4Methylphenyl

4-Methylphenyl, also known as p-tolyl, is the aromatic substituent derived from toluene by removing one hydrogen atom from the ring. Its empirical formula is C7H7 and its common nomenclature reflects the para-position of the methyl group relative to the attachment point on the phenyl ring. The structure consists of a benzene ring bearing a methyl group at the fourth carbon, giving the group a characteristic electron-donating influence through resonance.

The 4-methylphenyl group frequently appears in organic synthesis as a protecting group or as a leaving group in the formation of aryl halides and aryl boronic acids. Its presence in aromatic amides, esters, and ketones often enhances the electrophilicity of adjacent sites, facilitating further functionalization. In medicinal chemistry, the p-tolyl moiety is incorporated into drug candidates to improve metabolic stability or lipophilicity. Polymers containing the p-tolyl unit can exhibit increased crystallinity or altered thermal properties due to the steric bulk and electron-donating effect of the methyl substituent.

In organometallic chemistry, 4-methylphenyl ligands coordinate with transition metals such as nickel, palladium, and platinum in complexes that serve as catalysts in cross-coupling reactions. Common synthetic routes to 4-methylphenyl derivatives include Friedel–Crafts alkylation of benzene with methyl chloride, and directed ortho-metalation followed by quenching with electrophiles.

Safety data indicate that pure 4-methylphenyl compounds are relatively low in acute toxicity, but inhalation of vapors and skin contact should be avoided. Materials handling guidelines recommend personal protective equipment and adequate ventilation. The compound is typically stored in a cool, dry place away from oxidizing agents.