Continuous Synthesis of (R)-(+)-Benzaldehydecyanohydrin Using (R)-Oxynitrilase in Lyotropic Liquid Crystals

Abstract

The possibility of using the enzyme (R)-Oxynitrilase in a biphasic lyotropic liquid crystal/dibutylether system has been demonstrated. This reaction system is applicable for the continuous production of (R)-benzaldehydecyanohydrin in a fixed bed reactor. The optical purity was between 94 and 96% ee and independent of the flow rate. The space time yield was maximal (2650 g/(l* d)) at a flow rate of 1.6 ml/min. KEY WORDSEnzymatic synthesis, oxynitrilase, chiral cyanohydrin, organic solvents, lyotropic liquid crystals. t To whom all correspondence should be addressed 61 Biocatal Biotransformation Downloaded from informahealthcare.com by University of Newcastle on 01/05/15 For personal use only. Biocatal Biotransformation Downloaded from informahealthcare.com by University of Newcastle on 01/05/15 For personal use only. Table 1 Kinetic constants of (R)-Oxynitrilase in citrate buffer pH = 3.75, T = 20°C and cubic liquid crystals buffer liquid crystals u,,,

Characterization of the Nanostructures in Liquid Crystalline Mesophases Present in the Ternary System Brij-35/Dibutyl Ether/H2O by Small- and Wide-Angle X-ray Scattering

“…These phases have the capability to solubilize DBE at most up to 20−50% (w/w), whereby hexagonal H 1 and various cubic structures as well as oil-rich L 2 phases were found. The DBE excess phase in the biphasic region contains approximately 2% (w/w) H 2 O and 0.02% (w/w) Brij-35 . DBE leads to enhanced temperature stability in all the liquid-crystalline phases, with the exception of the lamellar structures.…”

“…Owing to their particular aggregation and phase behavior and their various technological and biotechnological applications, nonionic surfactants such as Brij-35 [poly(oxyethylene(∼23))lauryl ether, C 12 OE ∼ 23 ], have been the subject of extensive physical studies. − …”

Hydroxynitrile lyase-catalyzed addition of HCN to 2-substituted cyclopentanones

“…The conversion rates for esters 4b-f are below 10% even after long reaction times. The time dependent formations of the stereoisomers in the PaHNL-catalyzed reaction 6 of the methylester 4a are summarized in Table 5.…”

“…The (R)-PaHNL-catalyzed addition of HCN to rac-2-methylcyclopentanone described in a patent is the only example of this type of reaction. 6 The exact stereochemistry however of the thereby obtained cyanohydrin could not be determined. 6 Recently in a patent, the HNL-catalyzed addition of HCN to tetrahydrofuranones and tetrahydrothiophenones have been described.…”

“…6 The exact stereochemistry however of the thereby obtained cyanohydrin could not be determined. 6 Recently in a patent, the HNL-catalyzed addition of HCN to tetrahydrofuranones and tetrahydrothiophenones have been described. Before starting the enzyme-catalyzed reactions, we investigated the chemical addition of HCN, prepared in situ in aqueous solution from KCN with acetic acid, 8 to racemic 2-alkyl cyclopentanones rac-1a-e yielding the corresponding cyanohydrins 2a-e (Scheme 1, Table 1).…”