4-Chloro­anilinium 3-carb­oxy­prop-2-enoate

In the title compound, C(6)H(7)ClN(+)·C(4)H(3)O(4) (−), 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.