Cellulose reactivity in ethanol at elevate temperature and the kinetics of one-pot preparation of ethyl levulinate from cellulose

Making Levulinic Acid and Ethyl Levulinate Economically Viable: A Worldwide Technoeconomic and Environmental Assessment of Possible Routes

“…One strategy to avoid the formation of humins could be the use of alcohols in the one‐pot synthesis of levulinate esters. Investigators reported a reduced production of black residues when using pure ethanol as the solvent instead of a mixture of ethanol/water . In other work with methanol instead of ethanol, investigators reported that the presence of methanol protected the intermediate furans against condensation reactions that led to humins …”

“…[94] One strategy to avoid the formation of huminsc ould be the use of alcohols in the one-pot synthesis of levulinate esters.I nvestigators reportedareduced production of black residues when using pure ethanola st he solvent instead of am ixture of ethanol/water. [106] In other work with methanol insteado fe thanol, investigatorsr eportedt hat the presence of methanol protected the intermediatef urans against condensation reactions that led to humins. [107] Thec hoice of solventp lays an important role because of the change in the free energyo fs olvation of the protons, which,a ccordingly changes their reactivity,a ffecting several reactionsi nvolved in the process.…”

Rapid Depolymerization of Decrystallized Cellulose to Soluble Products via Ethanolysis under Mild Conditions

“…Ethanolysis, breaking the glycosidic bond with ethanol rather than water, has the potential to increase cellulose conversion and yields by circumventing the solvent‐induced recrystallization that is a barrier to hydrolysis‐based processes . The associated benefit of reduced reaction severity can thus compensate for the energy required for decrystallization as part of an economically competitive and energy‐efficient process.…”

“…Previous investigations of ethanolysis reported incomplete product characterization yet have provided sufficient evidence to formulate a putative mechanism. As shown in Scheme , reported products from ethanolysis are ethyl‐glucopyranoside, 5‐ethoxymethylfurfural (EMF), and ethyl levulinate, direct analogs to the well‐known platform chemicals obtained from hydrolysis . In analogy with hydrolysis, the primary products of ethanolysis are the ethoxy‐carbohydrates.…”

“…Previous attempts at cellulose ethanolysis employed conditions that promoted conversion of the solvent into byproducts, including diethyl ether and diethoxy methane . Conversion to diethyl ether is especially problematic as the economics and environmental benefits of the solvent‐based process rely on ethanol reuse.…”