What They Are:
Solvents, as chemicals that dissolve solutes and form solutions, facilitate many reactions. They are used for everything from extractions to dry cleaning to paints and much more. They can be as benign as water or as hazardous as dichloromethane. Because they are so ubiquitous, using toxic solvents affects millions of workers every year and has implications for consumers and the environment as well.
How They Relate to Green Chemistry:
Solvents are a key priority when greening chemistry because they are used in high volumes and many are volatile organic compounds. Their use creates large amounts of waste, air pollution, and other health impacts. Finding safer, more efficient alternatives or removing solvents altogether is one of the best ways to improve a process or product.
Below, find information on techniques and applications for solvent replacement and/or removal in various process conditions, as well as methods to assess the sustainability of solvents.
- Safer Solvents and Auxiliaries – The greenest solvents are the ones that aren’t used, but choosing innocuous ones when needed is a key component of green chemistry
- Inherently Safer Chemistry for Accident Prevention – Using safer solvents and preventing hazardous waste minimizes the potential for chemical accidents, including releases, explosions, and fires
- Eliminate and Minimize Hazards and Pollution – Choosing inherently safer solvents (or no solvents at all) prevents the generation of unnecessary hazardous waste while improving the safety of the chemical processes involved
Scientists at the Los Alamos National Laboratory have developed a process that uses supercritical carbon dioxide in one of the steps of chip preparation, and it significantly reduces the quantities of chemicals, energy, and water needed to produce chips.
Cosmetics and Personal Care Products
Eastman Chemical Company developed a solvent-free biocatalytic process for manufacturing cosmetics and personal care products. This method, which uses enzymes, achieves higher yields, saves energy and is less expensive. At the same time, it obviates the need for hazardous acids and organic solvents. Another bonus – milder reaction conditions enable the synthesis of an array of compounds (and, by extension, product opportunities) that weren’t possible under the conventional, harsher conditions. (PGCCA 2009)
Chem21 Solvent Selection Guide - A comprehensive selection guide of common solvents and emerging solvents ranked by health, safety, and environmental criteria.
Solvent Selection Tool - This interactive tool allows you to select solvents based upon the Principal Component Analysis (PCA) of the solvent's physical properties.
Solvent Selection Guides for Pharmaceutical Chemistry (GC&E Presentation, 2016)
Using Water to Replace Organic Solvents: Switchable Water (Webinar, 2013) - In this webinar recording, Dr. Philip Jessop (Queen's University) discusses his "switchable water" research which has applications in many areas including removing organic contaminants, collapsing emulsions and suspensions, catalysis, settling clay, and controlling conventional surfactants.
Smart Solvent Selection (ACS News, 2016)
What Do Solvents Do, Anyway? (The Nexus, 2016)
Green Solvents I—Properties and Applications in Chemistry (2012) - Covering biocatalysis to thin-layer chromatography to polymerizations applications, this book provides an overview of key bench to commercial level implementations of greener solvents
Green Solvents II—Properties and Applications of Ionic Liquids (2012) - Ionic liquids have long been considered greener solvent alternatives for many reasons, such as their good thermal stability and ability to not decompose over large temperature ranges. This text covers the history, developments, and applications of ionic liquids as solvents.