In this study, the selective crystallization and characterization of the stoichiometric forms of the p-to-luenesulfonamide/triphenylphosphine oxide (p-TSA-TPPO) co-crystal system in acetonitrile (MeCN) is demonstrated using batch and semi-batch crystallizers. In the batch study, both 1:1 and 3:2 p-TSA-TPPO were successfully isolated as pure forms. However, process variability was observed in a few experimental runs. To address the batch process variability issue, a control strategy was implemented using temperature cycling, aided by in situ process analytical technologies (PAT) to convert from 3:2 to 1:1 p-TSA-TPPO. In the semi-batch co-crystallization studies, the two molecular co-formers, p-TSA and TPPO, were dissolved in MeCN and pumped separately to the crystallizer. Changing the flow rates of the respective active ingredients allowed control over the co-crystallization outcome, and presents as a promising opportunity for development of a continuous co-crystallization process. (C) 2016 Published by Elsevier Ltd.

• University of Strathclyde
• Loughborough University
• Purdue University, University of Limerick

• API

1. API
2. Co-crystal
3. co-crystallization
4. Process analytical technologies
5. Research Article
6. Stoichiometric