Amine-Functionalized Sugarcane Bagasse: A Renewable Catalyst for Efficient Continuous Flow Knoevenagel Condensation Reaction at Room Temperature

Abstract

A biomass-based catalyst with amine groups (–NH2), viz., amine-functionalized sugarcane bagasse (SCB-NH2), was prepared through the amination of sugarcane bagasse (SCB) in a two-step process. The physicochemical properties of the catalyst were characterized through FT-IR, elemental analysis, XRD, TG, and SEM-EDX techniques, which confirmed the –NH2 group was grafted onto SCB successfully. The catalytic performance of SCB-NH2 in Knoevenagel condensation reaction was tested in the batch and continuous flow reactions. Significantly, it was found that the catalytic performance of SCB-NH2 is better in flow system than that in batch system. Moreover, the SCB-NH2 presented an excellent catalytic activity and stability at the high flow rate. When the flow rate is at the 1.5 mL/min, no obvious deactivation was observed and the product yield and selectivity are more than 97% and 99% after 80 h of continuous reaction time, respectively. After the recovery of solvent from the resulting solution, a white solid was obtained as a target product. As a result, the SCB-NH2 is a promising catalyst for the synthesis of fine chemicals by Knoevenagel condensation reaction in large scale, and the modification of the renewable SCB with –NH2 group is a potential avenue for the preparation of amine-functionalized catalytic materials in industry.

A small molecule inhibitor of Nox2 and Nox4 improves contractile function after ischemia–reperfusion in the mouse heart

“…A study by 54 showed that both overexpression of Nox 4 and reduced Nox activity by expression of a dominant negative forms impaired contractile function after ischemia reperfusion. Down regulation of Nox 4 using a plant derived flavonoid has also been shown to reduce chemical injury to isolated cardiomyocytes 55 . The available data thus suggest a complex interplay between the Nox isoforms, and that both protective and destructive processes can be initiated depending on activation state of the different enzymes, processes difficult to mimic using knockdown strategies.…”

A comprehensive review of flow chemistry techniques tailored to the flavours and fragrances industries

“…In 2017, Ma et al developed a sustainable amine-functionalised catalyst using sugarcane bagasse (SCB) as a support ( Scheme 29 ). The as-prepared catalyst was found to be highly active for effecting Knoevenagel condensation at room temperature [ 169 ].…”

Sodium Carboxymethylcellulose: A Low‐Cost and Renewable Catalyst for Solvent‐Free Knoevenagel Condensation Reaction at Room Temperature

“…designed a cellulose‐based base catalyst through in situ modification of cellulose paper with amino groups, and found it could be used as a microstructured flow‐type catalytic reactor for continuous Knoevenagel condensation; Wang et al. still prepared an amino‐functionalized cellulose membrane reactor with primary and secondary amino‐groups as the active centers for catalyzing the Knoevenagel condensation; In our recent work, we also prepared a renewable biomass‐based catalyst through amino‐functionalization of bagasse for continuous flow Knoevenagel condensation . Unfortunately, although these catalysts are effective for this reaction, there are still many drawbacks (such as the harsh preparation conditions, environmental pollution, expensive reagents used, tedious workup procedures, etc.)…”

“…Furthermore, CMC−Na is much more preferred in terms of cost and availability. Considering all of these advantages and in continuation of our efforts to develop environmental benign synthetic methodology, herein, the commercially available CMC−Na was directly used as the renewable and low‐cost superior heterogeneous base catalyst for Knoevenagel condensation under solvent‐free media at room temperature. The effect of catalyst, substance durability of this catalytic system, and recyclability of catalyst were assessed in depth.…”