Structure of a new crystal form of 2-{[3-(trifluoromethyl)phenyl]amino}benzoic acid (flufenamic acid)

Abstract

C₁₄H₁₀F₃NO₂, P2₁/c, a = 12.523 (4), b = 7.868(6), c = 12.874 (3)Å, β = 95.2 (2)°, D_m = 1.47 (4), D_c = 1.47 Mg m^-3, Z = 4. Final R = 0.074 for 2255 observed reflections. The carboxyl group and the phenyl ring bearing the carboxyl group are nearly coplanar whereas the two phenyl rings are inclined with respect to each other at 52.8°. The difference between the two polymorphs of flufenamic acid lies in the geometrical disposition of the [3-(trifluoromethyl)- phenyl]amino moiety with respect to the benzoic acid moiety. As in other fenamate structures, the carboxyl group and the imino N atom are connected through an intramolecular hydrogen bond; also, pairs of centro-symmetrically related molecules are connected through hydrogen bonds involving carboxyl groups.