Title : Inline concentration profiles in enzyme catalyzed reactive rectification using infrared spectroscopy
Enantiopure compounds are of high value to the pharmaceutical industry and enzymes such as the lipase B from Candida antarctica (CalB) can perform highly enantioselective reactions. On the contrary enzyme catalyzed reactions are often inhibited by a reaction product or thermodynamically limited. This can be avoided by using a reactive rectification column (RRC) setup to remove selectively a product in situ [1, 2].
The integration of enzymes in a reactive rectification process requires a detailed optimization which is enabled by inline analytical tools. In order to acquire precise data to correctly determine local concentration profiles Fourier Transform Infrared (FTIR) spectroscopy with multiple attenuated total reflection (ATR) probes is used. Omitting the time to take and analyze offline samples abbreviates the time required for process optimization. Furthermore ATR-FTIR spectroscopy can be applied without the knowledge of compound properties like vapor liquid equilibrium.
The racemic resolution of (R/S)-3-hydroxy ethyl butyrate is used as a model reaction system which is catalyzed by CalB in a solvent free environment. (S)-3-hydroxy ethyl butyrate is a precursor in the production of antibiotics . Along the height of the RRC a temperature difference up to 40 °C is observed during the course of the reaction under vacuum conditions. First chemometric models were established using the partial least squares method. To circumvent the temperature dependency of the IR spectra a chemometric model was calibrated by means of indirect hard modeling. First results indicate excellent agreement between offline gas chromatographic and inline FTIR analytics. Future experiments will focus on enzyme deactivation and obtaining a pure product over the top of the RRC.