Inside Cover: Solvent‐Free Catalytic Depolymerization of Cellulose to Water‐Soluble Oligosaccharides (ChemSusChem 8/2012)

Abstract

Several key factors that govern the catalytic conversion of lignin into smaller molecules have been neglected. In the report by Rinaldi et al. on some of the many different facets of solvents in the hydrogenolysis of diphenyl ether and, ultimately, of organosolv lignin with Raney nickel are uncovered. Most importantly, solvents are not bystanders in these reactions. The Lewis basicity of solvents very much affects the catalytic activity of Raney nickel, so in nonbasic solvents the catalyst is an extremely active catalyst for hydrogenolysis and hydrogenation, leading then to saturates. In basic solvents, however, Raney nickel is a less active, but much more selective catalyst for hydrogenolysis while preserving the aromatic products. As a result, the conversion of lignin with Raney Ni in methanol results mainly in phenols, even when performed at temperatures as high as 300 °C.

The scalability in the mechanochemical syntheses of edge functionalized graphene materials and biomass-derived chemicals

“…A rst step in realizing value from these materials is hydrolytic depolymerization to simple sugars. Previous work has shown that cellulose can be readily hydrolyzed by solid acids such as kaolinite 19 and through impregnation with minimal quantities of a strong acid [20][21][22] combined with mechanical processing. Using basic conditions, lignin can also be mechanocatalytically depolymerized.…”

Water‐Assisted Passerini Reactions under Mechanochemical Activation: A Simple and Straightforward Access to Oxindole Derivatives

“…[1,2] Mechanochemical reactions are usually carried out by milling, grinding, shearing, or pulling reactants in the absence of organic solvents or in the presence of a catalytic amount of them (liquid-assisted grinding, LAG). [3] In organic chemistry many reactions including metal-catalysed transformations, [4,5] organocatalytic [6] and enzymatic processes, [7] lignin [8] and cellulose depolymerizations, [9,10] multicomponent reactions [11] and many other [12,13] have been studied using various ball mill techniques. As a result of these studies, mechanochemical activation and techniques have revealed a variety of benefits, including faster reaction milling times, higher yield, less waste formation, enhanced selectivity, and stoichiometry control, to name a few.…”