Boron -fluoride

Boron fluoride. This gas, b.p. —101 , is avaUable in cyUnders and can be bubbled directly into a reaction mixture. 

Acetic anhydride adds to acetaldehyde in the presence of dilute acid to form ethyUdene diacetate [542-10-9], boron fluoride also catalyzes the reaction (78). Ethyfldene diacetate decomposes to the anhydride and aldehyde at temperatures of 220—268°C and initial pressures of 14.6—21.3 kPa (110—160 mm Hg) (79), or upon heating to 150°C in the presence of a zinc chloride catalyst (80). Acetone (qv) [67-64-1] has been prepared in 90% yield by heating an aqueous solution of acetaldehyde to 410°C in the presence of a catalyst (81). Active methylene groups condense acetaldehyde. The reaction of isobutfyene/715-11-7] and aqueous solutions of acetaldehyde in the presence of 1—2% sulfuric acid yields alkyl-y -dioxanes 2,4,4,6-tetramethyl-y -dioxane [5182-37-6] is produced in yields up to 90% (82). 

A. V. Topchiev, S. V. Zavgorodnii, and Y. M. Paushkiu, Boron Fluoride and Its Compounds as Catalysts in Organic Chemistry, Pergamon Press, New York, 1959. 

Several other catalyst systems have been suggested, including boron fluoride and both crystalline and noncrystalline siUcas and alurninosihcates. Although no commercial faciUty exists, the concept of using a crystalline siUca or alurninosihcate catalyst in an integral reaction and distillation apparatus has been proposed (9). 

Boron trifluoride etherate Ethyl ether, compd. with boron fluoride (BF )... 

The principal use of the alkylation process is the production of high octane aviation and motor gasoline blending stocks by the chemical addition of C2, C3, C4, or C5 olefins or mixtures of these olefins to an iso-paraffin, usually isobutane. Alkylation of benzene with olefins to produce styrene, cumene, and detergent alkylate are petrochemical processes. The alkylation reaction can be promoted by concentrated sulfuric acid, hydrofluoric acid, aluminum chloride, or boron fluoride at low temperatures. Thermal alkylation is possible at high temperatures and very high pressures. 

Ethyl acetoacetate reacts with ehaleone in the presence of boron fluoride etherate affording 3-carbethoxy-2-methyl-4,6-diphenylpyryl-ium this can be hydrolyzed and decarboxylated to 2-methyl-4,6-diphenylpyrylium which should theoretically result from acetone and ehaleone. 

Besides acetophenone, this reaction was also applied to p-chloro- andp-methoxyacetophenone, and even to an aliphatic ketone, acetone (although the yield was stated to be only half as large as that obtained from mesityl oxide, i.e., less than 30%, Dorofeenko and co-workers reported a 45% yield of 2,4,6-trimethylpyrylium perchlorate from acetone, acetic anhydride, and perchloric acid), and is the standard method for preparing pyrylium salts with identical substituents in positions 2 and 4. The acylating agent may be an anhydride in the presence of anhydrous or hydrated ferric chloride, or of boron fluoride, or the acid chloride with ferric chloride.Schneider and co-workers ... 

In the case when boron fluoride or its etherate is employed, the protonic acid is formed according to the following schemes (water is produced in the reaction) ... 

Bor-fluorid, n. boron fluoride borofluoride. fiuorwasserstoffsaure, /., -fiuorwasserstoff, m. fluoboric acid, hydrofluoboric acid, HBFi. -flusssSure,/. fluoboric add. 

Fluor-, of or combined with fluorine, fluoro-, fluo-, fluoride of (see instances following),. ammonium, n. ammonium fluoride, -an-thenchinon, n. fluoranthenequinone. -anti-mon, n. antimony fluoride, -arson, n. arsenic fluoride, -baryum, n. barium fluoride, -benzol, n. fluorobensene, fluobenaene. -bor, n. boron fluoride. -borsMure, /. fluo-boric acid. -brom, n. bromine fluoride, -chrom, n. chromium fluoride, -eisen, n. iron fluoride. 

Nitronium tetrafluoroborate has been prepared by interaction of nitric acid, hydrogen fluoride, and boron fluoride in nitromethane.5 However, mixtures of nitric acid and nitromethane are extremely explosive.6,7 The present modification of the procedure, in which the medium is methylene chloride instead of nitromethane, was developed to avoid this hazard. It has not been published before. 

Bismuth, excess entropy of solution of noble metals in liquid bismuth, 133 Block polymers, 181 Bond energies in the halogens, 61 Boron fluoride as initiator in polymerization, 156... 

E process To produce 1000kg of RDX, 630— 635kg of paraformaldehyde, 1800kg AN, 5000-S100kg of acetic anhydride, containing 19kg of boron fluoride are required. The consumption of acetic anhydride amounts to about 800kg... 

In a similar reaction of ketene with diethyl phosphite in the presence of boron fluoride etherate as catalyst, diethyl 1-acetoxyvinylphosphonate is formed [113] see Eq. (69) ... 

