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.
Posts Tagged ‘relative free energy’
Modelling the geometry of unbranched alkanes.
Saturday, March 29th, 2014By about C17H36, the geometry of “cold-isolated” unbranched saturated alkenes is supposed not to contain any fully anti-periplanar conformations. [cite]10.1002/anie.201202894[/cite] Indeed, a (co-crystal) of C16H34 shows it to have two-gauche bends.[cite]10.1002/chem.200801428[/cite]. Surprisingly, the longest linear alkane I was able to find a crystal structure for, C28H58 appears to be fully extended[cite]10.1107/S0108768191011059[/cite],[cite]10.1107/S0567740876005025[/cite] (an early report of a low quality structure for C36H74[cite]10.1107/S0365110X5600111X[/cite] also appears to show it as linear).‡ Here I explore how standard DFT theories cope with these structures.