Arenes having an alkyl side-chain with at least one benzylic hydrogen will undergo oxidation in the presence of neutral MnO₄^- anion to give the corresponding benzoic acid. Note that in the example given below, the same product (benzoic acid) is produced by all three reactions, with the remaining carbons appearing as secondary oxidation products. As with all reactions involving MnO₄^-, the reaction involves radical intermediates and side reactions are common.

Alkyl-substituted arylsulfonic acids undergo a somewhat brutal reaction know as "alkali fusion" in which the sulfonic acid residue is replaced by a hydroxyl group, yielding a substituted phenol. Because of the extreme reaction conditions, the reaction is limited to simple compounds, but is a useful pathway to forming phenols.

Since benzyl radicals are quite stable (being resonance-stabilized by the adjacent ring), free radical bromination occurs quite rapidly on alkyl benzenes having at least one benzylic hydrogen. The reaction conditions employed often utilize NBS (N-bromosuccinimide) in CCl₄ in the presence of a "radical initiator" to generate the bromine radical.

Since arenes are resistant to catalytic reduction, alkene side-chains can be specifically reduced to the alkane without reducing the ring. If you want to reduce the ring, high temperatures and pressure are required when standard catalysts are utilized (Pt or Pd), although Rh will catalyze the reduction under very mild conditions.

Catalytic reduction will also reduce aryl nitro groups to the corresponding amine (or, specific reduction can be accomplished using acidic SnCl₂). Likewise, aryl ketones are smoothly reduced catalytically to give the corresponding alkane. This latter reaction is quite often useful since an alkyl chain which would be prone to rearrangement in a Friedel-Crafts alkylation can be introduced using an acylation, and then simply reduced to the alkane.