Boron trifluoride, supported

Patents assigned to Mobil (217) describe the use of boron trifluoride supported on several porous carriers. BF3 supported on silica was found to exhibit a slightly higher performance with added water in the alkylation of a mixed alkene feed at 273 K. It was also shown that self-alkylation activity was considerably lower than that with HF as catalyst. Another patent (218) describes the use of a pillared layered silicate, MCM-25, promoted with BF3 to give a high-quality alkylate at temperatures of about 273 K. BF3 was also supported on zeolite BEA, with adsorbed water still present (219). This composite catalyst exhibited low butene isomerization activity, which was evident from the inferior results obtained with 1-butene. At low reaction temperatures, the product quality was superior to that of HF alkylate. 

Saffar-Teluri, A. 2013. Boron trifluoride supported on nano-SiOj An efficient and reusable heterogeneous catalyst for the synthesis of bis(indolyl)methanes and oxindole derivatives. Res. Chem. Intermediat. 40(3) 1061-1067. 

The Alkar process using boron trifluoride supported on alumina introduced in 1958 was a high pressure fixed-bed process. The process permitted the utilization of the light olefins (ethylene + propylene) of the refiners gas, which had been burnt as a fuel. The quality of ethylbenzene and isopropyl benzene was excellent. However, commerical experience showed that corrosion problems were still substantial and product pretreatment was necessary to remove boron trifluoride. 

Toluene reacts with carbon monoxide and butene-1 under pressure in the presence of hydrogen fluoride and boron trifluoride to give 4-methyl-j iYbutyrophenone which is reduced to the carbinol and dehydrated to the olefin. The latter is cycHzed and dehydrogenated over a special alumina-supported catalyst to give pure 2,6- dim ethyl n aph th a1 en e, free from isomers. It is also possible to isomerize various dim ethyl n aph th a1 en es to the... 

Catalysts. Nearly aU. of the industrially significant aromatic alkylation processes of the past have been carried out in the Hquid phase with unsupported acid catalysts. For example, AlCl HF have been used commercially for at least one of the benzene alkylation processes to produce ethylbenzene (104), cumene (105), and detergent alkylates (80). Exceptions to this historical trend have been the use of a supported boron trifluoride for the production of ethylbenzene and of a soHd phosphoric acid (SPA) catalyst for the production of cumene (59,106). 

The stereoselectivity of the boron trifluoride induced reactions was initially discussed in terms of open-chain, antiperiplanar transition states66. However studies of Lewis acid induced intramolecular allylstannane-aldehyde reactions are supportive of a synclinal process56,67. 

C21-0097. Construct a table of bond lengths that supports the existence of 7r bonding in boron trifluoride and boric acid. The relevant data can be found in the text. Label your table thoroughly. 

Two pieces of direct evidence support the manifestly plausible view that these polymerizations are propagated through the action of car-bonium ion centers. Eley and Richards have shown that triphenyl-methyl chloride is a catalyst for the polymerization of vinyl ethers in m-cresol, in which the catalyst ionizes to yield the triphenylcarbonium ion (C6H5)3C+. Secondly, A. G. Evans and Hamann showed that l,l -diphenylethylene develops an absorption band at 4340 A in the presence of boron trifluoride (and adventitious moisture) or of stannic chloride and hydrogen chloride. This band is characteristic of both the triphenylcarbonium ion and the diphenylmethylcarbonium ion. While similar observations on polymerizable monomers are precluded by intervention of polymerization before a sufficient concentration may be reached, similar ions should certainly be expected to form under the same conditions in styrene, and in certain other monomers also. In analogy with free radical polymerizations, the essential chain-propagating step may therefore be assumed to consist in the addition of monomer to a carbonium ion... 

A similar type of catalyst including a supported noble metal for regeneration was described extensively in a series of patents assigned to UOP (209-214). The catalysts were prepared by the sublimation of metal halides, especially aluminum chloride and boron trifluoride, onto an alumina carrier modified with alkali or rare earth-alkali metal ions. The noble metal was preferably deposited in an eggshell concentration profile. An earlier patent assigned to Texaco (215) describes the use of chlorinated alumina in the isobutane alkylation with higher alkenes, especially hexenes. TMPs were supposed to form via self-alkylation. Fluorinated alumina and silica samples were also tested in isobutane alkylation,... 

Studies by Nakane et al. also support the two-step mechanism when alkylation is carried out with alkyl halides under substantially nonionizing conditions. It was further shown that in nonpolar organic solvents carbocations rather than the polarized complexes participate directly in the formation of the first n complex. BF3—H20 catalyzes ethylation,130 isopropylation,131 and benzylation132 through the corresponding carbocations. Accordingly, ethylbenzene equally labeled in both a and p positions was obtained when [2-14C]-ethyl halides were reacted in hexane solution in the presence of boron trifluoride, BF3—H20, or aluminum... 

Figure 2 Preparation of supported boron trifluoride complex...

Effect of reaction mixture composition on the acidity of supported boron trifluoride complex as measured by spectrosopic titration with pyridine. 

Table 1 Typical surface areas of a supported boron trifluoride complex catalyst heated to different temperatures.

Typical reaction profile for the reaction of phenol with cyclohexene catalysed by supported boron trifluoride complex... 

Other Technologies. Ethylbenzene can he recovered from mixed Cs aromatics by superfractionalion. The Alkar process, commercialized in 1960, uses boron trifluoride on alumina support as the catalyst. It has been used for polymer-grade as well as dilute ethylene feeds. 

UOP introduced the Alkar process for ethylbenzene production in 1966. The Alkar process operates in the vapor-phase with boron trifluoride on an alumina support as the catalyst. By the 1980s, about 15% of the world s ethylbenzene was... 

Supported the catalysts used in this case are silica aluminas, phosphoric add deposited on kieselguiir, or boron trifluoride dqiosited on modified ahimiBa. 

The stereoselective formation of cw-fused dihydropyrans and the steric requirements for the reaction of the norbornenyl examples support a concerted mechanism. However, boron trifluoride catalyzed rearrangements of mixtures of endo- and exo-compounds to bicyclic pyrans, i.e., stepwise reactions through cationic intermediates, are also possible38. 

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