Continuous lipase-catalyzed

Orsat, B. Wirz, B. Bishof, S. (1999) A continuous lipase-catalyzed acylation process for the large-scale production of vitamin A precursors. Chimia, 53, 579-84. 

Severac, E Galy, O Turon, F Monsan, P Marty, A. Continuous lipase-catalyzed production of esters from crude high-oleic sunflower oil. Bioresource Technology, 2011, v. 102,4954-4961. 

Dalla Rosa, C., M. B. Morandim, J. L. Ninow, D. Oliveira, H. Treichel, and J. Vladimir Oliveira. 2009. Continuous Lipase-Catalyzed Production of Fatty Acid Ethyl Esters from Soybean Oil in Compressed Fluids. Bioresource Technology 100 (23) 5818-5826. 

Continuous lipase-catalyzed kinetic resolution of alcohols using scCO -flow reactor, (a)... 

Several reports on DKR of cyanohydrins have been developed using this methodology The unstable nature of cyanohydrins allows continuous racemization through reversible elimination/addition of HCN under basic conditions. The lipase-catalyzed KR in the presence of an acyl donor yields cyanohydrin acetates, which are not racemized under the reaction conditions. 

Performing a systematic comparison of lipase-catalyzed kinetic resolutions of several seeondaiy aleohols in continuous flow mode (Figure 7) and shake flask batch mode using immobilized and non-mobilized lipases was reported by Csajagi and eo-workers [25]. The results indieated that immobilized as well as lyophilized powder forms of liphases can be effeetively used in eontinuous flow mode kinetie resolutions of raeemic alcohols in non-aqueous solvent systems. The produetivity of the lipases was higher in continuous flow reactors than in batch mode systems, whereas the enantiomer selectivities were similar. 

The biphasic solvent system composed of PEG and scC02 is ideally suited for the lipase-catalyzed acylation of alcohols, both batch and continuous-flow acylations are possible (Scheme 3.1) [14]. 

Du, W., Xu, Y., and Liu, D. 2003. Lipase-catalyzed transesterification of soya bean oil for biodiesel production during continuous batch operation. Biotechnol. Appl. Biochem.,38,103-106. 

Effect of Acyl Donors. TTie synthesis of glucose fatty acid esters was investigated with continuous by-product removal in a stirred-tank membrane reactor by azeotropic distillation using EMK containing 20% hexane as reaction solvent and different fatty acids as acyl donors. From previous studies on the lipase-catalyzed synthesis of glucose esters in a solid-phase system (17,19,22,23), it was already known that the fatty acid chainlength had a considerable influence on product formation. This was due... 

Some groups have reported on their search for less reactive acylating agents, to suppress noncatalyzed chemical acylation and increase product enantiomeric excess. Irimescu and Kato carried out an enantioselective lipase catalyzed acylation of 1 phenylethylamine and 2 phenyl 1 propylamine by reacting the amines with carbox ylic acids in a nonsolvent system or in ionic liquids (Figure 14.9). The reaction equilibrium was shifted toward amide synthesis by the continuous removal of the... 

FIGURE 8.4 Effect of solvent removal and the stepwise addition of fructose on the percent conversion of saccharide (a) and on the solubility of fructose (b) for lipase-catalyzed fructose-oleic acid esterification. ( ) Fructose was added to 50 mmol oleic acid and 13.4 g tert-butanol in 5 mmol increments for 2-h cycles until the net amount of fructose added was 25 mmol tert-butanol underwent free evaporation for up to 10 h, at which time, the reaction was stopped, solvent was removed completely by rotary evaporation, then the reaction was continued. (A) Fructose (25 mmol) was added at time 0 to 50 mmol of oleic acid and 13.4 g (46.9 wt.% fructose-free basis) tert-butanol solvent freely evaporated away throughout at a rate of 0.47 g per h. Both reactions were operated in stirred batch mode using approximately 0.5 g immobilized C. antarctica lipase, (Chirazyme L-2, s.-f, c2, Lyo., Boehringer-Mannheim, Indianapolis, IN), a stir rate of 450 rev min and a reaction temperature of 65°C. (From Walde, P. et al., Chem. Phys. Lipids, 53, 265-288, 1990. With permission.)... 

Coniine (160) continues to be a popular synthetic target and numerous syntheses have been reported. In one recent synthesis, the reaction of a chiral cyclic 2-carbonylsultam-substituted N-hydroxy-2-propylpiperidine with NaH gave an amine which, after reduction, produced (-)-160 [427]. Another synthesis began with a trans-oxazolopiperidone and obtained (-)-160 after a separation of isomers in the penultimate step [428], Yet another example of a (-)-160 synthesis employed a lipase-catalyzed resolution of a racemic alcohol, followed by a Pd(II)-catalyzed cyclization to form the piperidine ring [429]. 

Russell et al. [43] studied lipase-catalyzed polymerizations of activated diesters and fluorinated diols. The effects of reaction time, continuous enzyme addition, enzyme concentration, and diol chain length were studied to determine factors that might limit chain growth. Potential limiting factors considered were enzyme inactivation, enzyme specificity, reaction thermodynamics, hydrolysis of activated esters and polymer precipitation. The polymer molecular weight at 50°C steadily increased and then leveled off after 30h at Mw 1773. 

Lipase-catalyzed interesterification of fats and oils can be accomplished either by using a stirred batch reactor or with continuous processing using a fixed-bed reactor. 

Based on their work on supercritical CO2 (see also Scheme 23), Reetz and Leitner introduced a technologically new and interesting continuous flow process for enzymatic reactions [65]. The group designed a protocol for enzymatic reactions, namely the lipase-catalyzed acylation (CAL B) of octan-1 -ol by vinyl acetate in ionic liquids (l-butyl-3-methylimidazolium bis(trifluo-romethanesulfonimide) [BMIM] [BTA]) using supercritical CO2 as the mobile phase (Scheme 25). The alcohol is pumped through the biphasic system and the products are obtained in solvent-free form in a cold trap. The enzyme/ionic liquid mixture can be recycled in batchwise or continuous flow operations. 

In the context of continuous-flow operations using SCCO2/ILS, it has to be mentioned that this concept has also been successfully applied to biocatalyzed reactions. Among others, Reetz et al. were able to demonstrate that kinetic resolution of alcohols is possible by lipase-catalyzed alcohol esterification in ILs and subsequent continuous extraction of the ester derivatives with SCCO2 [29]. For further information, see Chapter 8. 

The focus on lipase-catalyzed reaction in SC-CO2 is due to enhanced reaction rates (Lee et al, 2013). In biodiesel production systems, SC-CO2 offers easy product separation from the reaction mixture by selectively dissolving the biodiesel, due to its high solubility compared to the glycerol by-product (Rodrigues et al, 2011). In a continuous system, the product is continuously removed from the reaction system, which can then be easily separated from SC-CO2 by simple depressurization. 

Hydrolases — especially lipases — proved to be versatile biocatalysts for synthetic biotransformations [79, 80). The vast majority of the enzymatic stereoselective processes have been performed so far in batch mode [29, 30, 81]. Very recently, a review appeared on lipase-catalyzed reactions under continuous-flow conditions [82], and here we extend this overview with an analysis of the range of selectivities, effects of reaction conditions and the mode of enzyme immobilization on the lipase, and in general hydrolase-catalyzed continuous-flow biotransformations. 

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