Boranetetrahydrofuran

Boranetetrahydrofuran, commonly called the borane–THF complex, is a coordination complex formed between borane (BH3) and tetrahydrofuran (THF). In this adduct, THF donates a lone pair from its oxygen to boron, creating a relatively stable, air- and moisture-sensitive source of borane for laboratory use. The typical formulation is BH3·THF, sometimes described as a 1:1 adduct.

Preparation and characteristics

The complex is usually prepared by dissolving borane in dry THF or by treating THF with borane to form the BH3·THF adduct. It is a colorless, low-viscosity liquid or solution in THF at room temperature and is stored under inert atmosphere to prevent hydrolysis. The adduct serves as a more manageable alternative to gaseous borane, providing a convenient source of boron hydride for reactions carried out in THF.

Applications

BH3·THF is a key reagent in organic synthesis as a boron source and reducing agent. It is widely used for hydroboration of alkenes, yielding organoborane intermediates that can be oxidized to alcohols or further transformed. It also enables reductions of carboxylic acids and related derivatives to primary alcohols. Compared with borane gas, the BH3·THF complex offers easier handling, storage, and controlled reactivity in many laboratory settings.

Handling and safety

The borane–THF complex is moisture- and air-sensitive and reacts with water to release hydrogen gas. It should be stored under inert gas and handled with appropriate precautions to avoid exposure to moisture or heat. It can react vigorously with water and oxidants.

See also: hydroboration, borane, tetrahydrofuran, borane–ether complexes.