Homogeneous synthesis of cellulose acetoacetate by Michael addition in a CO2 switchable solvent for visible detection of Fe3+ ion

Herein, we propose the homogeneous synthesis of cellulose acetoacetate (CAA) by taking advantage of a CO₂ switchable solvent system. A nucleophilic carbonate cellulose intermediate was in situ formed during the dissolution process, which could initiate the grafting of diketone (DK) directly onto the cellulose backbone through Michael addition. A series of CAA samples with degree of substitution (DS) values ranging from 0.18 to 0.74 were prepared by adjusting different reaction conditions such as temperature, time, and the feeding ratio of DK. In addition, metal ion colorimetric test paper was prepared using the good solubility of the CAA sample, which can achieve selective color response to Fe³⁺ ions. This study further confirms the feasibility of novel cellulose derivatives by Michael addition in the CO₂ switchable solvent system. And it also indicates that CO₂ switchable solvents have great potential for functionalization of cellulose.