Search

Heterogeneous catalysis is an important way to realize green chemistry. Developing excellent heterogeneous catalysts by using appropriate supports is still a mainstream research area. Polyacrylonitrile fiber (PANF), a common textile material in our daily life, has excellent advantages of low cost, high strength, light density, mildew resistance, etc. Furthermore, PANF can be knitted into varieties of shapes, making them very suitable for fixed‐bed catalysis in industries. Consequently, PANF is a fine raw material for the synthesis of heterogeneous catalysts. Therefore, more and more PANF‐based heterogeneous catalysts had been developed and applied to various of reaction systems. In this paper, the research progress of PANF‐based catalysts was reviewed, and the research progress of different PANF catalytic systems and their applications in green chemistry were emphatically introduced, which provided reference to the development of PANF‐supported catalytic technology. Finally, the catalytic system supported by PANF is summarized and prospected. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fibrous superbase catalyst for organic conversions in continuous-flow processing. • Powerful combination of support and catalyst for prominent application performance. • Highly catalytic activity and general applicability for the mediated reactions. • Superior stability and strong practicality for efficient scale-up procedure. The development of clean catalytic technologies in continuous-flow processing for efficient organic conversions has a positive influence on the fine chemicals and pharmaceutical manufacturing. Herein, the commonly used organic superbase 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) was immobilized on the commercially available ultra-high strength textile fiber polyetheretherketone (PEEK) to report a polymer-supported basic catalyst (PEEK-TBD) for three types of organic conversions in cleaner continuous-flow processing. The fiber catalyst was prepared through an improvement strategy and verified as a heterogeneous fibrous superbase catalyst in the microtubule reactor to mediate the Knoevenagel condensation-cyclization between salicylaldehydes and activated nitriles for the synthesis of iminocoumarins in ethanol (10 samples, yields 91–97%) after turning the flow rate, substrate concentration, and catalyst padding quantity, additionally, PEEK-TBD was also effective for the cyanosilylation of carbonyl compounds for the synthesis of cyanogen compounds in acetonitrile, as well as the substitution reaction of aniline and carbonate for the synthesis of N , N '-substituted urea in toluene in continuous-flow processing. Moreover, the resulting fiber samples were characterized in detail by sorts of analytical methods and techniques to further confirm the dependability of this methodology, and the clean and valid gram-scalable procedure of PEEK-TBD in continuous-flow processing has extensive application prospects on the chemical productions. [ABSTRACT FROM AUTHOR]

A series of fiber catalysts promotes the condensation of a wide range of aromatic aldehydes with active methylene compounds. [ABSTRACT FROM AUTHOR]