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Physical Chemistry

‘Nothing Goes On Forever’

by Bibiana Campos Seijo
May 4, 2015 | A version of this story appeared in Volume 93, Issue 18

That’s the first sentence of a great Angewandte Chemie article by George M. Whitesides in which he looks at the evolution of chemistry from World War II until now (2015, DOI: 10.1002/anie.201410884).

The postwar years were very kind to chemistry. Efforts to analyze and understand complexity gave birth to academic chemistry, while society’s need for essential chemicals such as high-octane fuels or synthetic rubber created a vibrant chemical industry. But of course, “nothing goes on forever,” and by the time we get to the 1980s, Whitesides deems this prolific era “over.” He argues that the public perception of chemistry today remains “unarguably essential, but not exciting.” But he also points to opportunities. In fact, he goes on to describe many of these as “urgent necessities,” including rational design of drugs, determining how the brain works, and more. Whitesides offers chemistry as “the most plausible expertise” to resolve these challenges.

But if there is little appreciation of a field, there is little public support for it and ultimately little money. I agree this is a serious and real risk: Little support will influence the decisions made by governments, whose preference in terms of areas to invest in may fluctuate with public opinion, which will of course directly affect the monies that go to funding bodies.

Interestingly, Whitesides notes that other scientific fields “manage to be exciting.” I spoke about this during the American Chemical Society Board of Directors open meeting at the recent ACS national meeting in Denver. I argued that other sciences are perceived as “sexier.” Physicists talk about the stars, the origin of life, black holes, and the Big Bang Theory; biologists talk about Earth, oceans, and all living things including cute furry animals that make people go “ooooh.” But chemists talk about chemicals and man-made stuff, terms that often carry negative connotations. So I’d agree that chemistry has a serious image problem and advocate that individual chemists and organizations and societies like ACS need to work together to turn that around.

150 years of benzene

Besides BASF’s 150th anniversary (see page 9), 2015 marks another 150-year milestone: that of August Kekulé’s cyclohexatriene representation of the structure of benzene. Kekulé was a chemistry professor at Belgium’s University of Ghent when at the beginning of 1865 he revealed his molecular vision of benzene in a short article presented at a meeting of the Société Chimique de Paris (Bull. Soc. Chim. de Paris 1865,3, 98) .

The empirical formula for benzene had been known for some time, but its highly unsaturated structure was challenging to determine. In the preceding years, other scientists had suggested structures containing multiple rings or double bonds, but the evidence at the time was insufficient to pinpoint the correct structure. So chemists of Kekulé’s day had to rely on evidence from chemical reactions (wet chemistry) rather than using instrumental methods.

Kekulé suggested that benzene contained a six-membered ring of carbon atoms with alternating single and double bonds. But it wasn’t until 1929 that the cyclic structure of benzene was finally confirmed by crystallographic analysis.

In any case, Kekulé’s idea of assigning certain atoms to certain positions within the molecule and connecting them using what we now call bonds makes him the founder of the theory of chemical structure. He was hailed as one of the most prominent chemists in Europe at the time.

The new understanding of benzene, and hence of aromaticity, was very important for both pure and applied chemistry. To this day, aromaticity is a matter of discussion for the chemical science community as evidenced by the arguments expressed in “Aromaticity for All,” a recent article by C&EN Senior Correspondent Stephen Ritter about how the concept should be invoked. You can follow and contribute to the debate at http://cenm.ag/aromaticity.

Views expressed on this page are those of the author and not necessarily those of ACS.

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