Deracemization of NMPA via Temperature Cycles

Recent studies have shown that total deracemization of a racemic suspension of a conglomerate forming compound can be attained in the presence of a racemizing agent through either attrition enhanced deracemization or temperature cycles. We experimentally investigate the deracemization of N-(2-methylbenzylidene)-phenylglycine amide, in the presence of DBU as racemizing agent in a mixture of isopropanol and acetonitrile (95/5 w/w), at several different operating conditions. Based on several experiments, we determine how the operating parameters influence the temperature cycles, by varying the initial enantiomeric excess, the cooling rate, the operating temperature range, and the system volume. We examine how each parameter affects the phenomena characterizing the temperature cycles, e.g., total process time or total number of cycles to attain deracemization. Finally, we discuss in general how to improve the performance of the process.