Boron trichloride catalyst

The development of a synthesis for telechelic poly(isobutenes) with boron trichloride catalysts (Inifer technique) has led to an extension of the spectrum of isobutene block copolymers [600,601],... 

The boron trichloride-catalysed benzoylation of toluene gave a similar kinetic form, the average value of 106k2 being 3.17. Again k3 values should strictly be calculated since there is no association between catalyst and benzoyl chloride. 

Boron trichloride, BCI3, 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 ... 

Boron trichloride is used as a catalyst in polymerization reactions. Other applications include refining of alloys soldering flux and as a component in certain fire extinguishers. It also is used to prepare boron libers and other boron compounds including diborane, sodium borohydride and several adducts. 

An equilibrium mixture of 4 and 5 was prepared by the ligand exchange of boron trichloride and triphenyl borate (16) and found to be an effective catalyst.This suggests our effective catalyst may be produced by the in situ rearrangement of 1 to give 4 and/or 5 which then initiates the polymerization. 

Fatty acid analysis of a fat is nowadays a relatively routine analytical operation. After methylation of the fat using reaction with boron trifluoride/methanol, boron trichloride/methanol, methanolic hydrogen chloride solution, diazomethane or, if free fatty acids are not present, alkaline catalysts such as sodium methoxide/methanol, the prepared methyl esters are then analysed by GC on a polar column such as CpSil 88, BPX70 or SP2340. The high polarity of the column is necessary to separate the saturated and unsaturated fatty acids fully. The fatty acid composition of a milk fat sample is thus relatively easily obtained, and was therefore one of the first techniques investigated for authentication purposes. 

Substitution of the hydrogen of many other aromatic compounds is controllable, but the problem of site selectivity still limits the synthetic utility of this reaction (Table 9). In an attempt to improve selectivity the fluorination of chlorobenzene was investigated in the presence of Lewis acids (Table 10). The addition of the Lewis acid is found to increase both conversion and selectivity. The best results are obtained in the presence of 0.9 equivalents of boron trichloride the effect of the boron trichloride is explained by the formation of a complex 7 with the fluorine, which is the fluorinating species. Large amounts of Lewis acid are required due to the formation of a stable complex between the boron trichloride and the fluoride formed as the fluorination progresses which effectively removes the catalyst from the system. ... 

Hydrogenation of 2-isoxazolines over Raney nickel as catalyst and in the presence of acids often leads first to 1,3-hydroxyimines, and then, through hydrolysis, to 1,3-hydroxycarbonyl compounds. In some cases the stereochemical integrity of the starting material is maintained, but in others hydrolysis of the intermediate imines may cause scrambling of stereochemistry at the a-carbon atom. Rapid protonation of the imine function minimizes this possibility and the use of Lewis acids, such as boron trichloride or aluminum trichloride which release hydrochloric acid on contact with moist methanol, is frequently recommended. Boric acid serves a similar purpose and is effective in, for example, the stereocontrolled reductive ring opening of the 2-isoxazoline (135) en route to crispatic acid (136 Scheme 6). ... 

Lewis acids may also act as catalysts with an efficiency roughly parallel to that found in Friedel-Crafts and related reactions These rearrangements are first-order in acid and a substrate-acid adduct is believed to be rapidly formed which rearranges in a slow step with concomitant release of catalyst. Adducts of benzoyl azide with boron trichloride and trifluoride have been isolated at low temperatures... 

The ammonia is the base, while the boron trichloride is the acid, because it accepts the lone pair from the ammonia. This definition is of great use to the organic chemist in, for example, the Friedel-Crafts reaction. Here, the reagent, an alkyl halide, reacts with an aromatic compound such as toluene, in the presence of a catalyst such as aluminium trichloride. There must be approximately the same amount of the catalyst as there is alkyl halide, and not just trace amounts of the catalyst, i.e. the aluminium trichloride is acting in this reaction as a stoichiometric catalyst. The reason becomes apparent when... 

Chlorohydrosilanes also react with hydrocarbons at high temperatures, e.g., trichlorosilane and benzene in the gas phase at 600-850° give chloro-(triphenyl)silane.374 However, the yield is much improved by carrying out the reaction at a lower temperature in an autoclave under pressure and in presence of a catalyst, e.g., boron trichloride 375... 

Trichlorosilane and dichloro(methyl)silane375 377 react in the same way, not only with benzene, but also with other aromatic hydrocarbons such as toluene, biphenyl, and naphthalene, with boric acid, aluminum chloride, or Raney nickel as well as boron trichloride reported as catalysts. Barry et a/.378 have reviewed this direct process for synthesis of arylhalosilanes. 

Due to their reactivity towards substitution under conditions in which phenol itself is unreactive, 1-hydroxy-3-aikoxybenzenes require milder catalysts than generally employed for the former. Resorcinol monomethyl ether in benzene containing benzoyl chloride upon addition to boron trichloride (1 mole) in benzene at -lO C followed by refluxing for 10 hours and aqueous work-up at ambient temperature, afforded 2-hydroxy-4-methoxybenzophenone in 85% yield (ref.132). 

Alkyl fluorides are the most reactive of the alkyl halides. Boron trichloride (BCI3), boron trifluoride (BF3), boron triiodide (BI3), and boron tribfomide (BBr3) all catalyze the reaction of alkyl fluorides and benzene, although they are ineffective catalysts for the analogous reaction of alkyl chlorides and alkyl bromides. reaction with mixed halides, the C—F bond reacts faster than the C—Cl, C—Br or C—I bond. This is consistent with the observed order of reactivity for alkyl halides with aluminum chloride (AICI3) ... 

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