Green Manufacturing of Chemical Products
by Richard M. Goodman
Many lay persons think that all synthetic chemicals are inherently bad. They also think that natural chemicals are inherently good. Well, the reality is much more nuanced. After all, evolution has led to many natural plants, for example, developing toxic substances to ward off their destruction by insects and microbes. Also, natural products are often complex mixtures of chemical entities so that the interesting chemical species is diluted by many other chemicals, which are at best inert, at worst counter- productive. Purification from the natural product can be costly and introduce solvents or other species not beneficial.
On the contrary, synthesis can lead to the desired material without toxic or even impurities or diluents. The secret is what the chemical industry calls “Manufacture by Green Chemistry.” The concept is based on 12 principles first formulated 14 years ago. They are:
- Atom economy
- Less hazardous chemical syntheses
- Designing safer chemicals
- Safer solvents and auxiliaries
- Design for energy efficiency
- Use of renewable feed-stocks
- Reduce derivatives
- Design for degradation
- Real-time analysis for pollution prevention
- Inherently safer chemistry for accident prevention
Some of the terms are obvious, I’ll define the others.
Atom economy means: Synthetic methods should be designed to maximize the incorporation of all materials used in the process into the final product, i.e. not by products or impurities.
Catalysis means: Catalytic reagents (as selective as possible) are superior to stoichiometric reagents, that is, as in nature the right catalyst can cause the desired reaction without any excess chemical material.
Design for degradation means: Chemical products should be designed so that at the end of their function they break down into innocuous degradation products and do not persist in the environment.
This primer hopefully shows how the proper use of chemistry principles can lead to a greener environment.
Richard M. Goodman, PhD, is a chemical scientist and consultant focusing on how surface science concepts can solve real world problems. The periodic column considers aspects of sustainability from a scientific perspective. See Goodman’s profile with Association of Consulting Chemists and Chemical Engineers (ACC&CE) at www.chemconsult.org.