Scale-up of a chiral resolution using cross-linked enzyme crystals

The scale-lip of a biocatalytic process using a cross-linked enzyme crystal (ChiroCLEC-PC, Altus Biologics Inc., Cambridge, MA) for the resolution of a racemic mixture (R/S-sec-phenethyl acetate to R-sce-phenethyl alcohol) is reported, Reaction parameters were initially investigated at the 20-mL and 1-L scale to determine optimum reactor conditions for operation at the 100-L scale, At this scale, reproducibility trials were conducted with a single charge of 50 g of ChiroCLEC-PC for the entire nine trials. Results demonstrated that, although there was a steady decrease in reaction rate over the trials (primarily as a result of sub-optimal CLEC catalyst recovery between each trial) all nine reactions proceeded to >48% conversion, with ee(p)'s of 99.9% and ee(s)'s of 91-95% recorded. In total, 270 kg of racemate was converted into R-phenethyl alcohol and S-phenethyl acetate during the reproducibility trials using a standard stirred tank design with pH control, With further work to improve CLEC catalyst recovery between runs, the technology is suitable for industrial exploitation to compete favourably alongside alternative chiral technologies.