Tetra­ethyl­ammonium l-malate 1.36-hydrate

The asymmetric unit of the title compound, C(8)H(20)N(+)·C(4)H(5)O(5) (−)·1.36H(2)O, contains two independent ion pairs, with similar conformations, and three water mol­ecules of crystallization, one water mol­ecule haing a site-occupancy factor of 0.721 (5). Intra­molecular O—H⋯O hydrogen bonds, involving the hydr­oxy groups and an O atom of each carboxyl­ate anion, generate five-membered rings involving S(5) ring motifs. In the crystal structure, mol­ecules are linked together by water mol­ecules through four-membered O—H⋯O—H⋯O—H inter­actions to form one-dimensional infinite chains along the a axis. Since the mol­ecules are also linked into one-dimensional infinite chains along the b axis, mol­ecular sheets parallel to the (001) plane are created. Overall, the crystal structure is stabilized by two intra­molecular O—H⋯O hydrogen bonds, nine inter­molecular O—H⋯O and ten C—H⋯O hydrogen bonds.