What Is Boron Trifluoride?
Boron trifluoride is an inorganic compound with the chemical formula BF3. It is found both as a dihydrate and an anhydrous form, with CAS registration numbers 7637-07-2 and 13319-75-0, respectively. Due to its irritant properties to mucous membranes, it requires careful handling. The complex formed with diethyl ether is a liquid often used as a Lewis acid.
Uses of Boron Trifluoride
Boron trifluoride has several major applications, including as a catalyst in Lewis acid reactions, in semiconductor manufacturing for doping, as a polymerization initiator, and in optical fiber production.
1. Catalysts
It readily forms complexes with Lewis bases, such as ammonia and diethyl ether, serving as a catalyst in organic synthesis for reactions like isomerization, alkylation, esterification, and condensation.
2. Semiconductor Manufacturing
In semiconductor manufacturing, it serves as a dopant in ion implantation and epitaxial growth of silicon, making it a P-type semiconductor.
3. Polymerization Initiator
As a polymerization initiator, it can polymerize vinyl phenols and their derivatives with limited molecular weight distribution and achieve cationic polymerization with living polymerization properties.
Properties of Boron Trifluoride
With a molecular weight of 67.82, it is a colorless gas at room temperature, while the dihydrate is a colorless liquid. It has a density of 0.00276 g/mL (1.64 g/mL for the dihydrate) and is soluble in water and various organic solvents. Its molecular structure consists of three fluorine atoms bonded to a boron atom in an equilateral triangle.
Molecular Structure of Boron Trifluoride
The molecular structure is an equilateral triangle, with strongly polarized covalent bonds, yet the molecule itself is nonpolar, attributed to the sp2 orbitals of boron atoms and its 3-fold symmetry.
Types of Boron Trifluoride
Available as a high-pressure gas for industrial use and as a methanol complex for research and development, it is supplied in steel cylinders and cardles. Proper storage and usage must comply with relevant safety and control laws.
1. High-Pressure Gas Products
Used in semiconductor manufacturing, pharmaceutical synthesis, and as a polymerization catalyst, these products are supplied in various container sizes and must be handled according to safety regulations.
2. Reagent Products for Research and Development
As a methanol complex salt, it is available in convenient laboratory volumes, suitable for storage at room temperature and available in reagent and analytical grades for various applications.
Other Information on Boron Trifluoride
1. Synthesis of Boron Trifluoride
It is industrially synthesized from boron oxide and hydrogen fluoride, with laboratory methods including decomposition of diazonium salts or reaction of sodium tetrafluoroborate with acids.
2. Reactivity of Boron Trifluoride
As a corrosive substance, it reacts with moisture to corrode certain metals but is inert to materials like teflon or polypropylene. It acts as a Lewis acid in chemical reactions, forming tetrafluoroborates or undergoing hydrolysis.
3. Regulatory Information on Boron Trifluoride
Classified as toxic and hazardous, it is subject to various regulatory requirements under safety, health, and environmental protection laws.