Determination of the onset of crystallization of N-1-2-(thiazolyl)sulfanilamide (sulfathiazole) by UV-Vis and calorimetry using an automated reactionplatform; subsequent characterization of polymorphic forms using dispersive Raman spectroscopy

This work describes the use of UV/visible spectroscopy and calorimetry to f ollow the onset of crystallization of a commercially available compound, N' -2-(thiazolyl)sulfanilamide (sulfathiazole), during crystallization reactio ns performed using an automated reaction platform. Sulfathiazole has been t he subject of numerous publications through which considerable confusion ab out the morphic form is apparent. This work does not attempt to investigate exhaustively the polymorph issue, but rather to exploit the use of the HEL auto-MATE for monitoring the onset of crystal formation. Real-time calorim etry and UV-Vis spectroscopy are compared as tools for determining the onse t of crystallization. Subsequently, differential scanning calorimetry, disp ersive Raman, and infrared spectroscopy analysis serve to identify the crys tal forms generated by the HEL auto-MATE. A solvent anti-solvent matrix and several bench-top crystallization experiments were performed to supplement the investigation in terms of generating the desired polymorphs. (C) 2001 Elsevier Science B.V. All rights reserved.