BC13 Boron chloride

The boron trichloride can be reused in the experiment with only brief pumping at its melting point to remove excessive amounts of HC1. Traces of B2CU left in the BC13 have no adverse effects in subsequent runs. The reactor should be filled with nitrogen after all volatiles have been pumped out, opened to the air, and quickly put into a fume hood. The residues containing Cu, CuCl, and traces of boron chlorides, may fume slightly in air but they are not pyrophoric. 

Boron trichloride, a colorless, reactive gas of BC13 molecules, behaves chemically like BF3. However, the trichloride of aluminum, which is in the same group as boron, forms dimers, linked pairs of molecules. Aluminum chloride is a volatile white solid that vaporizes at 180°C to a gas of Al2Cl6 molecules. These molecules survive in the gas up to about 200°C and only then fall apart into A1C13 molecules. The Al,CI6 molecule exists because a Cl atom in one AlCI, molecule uses one of its lone pairs to form a coordinate covalent bond to the Al atom in a neighboring AICI molecule (33). This arrangement can occur in aluminum chloride hut not boron trichloride because the atomic radius of Al is bigger than that of B. 

BC13, BBr3, and BI3 undeigo exchange reactions to yield mixed boron halides. Exchange reactions also occur with trialkyl, triaryl, trialkoxy, or triaryloxy boranes and with diborane. Anhydrous metal bromides and iodides can be prepared by the exchange reaction of the metal chloride or oxide and BBr3 or BI3 (21). 

Boron carbide (B4C) is also an extremely hard, infusible, and inert substance, made by reduction of B203 with carbon in an electric furnace at 2500°C, and has a very unusual structure. The C atoms occur in linear chains of 3, and the boron atoms in icosahedral groups of 12 (as in crystalline boron itself). These two units are then packed together in a sodium chloride-like array. There are, of course, covalent bonds between C and B atoms as well as between B atoms in different icosahedra. A graphite-like boron carbide (BQ) has been made by interaction of benzene and BC13 at 800°C. 

Boron trichloride and tribromide successfully polymerize styrenes and isobutene. These Lewis acids are typically used in combination with water or alkyl chlorides, acetates, ethers, and alcohols [105,153]. In contrast to earlier reports, BC13 can self-initiate polymerization of styrene and isobutene [137] by haloboration, and subsequent activation of the resulting alkyl chlorides by excess Lewis acid. Direct initiation was confirmed by the formation of lower molecular weight polymers than pre-... 

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