From building blocks to innovations: a critical review of amino acid-based ionic liquids versus conventional ionic liquids

With the growing environmental concerns, numerous studies on the synthesis and application of ionic liquids (ILs) have been carried out. Researchers have investigated a trend in the development of ILs from natural renewable resources such as amino acids, also called amino acids-based ILs (AAILs). Unlike hazardous chemical solvents, AAILs are considered to obey the principles of green chemistry. This review compares the applications of AAILs with conventional ILs and covers the critical aspects. The first objective is to present an in-depth analysis of distinct synthetic methodologies tailored for the development of AAILs. The advantages and disadvantages of the various synthetic approaches are detailed. The second objective of this minireview also focuses on the ecotoxicity data and biodegradation data. The third objective of this minireview is to list AAILs for the extraction of metal ions, and AAILs as catalysts or solvents in organic transformation reactions in the recent five years. The last objective includes AAILs as anti-corrosion inhibitors, which is a useful aspect when the applications of AAILs are upscaled. All these objectives are compared with the conventional ILs where possible.