Temperature Cycling Induced Deracemization of <scp>dl</scp>-Asparagine Monohydrate with Immobilized Amino Acid Racemase
Kritsada Intaraboonrod, Isabel Harriehausen, Thiane Carneiro, Andreas Seidel-Morgenstern, Heike Lorenz, Adrian E. Flood
Abstract
Temperature cycling induced deracemization (TCID) is an attractive method to provide a pure enantiomer from a racemic solid phase. In this work, we performed deracemization of the nonessential amino acid asparagine using TCID of dl-asparagine monohydrate crystals (DL-ASN·H2O) and an immobilized amino acid racemase (imAAR) as a racemization agent. Experiments were performed with varying initial suspension densities and dosages of imAAR to better understand the process and included measurements of both solid-phase and solution-phase enantiomeric excesses. Furthermore, we demonstrate how to improve the productivity and yield of the TCID process by adding a temperature hold at the end of the process to ensure the maximum possible yield and compare these results to a process using only standard temperature cycles. Finally, we also discuss the effect of both temperature programs on the performances of the TCID process to be a strategy to further improve this process for industrial application.