Valuable new platform chemicals obtained by valorisation of a model succinic acid and bio-succinic acid with an ionic liquid and high-pressure carbon dioxide

The potential application of biomass and catalysts is crucial to form a bridge between the emerging biobased industry and the current process technology. Using this approach to succinic acid, a biomass derived acid, might lead to new routes for derivative production, opening its transition to the industrial scale. A considerable number of succinic acid-based products were obtained in this work in advanced, one-pot processes executed in a green solvent, supercritical carbon dioxide. Ionic liquids, which present an alternative to volatile and flammable solvents, allowed for a subsequent transformation of carbohydrate rich renewable feedstock by a simple reaction in alternative media. Reactions give a possibility of conversion of a cheap lignocellulosic biomass to succinic acid-based products, such as ethanol having a potential application in biorefinery, as well as to pyrrolidine-2,5-diones, representing antibiotics and to succinic acid esters, valuable platform chemicals. Mechanistic analysis of the formation of reaction products was successfully developed. The valorisation of a model succinic acid was compared with the valorisation of a bioderived succinic acid under identical reaction conditions and the results are discussed. The palladium catalyst nanoparticles formed seem to be stabilised by ionic liquids allowing for five successive cycles with efficient conversion and selectivity in the hydrogenation of bio-succinic acid. The presented valorisation of a biomass derived carboxylic acid is an excellent starting point for derivative production.