Barium hydroxide is a chemical compound with the formula Ba(OH)2. Monohydrate (x = 1), known as barite or barite water, is one of the main compounds of barium. This white granular monohydrate is the common commercial form.
Barium hydroxide can be prepared by dissolving barium oxide (BaO) in water: Barium hydroxide is used industrially as a precursor for other barium compounds. Monohydrate is used for dehydration and removal of sulfates from various products. [6] This application takes advantage of the extremely low solubility of barium sulfate. This industrial application is also suitable for laboratory use.
BaO + H2O → Ba(OH)2
It crystallizes as the octahydrate, which converts to the monohydrate when heated in air. In vacuum at 100 °C, the monohydrate produces BaO and water. [3] The monohydrate has a layered structure (see the figure above). The Ba2+ center adopts a square anti-prism geometry. Each Ba2+ center is bound by two water ligands and six hydroxide ligands, which double and triple bridge to adjacent Ba2+ center sites, respectively. [4] In octahydrates, a single Ba2+ center is also octacoordinated but does not share ligands.
Barium hydroxide is used in analytical chemistry for the titration of weak acids, especially organic acids. Unlike solutions of sodium hydroxide and potassium hydroxide, barium carbonate is insoluble in water, thus guaranteeing that its clear aqueous solution is carbonate-free. This allows the use of indicators such as phenolphthalein or thymolphthalein (which have a basic color change) without the risk of titration errors due to the presence of carbonate ions, which are much less basic. [7]
Barium hydroxide is occasionally used as a strong base in organic synthesis, such as the hydrolysis of esters [8] and nitriles [9][10][11], and as a base in aldol condensations.
Barium hydroxide has several uses, such as hydrolyzing one of the two equivalent ester groups in dimethyladipic acid. [12]
Barium hydroxide is also used to release barium carbonate during the decarboxylation of amino acids. [13]
