4-Chloro­anilinium 3-carb­oxy­prop-2-enoate

In the title compound, C₆H₇ClN⁺·C₄H₃O₄⁻, the cations and anions lie on mirror planes and hence only half of the mol­ecules are present in the asymmeric unit. The 4-chloro­anilinium cation and hydrogen maleate anion in the asymmetric unit are each planar and are oriented at an angle of 15.6 (1)° to one another and perpendicular to the b axis. A characterestic intra­molecular O—H...O hydrogen bond, forming an S(7) motif, is observed in the maleate anion. In the crystal, the cations and anions are linked by N—H...O hydrogen bonds, forming layers in the ab plane. The aromatic rings of the cations are sandwiched between hydrogen-bonded chains and rings formed through the amine group of the cation and maleate anions, leading to alternate hydro­phobic (z = 0 or 1) and hydro­philic layers (z = 1/2) along the c axis.