Fluoroform (CF(3)H), a large-volume by-product of the manufacture of Teflon, refrigerants, polyvinylidene fluoride (PVDF), fire-extinguishing agents, and foams, is a potent and stable greenhouse gas that has found little practical use despite the growing importance of trifluoromethyl (CF3) functionality in more structurally elaborate pharmaceuticals, agrochemicals, and materials. Direct nucleophilic trifluoromethylation using CF(3)H has been a challenge. Here, we report on a direct trifluoromethylation protocol using close to stoichiometric amounts of CF(3)H in common organic solvents such as tetrahydrofuran (THF), diethyl ether, and toluene. The methodology is widely applicable to a variety of silicon, boron, and sulfur-based electrophiles, as well as carbon-based electrophiles.
Bronsted sites must be able to react with adsorbed water molecules to form hydroxonium ions. This study shows by line-shape simulation of the NMR signal measured at 4 K that for water concentrations about equal to the concentration of bridging hydroxyl groups in defect-free HZSM-5 zeolites two configurations exist: water molecules hydrogen-bonded to the bridging OH group and the hydroxonium ion. The result is confirmed by 'H MAS NMR investigations at room temperature. In addition,27Al and 29Si MAS NMR were used to characterize HZSM-5 zeolites under study synthesized without template, with TPA+, with butylamine as template. All samples contain 4 bridging hydroxyl groups per unit cell. For the zeolite synthesized with butylamine and loaded with 2, 4, and 8.4 water molecules per unit cell the concentration of hydroxonium ions per unit cell is 0.28, 0.64, and 1.56, respectively.
Isoparaffin-olefin alkylation was investigated using liquid as well as solid onium poly(hydrogen fluoride) catalysts. These new immobilized anhydrous HF catalysts contain varied amines and nitrogen-containing polymers as complexing agents. The liquid poly(hydrogen fluoride) complexes of amines are typical ionic liquids, which are convenient media and serve as HF equivalent catalysts with decreased volatility for isoparaffin-olefin alkylation. Polymeric solid amine:poly(hydrogen fluoride) complexes are excellent solid HF equivalents for similar alkylation acid catalysis. Isobutane-isobutylene or 2-butene alkylation gave excellent yields of high octane alkylates (up to RON = 94). Apart from their excellent catalytic performance, the new catalyst systems significantly reduce environmental hazards due to the low volatility of complexed HF. They represent a new, "green" class of catalyst systems for alkylation reactions, maintaining activity of HF while minimizing its environmental hazards.
Gallium triflate catalyzed dehydration of aldoximes to nitriles is described in good to excellent yields. Good catalytic and dehydrating capabilities of gallium triflate are demonstrated through this dehydration reaction.
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