(E)-2-Methyl-5-(1-naphthyl­methyl)­cinnamic acid

The title compound, C₂₁H₁₈O₂, crystallized in the centrosymmetric space group P2₁/n with one mol­ecule in the asymmetric unit. There is a single hydrogen bond, with an O_donor⋯O_acceptor distance of 2.624 (2) Å, which forms a cyclic dimer about a center of symmetry. The carboxyl group O atoms are ordered, while the carboxyl-H atom is disordered. A single leading intermolecular C—H⋯O interaction has an H⋯O distance of 2.68 Å and a C—H⋯O angle of 178°; this interaction forms chains. Taken together with the hydrogen bond, it generates chains and rings. Structural comparisons are made with trans-cinnamic acid and with 4-methyl-trans-cinnamic acid.