Zinc- and Copper-Loaded Nanosponges from Cellulose Nanofibers Hydrogels: New Heterogeneous Catalysts for the Synthesis of Aromatic Acetals
Herein we report the synthesis of cellulose-based metal-loaded nano-sponges and their application as heterogeneous catalysts in organic synthesis. First, the combination in water solution of TEMPO-oxidized cellulose nanofibers (TOCNF) with branched polyethyleneimine (bPEI) and citric acid (CA), and...
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| Format: | Article |
| Language: | English |
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MDPI AG
2022-01-01
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| Online Access: | https://www.mdpi.com/2310-2861/8/1/54 |
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| author | Laura Riva Angelo Davide Lotito Carlo Punta Alessandro Sacchetti |
| author_facet | Laura Riva Angelo Davide Lotito Carlo Punta Alessandro Sacchetti |
| author_sort | Laura Riva |
| collection | DOAJ |
| description | Herein we report the synthesis of cellulose-based metal-loaded nano-sponges and their application as heterogeneous catalysts in organic synthesis. First, the combination in water solution of TEMPO-oxidized cellulose nanofibers (TOCNF) with branched polyethyleneimine (bPEI) and citric acid (CA), and the thermal treatment of the resulting hydrogel, leads to the synthesis of an eco-safe micro- and nano-porous cellulose nano-sponge (CNS). Subsequently, by exploiting the metal chelation characteristics of CNS, already extensively investigated in the field of environmental decontamination, this material is successfully loaded with Cu (II) or Zn (II) metal ions. Efficiency and homogeneity of metal-loading is confirmed by scanning electron microscopy (SEM) analysis with an energy dispersive X-ray spectroscopy (EDS) detector and by inductively coupled plasma-optical emission spectrometry (ICP-OES) analysis. The resulting materials perform superbly as heterogeneous catalysts for promoting the reaction between aromatic aldehydes and alcohols in the synthesis of aromatic acetals, which play a fundamental role as intermediates in organic synthesis. Optimized conditions allow one to obtain conversions higher than 90% and almost complete selectivity toward acetal products, minimizing, and in some cases eliminating, the formation of carboxylic acid by-products. ICP-OES analysis of the reaction medium allows one to exclude any possible metal-ion release, confirming that catalysis undergoes under heterogeneous conditions. The new metal-loaded CNS can be re-used and recycled five times without losing their catalytic activity. |
| first_indexed | 2024-03-10T01:26:22Z |
| format | Article |
| id | doaj.art-f46d29da31014492919aab80bf5ddc18 |
| institution | Directory Open Access Journal |
| issn | 2310-2861 |
| language | English |
| last_indexed | 2024-03-10T01:26:22Z |
| publishDate | 2022-01-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Gels |
| spelling | doaj.art-f46d29da31014492919aab80bf5ddc182023-11-23T13:50:33ZengMDPI AGGels2310-28612022-01-01815410.3390/gels8010054Zinc- and Copper-Loaded Nanosponges from Cellulose Nanofibers Hydrogels: New Heterogeneous Catalysts for the Synthesis of Aromatic AcetalsLaura Riva0Angelo Davide Lotito1Carlo Punta2Alessandro Sacchetti3Department of Chemistry, Materials, and Chemical Engineering “G. Natta”, Politecnico di Milano, 20131 Milan, ItalyDepartment of Chemistry, Materials, and Chemical Engineering “G. Natta”, Politecnico di Milano, 20131 Milan, ItalyDepartment of Chemistry, Materials, and Chemical Engineering “G. Natta”, Politecnico di Milano, 20131 Milan, ItalyDepartment of Chemistry, Materials, and Chemical Engineering “G. Natta”, Politecnico di Milano, 20131 Milan, ItalyHerein we report the synthesis of cellulose-based metal-loaded nano-sponges and their application as heterogeneous catalysts in organic synthesis. First, the combination in water solution of TEMPO-oxidized cellulose nanofibers (TOCNF) with branched polyethyleneimine (bPEI) and citric acid (CA), and the thermal treatment of the resulting hydrogel, leads to the synthesis of an eco-safe micro- and nano-porous cellulose nano-sponge (CNS). Subsequently, by exploiting the metal chelation characteristics of CNS, already extensively investigated in the field of environmental decontamination, this material is successfully loaded with Cu (II) or Zn (II) metal ions. Efficiency and homogeneity of metal-loading is confirmed by scanning electron microscopy (SEM) analysis with an energy dispersive X-ray spectroscopy (EDS) detector and by inductively coupled plasma-optical emission spectrometry (ICP-OES) analysis. The resulting materials perform superbly as heterogeneous catalysts for promoting the reaction between aromatic aldehydes and alcohols in the synthesis of aromatic acetals, which play a fundamental role as intermediates in organic synthesis. Optimized conditions allow one to obtain conversions higher than 90% and almost complete selectivity toward acetal products, minimizing, and in some cases eliminating, the formation of carboxylic acid by-products. ICP-OES analysis of the reaction medium allows one to exclude any possible metal-ion release, confirming that catalysis undergoes under heterogeneous conditions. The new metal-loaded CNS can be re-used and recycled five times without losing their catalytic activity.https://www.mdpi.com/2310-2861/8/1/54nanocellulose hydrogelscellulose-based nanospongesheterogeneous catalysisacetalizationmetal-catalyzed reactionssustainability |
| spellingShingle | Laura Riva Angelo Davide Lotito Carlo Punta Alessandro Sacchetti Zinc- and Copper-Loaded Nanosponges from Cellulose Nanofibers Hydrogels: New Heterogeneous Catalysts for the Synthesis of Aromatic Acetals Gels nanocellulose hydrogels cellulose-based nanosponges heterogeneous catalysis acetalization metal-catalyzed reactions sustainability |
| title | Zinc- and Copper-Loaded Nanosponges from Cellulose Nanofibers Hydrogels: New Heterogeneous Catalysts for the Synthesis of Aromatic Acetals |
| title_full | Zinc- and Copper-Loaded Nanosponges from Cellulose Nanofibers Hydrogels: New Heterogeneous Catalysts for the Synthesis of Aromatic Acetals |
| title_fullStr | Zinc- and Copper-Loaded Nanosponges from Cellulose Nanofibers Hydrogels: New Heterogeneous Catalysts for the Synthesis of Aromatic Acetals |
| title_full_unstemmed | Zinc- and Copper-Loaded Nanosponges from Cellulose Nanofibers Hydrogels: New Heterogeneous Catalysts for the Synthesis of Aromatic Acetals |
| title_short | Zinc- and Copper-Loaded Nanosponges from Cellulose Nanofibers Hydrogels: New Heterogeneous Catalysts for the Synthesis of Aromatic Acetals |
| title_sort | zinc and copper loaded nanosponges from cellulose nanofibers hydrogels new heterogeneous catalysts for the synthesis of aromatic acetals |
| topic | nanocellulose hydrogels cellulose-based nanosponges heterogeneous catalysis acetalization metal-catalyzed reactions sustainability |
| url | https://www.mdpi.com/2310-2861/8/1/54 |
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