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Crystal growth kinetics of Piracetam polymorphs in ethanol and isopropanol

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posted on 2019-09-30, 14:38 authored by Rodrigo Soto, Åke C. Rasmuson
The crystal growth kinetics of two different polymorphs of Piracetam have been investigated in ethanol and isopropanol. Isothermal seeded desupersaturation experiments were carried out at supersaturation ratios below 1.2 within the range of temperature 283-308 K. Liquid concentration was determined by in-situ ATR-FTIR spectroscopy by a calibration free method using Principal Component Analysis. The power law equation, the BCF and the B+S models were fitted to the experimental desupersaturation data by non-linear optimization. The growth rates ranged 10-7-10-8 m/s, the growth rate order is clearly higher than unity, and the activation energies are in the range 39-66 kJ/mol for all the systems studied suggesting surface integration control. The growth of the metastable polymorph is faster than that of the stable form in both solvents. The crystal growth proceeds faster in ethanol than in isopropanol for both polymorphs. The solid-liquid interfacial energy is lower for the metastable form, and is for both forms lower in ethanol than in isopropanol. The surface diffusion mass transfer rate is higher for the metastable form compared to the stable form and higher in ethanol than in isopropanol.

History

Publication

Crystal Growth and Design;9 (8), pp. 4273-4286

Publisher

American Chemical Society

Note

peer-reviewed

Other Funding information

SFI

Rights

© Year 2019 This document is the Accepted Manuscript version of a Published Work that appeared in final form in Crystal Growth and Design, 2019, 9 (8), pp. 4273-4286 Title, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://doi.org/10.1021/acs.cgd.8b01733

Language

English

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