Alkali Metal Salts of 4-Hydroxybenzoic Acid: a Structural and Educational Study

Although 4-hydroxybenzoic acid (H2hba) is a relatively simple organic molecule, it displays remarkable coordinative flexibility in its reactions with alkali metal hydroxides, forming ionic networks containing the dianion (hba2−), the monoanion (Hhba−) or the neutral acid species (H2hba). A common feature of the structures of the lattices is their layered arrangement: alternating hydrophilic layers made up of closely packed metal–oxygen polyhedra are separated by the hydrophobic nonpolar components of the hydroxybenzoate linking units.