Alkali lignin degradation with aqueous ammonium-based ionic liquid solutions

In this work, we developed a green route to increase the added value of the lignocellulose material. Our proposed method involves ammonium-based ionic liquid selective fractionation of the lignin into essential poly-hydroxy or phenolic compounds. The selected ionic liquids (ILs) are di-isopropylethylammonium chloride ([DIPEA][Cl]) and di-isopropylethylammoniumbenzoate ([DIPEA][Bn]). The depolymerized solution was characterized by chromatographic (GPC and GCMS) and spectroscopic (FT-IR, (HNMR)-H-1 and (CNMR)-C-13) techniques. The results of the analysis proved that the polymeric structure of lignin is converted into its monomers and oligomers. This confirms the potentiality of [DIPEA][Cl] and [DIPEA][Bn] ILs for the conversion of lignin into valuable aromatic compounds. In addition, our study reveals the bi-functional nature (solvation medium + catalytic agent) of the selected ILs for the depolymerization of the lignin. Since lignin is well recognized as a suitable resource for the essential chemicals, therefore, the present study is very useful in refining an alternative source for the clean production of the valuable chemicals. (C) 2020 Elsevier Ltd. All rights reserved.