Title: Examples of xylochemistry: colorants and polymers
Journal: Green Chemistry
Wood has been used for thousands of years for buildings, furniture, paper, and heat, but did you know that the components of wood can actually be used for far more interesting chemical applications? Today, the chemical industry relies primarily on petroleum and other nonrenewable resources to produce the countless chemical compounds that are used to make products that we use everyday. From plastics and polymers to dyes and pharmaceuticals, petroleum-based chemicals are ubiquitous in today’s society. However, with growing populations and diminishing fossil fuel supplies, the chemical industry will need to look elsewhere for future feedstock sources. A sustainable and renewable source capable of many different chemical conversions is right in our backyard: Wood!
Wood is not a simple material; it is actually a highly complex composite, made up primarily of the biopolymers cellulose, hemicellulose, and lignin (Figure 1). These components each have slightly different compositions and can thus each be broken down into distinct feedstocks that can chemically branch off into many unique products. The researchers here focused only on lignin and the conversion of lignin into indigo dyes – think blue jeans – and a variety of different polymer precursors shown in Figure 2.
Wood is a really tough material but many methods are available to break the strong bonds – you can heat it, zap it, or react it. These processes convert the lignin into smaller compounds known as xylochemicals (Figure 2). Xylochemicals are compounds related directly to woody material and are ready to undergo more useful chemical transformations because they are no longer in polymer form. Using a handful of well-established organic chemistry reactions, the authors were able to convert the xylochemicals into indigo dyes (compounds 3 and 4) and a variety of polymer precursors (5, 6, and 7). These polymer precursors are used to form the well-known polymers Nylon and Perlon which are used to produce fabrics, cookware, and machine parts. Most notably, Nylon is the durable polymer that keeps parachutes and hot air balloons from tearing and degrading.
The authors here only show a few examples of what wood can be used to produce, but there are many more like solar panel films, conductive fibers, biofuels! Interested readers are encouraged to check out a publication on wood-derived materials for green electronics, biological devices, and energy applications.