Process intensified anti-solvent crystallization of o-aminobenzoic acid via sonication and flow

Process intensification via flow and ultrasound can make crystallization much more efficient, economic, reproducible and safe. However, successful application requires obtaining substantial knowledge on the effect of these techniques on process parameters and product properties. Investigation of such effects on polymorphism is still limited. In this work, batch and flow anti-solvent crystallization of o-aminobenzoic acid (o-ABA – 3 polymorphs) was conducted in silent and sonicated conditions. A new type of continuous flow sono-crystallizer was also demonstrated. In batch experiments, form – I nucleated at low anti-solvent volume and form – II at high anti-solvent volume. However, differences in mixing led to a significant change in the nucleated polymorph in flow experiments where concomitant nucleation of form – II and III was observed for all cases. Ultrasound did not affect the polymorph in either systems but did enhance the process by reducing induction time and increasing yield. Ultrasound in flow with a residence time of mere 2.5 s, provided a yield of nearly 50 %, which was 2.4 times more than silent conditions. Ultrasound can be considered as a useful technique for continuous production of metastable polymorphs as it provides high yield at low residence time thus, alleviating risk of solvent-mediated transformation.

Publication year:2020

BOF-keylabel:yes

IOF-keylabel:yes

BOF-publication weight:1

CSS-citation score:1

Authors from:Higher Education

Accessibility:Open