Polyethylene glycol and solutions of polyethylene glycol as green reaction media

Abstract

In this review, we examine the concept that aqueous biphasic reactive extraction (ABRE) can successfully integrate the solvent properties of polyethylene glycol (PEG) and its phase-transfer characteristics into a single efficient system which can additionally be manipulated to facilitate the separation of reactants and/or catalysts from products. We also suggest that the properties of these systems may recommend them as being relatively environmentally benign in comparison to the current use of organic solvents in extraction and in reactive extraction. In developing this concept, we review a number of the physical and chemical properties of PEG and aqueous solutions of PEG in the context of recent applications to chemical reaction engineering. Thus, we cover the interesting physical properties of PEG solutions in water, their unique solvent properties, and finally the metal cation coordination ability of PEG solutions. These properties are important in the application of low molecular weight liquid PEG as a solvent in chemical reactions; in the use of PEG as an alternative phase-transfer catalyst (PTC); and in the application of ABRE in the development of alternative pulping processes, catalytic chemistry, and enzymatic catalysis.

Dissolving of cellulose in PEG/NaOH aqueous solution

“…Poly(ethylene glycol) (PEG) is a typical environmental benign molecule, and its aqueous solution, especially the PEG-base aqueous biphasic systems (ABSs), such as the mixture of PEG with NaOH, Na 2 S, Na 2 CO 3 etc., are regarded recently as a potential green solvent system (Chen et al 2005), which had been applied in both separation lignin from wood and organic reactions.…”

A Sustainable and Efficient Synthesis of Benzyl Phosphonates Using PEG/KI Catalytic System

“…Polyethylene glycol (PEG) is an environmentally benign alternative reaction medium in synthetic chemistry (Chen et al, 2005), and used in various substitution, oxidation and reduction reactions. PEG and its monomethyl ethers have been widely used as phase transfer catalyst (PTC) in many organic reactions (Timko et al, 1977; Dickerson et al, 2002; Chandrasekhar et al, 2003), due to their unique advantages of high thermal stability, negligible vapor pressure, low cost, easy availability and recyclability.…”

Microfluidic fabrication of water-in-water (w/w) jets and emulsions

“…In the field of green chemistry, immiscible water-based solutions have been used for alleviating harmful effects to the environment and allaying environmental concerns 21 in applications, such as solvent extraction where selected species, for instance, metal ion complexes 22 and ruthenium red, 23 are separated. These so-called aqueous two-phase systems (ATPS) can form when two chemically dissimilar polymers or a polymer and a salt are mixed in water at sufficiently high concentrations.…”