FIGURE 16.18 MECHANISM -

Mechanism of nucleophilic aromatic substitution. The reaction occurs in two steps and involves a resonance-stabilized carbanion intermediate.
(1) Nucleophilic addition of hydroxide ion to the electron-poor aromatic ring takes place, yielding a stabilized carbanion intermediate.
![](https://cdn.mathpix.com/cropped/2025_02_06_5556f7656cbdcaa0f9a7g-0536.jpg?height=158&width=388&top_left_y=428&top_left_x=1145)
(1)
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FIGURE 16.18 MECHANISM -

2 The carbanion intermediate undergoes elimination of chloride ion in a second step to give the substitution product.
(2)
![](https://cdn.mathpix.com/cropped/2025_02_06_5556f7656cbdcaa0f9a7g-0536.jpg?height=150&width=345&top_left_y=1036&top_left_x=1156)


FIGURE 16.18 MECHANISM -

Nucleophilic aromatic substitution occurs only if the aromatic ring has an electron-withdrawing substituent in a position ortho or para to the leaving group to stabilize the anion intermediate through resonance (FIGURE 16.19). A meta substituent offers no such resonance stabilization. Thus, $p$-chloronitrobenzene and $o$-chloronitrobenzene react with hydroxide ion at $130{ }^{\circ} \mathrm{C}$ to yield substitution products, but $m$-chloronitrobenzene is inert to $\mathrm{OH}^{-}$.


Ortho -


Ortho -

Para
![](https://cdn.mathpix.com/cropped/2025_02_06_5556f7656cbdcaa0f9a7g-0537.jpg?height=297&width=1386&top_left_y=513&top_left_x=342)


Ortho -

Meta
![](https://cdn.mathpix.com/cropped/2025_02_06_5556f7656cbdcaa0f9a7g-0537.jpg?height=342&width=673&top_left_y=889&top_left_x=374)


Ortho -

FIGURE 16.19 Nucleophilic aromatic substitution on nitrochlorobenzenes. Only in the ortho and para intermediates is the negative charge stabilized by a resonance interaction with the nitro group, so only the ortho and para isomers undergo reaction.


Ortho -

Note the differences between electrophilic and nucleophilic aromatic substitutions. Electrophilic substitutions are favored by electron-donating substituents, which stabilize a carbocation intermediate, while nucleophilic substitutions are favored by electron-withdrawing substituents, which stabilize a carbanion intermediate. Thus, the electron-withdrawing groups that deactivate rings for electrophilic substitution (nitro, carbonyl, cyano, and so forth) activate them for nucleophilic substitution. What's more, these functional groups are meta directors in electrophilic substitution but are ortho-para directors in nucleophilic substitution. And finally, electrophilic substitutions replace hydrogen on the ring, while nucleophilic substitutions replace a leaving group, usually halide ion.


Ortho -

PROBLEM The herbicide oxyfluorfen can be prepared by reaction between a phenol and an aryl fluoride.
16-16 Propose a mechanism.
![](https://cdn.mathpix.com/cropped/2025_02_06_5556f7656cbdcaa0f9a7g-0537.jpg?height=375&width=1166&top_left_y=1794&top_left_x=409)


Ortho -

Oxyfluorfen


Ortho - 16.7 Benzyne

Halobenzenes without electron-withdrawing substituents don't react with nucleophiles under most conditions. At high temperature and pressure, however, even chlorobenzene can be forced to react. Chemists at the Dow Chemical Company discovered in 1928 that phenol could be prepared on an industrial scale by treatment of chlorobenzene with dilute aqueous NaOH at $340^{\circ} \mathrm{C}$ under 170 atm pressure.
![](https://cdn.mathpix.com/cropped/2025_02_06_5556f7656cbdcaa0f9a7g-0538.jpg?height=270&width=862&top_left_y=190&top_left_x=645)


Ortho - 16.7 Benzyne

A similar substitution reaction occurs with other strong bases. Treatment of bromobenzene with potassium amide $\left(\mathrm{KNH}_{2}\right)$ in liquid $\mathrm{NH}_{3}$ solvent, for instance, gives aniline. Curiously, though, when using bromobenzene labeled with radioactive ${ }^{14} \mathrm{C}$ at the C 1 position, the substitution product has equal amounts of the label at both C 1 and C2, implying the presence of a symmetrical reaction intermediate in which C 1 and C 2 are equivalent.
![](https://cdn.mathpix.com/cropped/2025_02_06_5556f7656cbdcaa0f9a7g-0538.jpg?height=278&width=901&top_left_y=647&top_left_x=612)


