Polymorphism in an API ionic liquid: Ethambutol dibenzoate trimorphs

Abstract

Three polymorphs of the dibenzoate salt of the anti-tubercular drug ethambutol (EDB) were crystallized as ionic liquids (m.p. < 100 °C) and characterized by diffraction (PXRD), thermal (DSC) and spectroscopy (IR, Raman, ss-NMR) techniques. Their stability relationships were established by DSC and VT-PXRD: EDB form 1 is the most stable, followed by form 3, and form 2 is the least stable at room temperature (25 °C); form 3 is the most stable, then form 1, and form 2 is the least stable at high temperature (90 °C). © 2012 The Royal Society of Chemistry.