BC13 BORON TRICHLORIDE

BC13 BORON TRICHLORIDE 24.444 1.9076E-01 -2.6142E-04 1.6467E-07 -3.8875E-11 100 1500 gas... 

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. 

So there are 3 (N — H) polar covalent bonds in the ammonia (NH3) molecule and 3 (B —Cl) polar covalent bonds in the boron trichloride (BC13) molecule. 

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. Approximately 75-95% of the BC13 consumed in the United States is used to prepare boron filaments by CVD (7). These high performance fibers are used to reinforce composite materials (qv) made from epoxy resins and metals (Al, Ti). The principal markets for such composites are aerospace industries and sports equipment manufacturers. 

Boron trichloride, BC13, which is also widely used as a catalyst, is produced commercially by the action of chlorine gas on the oxide in the presence of carbon ... 

Nevertheless, a few years ago, Kennedy 66 69) developed a method yielding co-functional polymers by cationic polymerization of vinyl monomers. The principle of the socalled inifer method is to kinetically favor transfer to the initiating species with respect to all other kinds of transfer reactions (especially the transfer to monomer). A typical initiating system is composed of an allyl or benzyl halide and boron trichloride BCl3. This mixture behaves like an alkenium tetrachloro-borate and readily initiates the polymerization of monomers such as isobutene or a-methylstyrene. The efficiency of the halide as a transfer agent depends on the lability of the C—Cl bond and on the molar ratio [RC1]/[BC13],... 

BC13, 0°, 5-6 h, 90% yield.21 In this example a phenolic methyl group, normally cleaved with boron trichloride, was not affected. 

Boron trichloride, boron tribromide, and boron triiodide, in contrast to the trifluoride, are all rapidly hydrolyzed in water (explosively so in the case of BI3) to generate B(OH)3 and HX as indicated above, all are stronger Lewis acids than BF3. While BC13 and BBr3 are volatile liquids, BI3 is an unstable white solid that polymerizes on standing. The BX anions are all known, but the larger ones —especially BI4—require stabilization by a large cation. 

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