facile-biocatalytic-synthesis-of-a-macrocyclic-lactone-in-sub-and-supercritical-solvents
The paper reports a biocatalytic route to the macrocyclic lactone oxacyclohexadecan-2-one (OCO) using immobilised Candida antarctica lipase B (CALB) in a range of non‑conventional solvents, including supercritical carbon dioxide (scCO2), supercritical ethene, supercritical fluoroform, and sub‑/supercritical 1,1,1,2‑tetrafluoroethane (TFE). Batch experiments demonstrated that yields up to 78 % could be achieved in supercritical TFE, surpassing previously reported yields (41–56 %) for macrocyclic lactone synthesis in organic solvents. Continuous synthesis with in‑situ product extraction by scCO2 further increased the yield to 60 % in 24 h, highlighting the advantage of simultaneous reaction–separation. Enzyme stability tests showed that CALB retained or even increased activity after incubation in sub‑ and supercritical TFE, whereas CO2‑based supercritical fluids could depress enzyme activity due to acidification and interaction with amino‑acid residues. The authors argue that supercritical fluids—especially non‑CO2 SCFs such as TFE—enable higher reactant solubility, shift reaction equilibria toward intramolecular cyclisation, and simplify downstream processing, offering a greener, more intensified biocatalytic platform for macrocyclic lactone production.
Topics
Solvent Screening Results: Yield Trends Across SCFs and Pressures
Presents quantitative yields for OCO synthesis in scCO2 (max 46 % at 13 MPa), scC2H4, scCHF3, and especially sub‑/supercritical TFE (up to 78 %); highlights pressure‑dependent conversion patterns and the role of solvent polarity on substrate solubility.
Enzyme Stability in High‑Pressure Fluorinated Solvents
Reports activity assays showing CALB retains 84‑87 % activity after 6 h incubation in subcritical TFE and even gains up to 130 % activity after 6 h in supercritical TFE, contrasting with potential deactivation in CO2‑based SCFs.