From building blocks to innovations: a critical review of amino acid-based ionic liquids versus conventional ionic liquids Monisha V, Revathi Raghunath, Anisha Guha, Sunaina Sunil, Harshana Gurumoorthy, Sunita Rajamani Journal of Ionic Liquids, 2025 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.
A comparative study of ionothermal treatment of rice straw using triflate and acetate-based ionic liquids K.J. Jisha, Sunita Rajamani, Dharmendra Singh, Gyanendra Sharma, Ramesh L. Gardas Journal of Ionic Liquids, 2022 Ionic liquids (ILs) have found applications in the pretreatment of waste lignocellulosic biomass by interacting with the carbohydrate molecules present in the biomass materials. Pretreatment is essential before biomass conversion into valuable chemicals, fuels, and many other value-added products. This comparative study mainly focused on the pretreatment ability of four ILs having acetate or triflate as a common anion with different cations. Among various studied ILs, diazabicyclo[5.4.0]undec-7-ene (DBU)-based acidic ionic liquid when used as a dual solvocatalyst showed significant structural modifications of the rice straw (RS) sample, through C6-O bond breakage assisted by the tertiary nitrogen in DBU cation. Structural modifications due to the pretreatment were confirmed through SEM, PXRD, and FTIR analysis. The elemental analysis confirmed that carbon content in original RS is reduced to 29% and 20% upon ionothermal treatment of RS with IL at 90 °C and 120 °C, respectively. Additionally, TGA indicated that further pyrolysis could be easier with the pretreated rice straw yielding biochar up to 9% thereby reducing wastes. Conversion of RS was found to be 60% which reduced marginally to 50% after three cycles of recycling the IL. The findings of this work provide the proof of concept that studied IL with high thermal stability and recyclability should act as a potential solvocatalyst in sustainable pretreatment and other biomass applications.
Influence of Alkyl Substituent on Optical Properties of Carboxylate-Based Protic Ionic Liquids Gyanendra Sharma, Dharmendra Singh, Sunita Rajamani, Ramesh L. Gardas Chemistryselect, 2017 The solvation strength of N,N-dialkylethanolammonium based protic ionic liquids (PILs) have been determined by normalised Reichardt's parameter (ETN ) and molecular polarizability (αP). The solvation strength depends on the intermolecular interactions which are governed by the functional group and molecular structure of the species. So here in this work, the influence of functional groups such as –OH, –RCOOH and –R, on solvatochromic parameters of studied PILs have been discussed in terms of experimental results and relevant literature. Further the intermolecular interactions of PILs have been analyzed with the help of temperature dependant experimental refractive index data. Additionally, a positive correlation was obtained between the polarity and the refractive index of the studied PILs.
A dramatic effect of the ionic liquid structure in esterification reactions in protic ionic media Cinzia Chiappe, Sunita Rajamani, Felicia D'Andrea Green Chemistry, 2013 Bronsted acidic ionic liquids (ILs) have been synthesized and investigated as catalysts in esterification and transesterification reactions: simple and non-corrosive salts characterized by aliphatic cations associated with an “acidic” anion (in particular, [HSO4]−) gave the higher yields. A quite good correlation between IL acidity (H0) and catalytic ability was found although also the hydrophilic nature of the ionic medium probably affects the process efficiency.
Synthesis of glycerol carbonate from glycerol and dimethyl carbonate in basic ionic liquids Cinzia Chiappe, Sunita Rajamani Pure and Applied Chemistry, 2012 Glycerol carbonate is a key multifunctional compound used as solvent, additive, and building block in alternative chlorine-free processes. Here, we report the synthesis of glycerol carbonate from renewable materials (glycerol and dimethyl carbonate, DMC) using basic ionic liquids (ILs) as catalysts. After process optimization, it has been possible to isolate pure glycerol carbonate in quantitative yield using a three-fold excess of DMC and ca. 15 % of IL. The IL could be reused at least four times without any significant reduction in the conversion yield.
