Current Catalysis - Volume 10, Issue 3, 2021

Ionic Liquids (ILs) in their neoteric form have emerged to be a potential ‘green’ alternative to traditional Volatile Organic Compounds (VOCs) as solvents in different fields of industries and academia. Recent investigations on the development of multi-faceted applications of ionic liquids have revealed that they really stand for “environmentally-benign” solvents as far as their impact on the ecology is concerned. This caused them to be an exciting and lucrative subject to explore more and more, and many research groups are involved in the manifestation of their inherent undisclosed legacy. Recently, there has been a huge jump in search of an alternative to conventional metal catalysts in academia as well as in industries due to their pollution-evoking roles. Scientists have explored multiple numbers of homogeneous or heterogeneous mixtures of catalysts incorporating ionic liquids to reduce the extent of contamination in our global environment produced due to catalytic synthesis and chemical transformations. In this review, we have put our concentration on some beneficial and recently explored aspects of the successful implementation of Ionic Liquids in different forms in several fields of catalysis as a ‘green’ alternative catalyst/co-catalyst/solvent for catalysis to replace or minimize the lone and hazardous use of metal and metallic compounds as catalysts as well as chemicals like mineral acids or VOCs as solvents. Here, our study focuses on the inevitable role of ILs in several catalytic reactions like cycloaddition of CO2, electrolytic reduction of CO2, biocatalytic or enzymatic reactions, some of the important organic conversions, and biomass to biofuel conversion as catalysts, cocatalysts, catalyst activator, and solvents.

Hydrosilylation is an important transformation in organic synthesis. It has displayed widespread applications in homogenous catalysis and in the commercial production of organosilanes and organosilicon compounds. Though metals like Ru, Rh etc., were used widely for achieving hydrosilylation, the increasing environmental concerns and the search for less expensive alternatives resulted in the investigation of transition metals. Metals like Ni, Co etc., exhibit potential cost benefits, in addition to their low CO2 footprint and lower toxicity. Thus, transition metal catalysis has emerged as a promising strategy for hydrosilylation. This comprehensive review discusses the catalytic hydrosilylation of various functional groups with non-noble transition metals such as iron, cobalt and nickel in the last decade. Here, the topic is categorized based on the substrate functional groups such as aldehydes, ketones, alkenes, etc.

Aim: In the present work, the preparation and catalytic activity of spinel ferrite (MFe2O4; M = Fe, Mn, Co, Cu, Ni) nanoparticles to synthesize 5-hydroxymethylfurfural (HMF) have been discussed. Background: Ferrites possess unique physicochemical properties, including excellent magnetic characteristics, high specific surface area, active surface sites, high chemical stability, tunable shape and size, and easy functionalization. These properties make them essential heterogeneous catalysts in many organic reactions. Objective: This study aims to synthesize a series of transition metal ferrite nanoparticles and use them in the dehydration of carbohydrates for 5-hydroxymethylfurfural (HMF) synthesis. Method: The ferrite nanoparticles were prepared via the co-precipitation method, and PXRD confirmed their phase stability. The surface area and the crystallite size of the nanoparticles were calculated using BET and PXRD, respectively. Result: The easily prepared heterogeneous nanocatalyst showed a significant catalytic performance, and among all spinel ferrites, CuFe2O4 revealed maximum catalytic ability. Conclusion: Being a heterogeneous catalyst and magnetic in nature, ferrite nanoparticles were easily recovered by using an external magnet and reused up to several runs without substantial loss in catalytic activity. HMF was synthesized from fructose in a good yield of 71%.

Background: Bromination is a key reaction in the chemical industry since the organobromines find application in diverse fields like pharmaceuticals, dyes, fire retardants, and as intermediates in chemical synthesis. Objective: To carry out green, in-situ bromination of acetanilide in an aqueous medium using micellar SDS as a catalyst. Methods: Bromination of acetanilide in-situ using potassium bromide as a non-corrosive source of bromine, ceric ammonium nitrate as oxidant, micellar solution of sodium dodecyl sulphate (SDS) as catalyst and water as solvent. Results: p-Bromoacetanilide was prepared in excellent yields at room temperature using green chemistry principles. Conclusion: The presented method provides a fast and environmentally safe route for the preparation of p-bromoacetanilide from acetanilide. It avoids the use of volatile, corrosive, and hazardous substances like liquid bromine and acetic acid. The use of water makes it safer and free from hazardous organic solvents. This reaction can be suitably adopted at the undergraduate level and may find use in the synthesis of commercially important bromo compounds.