Organic Chemistry

John McMurry

Chapter 10 Organohalides - all with Video Answers

Educators

Chapter Questions

13:14

Problem 1

Give IUPAC names for the following alkyl halides: (FIGURE CANNOT COPY)

Tom Rutherford

Numerade Educator

11:16

Problem 2

Draw and name all monochloro products you would expect to obtain from radical chlorination of 2-methylpentane. Which, if any, are chiral?

Tom Rutherford

Numerade Educator

02:29

Problem 3

Draw and name all monochloro products you would expect to obtain from radical chlorination of 2-methylpentane. Which, if any, are chiral?

Tom Rutherford

Numerade Educator

03:53

Taking the relative reactivities of $1^{\circ}, 2^{\circ},$ and $3^{\circ}$ hydrogen atoms into account, what product(s) would you expect to obtain from monochlorination of 2-methylbutane? What would the approximate percentage of each product be? (Don't forget to take into account the number of each sort of hydrogen.)

David Taylor

Numerade Educator

02:04

Problem 5

Draw three resonance forms for the cyclohexadienyl radical. (FIGURE CANNOT COPY)

Lauren Irwin

Numerade Educator

05:01

Problem 6

The major product of the reaction of methylenecyclohexane with $N$ -bromosuccinimide is 1-(bromomethyl)cyclohexene. Explain. (FIGURE CANNOT COPY)

Lauren Irwin

Numerade Educator

15:59

Problem 7

What products would you expect from reaction of the following alkenes with NBS? If more than one product is formed, show the structures of all. (FIGURE CANNOT COPY)

Lauren Irwin

Numerade Educator

05:10

Problem 8

How would you prepare the following alkyl halides from the corresponding alcohols? (FIGURE CANNOT COPY)

Tom Rutherford

Numerade Educator

06:27

Problem 9

How strong a base would you expect a Grignard reagent to be? Look at Table 9.1 on page $326,$ and predict whether the following reactions will occur as written. (The $p K_{a}$ of $N H_{3}$ is 35.)
(a) $\mathrm{CH}_{3} \mathrm{MgBr}+\mathrm{H}-\mathrm{C} \equiv \mathrm{C}-\mathrm{H} \rightarrow \mathrm{CH}_{4}+\mathrm{H}-\mathrm{C} \equiv \mathrm{C}-\mathrm{MgBr}$
(b) $\mathrm{CH}_{3} \mathrm{MgBr}+\mathrm{NH}_{3} \rightarrow \mathrm{CH}_{4}+\mathrm{H}_{2} \mathrm{N}-\mathrm{MgBr}$

Tom Rutherford

Numerade Educator

02:09

Problem 10

How might you replace a halogen substituent by a deuterium atom if you wanted to prepare a deuterated compound? (FIGURE CANNOT COPY)

Tom Rutherford

Numerade Educator

07:02

Problem 11

How would you carry out the following transformations using an organocopper coupling reaction? More than one step is required in each case. (FIGURE CANNOT COPY)

Tom Rutherford

Numerade Educator

04:07

Problem 12

Rank each of the following series of compounds in order of increasing oxidation level: (FIGURE CANNOT COPY)

Tom Rutherford

Numerade Educator

02:53

Problem 13

Tell whether each of the following reactions is an oxidation, a reduction, or neither. (FIGURE CANNOT COPY)

Tom Rutherford

Numerade Educator

04:04

Problem 14

Give IUPAC names for the following alkyl halides (green = Cl): (FIGURE CANNOT COPY)

Tom Rutherford

Numerade Educator

06:49

Problem 15

Show the produ the following alkenes with NBS: (FIGURE CANNOT COPY)

Tom Rutherford

Numerade Educator

02:58

Problem 16

The following alkyl bromide can be prepared by reaction of the alcohol (S)-2-pentanol with PBr $_{3}$. Name the compound, assign ( $R$ ) or ( $S$ ) stereochemistry, and tell whether the reaction of the alcohol occurs with retention of the same stereochemistry or with a change in stereochemistry (reddish brown $=\mathrm{Br}$ ). (FIGURE CANNOT COPY)

Tom Rutherford

Numerade Educator

13:06

Problem 17

Name the following alkyl halides: (FIGURE CANNOT COPY)

Tom Rutherford

Numerade Educator

05:57

Problem 18

Draw structures corresponding to the following IUPAC names:
(a) 2,3 -Dichloro- 4 -methylhexane
(b) 4 -Bromo- 4 -ethyl- 2 -methylhexane
(c) 3-Iodo-2,2,4,4-tetramethylpentane
(d) cis-1-Bromo-2-ethylcyclopentane

David Taylor

Numerade Educator

04:18

Problem 19

Draw and name the monochlorination products you might obtain by radical chlorination of 2 -methylbutane. Which of the products are chiral? Are any of the products optically active?

David Taylor

Numerade Educator

07:08

Problem 20

How would you prepare the following compounds, starting with cyclopentene and any other reagents needed?
(a) Chlorocyclopentane
(b) Methylcyclopentane
(c) 3-Bromocyclopentene
(d) Cyclopentanol
(e) Cyclopentylcyclopentane
(f) 1,3 -Cyclopentadiene

Tom Rutherford

Numerade Educator

10:02

Problem 21

Predict the product(s) of the following reactions: (FIGURES CANNOT COPY)

Tom Rutherford

Numerade Educator

01:43

Problem 22

A chemist requires a large amount of 1-bromo-2-pentene as starting material for a synthesis and decides to carry out an NBS allylic bromination reaction. What is wrong with the following synthesis plan? What side products would form in addition to the desired product? (FIGURE CANNOT COPY)