Ortho - 16.7 Benzyne

Further mechanistic evidence comes from trapping experiments. When bromobenzene is treated with $\mathrm{KNH}_{2}$ in the presence of a conjugated diene, such as furan, a Diels-Alder reaction (Section 14.4) occurs, implying that the symmetrical intermediate is a benzyne, formed by elimination of HBr from bromobenzene. Benzyne is too reactive to be isolated as a pure compound but, in the presence of water, addition occurs to give phenol. In the presence of a diene, Diels-Alder cycloaddition takes place.
![](https://cdn.mathpix.com/cropped/2025_02_06_5556f7656cbdcaa0f9a7g-0538.jpg?height=674&width=1223&top_left_y=1151&top_left_x=451)


Ortho - 16.7 Benzyne

The electronic structure of benzyne, shown in FIGURE 16.20, is that of a highly distorted alkyne. Although a typical alkyne triple bond uses $s p$-hybridized carbon atoms, the benzyne triple bond uses $s p^{2}$-hybridized carbons. Furthermore, a typical alkyne triple bond has two mutually perpendicular $\pi$ bonds formed by $p-p$ overlap, but the benzyne triple bond has one $\pi$ bond formed by $p-p$ overlap and one $\pi$ bond formed by $s p^{2}-s p^{2}$ overlap. The latter $\pi$ bond is in the plane of the ring and is very weak.
![](https://cdn.mathpix.com/cropped/2025_02_06_5556f7656cbdcaa0f9a7g-0538.jpg?height=193&width=369&top_left_y=2213&top_left_x=561)


Ortho - 16.7 Benzyne

Side view
![](https://cdn.mathpix.com/cropped/2025_02_06_5556f7656cbdcaa0f9a7g-0538.jpg?height=397&width=489&top_left_y=2062&top_left_x=1081)


Ortho - 16.7 Benzyne

FIGURE 16.20 An orbital picture and electrostatic potential map of benzyne. The benzyne carbons are $s p^{2}$-hybridized, and the "third" bond results from weak overlap of two adjacent $s p^{2}$ orbitals.


Ortho - 16.7 Benzyne

PROBLEM Treatment of $p$-bromotoluene with NaOH at $300^{\circ} \mathrm{C}$ yields a mixture of two products, but treatment 16-17 of $m$-bromotoluene with NaOH yields a mixture of three products. Explain.


Ortho - 16.8 Oxidation of Aromatic Compounds


Oxidation of Alkyl Side Chains -

Despite its unsaturation, the benzene ring is inert to strong oxidizing agents such as $\mathrm{KMnO}_{4}$, which will cleave alkene carbon-carbon bonds (Section 8.8). It turns out, however, that the presence of the aromatic ring has a dramatic effect on the reactivity of alkyl side chains. These side chains react rapidly with oxidizing agents and are converted into carboxyl groups, $-\mathrm{CO}_{2} \mathrm{H}$.The net effect is conversion of an alkylbenzene into a benzoic acid, $\mathrm{Ar}-\mathrm{R} \rightarrow \mathrm{Ar}-\mathrm{CO}_{2} \mathrm{H}$. Butylbenzene is oxidized by aqueous $\mathrm{KMnO}_{4}$ to give benzoic acid, for instance.
![](https://cdn.mathpix.com/cropped/2025_02_06_5556f7656cbdcaa0f9a7g-0539.jpg?height=264&width=796&top_left_y=681&top_left_x=659)


