Quaternary ammonium functionalized polyacrylonitrile fiber supported phosphotungstic acid as efficient heterogeneous catalyst: Hydrophobic tuning of the catalytic microenvironment. (20th November 2020)

• Record Type: Journal Article
• Authors: Xiao, Jian; Wang, Lu; Ran, Jiaoru; Zhao, Jingyan; Ma, Ning; Tao, Minli; Zhang, Wenqin
• Is Part Of: Journal of cleaner production. Volume 274(2020)
• Publication Date: 2020-11-20
• Subjects: Polyacrylonitrile fiber -- Fiber catalyst -- Phosphotungstic acid -- 2, 3-Dihydroquinazolin-4(1H)-one -- Heterogeneous catalysis; Factory and trade waste -- Management -- Periodicals; Manufactures -- Environmental aspects -- Periodicals; Déchets industriels -- Gestion -- Périodiques; Usines -- Aspect de l'environnement -- Périodiques; 628.5
• DOI: 10.1016/j.jclepro.2020.122473
• Languages: English
• ISSNs: 0959-6526

Abstract

Abstract: Thirteen novel amine or quaternary ammonium functionalized polyacrylonitrile fiber (PANF) supported phosphotungstic acid (PTA) catalysts were designed and prepared, and their catalytic activities were screened by choosing condensation/annulation tandem synthesis of 2, 3-dihydroquinazolin-4(1 H )-one compound via C–N bond formation between 2-aminobenzamide and p -chlorobenzaldehyde as a model reaction. By adjusting the functionality and hydrophobic/hydrophilic property of the amine/ammonium structure as well as the density of PTA sites, the fiber catalyst CAT-12 prepared from quaternary ammonium functionalized PANF containing benzyl group with high PTA loading achieved the best catalytic activity for most reactions in water. The CAT-12 can be easily separated from the reaction system and recycled for 7 times without significant loss of catalytic activity. Moreover, the reaction proceeded smoothly in gram scale and gave nearly quantitative yield using this efficient, eco-friendly and easily recyclable catalyst with great industrial potential which was also demonstrated in Friedel-Crafts alkylation of indoles with β -nitrostyrene. Vivid PTA immobilization processes and the corresponding "catch-catalyze" catalytic modes were further schematically described to address the effect of microenvironment-tuning on immobilization and catalysis, and accordingly the possible catalytic mechanisms of the two reactions were proposed. Graphical abstract: Image 1 Highlights: Novel acid-functionalized PANFs serve as tunable catalysts to synthesize derivatives of heterocyclic compounds. The chosen fiber catalyst CAT-12 is highly efficient, selective and recyclable. Possible "catch-catalyze" pattern based on the fiber's microenvironment is newly proposed.