Boron oxide reaction with

Hazardous Decomp. Prods. Combustion boron oxide reaction with water releases methane NFPA Health 4, Flammability 4, Reactivity 3 Storage Handle only in sealed, purged systems store cylinders below 55 C away from direct sunlight, precipitation, mech. damage Uses Synthesis reagent as reactor fuel additive/surf. treatment doping material in semiconductor materials in amorphous devices for depositing a p-type silicon-carbon alloy with improved optical props. 

DOT CLASSIFICATION Forbidden SAFETY PROFILE A powerful oxidant which explodes above 140°C. Explosive reaction with boron. Hypergolic reaction with dimethyl hydrazine or other strong organic bases. Forms powerfully explosive mixtures with nitrogen containing organic compounds (e.g., 2-nitroaniline). Upon decomposition it emits toxic fumes of NOx. See also NITRO COMPOUNDS. 

Thus the weakly Bronsted acidic boron zeolites allow acid-catalyzed reactions to be carried out with high selectivity. Gallium substitution gives effective, sulfur-resistant catalysts for the synthesis of aromatics from lower alkanes, without the need for noble metal doping [8], The nonacidic titanium siUcalite exhibits very interesting properties in selective oxidation reactions with H2O2 [T32]. 

Chemical Properties. In addition to the reactions Hsted in Table 3, boron trifluoride reacts with alkali or alkaline-earth metal oxides, as well as other inorganic alkaline materials, at 450°C to yield the trimer trifluoroboroxine [13703-95-2] (BOF), MBF, and MF (29) where M is a univalent metal ion. The trimer is stable below — 135°C but disproportionates to B2O2 and BF at higher temperatures (30). 

Hafnium Boride. Hafnium diboride [12007-23-7] HfB2, is a gray crystalline soHd. It is usually prepared by the reaction of hafnium oxide with carbon and either boron oxide or boron carbide, but it can also be prepared from mixtures of hafnium tetrachloride, boron trichloride, and hydrogen above 2000°C, or by direct synthesis from the elements. Hafnium diboride is attacked by hydrofluoric acid but is resistant to nearly all other reagents at room temperature. Hafnium dodecaboride [32342-52-2] has been prepared by direct synthesis from the elements (56). 

The reaction of methyl propionate and formaldehyde in the gas phase proceeds with reasonable selectivity to MMA and MAA (ca 90%), but with conversions of only 30%. A variety of catalysts such as V—Sb on siUca-alumina (109), P—Zr, Al, boron oxide (110), and supported Fe—P (111) have been used. Methjial (dimethoxymethane) or methanol itself may be used in place of formaldehyde and often result in improved yields. Methyl propionate may be prepared in excellent yield by the reaction of ethylene and carbon monoxide in methanol over a mthenium acetylacetonate catalyst or by utilizing a palladium—phosphine ligand catalyst (112,113). 

These are made of boron carbide ia a matrix of aluminum oxide clad with Zircaloy. As the uranium is depleted, ie, burned up, the boron is also burned up to maintain the chain reaction. This is another intrinsic control feature. The chemical shim and burnable poison controls reduce the number of control rods needed and provide more uniform power distributions. 

Na2B0402 10H2O, and cmde oil residue (41) in a rotary kiln heated to 1038°C. Borax is fed at the rate of 1360 kg/h and sprayed with 635 kg/h of 17% residue cmde oil. The heated mixture then reacts with CI2 at 760°C in a separate reactor to yield BCl. On a smaller scale, BCl can be prepared by the reaction of CI2 and a mixture of boron oxide [1303-86-2] 2 3 coke, and lampblack in a fluidized bed (42). Other methods for the preparation... 

The alkylboranes obtained by the hydroboration reaction are versatile intermediates for further transformations. The most important transformation is the oxidation to yield alcohols 17 it is usually carried out by treatment with hydroperoxide in alkaline solution. The group R migrates from boron to oxygen with retention of configuration ... 

The boronic acid 2 is first converted to an activated species 8 containing a tetravalent boron center by reaction with a base. Halides or triflates (OTf = trilluoromethanesulfonate) are used as coupling partners R-X for the boronic acids. In many cases the rate-limiting step is the oxidative addition. With respect to the leaving group X, the rate decreases in the order ... 

Oxidation of C12-C14 n-paraffms using boron trioxide catalysts was extensively studied for the production of fatty alcohols.Typical reaction conditions are 120-130°C at atmospheric pressure. ter-Butyl hydroperoxide (0.5 %) was used to initiate the reaction. The yield of the alcohols was 76.2 wt% at 30.5% conversion. Fatty acids (8.9 wt%) were also obtained. Product alcohols were essentially secondary with the same number of carbons and the same structure per molecule as the parent paraffin hydrocarbon. This shows that no cracking has occurred under the conditions used. The oxidation reaction could be represented as ... 

Mesitaldehyde may be prepared from mesitylmagnesium bromide by the reaction with orthoformate esters3 or ethoxy-methyleneaniline 3 from acetylmesitylene by oxidation with potassium permanganate,4 from mesitoyl chloride by reduction,5 from mesityllithium by the reaction with iron pentacarbonyl and from mesitylene by treatment with formyl fluoride and boron trifluoride,7 by treatment with carbon monoxide, hydrogen chloride, and aluminum chloride,8 or by various applications of the Gatterman synthesis.9-11... 

The cyclohexyloxy(dimethyl)silyl unit in 8 serves as a hydroxy surrogate and is converted into an alcohol via the Tamao oxidation after the allylboration reaction. The allylsilane products of asymmetric allylboration reactions of the dimethylphenylsilyl reagent 7 are readily converted into optically active 2-butene-l, 4-diols via epoxidation with dimethyl dioxirane followed by acid-catalyzed Peterson elimination of the intermediate epoxysilane. Although several chiral (Z)-y-alkoxyallylboron reagents were described in Section 1.3.3.3.3.1.4., relatively few applications in double asymmetric reactions with chiral aldehydes have been reported. One notable example involves the matched double asymmetric reaction of the diisopinocampheyl [(Z)-methoxy-2-propenyl]boron reagent with a chiral x/ -dialkoxyaldehyde87. 

H.12 The reaction of boron trifluoride, BF,(g), with sodium borohydride, NaBH4(s), leads to the formation of sodium tetrafluoroborate, NaBF4(s), and diborane gas, B2Hfc(g). The diborane reacts with the oxygen in air, forming boron oxide, B20 j(s), and water. Write the two balanced equations leading to the formation of boron oxide. 

These compounds are thermally stable, but sensitive to oxidation. The boron atom is not very reactive, due to conjugation of its vacant orbital with the nitrogen lone electron pair, resulting in the absence of intermolec-ular coordination. However, these compounds undergo reactions with methanol, giving methoxy derivatives (172). The latter interact with lithium alkylides, and form, depending on their nature, borates (173) or 13-alkyl derivatives (174) [Eq. (131)]. 

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