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Henry Rzepa's Blog

Henry Rzepa's Blog
Chemistry with a twist
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General/RTAnomeric EffectsArrow PushingConfigurational IsomerQuímicaInglês
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Chemistry gets complex very rapidly. Consider the formula CH3NO as the topic for a tutorial in introductory chemistry. I challenge my group (of about 8 students) to draw as many different molecules as they can using exactly those atoms. I imply that perhaps each of them might find a different structure;

HypervalencyInteresting ChemistryHenry RzepaJahn-TellerPenceQuímicaInglês
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Do you fancy a story going from simplicity to complexity, if not absurdity, in three easy steps? Read on! The following problem appears in one of our (past) examination questions in introductory organic chemistry. From relatively mundane beginnings, one can rapidly find oneself in very unexpected territory.

Interesting ChemistryActivation Free EnergyBenzonitrile ProductChemical MythologyColoured SolutionsQuímicaInglês
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Janus was the mythological Roman god depicted as having two heads facing opposite directions, looking simultaneously into the past and the future. Some of the most ancient (i.e. 19th century) known reactions can be considered part of a chemical mythology; perhaps it is time for a Janus-like look into their future.

Interesting ChemistryEnergyFree EnergyHuckelPretty Straight ForwardQuímicaInglês
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More inspiration from tutorials. In a lecture on organic aromaticity, the 4n+2/4n Hückel rule was introduced (in fact, neither rule appears to have actually been coined in this form by Hückel himself!). The simplest examples are respectively the cyclopropenyl cation and anion.

Interesting ChemistryChemistChiropticalPhysicistSynthetic ChemistQuímicaInglês
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Our understanding of science mostly advances in small incremental and nuanced steps (which can nevertheless be controversial) but sometimes the steps can be much larger jumps into the unknown, and hence potentially more controversial as well.

Interesting ChemistryDavid ScheschkewitzIgor AlabuginPericyclicWatoc11QuímicaInglês
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On 8th August this year, I posted on a fascinating article that had just appeared in Science in which the crystal structure was reported of two small molecules, 1,3-dimethyl cyclobutadiene and carbon dioxide, entrapped together inside a calixarene cavity.

Interesting ChemistryAndrew WhiteChemical Heritage CollectionsDetectiveHistoricalQuímicaInglês
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In 1890, chemists had to work hard to find out what the structures of their molecules were, given they had no access to the plethora of modern techniques we are used to in 2010. For example, how could they be sure what the structure of naphthalene was?