Posts Tagged ‘Derek Barton’
Thursday, September 20th, 2018
Recently, the 100th anniversary of the birth of the famous chemist Derek Barton was celebrated with a symposium. One of the many wonderful talks presented was by Tobias Ritter and entitled “Late-stage fluorination for PET imaging” and this resonated for me. The challenge is how to produce C-F bonds under mild conditions quickly so that 18F-labelled substrates can be injected for the PET imaging. Ritter has several recent articles on this theme which you should read.[1],[2].
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References
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P. Tang, W. Wang, and T. Ritter, "Deoxyfluorination of Phenols", Journal of the American Chemical Society, vol. 133, pp. 11482-11484, 2011. http://dx.doi.org/10.1021/ja2048072
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C.N. Neumann, and T. Ritter, "Facile C–F Bond Formation through a Concerted Nucleophilic Aromatic Substitution Mediated by the PhenoFluor Reagent", Accounts of Chemical Research, vol. 50, pp. 2822-2833, 2017. http://dx.doi.org/10.1021/acs.accounts.7b00413
Tags:Antimatter, Barton, Chemistry, Derek Barton, Fluorine, Interesting chemistry, Medical physics, Medicinal radiochemistry, Natural sciences, Neuroimaging, Physical sciences, Positron emission tomography, Radiation therapy, Ritter, Tobias Ritter
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Wednesday, August 22nd, 2018
Following the general recognition of carbon as being tetrahedrally tetravalent in 1869 (Paterno) and 1874 (Van’t Hoff and Le Bell), an early seminal exploitation of this to the conformation of cyclohexane was by Hermann Sachse in 1890.[1] This was verified when the Braggs in 1913[2], followed by an oft-cited article by Mohr in 1918,[3] established the crystal structure of diamond as comprising repeating rings in the chair conformation.† So by 1926, you might imagine that the shape (or conformation as we would now call it) of cyclohexane would be well-known. No quite so for everyone!
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References
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H. Sachse, "Ueber die geometrischen Isomerien der Hexamethylenderivate", Berichte der deutschen chemischen Gesellschaft, vol. 23, pp. 1363-1370, 1890. http://dx.doi.org/10.1002/cber.189002301216
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"The structure of the diamond", Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character, vol. 89, pp. 277-291, 1913. http://dx.doi.org/10.1098/rspa.1913.0084
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E. Mohr, "Die Baeyersche Spannungstheorie und die Struktur des Diamanten", Journal f�r Praktische Chemie, vol. 98, pp. 315-353, 1918. http://dx.doi.org/10.1002/prac.19180980123
Tags:Carbon, chair, Chemistry, Conformation, Cycloalkanes, cyclohexane, Cyclohexane conformation, Derek Barton, Hermann Sachse, Hoff, Imperial College Chemical Society, Interesting chemistry, Isomerism, Physical organic chemistry, R. F Hunter, Stereochemistry, Van 't Hof
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Wednesday, September 12th, 2012
All organic chemists are familiar with the stereochemical notation for bonds, as shown below. But I had difficulty tracking down when it was introduced, and by whom. I offer a suggestion here, but if anyone reading this blog has got a better/earlier attribution, please let us know!
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Tags:Derek Barton, Historical, R. C. Cookson
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Monday, April 4th, 2011
Most scientific theories emerge slowly, over decades, but others emerge fully formed virtually overnight as it were (think Einstein in 1905). A third category is the supernova type, burning brightly for a short while, but then vanishing (almost) without trace shortly thereafter. The structure of DNA (of which I have blogged elsewhere) belongs to the second class, whilst one of the brightest (and now entirely forgotten) examples of the supernova type concerns the structure of proteins. In 1936, it must have seemed a sure bet that the first person to come up with a successful theory of the origins of the (non-random) relatively rigid structure of proteins would inevitably win a Nobel prize. Of course this did happen for that other biologically important system, DNA, some 17 years later. Compelling structures for larger molecules providing reliable atom-atom distances based on crystallography were still in the future in 1936, and so structural theories contained a fair element of speculation and hopefully inspired guesswork (much as cosmological theories appear to have nowadays!).
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Tags:Cambridge, chair, Derek Barton, Dorothy Wrinch, energy, high energy species, Historical, Interesting chemistry, mathematician, organic chemist, Patrick Coffey, relative free energy, thermodynamics, Tutorial material
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Wednesday, December 29th, 2010
Science is about making connections. Plenty are on show in Watson and Crick’s famous 1953 article on the structure of DNA[1] but often with the tersest of explanations. Take for example their statement “Both chains follow right-handed helices“. Where did that come from? This post will explore the subtle implications of that remark (and how in one aspect they did not quite get it right!).
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References
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J.D. WATSON, and F.H.C. CRICK, "Molecular Structure of Nucleic Acids: A Structure for Deoxyribose Nucleic Acid", Nature, vol. 171, pp. 737-738, 1953. http://dx.doi.org/10.1038/171737a0
Tags:Bijvoet, chemist, chiroptical, d(CGCG), Derek Barton, dispersion forces, DNA duplex, Historical, Interesting chemistry, Marcus du Sautoy, Note, Odile Crick, professional artist, Tartaric Acid, van der Waals, watoc11, Watson Crick, Web sense, Z-DNA
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Friday, April 2nd, 2010
One of the (not a few) pleasures of working in a university is the occasional opportunity that arises to give a new lecture course to students. New is not quite the correct word, since the topic I have acquired is Conformational analysis. The original course at Imperial College was delivered by Derek Barton himself about 50 years ago (for articles written by him on the topic, see DOI 10.1126/science.169.3945.539 or the original 10.1039/QR9561000044), and so I have had an opportunity to see how the topic has evolved since then, and perhaps apply some quantitative quantum mechanical interpretations unavailable to Barton himself.
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Tags:10.1021, conformational analysis, Derek Barton, energy maxima, Imperial College, Interesting chemistry, lower energy, overall energy, potential energy surface, Tutorial material
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Sunday, April 12th, 2009
The diagram below summarizes an interesting result recently reported by Hanson and co-workers (DOI: 10.1021/jo800706y. At ~neutral pH, compound 13 hydrolyses with a half life of 21 minutes, whereas 14 takes 840 minutes. Understanding this difference in reactivity may allow us to understand why some enzymes can catalyze the hydrolysis of peptides with an acceleration of up to twelve orders of magnitude.
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Tags:chair, conformational analysis, Derek Barton, energy, Hanson, Interesting chemistry, molecular mechanics energy, stable lactone product, stable product
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