Posts Tagged ‘final product’

Woodward’s symmetry considerations applied to electrocyclic reactions.

Monday, May 20th, 2013

Sometimes the originators of seminal theories in chemistry write a personal and anecdotal account of their work. Niels Bohr[1] was one such and four decades later Robert Woodward wrote “The conservation of orbital symmetry” (Chem. Soc. Special Publications (Aromaticity), 1967, 21, 217-249; it is not online and so no doi can be given). Much interesting chemistry is described there, but (like Bohr in his article), Woodward lists no citations at the end, merely giving attributions by name. Thus the following chemistry (p 236 of this article) is attributed to a Professor Fonken, and goes as follows (excluding the structure in red):

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References

  1. N. Bohr, "Der Bau der Atome und die physikalischen und chemischen Eigenschaften der Elemente", Z. Physik, vol. 9, pp. 1-67, 1922. http://dx.doi.org/10.1007/BF01326955

Secrets of a university tutor: unravelling a mechanism using spectroscopy.

Thursday, January 31st, 2013

It is always rewarding when one comes across a problem in chemistry that can be solved using a continuous stream of rules and logical inferences from them. The example below[1] is one I have been using as a tutor in organic chemistry for a few years now, and I share it here. It takes around 50 minutes to unravel with students.

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References

  1. K. Harano, M. Eto, K. Ono, K. Misaka, and T. Hisano, "Sequential pericyclic reactions of unsaturated xanthates. One-pot synthesis of hydrobenzo[c]thiophenes", J. Chem. Soc., Perkin Trans. 1, pp. 299, 1993. http://dx.doi.org/10.1039/P19930000299

Dynamic effects in nucleophilic substitution at trigonal carbon.

Monday, July 16th, 2012

Singleton and co-workers have produced some wonderful work showing how dynamic effects and not just transition states can control the outcome of reactions. Steve Bachrach’s blog contains many examples, including this recent one.

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The mechanism of the Baeyer-Villiger rearrangement.

Monday, May 7th, 2012

The Baeyer-Villiger rearrangement was named after its discoverers, who in 1899 described the transformation of menthone into the corresponding lactone using Caro’s acid (peroxysulfuric acid). The mechanism is described in all text books of organic chemistry as involving an alkyl migration. Here I take a look at the scheme described by Alvarez-Idaboy, Reyes and Mora-Diez[1], and which may well not yet have made it to all the text books!

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References

  1. J.R. Alvarez-Idaboy, L. Reyes, and N. Mora-Diez, "The mechanism of the Baeyer–Villiger rearrangement: quantum chemistry and TST study supported by experimental kinetic data", Org. Biomol. Chem., vol. 5, pp. 3682, 2007. http://dx.doi.org/10.1039/b712608e