Green Chemistry: Theory and Practice Chemical Engineering Progress, Sep 2000 by Alexander, Gregory The concept of green chemistry has gained prominence in the last several years, as evidenced by the annual Green Chemistry and Engineering Conference sponsored by the American Chemical Society, and by the Presidential Green Chemistry Challenge Award. Anastasia and Warner have written a short and useful introductory text on the subject. Their working definition of green chemistry is "... the utilization of a set of principles that reduces or eliminates the use or generation of hazardous substances in the design, manufacture, and application of chemical products." The authors clarify the definition by listing the 12 principles of green chemistry. These, paraphrased, are: (1) minimize waste generation; (2) maximize atom economy; (3) minimize the use of toxic ingredients; (4) maximize the product efficacy/toxicity ratio; (5) minimize the use of solvents and other auxiliary substances; (6) maximize the use of renewable resources; (7) minimize energy use; (8) avoid derivitization (use of blocking groups, protection/deprotection, temporary modification of physical/chemical processes) to the lowest practical limit, since such steps can require additional reagents and generate waste; (9) use catalytic, rather than stoichiometric, reagents; (10) make products that do not persist in the environment; (11) measure and control processes for the prevention of hazardous-substance production; and (12) select raw materials and intermediates so as to minimize accidents and exposure. Several of the concepts are familiar. For example, principles Nos. 3 and 4 are the tenets behind the research in formaldehyde-free and non-isocyanate cure coatings. Principle No. 10 is the one behind research in biodegradable plastics. No. 12 proposes that we design safety into the process from a chemistry standpoint, which is consistent with today's standard approach of engineering safety into a process. Others are less familiar, yet obvious upon reflection. Nevertheless, implementation of these criteria is not necessarily so straightforward. Consider, for example, principle No. 5. Industrial chemists and engineers typically focus on ease of processing, yield, process safety, and economics. Our training has prepared us to focus on these issues. We are rewarded for achieving positive outcomes against these metrics. Reducing or eliminating solvents as an a priori goal in developing a new product or process requires a major shift in mindset.