Facile Synthesis of Novel Polyethyleneimine Functionalized Polymeric Protic Ionic Liquids (PolyE‐ILs) with Protagonist Properties for Acid Catalysis

Abstract

Polyethyleneimine (PEI), a potent architecture backbone was explored for the synthesis of novel polymeric ionic liquids (PolyE-ILs) with protagonist properties. The simple quaternization of PEI dendrimer with Bronsted acids (H 2 SO 4 , H 3 PO 4 , CH 3 SO 3 H, CF 3 COOH and TsOH) leads to formation of series of protic PolyE-ILs with corresponding counter anions [HSO 4 ] À , [H 2 PO 4 ] À , [CH 3 SO 3 ] À , [CF 3 COO] À and [TsO] À. The physicochemical properties of synthesized PolyE-ILs were studied by using TGA, Hammett acidity, hydrodynamic radii, solubility, and elemental analysis. PolyE-ILs showed characteristic Hammett acidity (0.94-1.78), good thermal stability (< 250°C) and enhanced hydrodynamic radii. However, use of PolyE-IL can be promoted for their wide applications as an acid catalysts. The reported PolyE-IL-1 with sulfonic acid counter ion was explored as catalyst for esterification of (E)-cinnamic acids and it showed good catalytic activity. The enhanced hydrodynamic radii due to the branched architecture of PEI dendrimers facilities the separation process via Nanofiltration (NF) membrane with no membrane fouling. Thus, PolyE-ILs can be highly active, easily recoverable, and reusable catalyst for esterification reactions with superior sustainability and economics. In addition to this the present one pot PolyE-IL synthesis process is non-complex and simple as compared to conventional post polymerization, ion exchange, and nucleophilic addition etc., strategies for synthesis of PILs.

PolyE‐IL: A polymeric Brønsted acid ionic liquid catalyst for catalytic thermo liquefaction of sugarcane bagasse into carboxylic acids

“…Recently, Ukarde et al synthesized PolyE‐ILs with variable counter ions via a simple one‐pot neutralization reaction with PE using Brønsted acids such as H 2 SO 4 , H 3 PO 4 , CH 3 SO 3 H and TsOH to produce the corresponding PolyE‐ILs, i.e. [PEI] + [HSO 4 ] − , [PEI] + [H 2 PO 4 ] − , [PEI] + [CH 3 SO 3 ] − and [PEI] + [OTs] − , respectively 32 . In addition, [PEI] + [HSO 4 ] − showed excellent acidity in comparison with sulfuric acid, thus it can provide a potent substitute for sulfuric acid.…”

“…The preparation of [PEI] + [HSO 4 ] − was carried out in a fournecked round-bottom flask (RBF) along with the condenser, thermometer, addition funnel, vent, magnetic stirrer and heating plate, as reported previously. 32 A 1 g aliquot of polyethylenimine (PEI; 22.9 mmol of N on the basis of elemental analysis) and 2 g of deionized water were added to the RBF under stirring and an inert atmosphere. The solution was stirred for 15 min at room temperature (35 °C).…”

“…Bioref. 16:999-1014 (2022); DOI: 10.1002/bbb.2352[PEI] + [OTs] − , respectively 32. In addition, [PEI] + [HSO 4 ] − showed excellent acidity in comparison with sulfuric acid, thus it can provide a potent substitute for sulfuric acid.…”

A Polyethylenimine‐Functionalized Protic Ionic Liquid (PolyE‐IL) Catalyst for Conversion of Aqueous 2,3‐Butanediol into Methyl Ethyl Ketone (MEK)

“…The catalyst recycle and regeneration is an important and significant parameter for the process scale up and development of industrial catalyst. In the present process PolyE‐IL catalyst is homogenous and can be separated through membrane separation [35] . The operating temperature of the optimized process is 220 °C which is quite higher than the boiling point of MEK and water.…”

“…Concentration of nitrogen in the PEI will provide the range for sulphuric acid to be used for synthesis of PolyE‐IL‐1. It was observed that from elemental analysis PEI contains about 23mmoles of N/g of PEI [35] . Thus, the stoichiometric amount of Bronsted acid is required for complete neutralization of amine present on PEI backbone.…”