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Henry Rzepa's Blog

Henry Rzepa's Blog
Chemistry with a twist
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Curly ArrowsInteresting Chemistry/RTActivation EnergyActivation Free EnergyChemical Sciences
Published

Students learning organic chemistry are often asked in examinations and tutorials to devise the mechanisms (as represented by curly arrows) for the core corpus of important reactions, with the purpose of learning skills that allow them to go on to improvise mechanisms for new reactions.

Interesting ChemistryAntiaromaticityAromaticityBaird's RuleConjugated SystemChemical Sciences
Published

There is emerging interest in cyclic conjugated molecules that happen to have triplet spin states and which might be expected to follow a 4n rule for aromaticity. The simplest such system would be the triplet state of cyclobutadiene, for which a non or anti-aromatic singlet state is always found to be lower in energy.

Chemical ITAcademic PublishingAcrobatArticlesChemical DiscoveriesChemical Sciences
Published

The traditional structure of the research article has been honed and perfected for over 350 years by its custodians, the publishers of scientific journals. Nowadays, for some journals at least, it might be viewed as much as a profit centre as the perfected mechanism for scientific communication.

Interesting ChemistryChemical KineticsChemical ReactionChemistryDeuteriumChemical Sciences
Published

Five years back, I speculated about the mechanism of the epoxidation of ethene by a peracid, concluding that kinetic isotope effects provided interesting evidence that this mechanism is highly asynchronous and involves a so-called “hidden intermediate”. Here I revisit this reaction in which a small change is applied to the atoms involved.

HistoricalAlan DronsfieldAlizarinAnthraquinone DyesArt MaterialsChemical Sciences
Published

The Royal Society of Chemistry historical group (of which I am a member) organises two or three one day meetings a year. Yesterday the October meeting covered (amongst other themes) the fascinating history of madder and its approximately synthetic equivalent alizarin.