Archive for October, 2015
Friday, October 23rd, 2015
Steve Bachrach on his own blog has commented on a recent article[1] discussing the structure of the trimer of fluoroethanol. Rather than the expected triangular form with three OH—O hydrogen bonds, the lowest energy form only had two such bonds, but it matched the microwave data much better. Here I explore this a bit more.
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References
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J. Thomas, X. Liu, W. Jäger, and Y. Xu, "Unusual H‐Bond Topology and Bifurcated H‐bonds in the 2‐Fluoroethanol Trimer", Angewandte Chemie International Edition, vol. 54, pp. 11711-11715, 2015. http://dx.doi.org/10.1002/anie.201505934
Tags:Atoms in molecules, chemical bonding, Diagram, Hydrogen bond, Interesting chemistry, low energy structure, lowest energy form, microwave, Steve Bachrach
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Friday, October 23rd, 2015
I have previously shown the grave of William Perkin, a great british organic chemist. On a recent visit to Paris, I went to see the crypt in the Panthéon, the great french secular necropolis. What a contrast to Perkin!
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Tags:Historical
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Wednesday, October 14th, 2015
In Jingdezhen an Imperial Kiln was built in 1369 to produce porcelain that was “white as jade, thin as paper, bright as a mirror and tuneful as a bell”. It’s the colours of the glazes that caught my eye, achieved by a combination of oxidative and reductive firing in the kiln, coupled with exquisite control of the temperature.
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Tags:Historical, Interesting chemistry
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Friday, October 9th, 2015
This comes to you from China, and the city of Suzhou. To set the scene, cities in China have a lot of motorbikes. Electric ones. With their own speed units, a % of Panda speed. 
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Tags:Interesting chemistry
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Thursday, October 1st, 2015
A fascinating re-examination has appeared[1] of a reaction first published[2] in 1960 by Wittig and then[3] repudiated by him in 1964 since it could not be replicated by a later student. According to the new work, the secret to a successful replication seems to be the presence of traces of a nickel catalyst (originally coming from e.g. a nickel spatula?). In this recent article[1] a mechanism for the catalytic cycle is proposed. Here I thought I might explore this mechanism using calculations to see if any further insights might emerge.
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References
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S.A. Künzi, J.M. Sarria Toro, T. den Hartog, and P. Chen, "Nickel‐Catalyzed Cyclopropanation with NMe4OTf and nBuLi", Angewandte Chemie International Edition, vol. 54, pp. 10670-10674, 2015. http://dx.doi.org/10.1002/anie.201505482
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V. Franzen, and G. Wittig, "Trimethylammonium‐methylid als Methylen‐Donator", Angewandte Chemie, vol. 72, pp. 417-417, 1960. http://dx.doi.org/10.1002/ange.19600721210
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G. Wittig, and D. Krauss, "Cyclopropanierungen bei Einwirkung von N‐Yliden auf Olefine", Justus Liebigs Annalen der Chemie, vol. 679, pp. 34-41, 1964. http://dx.doi.org/10.1002/jlac.19646790106
Tags:activation free energy barriers, Cambridge, energy, energy relative, Interesting chemistry, nickel-carbene product
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