Enzymatic Synthesis of Aliphatic Nitriles at a Substrate Loading of up to 1.4 Kg/L: A Biocatalytic Record Achieved with a Heme Protein

A biocatalytic approach towards linear aliphatic nitriles being widely used as industrial bulk chemicals has been developed, which runs at high substrate loadings of up to 1.4 kg/L as demonstrated for the synthesis of n-octanenitrile. This substrate loading is one of the highest ever reported in biocatalysis and to best of our knowledge the highest obtained for a water-immiscible product in aqueous medium. It is noteworthy that the biotransformation at such a high substrate loading was achieved by means of a metalloprotein bearing an iron-containing heme subunit in the active site. In detail, an aldoxime dehydratase from Bacillus sp. OxB-1 was used as a biocatalyst for a dehydration of aldoximes as readily available starting materials due to their easy preparation from aliphatic aldehydes through spontaneous condensation with hydroxylamine as bulk chemicals. Excellent conversions towards the nitriles in the two-phase system were achieved and the products are easily separated from the reaction mixture with...