1422444-20-9Relevant articles and documents
Solid Phase Behavior, Polymorphism, and Crystal Structure Features of Chiral Drug Metaxalone
Bredikhin, Alexander A.,Zakharychev, Dmitry V.,Gubaidullin, Aidar T.,Bredikhina, Zemfira A.
, p. 6627 - 6639 (2018)
In addition to the previously known A-rac and B-rac polymorphs of the chiral drug metaxalone 1, an enantiopure A-(S)-form was obtained and studied. According to X-ray analysis, the crystalline organization of this form is close to the A-rac-1 polymorph. Crystallization of metaxalone melts is accompanied by the formation of a previously unknown metastable C-phase, which in the case of both racemic and enantiomeric samples are transformed into A-rac-1 or A-(S)-1. Analysis of the PXRD and IR spectra of crystalline samples revealed a similarity of the internal structure for the A-(S)-1, A-rac-1, C-(S)-1, and C-rac-1 crystalline forms and the essential difference of all of these phases from the B-rac-1 phase. According to the thermochemical data, the dependences of the change in the Gibbs free energy for all the phases studied are plotted in the interval from the melting point to 20 °C. Under standard conditions, the crystalline modifications of metaxalone, relative to δG0, form such a series: B-rac-1 A-(S)-1 ≈ A-rac-1 C-rac-1 C-(S)-1. A model that describes all the experimentally revealed features of metaxalone crystallization is proposed.