Tom Rutherford

Numerade Educator

08:25

Problem 23

What product(s) would you expect from the reaction of 1 -methylcycloHexene with NBS? Would you use this reaction as part of a synthesis? (FIGURE CANNOT COPY)

Tom Rutherford

Numerade Educator

06:48

Problem 24

What product(s) would you expect from the reaction of 1,4 -hexadiene with NBS? What is the structure of the most stable radical intermediate? (FIGURE CANNOT COPY)

Tom Rutherford

Numerade Educator

02:10

Problem 25

What product would you expect from the reaction of 1-phenyl-2-butene with TNBS? Explain. (FIGURE CANNOT COPY)

Tom Rutherford

Numerade Educator

05:17

Problem 26

Rank the compounds in each of the following series in order of increasing oxidation level: (FIGURE CANNOT COPY)

Tom Rutherford

Numerade Educator

02:28

Problem 27

Which of the following compounds have the same oxidation level, and which have different levels? (FIGURE CANNOT COPY)

Tom Rutherford

Numerade Educator

05:34

Problem 28

Tell whether each of the following reactions is an oxidation, a reduction, or neither: (FIGURE CANNOT COPY)

Tom Rutherford

Numerade Educator

02:23

Problem 29

Alkylbenzenes such as toluene (methylbenzene) react with NBS to give products in which bromine substitution has occurred at the position next to the aromatic ring (the benzylic position). Explain, based on the bond dissociation energies in Table 6.3 on page 204.(FIGURE CANNOT COPY)

Tom Rutherford

Numerade Educator

05:16

Problem 30

Draw resonance structures for the benzyl radical, $\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{CH}_{2}$, the intermediate produced in the NBS bromination reaction of toluene (Problem 10.29).

David Taylor

Numerade Educator

08:51

Problem 31

Draw resonance structures for the following species: (FIGURE CANNOT COPY)

Tom Rutherford

Numerade Educator

03:53

Problem 32

(S)-3-Methylhexane undergoes radical bromination to yield optically inactive 3 -bromo- 3 -methylhexane as the major product. Is the product chiral? What conclusions can you draw about the radical intermediate?

David Taylor

Numerade Educator

03:56

Problem 33

Assume that you have carried out a radical chlorination reaction on (R)-2-chloropentane and have isolated (in low yield) 2,4 -dichloropentane. How many stereoisomers of the product are formed and in what ratio? Are any of the isomers optically active? (See Problem 10.32.)

Tom Rutherford

Numerade Educator

03:36

Problem 34

How would you carry out the following syntheses? (FIGURE CANNOT COPY)

Tom Rutherford

Numerade Educator

04:18

Problem 35

The syntheses shown here are unlikely to occur as written. What is wrong with each? (FIGURE CANNOT COPY)

Tom Rutherford

Numerade Educator

02:58

Problem 36

Why do you suppose it's not possible to prepare a Grignard reagent from a bromo alcohol such as 4 -bromo-1-pentanol? Give another example of a molecule that is unlikely to form a Grignard reagent. (FIGURE CANNOT COPY)

Tom Rutherford

Numerade Educator

02:02

Problem 37

Addition of HBr to a double bond with an ether (-OR) substituent occurs regiospecifically to give a product in which the -Br and -OR are bonded to the same carbon. Draw the two possible carbocation intermediates in this electrophilic addition reaction, and explain using resonance why the observed product is formed. (FIGURE CANNOT COPY)

Tom Rutherford

Numerade Educator

01:50

Problem 38

Alkyl halides can be reduced to alkanes by a radical reaction with tributyltin hydride, $\left(\mathrm{C}_{4} \mathrm{H}_{9}\right)_{3} \mathrm{SnH},$ in the presence of light $(h \nu) .$ Propose a radical chain mechanism by which the reaction might occur. The initiation step is the light-induced homolytic cleavage of the Sn-H bond to yield a tributyltin radical. (FIGURE CANNOT COPY)

Tom Rutherford

Numerade Educator

04:00

Problem 39

Identify the reagents a-c in the following scheme: (FIGURE CANNOT COPY)

Tom Rutherford

Numerade Educator

01:55

Problem 40

Tertiary alkyl halides, $\mathrm{R}_{3} \mathrm{CX}$, undergo spontaneous dissociation to yield a carbocation, $\mathrm{R}_{3} \mathrm{C}^{+},$ plus halide ion. Which do you think reacts faster, $\left(\mathrm{CH}_{3}\right)_{3} \mathrm{CBr}$ or $\mathrm{H}_{2} \mathrm{C}=\mathrm{CHC}\left(\mathrm{CH}_{3}\right)_{2} \mathrm{Br} ?$ Explain. (FIGURE CANNOT COPY)

Tom Rutherford

Numerade Educator

02:07

Problem 41

In light of the fact that tertiary alkyl halides undergo spontaneous dissociation to yield a carbocation plus halide ion (Problem 10.40 ), propose a mechanism for the following reaction. (FIGURE CANNOT COPY)

Tom Rutherford

Numerade Educator

03:01

Problem 42

Carboxylic acids $\left(\mathrm{RCO}_{2} \mathrm{H} ; \mathrm{p} K_{\mathrm{a}} \approx 5\right)$ are approximately $10^{11}$ times more acidic than alcohols (ROH; $\mathrm{pK}_{\mathrm{a}} \approx 16$ ). In other words, a carboxylate ion $\left(\mathrm{RCO}_{2}^{-}\right)$ is more stable than an alkoxide ion (RO-). Explain, using resonance.

David Taylor

Numerade Educator

01:40

Problem 43

How might you use a Suzuki-Miyaura coupling to prepare the following biaryl compound? Show the two potential reaction partners.

Tom Rutherford

Numerade Educator