Contributed by Professor James Mack, Associate Professor and Assistant Head, Dept. of Chemistry, University of Cincinnati
It is amazing that it has been about 20 years since I was first introduced to both green chemistry and mechanochemistry. I will admit when I first learned about mechanochemistry it wasn’t under the best of circumstances.
To put this in context, I was a graduate student at the University of New Hampshire studying the Diels-Alder reaction of linear acenes and fullerenes. I wanted to synthesize a novel molecule consisting of two fullerenes attached to a pentacene backbone. I worked really hard to try to make this molecule but failed each time. In my third year as a graduate student, I saw an article by Koichi Komatsu and Guan-Wu Wang where they synthesized the aforementioned molecule I spent a lot of effort trying to make. As I was reading the article, my stomach churning the whole time, I saw that they used something called “High Speed Vibrational Milling.” I remember saying “What the **** is that? You mean they did chemistry in a ‘Wig-L-Bug’?” That just seemed so wrong (for those that don’t know, a Wig-L-Bug was sometimes used to make KBr pellets for IR samples. I used it in college—who knew that it would be the focal point of my current research? Funny how that works). I was confused and skeptical, but intrigued and inspired all at the same time.
In 2002, I saw an article on the Wittig reaction using mechanochemistry. After reading that article, I knew this was an area of research I wanted to pursue further. At that time as I was thinking about starting my academic career, I thought back to a seminar visit from Mary Kirchhoff (who is now director of education at the ACS) while I was in graduate school. I first learned about green chemistry from Mary at this seminar. She talked about the 12 Principles of Green Chemistry and how we need to change the way we do chemistry in order to preserve the environment. Fortunately, I was one of the students that had a chance to meet Mary that afternoon and started asking more questions about green chemistry. Mary probably doesn’t quite remember, but my stance at the time was, “great idea, but who is going to re-learn chemistry?” I spent my undergraduate and graduate school years memorizing all of these organic reactions, how can I abandon them now? That day Mary challenged me to think about new ways that green chemistry can be part of my future. I never forgot her seminar and as I was thinking about my academic career, I thought mechanochemistry could be the key ingredient. My rationale was not to focus on changing chemical reactions, but changing the way we conduct these reactions.
Over the years, we have learned so much about mechanochemistry. Studying this area has led to fruitful collaborations with other scientists who have also embraced this new methodology and share a passion for green chemistry. Since the union between mechanochemistry and green chemistry seem like a perfect match, what prevents scientists from embracing these areas? The answer is quite simple: change. Change is hard for people, especially change in thought. Typically, when we encounter something different, our first response is skepticism and fear and my first response was not very different. In 1912, Alfred Wegener proposed that the land masses of the continents were all connected together at one point and over time they drifted apart. This was a very controversial hypothesis at the time. It took until the 1960’s for scientists to believe that continental drift actually occurs, something that I learned in the eighth grade.
There are many stories like this in chemistry and one specifically about solvent use, but I will leave that story for another time. Since chemists have been doing things a certain way for a long period of time with a lot of success, one could ask, why change? Change is not only good, but it is inevitable. The development of new research areas allows us to discover challenges and take chemistry to new heights. Going back to Alfred Wegener who passed away in 1930, it took more than 30 years after his death before his theory went mainstream, but it did go mainstream. I am very excited about the future of green chemistry and mechanochemistry. Just like you can’t teach geology without discussing plate tectonics, I look forward to the day where you can’t teach chemistry without discussing green chemistry or mechanochemistry. Maybe my grandchildren will learn about it when they are in the eighth grade.
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