Safer solvent use in the pharmaceutical industry

Bio-based solvents

Bio-based solvents (those derived from biomass) are varied in their sources, but can broadly be classified as either carbohydrate-based by fermentation, carbohydrate-based by pyrolysis and/or chemical methods, essential oil-based, or vegetable oil-based.    

A biomass feedstock may be directly transformed into a solvent, such as bio-ethanol by the fermentation of sugars, or limonene by the steam distillation of citrus fruit peels. Some bio-based solvents are obtained after further chemical transformations of bio-based intermediates: dimethyl isosorbide is produced by methylating isosorbide (which in turn is made from hydrogenated glucose).  

There are bio-based solvents that have familiar structures and known petrochemical equivalents (ethanol, acetone, ethyl acetate etc.). These bio-based solvents can be introduced into products and processes as direct replacements if their biogenic origin is advantageous (e.g. for labelling or regulatory purposes, or for sustainability reasons). There are many other bio-based solvents with unusual chemical structures that are not easily produced from crude oil. These so-called ‘neoteric’ solvents impart unique combinations of properties that can be advantageous if understood and deployed correctly.  

Get familiar with the neoteric bio-based solvents by checking out these infographics!  

The neoteric bio-based solvents are often water soluble, high boiling and viscous. As such, the handling and application of these solvents cannot always be the same as conventional solvents. This has generated a lot of interest within academic circles, with work dedicated to overcoming any limitations and excelling in new applications. However, the redesign of large industrial processes to accommodate a viscous (and usually more expensive) solvent for instance is not greeted with the same enthusiasm. This has led to the slow adoption of bio-based solvents and the other categories of neoteric solvents.