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Henry Rzepa's Blog

Henry Rzepa's Blog
Chemistry with a twist
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Published

The folks at DataCite have announced a new research object discovery service which aims to give users a “ comprehensive overview of connections between entities in the research landscape” . The portal https://commons.datacite.org acts as the entry point for three basic types of persistent identifiers (PIDs); Research works, using the DOI (digital object identifier) as a PID.

Published

The two previous surveys of the potential energy surface for this, it has to be said, rather obscure reaction led to energy barriers that were rather to high to be entirely convincing. So here is a third possibility. The red section corresponds to the previous exploration, in which a 3-membered sulfur ring intermediate was mooted. Here we go back to a 3-ring with nitrogen instead.

Published

Continuing an exploration of the mechanism of this reaction, an alternative new mechanism was suggested in 1989 (having been first submitted to the journal ten years earlier!).[cite]10.1002/jhet.5570260518[/cite] Here the key intermediate proposed is a thiirenium cation (labelled 8 in the article) and labelled Int3 below.

Published

Sometimes a (scientific) thought just pops into one’s mind. Most are probably best not shared with anyone, but since its the summer silly season, I thought I might with this one. Famously, according to Einstein, m  = E/c^^2, the equivalence of energy to mass. Consider a typical exoenergic chemical reaction:  A → B, ΔG -100 kJ/mol.

Published

The Willgerodt reaction[cite]10.1002/cber.18870200278[/cite], discovered in 1887 and shown below, represents a transformation with a once famously obscure mechanism. A major step in the elucidation of that mechanism came[cite]10.1021/ja01157a034[/cite] using the then new technique of 14 C radio-labelling, shortly after the atom bomb projects during WWII made 14 CO 2 readily available to researchers.

Published

One of the most fascinating and important articles dealing with curly arrows I have seen is that by Klein and Knizia on the topic of C-H bond activations using an iron catalyst.[cite]10.1002/anie.201805511[/cite] These are so-called high spin systems with unpaired electrons and the mechanism of C-H activation involves both double headed (two electron) and fish-hook (single electron) movement.