Benzene reacts with halogen (HX) under the catalyst (FeX3 or Fe)

Activity: F>Cl>Br>I;

Alkylbenzenes and halogens are more easily substituted than benzene, mainly producing ortho- and para-position products.

Halogenation reaction mechanism

Halogenation reaction: benzene halogen → halobenzene HX (catalyst: ferric trihalide; in the absence of a catalyst, benzene, bromine and chlorine do not react. Not only is the iodination reaction too slow, but the HI generated is a reducing agent, which can reverse the reaction)

Nitration reaction: benzene concentrated nitric acid/concentrated sulfuric acid → nitrobenzene water (exothermic reaction)

Sulfonation reaction: benzene, concentrated sulfuric acid (or fume) → benzene sulfonic acid, water (reversible reaction)

Bo–K reaction: When the benzene ring is connected with a strong electron-withdrawing group (such as nitro group, sulfonic acid group, acyl group, cyano group, etc.), acylation and alkylation reactions generally do not occur.

Chloromethylation reaction

The benzene ring is not easily oxidized, special conditions can be: benzene O2 → maleic anhydride (in the presence of vanadium pentoxide)

Hydroxybenzene (has α-H side chain, regardless of the length of the alkyl side chain) → carboxylic acid

Hydrogenation: under pressurized conditions/Ni, benzene 3 hydrogen → cyclohexane

Adding chlorine: under ultraviolet light, benzene 3 chlorine → hexachlorocyclohexane (pesticide hexachlorocyclohexane)

C electron-donating conjugation effect; —C electron-withdrawing conjugation effect

I electron-donating induction effect; -I electron-withdrawing induction effect

I&C, here mainly C

Cl substituent

—NO3: —I, —C

If the positioning effect is consistent, the two will jointly determine

If the positioning effect is inconsistent, obey the stronger one

Generally obey the first type of positioning base-neighbor para-position substitution

① Solubility: mostly colorless liquid, insoluble in water, easily soluble in organic solvents

②Boiling point: The boiling point increases with the increase of molecular weight.

③Melting point: Due to molecular symmetry, the para-isomer has larger lattice energy, higher melting point, and smaller solubility.

④ Generally lighter than water

⑤ Liquid aromatic hydrocarbons are also good solvents. The vapors of monocyclic aromatic hydrocarbons are toxic and can damage hematopoietic organs and nervous system.

Naphthalene (C10H8):

Anthracene (C14H10)

Philippines (C14H10)

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