https://doi.org/10.1140/epjst/e2016-60257-3
Regular Article
Effect of additives on the preferential crystallization of L-asparagine monohydrate
1 School of Chemical Engineering, Suranaree University of Technology, 111 University Avenue, Nakhon Ratchasima, Thailand
2 EPSRC Centre for Innovative Manufacturing in Continuous Manufacturing and Crystallisation (CMAC), Strathclyde Institute of Pharmacy and Biomedical Sciences, Technology and Innovation Centre, University of Strathclyde, 99 George Street, Glasgow G1 1RD, UK
3 Department of Chemical and Biomolecular Engineering, School of Energy Science and Engineering, Vidyasirimedhi Institute of Science and Technology, 555 Moo 1, Payupnai, Wang Chan, Rayong 21210, Thailand
a e-mail: adrian.f.vistec@gmail.com
Received: 3 September 2016
Revised: 30 October 2016
Published online: 18 April 2017
Preferential Crystallization (PC) is a popular process to separate enantiomers, however the nucleation and growth of the counter enantiomer during the process can compromise the enantiopurity of the final crystalline product. This research investigates the use of additives to inhibit the nucleation and growth of the counter enantiomer. In this study, we use L-asparagine monohydrate (L-Asn·H2O) as the preferred enantiomer in crystallization from DL-Asn·H2O solutions. Additives include both pure enantiomers of several related amino acid species. This allows investigation of differences in inhibition caused by additives that are of the same chirality and different chirality as the preferred enantiomer. The additives had no discernible effect on the solubility but had a small effect on the metastable limit, with additives tending to slightly widen the metastable zone but also make the zone widths more disperse. D-additives have a small effect on the growth rate of L-Asn·H2O but L-Asp and L-Glu strongly inhibit the growth rate of L-Asn·H2O in DL-Asn·H2O solution; there must also be a corresponding effect for D-Asp and D-Glu on D-Asn·H2O. Indeed, PC experiments showed that in order to obtain L-Asn·H2O from a PC while preventing the formation of D-Asn·H2O, D-Asp and D-Glu are suitable additives, leading to high yield and purity of pure L-Asn·H2O.
© EDP Sciences, Springer-Verlag, 2017
