Conformational polymorphism occurs when a compound crystallises in two polymorphs differing only in the relative orientations of flexible groups (e.g. Ritonavir). At the Beilstein conference, Ian Bruno mentioned another type; tautomeric polymorphism, where a compound can crystallise in two forms differing in the position of acidic protons. Here I explore three such examples.
Posts Tagged ‘Isomerism’
Tautomeric polymorphism.
Thursday, June 1st, 2017The conformation of enols: revealed and explained.
Thursday, April 6th, 2017Enols are simple compounds with an OH group as a substituent on a C=C double bond and with a very distinct conformational preference for the OH group. Here I take a look at this preference as revealed by crystal structures, with the theoretical explanation.
Bond stretch isomerism. Did this idea first surface 100 years ago?
Tuesday, February 9th, 2016The phenomenon of bond stretch isomerism, two isomers of a compound differing predominantly in just one bond length, is one of those chemical concepts that wax and occasionally wane.[1] Here I explore such isomerism for the elements Ge, Sn and Pb.
References
- J.A. Labinger, "Bond-stretch isomerism: a case study of a quiet controversy", Comptes Rendus Chimie, vol. 5, pp. 235-244, 2002. http://dx.doi.org/10.1016/S1631-0748(02)01380-2