favored, one with ΔG° = −44 kJ/mol or one with ΔG° = +44 kJ/mol?

Answer

Negative ΔG° is favored.

6-11 §6.7 source ↗

Which reaction is more exergonic, one with K_eq = 1000 or one with K_eq = 0.001?

Answer

Larger K_eq is more exergonic.

6-12 §6.9 source ↗

Which reaction is faster, one with ΔG^‡ = +45 kJ/mol or one with ΔG^‡ = +70 kJ/mol?

Answer

Lower ΔG^‡ is faster.

6-13 §6.10 source ↗

Sketch an energy diagram for a two-step reaction in which both steps are exergonic and in which the second step has a higher-energy transition state than the first. Label the parts of the diagram corresponding to reactant, product, intermediate, overall ΔG^‡, and overall ΔG°.

Answer

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Problems and answers are adapted from Organic Chemistry: A Tenth Edition by John McMurry, OpenStax, and are used under the CC BY-NC-SA 4.0 licence. Access for free at https://openstax.org/books/organic-chemistry/pages/1-why-this-chapter. Illustrations: Copyright Rice University, OpenStax, under CC BY-NC-SA 4.0 license. This adaptation is released under the same licence, is non-commercial, and is neither affiliated with nor endorsed by OpenStax or Rice University.