Complex sentence: Electrophilic reagents are then able to attack the methyl group; for example, oxidation with permanganate converts the methyl group to carboxyl (- COOH), which produces benzoic acid.
Split into simpler sentences: Electrophilic reagents are then able to attack the methyl group. For example, oxidation with permanganate converts the methyl group to carboxyl (- COOH), to produce benzoic acid.