1. Dual-functionalized ZIF-8 as an efficient acid-base bifunctional catalyst for the one-pot tandem reaction
- Author
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Kyung Youl Baek, Lee Yu Ri, Xuan Huy Do, and Seung Sang Hwang
- Subjects
chemistry.chemical_classification ,02 engineering and technology ,General Chemistry ,Sulfonic acid ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensation reaction ,Heterogeneous catalysis ,01 natural sciences ,Catalysis ,0104 chemical sciences ,Bifunctional catalyst ,chemistry.chemical_compound ,chemistry ,Polymer chemistry ,Knoevenagel condensation ,0210 nano-technology ,Bifunctional ,Zeolitic imidazolate framework - Abstract
An acid-base bifunctional zeolitic imidazolate framework catalyst (ZIF8-A61-SO3H) with amine and sulfonic acid groups was successfully prepared through simple two step post-synthetic modification: preparation of amine-functionalized ZIF-8 with amine contents of 61% (ZIF8-A61) by the ligand exchange of 2-mIM with 3-amino-1,2,4-triazole (Atz), followed by the sulfonic acid functionalization by the ring-opening reaction of 1,3-propanesultone with –NH2 groups in ZIF8-A61. Amine-functionalized ZIF8-A materials with difference amine contents (15%, 34%, and 61%, respectively) were also prepared by controlling the synthesis time. All obtained ZIF catalysts evaluated as a heterogeneous catalyst for one-pot deacetalization-Knoevenagel condensation tandem reaction. Compared with ZIF-8 and amine-functionalized ZIF-8 catalysts, ZIF8-A61-SO3H catalyst showed good catalytic performance with 100% conversion of the reactant and 98% selectivity of the final Knoevenagel product. An enhanced catalytic activity can be attributed to the co-existence of site-isolated acid-base groups on the ZIF8-A61-SO3H catalyst in close proximity. The heterogeneous nature of the catalytic system was confirmed by a hot-filtering test and the catalyst also exhibited reusable in the five repeated cycles. A plausible catalytic mechanism of deacetalization-Knoevenagel condensation reaction over ZIF8-A61-SO3H was also proposed.
- Published
- 2021
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