Oxidation of Alkyl Side Chains -

A similar oxidation is employed industrially for the preparation of the terephthalic acid used in the production of polyester fibers. Worldwide, approximately 118 million tons per year of terephthalic acid is produced by oxidation of $p$-xylene, using air as the oxidant and $\mathrm{Co}(\mathrm{III})$ salts as catalyst.
![](https://cdn.mathpix.com/cropped/2025_02_06_5556f7656cbdcaa0f9a7g-0539.jpg?height=307&width=457&top_left_y=1099&top_left_x=815)
$p$-Xylene $\quad$ Terephthalic acid
The mechanism of side-chain oxidation is complex and involves reaction of $\mathrm{C}-\mathrm{H}$ bonds at the position next to the aromatic ring to form intermediate benzylic radicals. tert-Butylbenzene has no benzylic hydrogens, however, and is therefore inert.
![](https://cdn.mathpix.com/cropped/2025_02_06_5556f7656cbdcaa0f9a7g-0539.jpg?height=193&width=592&top_left_y=1622&top_left_x=764)
tert-Butylbenzene
Analogous side-chain oxidations occur in various biosynthetic pathways. The neurotransmitter norepinephrine, for instance, is biosynthesized from dopamine by a benzylic hydroxylation reaction. The process is catalyzed by the copper-containing enzyme dopamine $\beta$-monooxygenase and occurs by a radical mechanism. A copper-oxygen species in the enzyme first abstracts the pro-R benzylic hydrogen to give a radical, and a hydroxyl is then transferred from copper to carbon.
![](https://cdn.mathpix.com/cropped/2025_02_06_5556f7656cbdcaa0f9a7g-0539.jpg?height=283&width=1399&top_left_y=2122&top_left_x=363)


Oxidation of Alkyl Side Chains -


Bromination of Alkylbenzene Side Chains -

Side-chain bromination at the benzylic position occurs when an alkylbenzene is treated with $N$-bromosuccinimide (NBS). For example, propylbenzene gives (1-bromopropyl)benzene in 97\% yield on reaction with NBS in the presence of benzoyl peroxide, $\left(\mathrm{PhCO}_{2}\right)_{2}$, as a radical initiator. Bromination occurs exclusively in the benzylic position next to the aromatic ring and does not give a mixture of products.
![](https://cdn.mathpix.com/cropped/2025_02_06_5556f7656cbdcaa0f9a7g-0540.jpg?height=372&width=1183&top_left_y=649&top_left_x=471)

The mechanism of benzylic bromination is similar to that discussed in Section 10.3 for allylic bromination of alkenes. Abstraction of a benzylic hydrogen atom first generates an intermediate benzylic radical, which then reacts with $\mathrm{Br}_{2}$ in step 2 to yield product and a Br • radical, which cycles back into the reaction to carry on the chain shown below as a summary. The $\mathrm{Br}_{2}$ needed for reaction with the benzylic radical is produced in step 3 by a concurrent reaction of HBr with NBS.
![](https://cdn.mathpix.com/cropped/2025_02_06_5556f7656cbdcaa0f9a7g-0540.jpg?height=717&width=958&top_left_y=1257&top_left_x=578)


Reaction occurs exclusively at the benzylic position because the benzylic radical intermediate is stabilized by resonance. FIGURE 16.21 shows how the benzyl radical is stabilized by overlap of its $p$ orbital with the ringed $\pi$ electron system.
![](https://cdn.mathpix.com/cropped/2025_02_06_5556f7656cbdcaa0f9a7g-0540.jpg?height=350&width=1693&top_left_y=2145&top_left_x=235)


FIGURE 16.21 A resonance-stabilized benzylic radical. The spin-density surface shows that the unpaired electron is shared by the ortho
and para carbons of the ring.
PROBLEM Refer to Table 6.3 for a quantitative idea of the stability of a benzyl radical. How much more stable
16-19 (in $\mathrm{kJ} / \mathrm{mol}$ ) is the benzyl radical than a primary alkyl radical? How does a benzyl radical compare in stability to an allyl radical?


PROBLEM Styrene, the simplest alkenylbenzene, is prepared commercially for use in plastics manufacture
16-20 by catalytic dehydrogenation of ethylbenzene. How might you prepare styrene from benzene using reactions you've studied?
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Styrene


Bromination of Alkylbenzene Side Chains - 16.9 Reduction of Aromatic Compounds


Catalytic Hydrogenation of Aromatic Rings -

Just as aromatic rings are generally inert to oxidation, they're also inert to catalytic hydrogenation under conditions that reduce typical alkene double bonds. As a result, it's possible to reduce an alkene double bond selectively in the presence of an aromatic ring. For example, 4-phenyl-3-buten-2-one is reduced to 4-phenyl-2-butanone using a palladium catalyst at room temperature and atmospheric pressure. Neither the benzene ring nor the ketone carbonyl group is affected.
![](https://cdn.mathpix.com/cropped/2025_02_06_5556f7656cbdcaa0f9a7g-0541.jpg?height=302&width=822&top_left_y=1145&top_left_x=657)


