methylenediphenyl

Methylenediphenyl, also known as diphenylmethane, is an aromatic hydrocarbon with the molecular formula C₁₄H₁₂. It consists of two phenyl rings linked by a single methylene (‑CH₂‑) bridge, giving the compound a planar‑like structure that allows for moderate rotational freedom around the central carbon‑carbon bond. The molecule is a colorless liquid at room temperature, with a characteristic mild odor and a density of about 1.06 g cm⁻³. Its boiling point is approximately 256 °C and its melting point is –70 °C, reflecting the relatively weak intermolecular forces typical of non‑polar aromatic compounds.

The compound is obtained industrially by the Friedel‑Crafts alkylation of benzene with formaldehyde in the presence of a Lewis acid catalyst such as aluminum chloride. Alternative laboratory syntheses include the condensation of benzyl chloride with benzene under acidic conditions, or the Grignard reaction of phenylmagnesium bromide with benzaldehyde followed by dehydration. Purification is usually achieved by fractional distillation due to the close boiling points of related aromatic hydrocarbons.

Methylenediphenyl serves primarily as an intermediate in organic synthesis. It is a precursor to diphenylmethanol, diphenylacetyl chloride, and various polymerizable monomers. The compound also appears as a minor component in coal tar and as an additive in some plasticizers and lubricants, where its aromatic character imparts thermal stability.

While not classified as highly toxic, methylenediphenyl may cause irritation to the skin, eyes, and respiratory tract upon prolonged exposure. Standard laboratory safety measures—use of gloves, goggles, and adequate ventilation—are recommended when handling the substance.