Candida dioxide

Respiratory, or oxidative, metaboHsm produces more energy than fermentation. Complete oxidation of one mol of glucose to carbon dioxide and water may produce up to 36 mol ATP in the tricarboxyHc acid (TCA) cycle or related oxidative pathways. More substrates can be respired than fermented, including pentoses (eg, by Candida species), ethanol (eg, by Saccharomjces), methanol (eg, by Hansenu/a species), and alkanes (eg, by Saccharomjces lipoljticd). 

A novel continuous-flow SCCO2 process for the kinetic resolution of 1-phenyethanol enantiomers (Figure 30) using Novozym 435 immobilized enzyme from Candida antarctica was described by Matsuda et al. [51], The lipase enzyme, selectively acetylated the R)-alcohol component. A mixture of starting material and vinyl acetate was passed through the enzyme with supercritical carbon-dioxide (Figure 31). The reaction zone was pressurized and heated, so the reaction could be performed imder supercritical conditions, synthesizing the desired (i )-acetate with 99.7% ee. and 47% yield. 

DNB was biodegraded under aerobic conditions to carbon dioxide by a microbial strain, Candida pulcherrima, isolated from soil contaminated with 1,3-DNB manufacture wastes (Dey and Godbole 1986). Some biotransformation products detected in the metabolic pathway of biodegradation of... 

Lozano, P., G. Villora, D. Gomez, A.B. Gayo, J.A. Sanchez-Conesa, M. Rubio and J.L. Iborra, Membrane Reactor with Immobilized Candida Antarctica Lipase B for Ester Synthesis in Supercritical Carbon Dioxide, Journal of Supercritical Fluids, 29, 121-128 (2004). 

In tandem with the use of supercritical carbon dioxide, in ester synthesis employing Candida Antarctica lipase B, adsorbed on silica gel, as the esterification catalyst under minimum water conditions.50... 

Lozano P, Villora G, Gomez D, Gayo AB, Sanchez-Conesa JA, Rubio M, and Iborra JL. Membrane reactor with immobilized Candida antarctica lipase B for ester synthesis in supercritical carbon dioxide. J. Supercrit. Fluids 2004 29(1-2) 121-128. 

Romero, M.D. Calvo, L. Alba, C. Habulin, M. Primozic, M. Knez, Z. Enzymatic synthesis of isoamyl acetate with immobilized Candida ant-arc tica lipase in supercritical carbon dioxide. J. Supercritic. Fluids 2005, 33 (1), 77-84. 

Fig. 8.1 Experimental set-up of the recirculating enzymatic membrane reactor used for the synthesis of butyl propionate from vinyl propionate and 1-butanol catalysed by Candida antarctica lipase B in supercritical carbon dioxide and supercritical carbon dioxide/ionic liquid biphasic system [17]...

Other lipases have also been tested in supercritical carbon dioxide for ester synthesis. In this context, the synthesis of terpinyl acetate from a-terpineol and acetic anhydride in supercritical carbon dioxide (scCO ) was carried out using five different lipases as catalysts (Candida rugosa type Vll, Amano PS, Amano AP-6,... 

Fig. 8.4 Initial reaction rate (bars) and selectivity (points) exhibited by free Candida antarctica lipase B for butyl propionate synthesis in supercritical carbon dioxide and in four different ionic liquids/supercritical carbon dioxide systems. The reaction conditions were r=50°C, vinyl propionate 150 mM and 1-butanol 100 Mm [38]...

As evident from Fig. 8.4, an increase in the selectivity has been observed in IL/ scCOj biphasic systems media (>99.5%) with respect to scCO assayed alone (95%). These results could be explained by the use of water-immiscible ILs which have a specific ability to reduce water activity in the enzyme microenvironment. The synthetic activity of the immobilized lipase in IL/scCO biphasic systems is lower than that in scCO assayed alone. Similar results were found by Mori et al. [40] in IL/ hexane biphasic systems. These authors reported that the enzymatic membranes prepared by simple adsorption of CaLB onto the surface were more reactive than membranes prepared with ILs. As can be observed in Fig. 8.4, the initial reaction rate in the assayed IL/scCO biphasic systems increased in the following sequence [bdimim ][PF ]<[bmim ][PFg ]<[bmim ][NTfj ]<[omim ] [PF ], which was practically in agreement with flie activity sequence reported by these authors using free Candida antarctica lipase B in homogeneous ionic liquid systems ([bmim ] [PF ]<[bdmim+][PFg ]<[bmim+][NTfj ]<[omim ][PF ]), with the exception of [bmim [PF ] and [bdimim+][PFg ]. These results were explained taking into account that biotransformation occurs within the ionic liquid phase, so substrates have to be transported from scCOj to the ionic liquid phase. The mechanism of substrate transport between the ionic liquid and the supercritical carbon dioxide could be by three consecutive steps diffusion of the substrates through the diffusion... 

Romero MD, Calvo L, Alba C et al (2005) Enzymatic synthesis of isoamyl acetate with immobilized Candida antarctica lipase in supercritical caibon dioxide. J Supercrit Fluids 33 77-84... 

The separation of the products from the IL catalytic mixture can be performed in various cases by simple decanting and phase separation or by product distillation. In this respect, a continuous-flow process using toluene as extractant has been appHed for the selective Pd-catalyzed dimerization of methyl acrylate in ILs [136]. However, in cases where the products are retained in the IL phase, extraction with supercritical carbon dioxide can be used instead of classical liquid-liquid extractions that necessitate the use of organic solvents, which may result in cross-contamination of products. This process was successfully used in catalyst recycling and product separation for the hydroformylation of olefins employing a continuous-flow process in supercritical carbon dioxide-IL mixtures [137]. Similarly, free and immobilized Candida antarctica lipase B dispersed in ILs were used as catalyst for the continuous kinetic resolution of rac-l-phenylethanol in supercritical carbon dioxide at 120°C and 150°C and 10 Mpa with excellent catalytic activity, enzyme stability and enantioselectivity levels (Fig. 3.5-11). 

Biocatalytic kinetic resolution of racemic hydroxymethylphosphinates 271 via their lipase-promoted acetylation in supercritical carbon dioxide as the reaction medium was investigated. The reaction was fastest when pressure was closer to the critical pressure at 11 MPa the reaction rate reached its maximum when the pressure was increased to 15 MPa. The optimal conditions were obtained at 13 MPa (yields 50%, 30% ee). The stereoselectivity of the reaction depended on solvent, substituents at phosphorus, and solubility of substrates in SCCO2. The best results were obtained with the Candida antarctica lipase (Novozym 435) (Scheme 89) [183, 184]. 

Ammonium sulfate Calcium acetate Calcium chloride Calcium hydroxide Calcium sulfate Candida guilliermondii Candida lipolytica Carbohydrase Carbon, activated Carbon dioxide... 

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