To hydrogenate an aromatic ring, it's necessary either to use a platinum catalyst with hydrogen gas at a pressure of several hundred atmospheres or to use a more effective catalyst such as rhodium on carbon. Under these conditions, aromatic rings are converted into cyclohexanes. For example, $o$-xylene yields 1,2-dimethylcyclohexane, and 4-tert-butylphenol gives 4-tert-butylcyclohexanol.
![](https://cdn.mathpix.com/cropped/2025_02_06_5556f7656cbdcaa0f9a7g-0541.jpg?height=321&width=703&top_left_y=1626&top_left_x=573)
![](https://cdn.mathpix.com/cropped/2025_02_06_5556f7656cbdcaa0f9a7g-0541.jpg?height=334&width=963&top_left_y=1969&top_left_x=581)


Reduction of Aryl Alkyl Ketones -

In the same way that an aromatic ring activates a neighboring (benzylic) $\mathrm{C}-\mathrm{H}$ toward oxidation, it also activates a benzylic carbonyl group toward reduction. Thus, an aryl alkyl ketone prepared by Friedel-Crafts acylation of an aromatic ring can be converted into an alkylbenzene by catalytic hydrogenation over a palladium catalyst.

Propiophenone, for instance, is reduced to propylbenzene by catalytic hydrogenation. Because the net effect of Friedel-Crafts acylation followed by reduction is the preparation of a primary alkylbenzene, this two-step sequence of reactions makes it possible to circumvent the carbocation rearrangement problems associated with direct Friedel-Crafts alkylation using a primary alkyl halide (Section 16.3).
![](https://cdn.mathpix.com/cropped/2025_02_06_5556f7656cbdcaa0f9a7g-0542.jpg?height=652&width=1161&top_left_y=387&top_left_x=474)


Reduction of Aryl Alkyl Ketones -

The conversion of a carbonyl group into a methylene group $\left(\mathrm{C}=\mathrm{O} \rightarrow \mathrm{CH}_{2}\right)$ by catalytic hydrogenation is limited to aryl alkyl ketones; dialkyl ketones are not reduced under these conditions. Furthermore, the catalytic reduction of aryl alkyl ketones is not compatible with the presence of a nitro substituent on the aromatic ring because a nitro group is reduced to an amino group under reaction conditions. We'll see a more general method for reducing ketone carbonyl groups to yield alkanes in Section 19.9.
![](https://cdn.mathpix.com/cropped/2025_02_06_5556f7656cbdcaa0f9a7g-0542.jpg?height=258&width=871&top_left_y=1275&top_left_x=622)


Reduction of Aryl Alkyl Ketones -

PROBLEM How would you prepare diphenylmethane, $(\mathrm{Ph})_{2} \mathrm{CH}_{2}$, from benzene and an acid chloride? 16-21


Reduction of Aryl Alkyl Ketones - 16.10 Synthesis of Polysubstituted Benzenes

As discussed in the Introduction to Organic Synthesis in Section 9.9, one of the surest ways to learn organic chemistry is to work synthesis problems. The ability to plan a successful multistep synthesis of a complex molecule requires a working knowledge of the uses and limitations of a great many organic reactions. Not only must you know which reactions to use, you must also know when to use them because the order in which reactions are carried out is often critical to the success of the overall scheme.


The ability to plan a sequence of reactions in the right order is particularly important in the synthesis of substituted aromatic rings, where the introduction of a new substituent is strongly affected by the directing effects of other substituents. Planning syntheses of substituted aromatic compounds is therefore a good way to gain confidence in using the many reactions discussed in the past few chapters.


As we said in Section 9.9, it's usually best to work a synthesis problem backward, or retrosynthetically. Look at the target molecule and ask yourself, "What is an immediate precursor of this compound?" Choose a likely answer and continue working backward, one step at a time, until you arrive at a simple starting material. Let's try some examples.


Synthesizing a Polysubstituted Benzene -

How would you synthesize 4-bromo-2-nitrotoluene from benzene?


Strategy -


Strategy -

The three substituents on the ring are a bromine, a methyl group, and a nitro group. A bromine can be introduced by bromination with $\mathrm{Br}_{2} / \mathrm{FeBr}_{3}$, a methyl group can be introduced by Friedel-Crafts alkylation with $\mathrm{CH}_{3} \mathrm{Cl} / \mathrm{AlCl}_{3}$, and a nitro group can be introduced by nitration with $\mathrm{HNO}_{3} / \mathrm{H}_{2} \mathrm{SO}_{4}$.