Xuebing Xu, Aarhus University, Aarhus C, Denmark, and colleagues have investigated the potential of a special class of ionic liquids (Ammoeng ILs) for biocatalytic production of biodiesel. Ammoeng ILs are acyclic ammonium salts that contain cations with alkyl or acyl substituents and oligoethyleneglycol units of different chain lengths.

The enzymatic production of biodiesel with oil/IL biphasic systems was investigated by testing a variety of ILs with different cations and anions. The reaction specificities are strongly dependent on the molecular structures of the ILs. Among the ILs evaluated, Ammoeng 102 and 120 display excellent reaction profiles in terms of oil conversion and biodiesel yield.

The oil/Ammoeng 102 system also shows some unique properties, such as very less MG and DG in the final product, only small amounts of ILs are needed to host an efficient reaction, protective effect for enzyme against inactivation by methanol, and automatic phase separation for biodiesel recovery.
These characteristics are of paramount importance to explore the industrial interests of the system.

The reactions can be described by an experiment-independent model, COSMO-RS.

• Characterization of ionic liquid-based biocatalytic two-phase reaction system for production of biodiesel,
  B. L. A. Prabhavathi Devi, Zheng Guo, Xuebing Xu
  AIChE J. 2010.
  DOI: 10.1002/aic.12355