Green chemistry brings its virtues to the classroom

June ACCN
GREEN CHEMISTRY

Why teach green chemistry? It’s a reasonable question to ask. Green chemistry is not so much a sub-discipline of chemistry — like analytical or organic chemistry — as it is an overarching philosophy of how to think about implementing the tools in the chemical tool-box in a way that leads to safer products and more sustainable processes.

From an industrial perspective this philosophy is critical. New technologies to address the environmental impact of current processes are gradually being implemented across various markets. At the same time incumbent industrial processes are increasingly subject to greater regulation and higher environmental standards. Training the next generation of chemists and engineers in the principles of green chemistry will make them more competitive in the job market and strengthen the capacity of industry to address the environmental challenges of doing chemistry. Above all, students will acquire the background and knowledge to determine how a new molecule they might make can influence the environment or human health.

The chemical industry has an interest in becoming greener, a qualification that is of ever increasing importance to successful businesses. Of the 12 fundamental principles put forward by Paul Anastas and John Warner in their seminal book Green Chemistry: Theory and Practice, almost half deal with process efficiency and the reduction of waste. By applying these principles to a chemical synthesis, the result could lower costs and enhance the process’ business viability.

In fact, I would argue that chemists who have been involved in scale-up efforts have already grappled with incorporating these principles into their work. It might mean looking for opportunities to use catalysis, avoiding auxiliaries and protecting groups, or increasing the intensity or throughput of a set of reactions. Introducing young chemists to these concepts will highlight the practical relevance of many of the chemical tools and approaches they learn in undergraduate courses and their early research careers. The message should be: “Not only can you make useful molecules, you can use your knowledge to make them in cheaper, cleaner, and safer ways”.

Green Chemistry

Consumers are also putting greater demands on the chemical industry by demanding safer products that can be produced in an environmentally responsible fashion. Here green chemistry can also guide chemists in meeting these challenges. For example, searching for less toxic ingredients for personal care products requires researchers to understand what chemical structures and their properties give the desired activity and which lead to potential hazards and toxicity. The full assessment of diverse hazards may not be straightforward, since it must weigh the negative impacts of one chemical compound against those of another. Green chemistry offers a framework for understanding the merits and drawbacks of potential solutions, facilitating the selection or invention of a new approach.

More significantly, these real-world problems of toxicity, safety, and sustainability call for a multi-disciplinary approach and familiarity with many branches of chemistry. By educating students in green chemistry, they will have a guide to make connections between disparate fields of chemistry and a strategy for applying these fields to particular chemical problems.

Such an education can overcome curriculum limitations such as those cited by Warner himself, who has repeatedly lamented the fact that a typical chemistry undergraduate program includes no training or background in toxicology. His complaint is warranted: we give young chemists a great education in modern synthetic methods and the background needed to make new compounds and materials, but we fail to give them the tools to recognize the potential toxicity and environmental impact of any new substance they may bring into the world.

What, then, should an education in green chemistry include? There are numerous ways that these principles can be incorporated into undergraduate and graduate training. For example, an advanced course in organic synthesis can readily include an introduction to scale-up work and process development. Case studies could be taken from winners of the US Environmental Protection Agency’s Green Chemistry Challenge awards, which can facilitate discussions of topics such as process mass intensity or innovative catalysis. An introduction to toxicology would give young chemists the capacity to recognize the toxicity inherent in certain chemical structures and approach their work from the standpoint of making or using safer chemicals.

Educators, for their part, can readily assemble this material from places like Beyond Benign, which is dedicated to developing and disseminating teaching resources. As part of its “Green Chemistry Commitment”, this organization calls on chemistry departments to share best practices and participate in working groups to create even more of these educational resources.

A course dedicated to green chemistry principles and industrial practice would be ideal for advanced undergraduate or graduate students. The multidisciplinary nature of green chemistry lends itself to themes that would not otherwise be covered in a chemistry degree, including life-cycle analysis, resource depletion of non-renewables, and strategies for designing greener chemical processes.

Ultimately, although it is not among the principles of green chemistry, a key concept we should convey is that of continuous improvement. The ideal chemical process may be unobtainable, but we can almost always improve upon an existing product or process through the application of knowledge, innovation, and determination.