Rapid Homogeneous Acylation of Cellulose in a CO₂ Switchable Solvent by Microwave Heating

Abstract

The acylation modification of cellulose to make it processable is an important method to utilize this green, renewable material with broad prospects. However, it usually takes several hours or even more than 20 h to obtain products with a high degree of substitution (DS) through the methods reported in the existing literature, especially for cellulose acetate (CA). In this study, rapid homogeneous acylation of cellulose is achieved in a novel CO 2 switchable solvent system by using microwave heating. CA products with DS ranging from 1.83 to 2.91 can be obtained within 3−15 min by using acetic anhydride as the acylation reagent. This strategy can also be applied for the synthesis of a series of cellulose esters with different side chain lengths, and it takes only 10 min to produce cellulose esters with a DS higher than 2.20 under microwave heating. This study suggests a facile and effective method for the synthesis of cellulose esters.

Cellulose Functionalization with Methyl Ferulate in a Switchable Solvent System

“…Moreover, the solvent system used herein offers easy recovery, which is beneficial from a sustainability point of view. The solubilization of cellulose via this switchable solvent system allows further modifications to produce cellulose esters, ethers, and other cellulose derivatives. − A homogeneous modification can overcome the previously mentioned difficulties of heterogeneous processes, and, at the same time, it is a valid sustainable alternative if a switchable solvent system is used, as for instance recently demonstrated for cellulose acetate …”

Facile Fabrication of Fluorescent Cellulose with Aggregation‐Induced Emission Characteristic in a CO2 Switchable Solvent

“…As a result, the cellulose is dissolved. Interestingly, this intermediate is nucleophilic and able to induce a series of reactions such as transesterification [ 30 ] and ring‐opening polymerization, [ 26 ] and Michael addition, [ 27 ] resulting in cellulose esters and cellulose ether, respectively. What's more important, this intermediate can be trapped by using electrophiles such as benzyl bromide or methyl iodide, leading to the synthesis of cellulose carbonate with high DS (1.06).…”

Continuous-Flow Microwave Reactor for High-Performance Heating of a Dynamic Chemical Reaction System

“…8 The selectivity attained through microwave heating is remarkable at 94.2%, while air heating yields only 51.1%. In the homogeneous acylation reaction of cellulose, microwave heating can be used to obtain cellulose acetate with a degree of substitution of 1.83 to 2.91 within 3 to 15 min, while the traditional method requires more than 20 h. 9 In biodiesel production using vegetable oil and methanol, microwave continuous-flow reaction chambers are a promising alternative to the traditional heating method. The energy consumption of the biodiesel prepared through the microwave continuous flow reaction chamber is significantly lower at 26 kJ/L than the traditional heating method, which requires 94.3 kJ/L.…”