needles or crystal(s) with 99.9% purity; unstable; enthalpy of vaporization 40.5 kJ/mol. It is a crystalline solid, which reacts vigorously with water to form hydroiodic acid and boric acid. Boron triiodide is easily decomposed when heated, and reacts with red phosphorus or white phosphorus to incandescent. Boron triiodide is an electron-deficient compound with unsaturated boron atoms, so its chemical properties are mainly Lewis acid properties, and it can react with various Lewis bases to form complexes.
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Boron triiodide is used as pharmaceutical, chemical and organic intermediate. It is also used as a catalyst and for preparation of boron compounds.
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Boron triiodide can be synthesized by refluxing lithium borohydride and iodine in hexane, or by reacting alkali metal borohydride with iodine at a suitable temperature.
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Boron triiodide is a strong Lewis acid. It can be prepared by treating iodine (I2) with potassium borohydride (KBH4) in heptane.
