Boron tri fluoride

The present authors12,13) also studied the polymerization of 2 with boron tri-fluoride etherate as the initiator. High molecular weight polymers with intrinsic viscosities up to 1.87 dl/g were obtained in methylene chloride at —78 °C. The polymers melted at 160—180 °C, and showed some crystallinity as observed by X-ray diffraction. 

Proportional counters can also count neutrons by introducing boron into the chamber. The most common means of introducing boron is by combining it with tri-fluoride gas to form Boron Tri-Fluoride (BF3). When a neutron interacts with a boron atom, an alpha particle is emitted. The BF3 counter can be made sensitive to neutrons and not to gamma rays. 

Isodurene, oxidation with peroxytri-fluoroacetic acid and boron tri-fluoride, 48, 90 Isodurenol, 48, 90. ... 

The first reported instance of stereoselective polymerization was probably the cationic polymerization of isobutyl vinyl ether in 1947 [Schildknecht et al., 1947]. A semicrystalline polymer was obtained when the reaction was carried out at —80 to —60°C using boron tri-fluoride etherate as the initiator with propane as the solvent. The full significance of the polymerization was not realized at the time as the crystallinity was attributed to a syndiotactic structure. X-Ray diffraction in 1956 indicated that the polymer was isotactic [Natta et al., 1956a,b], (NMR would have easily detected the isotactic structure, but NMR was not a routine tool in 1947.)... 

It easily forms double compds, such as boron trifluoride etherate. Another compd, boron tri fluoride-mono ethyl amine, BFa— C2H6NH2 is wh to pale tan flakes, melting at 88—90°. It released BFa above 110° and is used for elevated temp cure of epoxy resins Refs 1) Gmelin-Kraut Syst Number 13(1954), 168 2) CondChemDict (1961), I661L R ... 

In this Sect, we report systematic DSC studies of (i) the constituents of boron tri-fluoride monoethylamine (BF3 NH2C2H5) catalyzed TGDDM-DDS epoxies and their mixtures (ii) the nature of the catalyzed cure reactions and (iii) the environmental sensitivity of the BF3 NH2CzH5 catalyst. DSC studies are also reported on the cure reaction characteristics and environmental sensitivity of commercial prepregs that contain BF3 amine catalysts. 

Nitronium Tetrafluoroborate. We followed the procedure of Olah and Kuhn (10) in which nitric acid, hydrogen fluoride, and boron tri-fluoride were allowed to react in a suitable solvent. The previously reported solvent was nitromethane however, in view of the reported mineral acid sensitization of nitromethane toward detonation, we decided to use 2-nitropropane as solvent. With this modified procedure it was necessary to wash the nitronium tetrafluoroborate with Freon 113 (1,1,2-trichloro-... 

Methyl benzenesulfenate activated by Lewis acids, such as trimethylsilyl triflate or boron tri-fluoride-diethyl ether complex, induces arenealkene cyclization, presumably via an episulfonium... 

Butyl alcohol and phenol are converted to their acetates in 38% and 50% yields, respectively. Alcohols and amino alcohols are quantitatively converted to the corresponding acetates by a solution of boron tri fluoride in glacial acetic acid. ... 

ESTERIFICATION Boric acid. Boron tri-fluoride ethcratc. Hcxamcthylphosphoric ttiamidc. lon-cxchange resins. Methyl f-butyl ether. Tricthyloxonium fluoro-borate. Trimethyl phosphite. 

A second curious example taken from the Bteroid field concerns the reaction of 5a,6o -epoxy-B-norcholesteryl acetate with boron tri fluoride, which gives an unsaturated oJcohol in which the C(is> methyl has migrated in the manner depicted in Eq. (480). 

Diborane is produced by the reaction of sodium borohydride with boron tri fluoride ... 

There are examples in the literature of the reduction of simple aliphatic ketones to the corresponding hydrocarbons using gaseous boron tri fluoride and tri ethyl si lane in dichlorcmethane (32). 

The preparation of tetrasaccharide 11.41 is outlined in Scheme 15. Boron tri-fluoride etherate mediated glycosylation of 11.51 with imidate 11.46 produced the corresponding trisaccharide (88%), which was readily converted to the glycosyl acceptor 11.53 upon removal of the allyloxycarbonyl group. Under TMSOTf-catalyzed... 

AMMONERIC (12125-02-9) Can be self-reactive explosion may occur when closed containers are opened after long storage. Contact with water can cause a violent reaction with heat and formation of hydrogen chloride. Violent reaction with boron tri fluoride, boron penta-fluoride, bromine trifluoride, iodine heptafluoride, potassium chlorate. Mixture with hydrogen cyanide may form explosive nitrogen trichloride. Incompatible with alkalis, alkali carbonates, acids, salts of lead or silver. At fire temperature conditions, fumes corrode metals. 

Organocopper reagents-Boron tri-fluoride cthcratc, 208 Oiganolithium teagcnts-Coppct(l) halides. 58... 

Conjugate addition reactions, including the Robinson annulation, which make use of reactive Michael acceptors such as methyl vinyl ketone, can suffer from low yields of the desired adduct. The basic conditions required for enolate formation can cause polymerization of the vinyl ketone. Further difficulties arise from the fact that the Michael adduct 42 and the original cyclohexanone have similar acidities and reactivities, such that competitive reaction of the product with the vinyl ketone can ensue. These problems can be minimized by the use of acidic conditions. Sulfuric acid is known to promote the conjugate addition and intramolecular aldol reaction of 2-methylcyclohexanone and methyl vinyl ketone in 55% yield. Alternatively, a silyl enol ether can be prepared from the ketone and treated with methyl vinyl ketone in the presence of a Lewis acid such as a lanthanide triflate" or boron tri fluoride etherate (BF3 OEt2) and a proton source to effect the conjugate addition (followed by base-promoted aldol closure). 

Treatment of alkyl l-thio-j3-D-glucopyranoside tetra-acetates with boron tri-fluoride in dichloromethane at room temperature afforded mixtures of the a-and jS-anomers, in the ratio of ca. 7 3, which were readily separated by chromatography on silica gel. Boron trifluoride also catalysed the condensation of equimolar proportions of 1,2-/rflnj-related monosaccharide peresters and alkyl, alkenyl, and some aryl thiols to provide a convenient synthesis of esters... 

Obtained (poor yield) by prenylation of 2,4-dihydro-xy-6-methoxyphenyl 3,4-methylenedioxybenzyl ket one with 2-hydroxy-2-met hyl-3-butene in dioxane in the presence of boron tri-fluoride etherate for 1 h at r.t. (4%) [5352],... 

Alternate Names boron trifluoride diethyl etherate boron tri fluoride ethyl etherate boron trifluoride ethyl ether complex tri-fluoroboron diethyl etherate. 

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