A new polyacrylonitrile fiber-supported Brønsted acid catalyst has been developed and verified to efficiently (high yield, 10 cycles) mediate Biginelli reactions in ethanol, Pechmann condensations in toluene, Friedel-Crafts alkylations of indoles in water and conversion of fructose in dimethyl sulfoxide (DMSO) and mixed-aqueous system.
Highly efficient, easily recyclable and reusable polyacrylonitrile fiber-supported quaternary ammonium salts for the reduction of aldehydes, ketones, azides, and benzyl halides in water using NaBH4 as the reducing reagent.
A series of ionic liquids supported on polyacrylonitrile fibers (FSILs) served as “release and catch” catalysts to mediate the Friedel–Crafts alkylation of indoles exclusively in water. Detailed characterization by elemental analysis, FTIR spectroscopy, and SEM confirmed that a significant amount of ionic liquid was immobilized on the surface layer of the fiber, and excellent results, in terms of the simple procedure, high yields (87–96 %), and superior catalytic recyclability (over 10 cycles), are reported for the metal and cosolvent‐free synthesis of a wide variety of bis(indolyl)methanes at room temperature. The reason why the reaction catalyzed with FSILs only proceeded in water is explained, and a “release and catch” catalytic mechanism is proposed. Moreover, the procedures can be scaled up efficiently, and the solvent can be recovered and reused without contamination. The prominent features of the fiber catalyst are very attractive for fixed‐bed reactors in the chemical industry.
A highly efficient catalytic system composed of a bifunctional polyacrylonitrile fiber (PANF-PA[BnBr]) and a metal chloride was employed to produce 5-hydroxymethylfurfural (HMF) from sucrose in mixed-aqueous systems. The promoter of PANF-PA[BnBr] incorporates protonic acid groups that promote the hydrolysis of the glycosidic bond to convert sucrose into glucose and fructose, and then catalyzes fructose dehydration to HMF, while the ammonium moiety may promote synergetically with the metal chloride the isomerization of glucose to fructose and transfer HMF from the aqueous to the organic phase. The detailed characterization by elemental analysis, FTIR spectroscopy, and SEM confirmed the rangeability of the fiber promoter during the modification and utilization processes. Excellent results in terms of high yield (72.8%) of HMF, superior recyclability (6 cycles) of the process, and effective scale-up and simple separation procedures of the catalytic system were obtained. Moreover, the prominent features (high strength, good flexibility, etc.) of the fibers are very attractive for fix-bed reactor.
Highly efficient and recyclable polyethylene polyamine functionalized polyacrylonitrile fiber as the heterogeneous base catalyst and supported phase-transfer catalyst.
Synthesis of Polyacrylonitrile Fiber-Supported Poly(ammonium methanesulfonate)s as Active and Recyclable Heterogeneous Broensted Acid Catalysts. -The synthesis of the catalyst and its recyclability (ten cycles without loss of activity) is described. The synthetic utility of the catalyst is illustrated by the conduction of large-scale reactions of all processes. -(SHI*, X.-L.; XING, X.; LIN, H.; ZHANG, W.; Adv. Synth. Catal. 356 (2014) 10, 2349-2354, http://dx.
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