Borontrifluorid

Boron trifluoride (BF3) is a colorless, highly reactive gas at room temperature and a potent Lewis acid. The molecule is planar and trigonal, with boron bearing an electron-deficient center that readily accepts electron pairs. BF3 forms adducts with bases such as diethyl ether and amines, which stabilize it for handling.

Industrial BF3 is produced by fluorinating boron-containing oxides or by reacting boron oxide with hydrofluoric acid, for example B2O3 + 6 HF → 2 BF3 + 3 H2O. The gas is collected and often converted to adducts (for example BF3·Et2O) to ease handling and storage.

BF3 hydrolyzes readily in the presence of water to form boric acid and hydrogen fluoride: BF3 + 3 H2O → B(OH)3 + 3 HF. Because of this, BF3 is strictly moisture-sensitive and is typically stored and transported under dry, inert conditions. It reacts with alcohols and other Lewis bases to form reversible adducts that are widely used as catalysts.

Across organic synthesis and refining, BF3 serves as a Lewis acid catalyst for Friedel-Crafts alkylation and acylation, polymerization and isomerization reactions, and as a component in catalytic systems such as BF3·Et2O. It is also used in certain hydrofluorination and rearrangement processes.

BF3 is corrosive to skin, eyes, and mucous membranes. Inhalation of BF3 gas or vapors can cause severe respiratory irritation; contact and inhalation hazards are intensified by moisture, which converts BF3 to HF. It should be stored under strictly dry conditions, handled in a fume hood with appropriate PPE, and kept away from water and reactive metals.