March 20, 2014

Rules to Design By: Green Chemistry Principles

Science Lab at Seventh Generation

While researching an article on Green Chemistry, I stumbled across an entry on the subject in the ever amazing Wikipedia. It contained something that I didn't know existed: a set of principles to guide chemists in greening their labs and the things those labs create.

Principles, of course, are always a good thing because they set certain benchmarks and establish concrete guidelines for whatever it is we're trying to do. Whenever a decision comes up as we proceed, we can compare all our possible choices to the principles at hand. When we do, we often find that there's no decision to be made at all. The principles make it for us.

In the case of green chemistry, the 12 principles were created to encourage the design of products and processes that minimize the use and generation of hazardous substances. I can't for a moment pretend to know what some of these principles are about. ("Stoichiometric reagents," for example, is a pretty scary term.) But the principles are not for me. They're for the people who are actually out there mixing things up. They're only for you and me in the sense that as they ripple through the chemical community, they'll eventually trickle down to us in the form of safer, healthier alternatives to today's more hazardous products and processes.

When it comes to chemistry and all the substances it's constantly creates (The EPA gets approval applications for roughly 2,000 new chemicals every year - more than five new materials every day), it's obvious that some guidance is definitely needed, but clearly lacking. Until chemical reform is a reality, these 12 Principles of Green Chemistry can help provide this:

1. Prevent waste: Design chemical syntheses to prevent waste. Leave no waste to treat or clean up.

2. Maximize atom economy: Design syntheses so that the final product contains the maximum proportion of the starting materials. Waste few or no atoms.

3. Design less hazardous chemical syntheses: Design syntheses to use and generate substances with little or no toxicity to either humans or the environment.

4. Design safer chemicals and products: Design chemical products that are fully effective yet have little or no toxicity.

5. Use safer solvents and reaction conditions: Avoid using solvents, separation agents, or other auxiliary chemicals. If you must use these chemicals, use safer ones.

6. Increase energy efficiency: Run chemical reactions at room temperature and pressure whenever possible.

7. Use renewable feedstocks: Use starting materials (also known as feedstocks) that are renewable rather than depletable. The source of renewable feedstocks is often agricultural products or the wastes of other processes; the source of depletable feedstocks is often fossil fuels (petroleum, natural gas, or coal) or mining operations.

8. Avoid chemical derivatives: Avoid using blocking or protecting groups or any temporary modifications if possible. Derivatives use additional reagents and generate waste.

9. Use catalysts, not stoichiometric reagents: Minimize waste by using catalytic reactions. Catalysts are effective in small amounts and can carry out a single reaction many times. They are preferable to stoichiometric reagents, which are used in excess and carry out a reaction only once.

10. Design chemicals and products to degrade after use: Design chemical products to break down to innocuous substances after use so that they do not accumulate in the environment.

11. Analyze in real time to prevent pollution: Include in-process, real-time monitoring and control during syntheses to minimize or eliminate the formation of byproducts.

12. Minimize the potential for accidents: Design chemicals and their physical forms (solid, liquid, or gas) to minimize the potential for chemical accidents including explosions, fires, and releases to the environment.

About the Inkslinger
The Inkslinger has written about environmental issues for over 20 years and is a freelance writer for some of America's most iconoclastic companies and non-profits. His true loves include nature, music of the Americana/rock and roll variety, interior design, books, old things, good stories, pagan rituals, and his wife of 24 years, with whom he lives in an undisclosed chemical-free rural Vermont location along with his teenage daughter and two infinitely hilarious Australian shepherds.