Posts Tagged ‘physicist’

Are close H…H contacts bonds?

Friday, October 7th, 2011
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The properties of electrons are studied by both chemists and physicists. At the boundaries of these two disciplines, sometimes interesting differences in interpretation emerge. One of the most controversial is that due to Bader (for a recent review, see DOI: 10.1021/jp102748b) a physicist who brought the mathematical rigor of electronic topology to bear upon molecules. The title of his review is revealing: “Definition of Molecular Structure: By Choice or by Appeal to Observation?”. He argues that electron density is observable, and that what chemists call a bond should be defined by that observable (with the implication that chemists instead often resort to arbitrary choice). Here I explore one molecule which could be said to be the focus of the differences between physics and chemistry; cis-but-2-ene.

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Gravitational fields and asymmetric synthesis

Saturday, November 20th, 2010
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Our understanding of science mostly advances in small incremental and nuanced steps (which can nevertheless be controversial) but sometimes the steps can be much larger jumps into the unknown, and hence potentially more controversial as well. More accurately, it might be e.g. relatively unexplored territory for say a chemist, but more familiar stomping ground for say a physicist. Take the area of asymmetric synthesis, which synthetic chemists would like to feel they understand. But combine this with gravity, which is outside of their normal comfort zone, albeit one we presume is understood by physicists. Around 1980, one chemist took such a large jump by combining the two, in an article spectacularly entitled Asymmetric synthesis in a confined vortex; Gravitational fields and asymmetric synthesis[1]. The experiment was actually quite simple. Isophorone (a molecule with a plane of symmetry and hence achiral) was treated with hydrogen peroxide and the optical rotation measured.

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References

  1. R.C. Dougherty, "Chemical geometrodynamics: gravitational fields can influence the course of prochiral chemical reactions", Journal of the American Chemical Society, vol. 102, pp. 380-381, 1980. http://dx.doi.org/10.1021/ja00521a067