Бор фосфа

Химические свойства

white not hygroscopic crystal(s); prepared by reacting boric acid and phosphoric acid up to 1200°C: B(OH)3+H3PO4=BPO4+3H2O; used in special glasses [HAW93]

Физические свойства

Physical Properties White infusible solid; density 1.873 g/mL; sublimates slowly above 1,450°C; soluble in water, decomposes to phosphoric acid and boric acid; pH of 1% solution is ~2.0.

Использование

Boron phosphate is used as an acid catalyst for dehydration of alcohols to olefins; isomemization of olefins; nitration of aromatic hydrocarbons; polymerization of aldehydes and other synthetic reactions. It also is used as a flux in silica-based porcelain and ceramics; special glasses; and acid cleaners.

Подготовка

Boron phosphate is prepared by heating an equimolar mixture of boric acid and phosphoric acid at 1,000 to 1,200°C:
H₃BO₃ + H₃PO₄ → BPO₄ + 3H₂O
Various preparative methods are adopted at nonstoichiometric formulations, incomplete dehydration or using oxide additives to obtain boron phosphate of varying purity for its catalytic applications. The compound also forms hydrates (tri- tetra-, penta-, and hexahydrates) which readily decompose in water to phosphoric acid and boric acid.