Biocatalytic production of adiponitrile and related aliphatic linear α,ω-dinitriles

Abstract

Linear α,ω-dinitriles are important precursors for the polymer industry. Most prominently, adiponitrile is produced on an annual scale of ca. 1 million tons. However, a drawback of today’s dominating process is the need for large amounts of highly toxic hydrogen cyanide. In this contribution, an alternative approach towards such linear dinitriles is presented based on dehydration of readily available α,ω-dialdoximes at ambient conditions by means of aldoxime dehydratases. In contrast to existing production routes this biocatalytic route enables a highly regio- and chemoselective approach towards dinitriles without the use of hydrogen cyanide or harsh reaction conditions. In addition, a selective synthesis of adiponitrile with substrate loadings of up to 100 g/L and high yields of up to 80% was achieved. Furthermore, a lab scale process on liter scale leading to > 99% conversion at 50 g/L underlines the potential and robustness of this method for technical applicability.

Heterogeneous Catalysts “on the Move”: Flow Chemistry with Fluid Immobilised (Bio)Catalysts

“…With these results in hand, another catalytic system, namely the dehydration of oximes catalyzed by an aldoxime dehydratase (Oxd) under the formation of nitriles, was investigated. Oxd‐type enzymes recently gained much attention as catalysts enabling a cyanide‐free synthesis of nitriles.…”

Aldoxime Dehydratase Mutants as Improved Biocatalysts for a Sustainable Synthesis of Biorenewables-Based 2-Furonitrile

“…Even though the K m value of OxdYH3-3 N266S was much higher than the one for the WT, the catalytic efficiency of N266S was approximately five times higher than WT. In addition, kinetic data of other Oxd enzymes were determined in previous studies, and the K m values of OxdRG and OxdA towards aromatic aldoximes such as pyridine-3-aldoxime and pyridine-2-aldoxime were 20 and 3.4 mM, respectively [13][14][15][16][17][18][19][20][21][22][23]26,27]. Compared to these results, the K m values of OxdYH3-3 WT and N266S were significantly lower towards the aromatic aldoxime 2-furfuryl aldoxime.…”

“…The clones that showed an absorbance between 0 and 1 (lower 10%) at 270 nm ( Figure 1) were chosen for further studies. In continuation of our research on the biocatalytic synthesis of nitriles under cyanide-free conditions as an alternative synthetic technology for nitriles [13][14][15][16][17][18][19][20][21][22][23][24][25], we could also demonstrate a proof of concept for the two-step conversion of furfural into 2-furonitrile (Scheme 1) [24,25]. In detail, furfural (1) is transformed into its aldoxime (2) by spontaneous condensation with hydroxylamine, which is a bulk chemical that is utilized in α-caprolactam manufacturing.…”

Synthesis of Bifunctional Molecules for the Production of Polymers Based on Unsaturated Fatty Acids as Bioderived Raw Materials

“…Due to this simple isolation of the n-products, we used the pure n-aldoxime for the next step of the cascade. The aldoximes were converted by Oxds, which are enzymes that catalyze efficiently the dehydration of aldoximes to nitriles [12,15,20]. We conducted these biotransformations in potassium phosphate buffer (PPB) at a 30 • C reaction temperature (Figure 2).…”

“…Access to a fatty acid-derived amino acid as polymer building block exemplified for the synthesis of 11-aminoundecanoic acid(20).…”