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Henry Rzepa's Blog

Henry Rzepa's Blog
Chemistry with a twist
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Interesting ChemistryAnimationChemical BondsFree EnergyH 2 N-NHCiencias QuímicasInglés
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Car transmissions come in two types, ones with fixed ratio gears, and ones which are continuously variable. When it comes to chemical bonds, we tend to think of them as being very much of the first type. Bonds come in fixed ratios; single, aromatic, double, triple, etc.

Interesting ChemistryAluminum CarrierCarboxylic AcidChiropticalCyanoCiencias QuímicasInglés
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In the first part of the post on this topic, I described how an asymmetric sulfoxide could be prepared as a pure enantiomer using a chiral oxygen transfer reagent. In the second part, we now need to deliver a different group, cyano, to a specific face of the previously prepared sulfoxide-imine.

Interesting ChemistryEnergyFree EnergyNatural ProductSynthetic ChemistCiencias QuímicasInglés
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The assembly of a molecule for a purpose has developed into an art form, one arguably (chemists always argue) that is approaching its 100th birthday (DOI: 10.1002/cber.191104403216) celebrating Willstätter’s report of the synthesis of cyclo-octatetraene. Most would agree it reached its most famous achievement with Woodward’s synthesis of quinine (DOI: 10.1021/ja01221a051) in 1944.

Chemical ITGeneralInteresting ChemistryChairChemical ConnectionsCiencias QuímicasInglés
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Peter Murray-Rust in his blog asks for examples of the Scientific Semantic Web, a topic we have both been banging on about for ten years or more (DOI: 10.1021/ci000406v). What we are seeking of course is an example of how scientific connections have been made using inference logic from semantically rich statements to be found […]

GeneralAromatic SystemsHttpMissouriRemi ChauvinCiencias QuímicasInglés
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Some molecules, when you first see them, just intrigue. So it was with carbobenzene, the synthesis of a derivative of which was recently achieved by Remi Chauvin and co-workers (DOI: 10.1002/chem.200601193). Two additional carbon atoms have been inserted into each of the six C-C bonds in benzene.

Interesting ChemistryAppropriate AlgorithmsConformational AnalysisEnergy GapHere ICiencias QuímicasInglés
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Here I offer another spin-off from writing a lecture course on conformational analysis. This is the famous example of why 1,2-difluoroethane adopts a gauche rather than antiperiplanar conformation.