Innovative processes for synthesis of ionic liquids and their industrial applications

The present PhD Thesis has been focused on the development of innovative processes for the synthesis of ionic liquids and their industrial applications. With this aim in view, three main synthetic pathways have been studied and optimized according to the principles of green chemistry. In particular, concerning the ionic liquids (ILs) obtained directly by simple alkylation reaction, [BMIM]Cl has been chosen being today, probably, the most used IL. It is indeed the precursor of the widely employed class of [BMIM] based ILs and, furthermore, it is one of the few ILs able to dissolve cellulose and other biopolymers. On the other hand, concerning hydrophobic ILs arising from metathesis reactions, fatty acid ionic liquids have been selected. Finally, different types of protic ionic liquids have been synthesized, such as guanidinium hydrogen sulfate and methylcarbonate. The prepared ionic liquids have been successfully applied for the transformation of biopolymers such as cellulose into natural building blocks or into new materials such as 5-hydroxymethylfurfural (HMF), levulinic acid (LA) or cross-linked chitosan. Today, the challenge is to establish if many promising laboratory results can become commercially sustainable processes. To achieve this objective, it is necessary to verify if the processes carried out in ILs are lesser waste producing, energy demanding and material consuming than the alternative reactions with molecular solvents or catalysts. This comparison should take into account all the above-mentioned processes, including IL synthesis, product extraction and IL recycle. This thesis, taking into account some processes and products that are today chemical engineering challenges, aimed to demonstrate how it is possible to develop new processes applicable on industrial scale based on ionic liquids, starting from the adequate choice of the ionic liquid and the optimization of its synthesis procedure.