Posts Tagged ‘Reaction Mechanism’
Friday, July 20th, 2012
Twenty years are acknowledged to be a long time in Internet/Web terms. In the early days (in 1994), it was a taken that the passage of 1 Web day in the Internet time-warp was ~≡ 7 for the rest of the world (the same factor as applied to the lives of canines). This temporal warping can also be said to apply to computational chemistry. I previously revisited some computational work done in 1992, and here I rediscover another investigation from that year[1] and that era. The aim in this post is to compare not only how the presentation of the results has changed, but how the computational models have as well.
(more…)
References
- R.A. Batey, P. Grice, J.D. Harling, W.B. Motherwell, and H.S. Rzepa, "Origins of the regioselectivity of cyclopropylcarbinyl ring opening reactions in bicyclo [n.1.0] systems", Journal of the Chemical Society, Chemical Communications, pp. 942, 1992. https://doi.org/10.1039/c39920000942
Tags:computational chemistry, hardware tools, Historical, Internet time-warp, Internet/Web terms, Reaction Mechanism, Skolnik, Web day
Posted in Uncategorised | No Comments »
Friday, July 20th, 2012
I was first taught curly arrow pushing in 1968, and have myself taught it to many a generation of student since. But the other day, I learnt something new. Nick Greeves was kind enough to send me this link‡to the origin of curly arrow pushing in organic chemistry, where the following diagram is shown and Alan Dronsfield sent me two articles he co-wrote on the topic (T. M. Brown, A. T. Dronsfield and P. J. T Morris, Education in Chemistry, 2001, 38, 102-104, 107 and 2003, 40, 129-134);† thanks to both of them.
(more…)
Tags:Alan Dronsfield, Historical, Indiana, Nick Greeves, Reaction Mechanism, Robert Robinson, Tutorial material
Posted in Curly arrows | 12 Comments »
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.
(more…)
Tags:dielectric, energy surface, final product, Molecular dynamics, potential energy surface, Reaction Mechanism, Singleton & co., Steve Bachrach, substitution products
Posted in Interesting chemistry | 3 Comments »
Thursday, July 12th, 2012
Years ago, I was travelling from Cambridge to London on a train. I found myself sitting next to a chemist, and (as chemists do), he scribbled the following on a piece of paper. When I got to work the next day Vera (my student) was unleashed on the problem, and our thoughts were published[1]. That was then.
(more…)
References
- M.S. Baird, J.R. Al Dulayymi, H.S. Rzepa, and V. Thoss, "An unusual example of stereoelectronic control in the ring opening of 3,3-disubstituted 1,2-dichlorocyclopropenes", Journal of the Chemical Society, Chemical Communications, pp. 1323, 1992. https://doi.org/10.1039/c39920001323
Tags:Cambridge, chemist, conformational analysis, free energy, Historical, Internet era, London, pericyclic, perturbation energy, re-analysis using modern algorithms, Reaction Mechanism, Skolnik
Posted in Interesting chemistry, reaction mechanism | 1 Comment »
Monday, July 9th, 2012
Sometimes, connections between different areas of chemistry just pop out (without the help of semantic web tools, this is called serendipity). So here, I will try to join up some threads which emerge from previous posts.
(more…)
Tags:alkyne, gas phase, gas phase model, perepoxidation, Reaction Mechanism, semantic web tools
Posted in Curly arrows, reaction mechanism | 3 Comments »
Friday, May 25th, 2012
If you have not previously visited, take a look at Nick Greeves’ ChemTube3D , an ever-expanding gallery of reactions and their mechanisms. The 3D is because all molecules are offered with X, Y and z coordinates. You also get arrow pushing‡ in 3D. Here, I argue that we should adopt Einstein, and go to the space-time continuum! By this, I mean one must also include the order in which things happen. To my knowledge, no compendium of (organic) reaction mechanisms incorporates this 4th dimension. My prelude to this post nicely illustrated this latter aspect. Here I continue with an exploration of the mechanism of forming an acyl chloride from a carboxylic acid using thionyl chloride. The mechanism shown at ChemTube3D is as below and will now be tested for its reasonableness using quantum mechanics.
(more…)
Tags:acetic acid, Reaction Mechanism, Tutorial material
Posted in Uncategorised | 3 Comments »