Immobilized enzymes in organic media: Chiral monomer production in organic media. Final report

The overall goals of this project were to investigate the critical factors that limit commercial scale applications of enzymes in organic solvents, and to scale-up a process for the production of a precursor to a specialty polymer. In the last phase of the project, we focused on optimizing and scaling up a trans-esterification reaction catalyzed by Subtilisin Carlsberg in very dry organic solvent. The reaction system we have employed has been reported. It involves the trans-esterification of vinyl acrylate with (R,S)-sec-(2-naphthyl)ethyl alcohol catalyzed by Subtilisin Carlsberg in tert-amyl-alcohol as a solvent. Only the S ester is produced. The other product, vinyl alcohol, converts spontaneously to acetaldehyde, thus shifting the equilibrium towards production of the desired product. The scaled up reaction was run under various conditions in order to identify the controlling factors. We have been able to scale up successfully the trans-esterification reaction from 5ml to 75ml. By varying the immobilization and reaction conditions, we increased the initial rate of the reaction by two orders of magnitude and the conversion from 20% to 100%. We have isolated several grams of the S-sec-(2-naphthyl)ethyl acrylate product. It contains two minor impurities, none of which is the R enantiomer. This and other chiral acrylic monomers could be polymerized to form polymers with special optical properties. In our dry enzymatic trans-esterification system, we found that two factors dominate the observed Subtilisin activity: Iyoprotection and water control. This is in agreement with other reports. Our results are consistent with the observed initial rate affected mostly by changes in the amount of active protease rather than in the enzyme`s intrinsic catalytic rate