Sustainable solvents are a topic of growing interest in both the research community and the chemical industry due to a growing awareness of the impact of solvents on pollution, energy usage, and contributions to air quality and climate change. Solvent losses represent a major portion of organic pollution, and solvent removal represents a large proportion of process energy consumption. To counter these issues, a range of greener or more sustainable solvents have been proposed and developed over the past three decades. Much of the focus has been on the environmental credentials of the solvent itself, although how a substance is deployed is as important to sustainability as what it is made from. In this Review, we consider several aspects of the most prominent sustainable organic solvents in use today, ionic liquids, deep eutectic solvents, supercritical fluids, switchable solvents, liquid polymers, and renewable solvents. We examine not only the performance of each class of solvent within the context of the...

Green and Sustainable Solvents in Chemical Processes

Unique low-molecular-weight lignin with high purity extracted from wood by deep eutectic solvents (DES): a source of lignin for valorization

The purpose of this review is to give the reader a thorough background to the fundamentals and applications of pressurized hot water extraction (PHWE) for the analysis of bioactive compounds. We summarize the field in the period 2009-14, and include fundamentals of water as a solvent: equipment; method optimization; applications; coupling; and, future prospects. We highlight that solvent properties of water are tunable by changing the temperature, particularly self-ionization, dielectric constant, viscosity, diffusivity, density and surface tension. Furthermore, important aspects to consider are the risk of degradation of the analytes and other potential reactions, such as hydrolysis, caramelization and Maillard reactions that may lead to erroneous results. For the extraction of bioactive compounds, we report PHWE methods based on using water of 80-175 degrees C and short extraction times. In conclusion, PHWE provides advantages over conventional extraction methods, such as being "greener", faster and more efficient. (C) 2015 The Authors. Published by Elsevier B.V. (Less)

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Pressurized hot water extraction of bioactives

The many faces of packed column supercritical fluid chromatography--a critical review.

Dihydrolevoglucosenone (Cyrene) as a bio-based alternative for dipolar aprotic solvents.

Solvatochromic parameters for solvents of interest in green chemistry

Solvatochromic data have been collected from the literature or newly measured for 83 molecular solvents, 18 switchable solvents, and 187 ionic liquids that have been cited in the green chemistry literature. The data include the normalized Reichardt's parameter (ENT), the Nile red λmax, and the Kamlet–Taft parameters (α, β, and π*). Disagreements within the literature about the properties of glycerol and poly(ethylene glycol) have been resolved with new data. The switching of a switchable-polarity solvent (also known as a reversible ionic liquid) by CO2 causes a significant increase in polarity/polarizability (π*) but no change in the basicity (β). A switchable-hydrophilicity solvent undergoes an even greater change in polarity because it merges with an aqueous phase upon exposure to CO2. Trends observed from the data of ionic liquids are presented, along with concerns about the best method for determining the Kamlet–Taft parameters.

David A. Jessop

Papers

Solvatochromic parameters for solvents of interest in green chemistry

Solvatochromic Parameters for Solvents of Interest in Green Chemistry