Meet the Scientists
Turning to the Kitchen for Help
The ubiquitous microwave oven. A huge time-saver for the cook in a hurry. And now, an
environmental benefactor? That’s what Rajender S. Varma is working to accomplish in his
research as a chemist at the EPA. In the May 2008 issue of the ACS journal Accounts of
Chemical Research, Dr. Varma reviewed his and other researchers’ work that uses modified
microwave ovens to carry out the wide variety of chemical reactions needed to make pharmaceuticals and other fine chemicals without the use of toxic solvents.
“We started doing this chemistry using kitchen microwaves for doing reactions in the
solid state, meaning no solvent use at all. You just mix two things together, sometimes
using clay, silica, or alumina as a support or even as a catalyst, to do the things. Actually, I started this chemistry with a high school student who wanted to do some chemistry
with me, and I wondered how I can give some high school student who was not exposed
to chemical techniques something valuable to do…. And that was the humble beginning, which grew into a big, big area afterward, and we were so busy ourselves and folks
around the globe doing all kinds of experiments. Initially, there was no controlled microwave devices available for chemical reactions, and people were using kitchen microwaves.”
Joseph DeSimone, Ph.D.
Microwave ovens designed for home use proved to be too powerful for chemists, but now
there are commercial chemical microwave reactors that researchers can use to carry out
chemical reactions in a finely tuned manner. As a result, microwave-assisted chemistry has
become an important tool in the green chemistry workshop. Using microwaves to power
chemical reactions enables chemists to eliminate solvents completely in some instances. In
other cases, water or the environmentally friendly solvent known as polyethylene glycol can
replace a variety of organic solvents.
The ability to fine-tune chemical reactions has also improved the efficiency of these reactions, meaning that they use fewer raw materials to create more useful chemicals with less
waste. Microwaves can also slash the amount of energy used to make drugs and other useful
chemicals.
But ask Dr. Varma if he’s pleased that microwave-assisted chemistry is being widely
adopted by the green chemistry community, and the answer is not what you might expect.
James E. Hutchison, Ph.D.
“The ‘green’ word should go away, that everything we do should pertain to green. Everybody should think about the implications of using a reagent or a chemical or a catalyst
or a solvent that is not going to be that harmful once you’re done with the materials.
Once you have that thinking process embedded in the psyche of the practicing chemist,
we won’t have to use the word green anymore.”
From Ultra Big to Ultra Small
Each year, chemical companies manufacture thousands and thousands of tons of polymers
and other bulk chemicals that are essential for everyday life. Pharmaceutical companies
make hundreds of tons of the biologically active ingredients that make up the drugs we take
for a wide range of ailments. When chemicals are produced on such an enormous scale, the
potential is huge for saving some green by going green. Not surprisingly, then, chemical and
pharmaceutical companies are remaking themselves into more sustainable, resource-con-serving operations. No longer is the attitude one of make it, sell it, and worry about cleaning
up any mess later. Instead, green chemistry is now, by and large, an ethos that is spreading
rapidly throughout these two industries.
Today, though, there is an opportunity to get things right from the get-go in what many
experts are hailing as an industry that will become an integral part of nearly every aspect of
modern life. Here is Dr. James E. Hutchison of the University of Oregon, who in March 2008
discussed nanotechnology and sustainability in ACS’s peer-reviewed journal ACS Nano:
“I expect nanomaterials or nano-enabled materials will touch every single sector of our
society, of our economy and our society, so the distribution of this technology is likely
to be broader than any single thing we’ve seen before…. Nano is also viewed as the
