Room‐temperature ionic liquids as replacements for organic solvents in multiphase bioprocess operations

Abstract

Organic solvents are widely used in a range of multiphase bioprocess operations including the liquid-liquid extraction of antibiotics and two-phase biotransformation reactions. There are, however, considerable problems associated with the safe handling of these solvents which relate to their toxic and flammable nature. In this work we have shown for the first time that room-temperature ionic liquids, such as 1-butyl-3-methylimi- dazolium hexafluorophosphate, [bmim][PF(6)], can be successfully used in place of conventional solvents for the liquid-liquid extraction of erythromycin-A and for the Rhodococcus R312 catalyzed biotransformation of 1, 3-dicyanobenzene (1,3-DCB) in a liquid-liquid, two-phase system. Extraction of erythromycin with either butyl acetate or [bmim][PF(6)] showed that values of the equilibrium partition coefficient, K, up to 20-25 could be obtained for both extractants. The variation of K with the extraction pH was also similar in the pH range 5-9 though differed significantly at higher pH values. Biotransformation of 1,3-DCB in both water-toluene and water-[bmim][PF(6)] systems showed similar profiles for the conversion of 1,3-DCB initially to 3-cyanobenzamide and then 3-cyanobenzoic acid. The initial rate of 3-cyanobenzamide production in the water-[bmim][PF(6)] system was somewhat lower, however, due to the reduced rate of 1,3-DCB mass transfer from the more viscous [bmim] [PF(6)] phase. It was also shown that the specific activity of the biocatalyst in the water-[bmim] [PF(6)] system was almost an order of magnitude greater than in the water-toluene system which suggests that the rate of 3-cyanobenzamide production was limited by substrate mass transfer rather than the activity of the biocatalyst.

Perstraction of intracellular pigments by submerged cultivation of Monascus in nonionic surfactant micelle aqueous solution

“…Organic solvent, ionic liquid, and polymer and nonionic surfactant were chosen because water-organic solvent two-phase system (Daugulis 2001;Straathof 2003), water-ionic liquid two-phase system (Cull et al 2000), aqueous two-phase system (Kumn 1980), and cloud point system (Wang et al 2004;Wang and Dai 2010) were often used in extractive microbial fermentation. Submerged cultivation of Monascus in the presence of different kinds of nonaqueous solvents (4 g/l) had been carried out.…”

Polarity study of some 1-alkyl-3-methylimidazolium ambient-temperature ionic liquids with the solvatochromic dye, Nile Red

“…[21][22][23][24][25][26][27] To give a sense of the scope for these solvents, it is worth mentioning that recent studies have shown that ambient-temperature ionic liquids can be used as media for a wide range of chemical reactions, including hydrodimerization, 28 hydrogenation, [29][30][31][32][33][34] dimerization, 35 polymerization, 36 alkylation, 37 FriedelCrafts reactions, [38][39][40][41] Heck coupling, 42,43 the DielsAlder reaction [44][45][46] and enzymatic catalysis of biotransformations. 47 As part of a programme aimed at understanding more about the nature of these ambient-temperature ionic liquids, and how they compare with conventional solvents, we have undertaken a study of their polarity using the solvatochromic dye Nile Red (Fig. 2).…”

Yeast‐Mediated Stereoselective Synthesis

“…As an alternative the use of an ionic liquid may be considered. A very early example for such a reaction has been reported by Cull in 2000 [360]. The ionic liquid, however, has to be biocompatible; it must not be toxic to the yeast, and its biocompatibility strongly depends on the nature of the composing cation and anion.…”

“…For cations possessing alkyl substituents, the length of these alkyl chains seems crucial: the longer the alkyl chains, the lower is the tolerance of the microorganism to the ionic liquid [361][362][363][364]. This might be due to an insertion of the cation into the yeast's membrane followed by its disintegration or by an accumulation of toxic molecules inside the cells [360,363].…”

“…Several (a)-cyclic ketones, 1,3-diketones, and (a)-cyclic β-keto esters were reduced to yield the corresponding alcohols by alginateimmobilized baker's yeast in ionic liquid/water mixtures [360]. The yields were moderate, and the enantioselectivity was similar to that from "classical" reactions or lower [383,384].…”