Chapter 22 - Reactions of Benzene and Its Derivatives

Halogens

Halogens

________ are an anomaly in that they are ortho- para directing but electron withdrawing, hence they are mildly deactivating toward electrophilic aromatic substitution when compared to benzene.

Bromoarenes

________ are formed when they react with Br2 in the presence of the Lewis acid catalyst FeBr3.

Aromatic rings

________ react with Cl2 in the presence of the Lewis acid catalyst FeCl3 to produce chloroarenes in a halogenation process.

NaNH2

At high temperatures (300°C to 500°C), haloarenes react with extremely strong bases (________) or moderate bases (NaOH) to produce products in which the halogen is replaced.

nitronium ion

The ________, NO2 1, produced by the reaction of nitric acid with sulfuric acid, is the electrophile.

Haloarenes

________ that have ortho and /or para highly electron withdrawing groups react with strong nucleophiles such as hydrazine to generate regioselective substitution.

Rearrangements

________ can be an issue since carbocations are involved in the action, especially with primary or secondary haloalkanes or any other haloalkane that would form a carbocation prone to ________.

arenium ion

A(n) ________ is a resonance- stabilized cation intermediate.

term electrophile

The ________ refers to a carbocation that forms as an ion pair when a haloalkane interacts with a Lewis acid.

Alkyl groups

________ and all groups in which the atom linked to the ring contains an unshared pair of electrons are ortho- para directing, and the majority are electron releasing; hence, they are activating toward electrophilic aromatic substitution as compared to benzene.

strong electrophile

As a very ________, the nitronium ion combines with the weakly nucleophilic aromatic p cloud to generate a resonance- stabilized cation intermediate that loses a proton to yield the end product.

acylium ions

There are no rearrangements because ________ do not rearrange like carbocations.

halonium ion

A(n) ________ is produced as an ion pair by the interaction of chlorine or bromine with a Lewis acid.

o bromonitrobenzene

When ________ and p- bromonitrobenzene are synthesized from benzene, the bromine (ortho- para directing) must come first, followed by the nitro group (meta directing)

strong electrophile

As a very ________, the Cl1 combines with the weakly nucleophilic aromatic p cloud to generate a resonance- stabilized cation intermediate that loses a proton to yield the chloroarene product.

Aromatic rings

________ react with haloalkanes in the presence of a Lewis acid, such as AlCl3, to form alkylbenzenes in a Friedel- Crafts alkylation.