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Henry Rzepa's Blog

Henry Rzepa's Blog
Chemistry with a twist
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Interesting ChemistryFree EnergyFree Energy BarrierMetal CatalystsNucleotide Synthesizer TechnologiesChemical Sciences
Published

One future vision for chemistry over the next 20 years or so is the concept of having machines into which one dials a molecule, and as if by magic, the required specimen is ejected some time later. This is in some ways an extrapolation of the existing peptide and nucleotide synthesizer technologies and sciences.

HypervalencyBondingELFFluorineHiberty And CoChemical Sciences
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In the previous post, I ruminated about how chemists set themselves targets. Thus, having settled on describing regions between two (and sometimes three) atoms as bonds, they added a property of that bond called its order. The race was then on to find molecules which exhibit the highest order between any particular pair of atoms.

HypervalencyGas PhaseMt. EverestPenceChemical Sciences
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Climbers scale Mt. Everest, because its there, and chemists have their own version of this. Ever since G. N. Lewis introduced the concept of the electron-pair bond in 1916, the idea of a bond as having a formal bond-order has been seen as a useful way of thinking about molecules.

Interesting ChemistryChairConformational AnalysisFinal Resting EnergyFree EnergyChemical Sciences
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In an earlier post, I re-visited the conformational analysis of cyclohexane by looking at the vibrations of the entirely planar form (of D6h symmetry). The method also gave interesting results for the larger cyclo-octane ring. How about a larger leap into the unknown?

General3gConformational AnalysisCuyclooctaneEnergyChemical Sciences
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In the previous post, I suggested that inspecting the imaginary modes of planar cyclohexane might be a fruitful and systematic way in which at least parts of the conformational surface of this ring might be probed. Here, the same process is conducted for cyclo-octane.

GeneralInteresting ChemistryAdolf Von BaeyerAnimationCChemical Sciences
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Like benzene, its fully saturated version cyclohexane represents an icon of organic chemistry. By 1890, the structure of planar benzene was pretty much understood, but organic chemistry was still struggling somewhat to fully embrace three rather than two dimensions.

HypervalencyInteresting ChemistryBondQuadrupleChemical Sciences
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So ingrained is the habit to think of a bond as a simple straight line connecting two atoms, that we rarely ask ourselves if they are bent, and if so, by how much (and indeed, does it matter?). Well Hursthouse, Malik, and Sales, as long ago as 1978, asked just such a question about the […]

Interesting ChemistryAnimationCatalytic SystemsChemical IntimacyEnergyChemical Sciences
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The scheme below illustrates one of the iconic reactions in organic chemistry. It is a modern representation of Meerwein’s famous experiment from which he inferred a carbocation intermediate, deduced from studying the rate of enantiomerization of isobornyl chloride when treated with the Lewis acid SnCl4.