As an example, an NMR spectrum of a 1,3-dioxolane-/3-propiolactone copolymer, obtained by using a boron-fluoride catalyst, is shown in Fig. 1101. The 1,3-dioxolane (DOL) homopolymer spectrum contains two singlet peaks of area 1 2 numbered 1 and 5, whereas the spectrum of the 0-propiolactone (PL) homopolymer contains two triplet peaks of area 1 1 numbered 2 and 6. Variation of initial feed ratios disclosed that peaks 1,3 and S are associated with the DOL units and that... 

At a deposition temperature of 1300°C., a low-density material is obtained (1.5 g/cm ). Density increases with increasing temperature and reaches 2.0 g/cm at 1600°C. Vapor phase precipitation can be a problem in the high-temperature range. A more convenient reaction uses boron fluoride ... 

Acetylcyclohexanone. Method A. Place a mixture of 24-6 g. of cyclohexanone (regenerated from the bisulphite compound) and 61 g. (47 5 ml.) of A.R. acetic anhydride in a 500 ml. three-necked flask, fitted with an efficient sealed stirrer, a gas inlet tube reaching to within 1-2 cm. of the surface of the liquid combined with a thermometer immersed in the liquid (compare Fig. II, 7, 12, 6), and (in the third neck) a gas outlet tube leading to an alkali or water trap (Fig. II, 8, 1). Immerse the flask in a bath of Dry Ice - acetone, stir the mixture vigorously and pass commercial boron trifluoride (via an empty wash bottle and then through 95 per cent, sulphuric acid) as fast as possible (10-20 minutes) until the mixture, kept at 0-10°, is saturated (copious evolution of white fumes when the outlet tube is disconnected from the trap). Replace the Dry Ice-acetone bath by an ice bath and pass the gas in at a slower rate to ensure maximum absorption. Stir for 3 6 hours whilst allowing the ice bath to attain room temperature slowly. Pour the reaction mixture into a solution of 136 g. of hydrated sodium acetate in 250 ml. of water, reflux for 60 minutes (or until the boron fluoride complexes are hydrolysed), cool in ice and extract with three 50 ml. portions of petroleum ether, b.p. 40-60° (1), wash the combined extracts free of acid with sodium bicarbonate solution, dry over anhydrous calcium sulphate, remove the solvent by... 

II) chloride plumbous chloride lead(2+) salt lead chromate (VI) phoenicochroite and others lead(2+) lead borofluoride lead boron fluoride lead tetrafluoroborate iodide plumbous iodide... 

Boron trifluoride etherate Ethyl ether, compd. with boron fluoride (BF3) (1 1) (8) Ethane, 1,1-oxybis-, compd. with trifluoroborane (1 1) (9) (109-63-7)... 

Bordetella pertussis Toxin Borer Sol Boroethane Boron Bromide Boron Chloride Boron Fluoride Boron Hydride Boron Tribromide Boron Trichloride Boron Trifluoride Botox... 

A ubiquitous co-catalyst is water. This can be effective in extremely small quantities, as was first shown by Evans and Meadows [18] for the polymerisation of isobutene by boron fluoride at low temperatures, although they could give no quantitative estimate of the amount of water required to co-catalyse this reaction. Later [11, 13] it was shown that in methylene dichloride solution at temperatures below about -60° a few micromoles of water are sufficient to polymerise completely some decimoles of isobutene in the presence of millimolar quantities of titanium tetrachloride. With stannic chloride at -78° the maximum reaction rate is obtained with quantities of water equivalent to that of stannic chloride [31]. As far as aluminium chloride is concerned, there is no rigorous proof that it does require a co-catalyst in order to polymerise isobutene. However, the need for a co-catalyst in isomerisations and alkylations catalysed by aluminium bromide (which is more active than the chloride) has been proved [34-37], so that there is little doubt that even the polymerisations carried out by Kennedy and Thomas with aluminium chloride (see Section 5, iii, (a)) under fairly rigorous conditions depended critically on the presence of a co-catalyst - though whether this was water, or hydrogen chloride, or some other substance, cannot be decided at present. 

Very many acidic solids and liquids, immiscible with hydrocarbons, will catalyse the oligomerisation of isobutene at ambient temperatures. Among the more common are syncatalysts prepared from boron fluoride and a protonic substance BH (B = OH, CHsO, C2H50, t-C4H90, CH3C02, etc.) mineral acids natural and synthetic alumino-silicates, (e.g., Fuller s earth, bentonite, attapulgite) and metal oxides containing small quantities of water. 

The only solid acidic catalyst which has given high polymers at an appreciable rate at low temperatures, and which has been studied in some detail, is that described by Wichterle [41, 42]. This was prepared as follows A 10 per cent solution in hexane of aluminium tri-(s- or t-butoxide) was saturated with boron fluoride at room temperature, and excess boron fluoride was removed from the precipitate by pumping off about half the hexane. Two moles of boron fluoride were absorbed per atom of aluminium, and butene oligomers equivalent to two-thirds of the alkoxy groups were found in the solution the resulting solid had hardly any catalytic activity. When titanium tetrachloride was added to the suspension in hexane, an extremely active catalyst was formed but the supernatant liquid phase had no catalytic activity. The DP of the polymers formed by the catalyst prepared from the s-butoxide was much lower than that of polymers formed with a catalyst prepared from the r-butoxidc. 

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