Henry Rzepa's Blog Chemistry with a twist

August 8, 2018

The “White City Trio” – The formation of an amide from an acid and an amine in non-polar solution (updated).

White City is a small area in west london created as an exhibition site in 1908, morphing over the years into an Olympic games venue, a greyhound track, the home nearby of the BBC (British Broadcasting Corporation) and most recently the new western campus for Imperial College London. The first Imperial department to move into the MSRH (Molecular Sciences Research Hub) building is chemistry. As a personal celebration of this occasion, I here dedicate three transition states located during my first week of occupancy there, naming them the White City trio following earlier inspiration by a string trio and their own instruments.


April 8, 2016

Ways to encourage water to protonate an amine: superbasing.

Previously, I looked at models of how ammonia could be protonated by water to form ammonium hydroxide. The energetic outcome of my model matched the known equilbrium in water as favouring the unprotonated form (pKb ~4.75). I add here two amines for which R=Me3Si and R=CN. The idea is that the first will assist nitrogen protonation by stabilising the positive centre and the second will act in the opposite sense; an exploration if you like of how one might go about computationally designing a non-steric superbasic amine that becomes predominantly protonated when exposed to water (pKb <1) and is thus more basic than hydroxide anion in this medium.


September 5, 2015

π-Resonance in thioamides: a crystallographic “diff” with amides.

Filed under: Chemical IT,crystal_structure_mining — Tags: , , — Henry Rzepa @ 11:17 am

The previous post explored the structural features of amides. Here I compare the analysis with that for the closely related thioamides.


π-Resonance in amides: a crystallographic reality check.

The π-resonance in amides famously helped Pauling to his proposal of a helical structure for proteins. Here I explore some geometric properties of amides related to the C-N bond and the torsions about it.


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