Isothermal Deracemization of Sodium Chlorate in an Agitated Reactor: The Effect of Crystal Size Variables - Normandie Université Accéder directement au contenu
Article Dans Une Revue Crystal Growth & Design Année : 2023

Isothermal Deracemization of Sodium Chlorate in an Agitated Reactor: The Effect of Crystal Size Variables

Bowen Zhang
  • Fonction : Auteur
Gerard Coquerel
Woo-Sik Kim

Résumé

Preparation of enantiomerically pure chiral substances is an important issue in the pharmaceutical industry. A better understanding of the deracemization process and mechanism can significantly benefit the development of the industry. In the present study, the effect of l- and d-crystal sizes on deracemization of sodium chlorate was investigated using an agitated reactor with an isothermal mode of operation. The direction of deracemization was always determined by the difference in the crystal size between the two enantiomers. In other words, the small crystals fed the large crystals regardless of the initial asymmetry of the enantiomer mixture. Moreover, the agglomeration of crystals played a critical role in deracemization. The large l-crystals slowly grew due to the layer growth via dissolution of small d-crystals in the deracemization process. Meanwhile, the d-crystals quickly grew, particularly at the early stage of deracemization, due to the rapid agglomeration and layer growth at the expense of the small d-crystals. Thus, when the d-crystals grew over a certain size (called critical size), they were no longer deracemized into l-crystals, resulting in an incomplete deracemization. Otherwise, they eventually dissolved for complete deracemization. When the initial enantiomeric excess (ee) was reduced, the number of d-seeds increased and more d-crystals grew above the critical size because of the promotion of crystal agglomeration, resulting in the reduction in deracemization. In addition, deracemization degraded as the d-seed size increased. Thus, no deracemization occurred at equal seed sizes of the l- and d-forms. The described deracemization was considered to be driven by the Ostwald ripening effect, which was promoted by agitation-induced crystal attrition.

Domaines

Matériaux
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Dates et versions

hal-03967481 , version 1 (01-02-2023)

Identifiants

Citer

Bowen Zhang, Gerard Coquerel, Woo-Sik Kim. Isothermal Deracemization of Sodium Chlorate in an Agitated Reactor: The Effect of Crystal Size Variables. Crystal Growth & Design, 2023, 23 (2), pp.741-750. ⟨10.1021/acs.cgd.2c00871⟩. ⟨hal-03967481⟩
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