Ionic Liquid‐Catalyzed Synthesis of Biomass‐Derived Tri(furyl)Methanes: A Green Approach for Electrochromic Device Fabrication

Abstract We introduce an environmentally friendly one‐pot approach for the efficient synthesis of functionalized tri(furyl)methane (TFM‐x). This method involves the reaction of biomass‐derived furans such as furfural (FAL), functionalized FAL, or 5‐hydroxymethylfurfural (HMF) with 2‐methylfuran (2‐MF) using a cost‐effective 2‐hydroxy‐ N,N ‐dimethylethane‐based acidic ionic liquid (AIL) catalyst. AIL catalyst at 60 °C showed a high yield of (5‐(bis(5‐methylfuran‐2‐yl)methyl)furan‐2‐yl)methanol (TFM‐OH) and 2‐[bis‐(5‐methylfuran‐2‐yl)methyl]‐5‐furaldehyde (TFM‐CHO), achieving complete conversion of the furan‐containing aldehyde functional group. The product selectivities were nearly 95% for TFM, 81% for TFM‐OH, and 90% for TFM‐CHO. In addition, the TFM‐x synthesis under optimized conditions were performed without using solvent. The structures of the synthesized AIL, TFM, and TFM‐x were fully characterized using 1 H‐NMR, whereas the functional groups in the prepared AIL were confirmed using FT‐IR analysis. Moreover, both TFM‐OH and TFM‐CHO were then employed as functional materials for electrochromic devices. The results showed that both compounds undergo clear reversible transitions between the transmissive yellow and red states upon exposure to different voltage conditions, with TFM─OH demonstrating a higher coloration efficiency than TFMCHO. This study presents a green and sustainable approach for synthesizing TFMs using AIL catalyst. It also emphasizes both the eco‐friendly characteristics of the catalytic system and the potential applications of the synthesized TFMs in organic‐based electrochromic devices.