Polyalkylation can occur in Friedel-Crafts alkylation, leading to multiple alkyl groups being added to the benzene ring.

The IUPAC name of C6H5CH2OH is benzyl alcohol, which consists of a benzene ring attached to a -CH2OH group.

The major product is bromobenzene, formed when bromine reacts with benzene in the presence of a Lewis acid catalyst like FeBr3.

The mechanism of nitration of benzene is electrophilic substitution, where the nitronium ion acts as the electrophile.

The product is toluene sulfonic acid, formed when toluene reacts with sulfuric acid in an electrophilic substitution reaction.

The product of the Friedel-Crafts acylation of benzene with acetyl chloride is acetophenone, formed by the introduction of the acetyl group onto the benzene ring.

Only one product is formed when 1,2-dimethylbenzene is substituted at the 4-position, as the two methyl groups are in positions that do not create stereoisomers.

Nitrobenzene is least reactive towards electrophilic substitution due to the strong electron-withdrawing effect of the nitro group, which deactivates the ring.

Toluene will undergo electrophilic aromatic substitution most readily due to the electron-donating effect of the methyl group.

A characteristic feature of electrophilic aromatic substitution reactions is the formation of a sigma complex (arenium ion) during the reaction.

The nitronium ion (NO2+) is the active electrophile in the nitration of benzene, generated from nitric acid and sulfuric acid.

The –NO2 group is a meta-directing group because it withdraws electrons from the aromatic ring, directing incoming electrophiles to the meta position.

The hydroxyl group (-OH) is a strong electron-donating group that activates the benzene ring towards electrophilic substitution.