Micro-aqueous

AOT, could form w/c RMs in the presence of the commercially available perfluoropentanol (F-pentanol) as a co-surfactant, and the RMs formed could provide polar micro-aqueous for highly ionic chemicals[4,5]. Herein, we present the synthesis of crystalline nanoparticles of Ag, Agl, and Ag2S (which have potential application as photoelectric and thermoelectric devices) in the polar micro-aqueous domains of the w/c RMs stabilized by the AOT/F-pentanol (AOTF) surfactant/co-solvent combination, suggesting the possibility of the commercial utilization of SCCO2 in nanomaterials synthesis. 

Lin and coworkers disclosed that, at room temperature, nonenzymatic chemical addition was still observed in a water-organic solvent biphasic reaction system, though the volume of aqueous phases was relative small. Lin developed a method of preparing an active enzyme meal that contained essential water to retain its power for catalysis and found a new catalytic reaction system by application of the prepared meal in a nonaqueous monophasic organic medium (Figure 5.7). There was no problem over a wide range of temperature (from 0-30 °C) when the reactions were carried out under micro-aqueous conditions [50]. 

Figure 5.7 Comparison of a water-organic solvent biphasic system with a micro-aqueous organic phase system...

Chen, P., Han, S., Lin, G., Huang, H. and Li, Z., A study of asymmetric hydrocyanation of heteroaryl carboxaldehydes catalyzed by (i )-oxynitrilase under micro-aqueous conditions. Tetrahedron Asymm., 2001,12, 3273. 

Iin and co-workers [40] have developed a so-called micro-aqueous organic reaction system. In contrast to former preparations of almond meal, the almond kernels are soaked in water prior to grinding. After the defatting step, the meal contains 8-10% water (w/w), making it unnecessary to add the amount of water needed for enzyme activity. The reactions are carried out in buffer-saturated organic solvents to avoid a possible drying effect of the solvent on the biocatalyst. Further addition of water to the reaction results in lower conversions and values,... 

The conversion of co-hydroxyalkanals to the corresponding cyanohydrins in moderate enantioselectivities could also be accomplished by transhydrocyanation with acetone cyanohydrin as the cyanide source. These substrates are considered difficult because of their high solubility in water. Through the employment of an almond meal preparation in a micro-aqueous organic reaction system, the ee-values could be significantly improved [54]. 

In all reported cases where neutral peptides were synthesized, product precipitation was observed in the (micro-) aqueous media. Z%t could be calculated on the basis of the melting points of a large number of neutral di- and tri-peptides and their amino acid substrates, and it was found that it was always between two and six orders of magnitude smaller in value than the reference equilibrium constant for amide synthesis [39]. Hence, conversion of solid substrates to solid product was predicted to be favorable. 

Under non-aqueous or micro-aqueous conditions, this fungal catalyst shows high efficiency and good operational stability. As neither purification, nor immobilization step are needed, total cost is low. and fully compatible with industrial uses. 

The interesterification of fats and oils is the only way to create new hybrid products with new physical, and especially new rheological properties. Chemical interesterification is well known, but has no position or chain specificity, and is not very clean. With lipases in micro-aqueous media, the exchange of acyl groups between the different triglycerides may be oriented, and designed according to the specificity of the enzyme. 

Kang, I.J. Rezac, M.E. Pfromm, P.H. Membrane permeation based sensing for dissolved water in organic micro-aqueous media. J. Membr. Sci. 2004, 239 (2), 213-217. 

Finally, an excess aqueous phase may not lead to inactivation if the method of enzyme and water introduction into nonaqueous media is performed carefully. It is best to introduce enzymes (after their lyophilization at optimal conditions, as discussed above) as highly concentrated aqueous solutions ( 60 mg/ml) into organic media rather than to add solid-phase enzymes to micro-aqueous solvents. - ° Such a procedure was particularly effective for incorporating highly purified lipase into nonaqueous media, in contrast to previous results indicating such purified hpases are highly inactive. ... 

Solvent-free micro-aqueous systems (Diffusion-controlled synthesis using sonification and fluidization, resp.)... 

Commercial laccase was immobilized onto a spiral-wound asymmetric polyethersulfone membrane. The laccase membrane reactor was applied to the biodegradation of a model phenol solution. The feasibility of using a hollow-fiber membrane reactor for the Upase-catalyzed interesterification reaction of triglycerides and fatty acids in a micro aqueous n-hexane system was developed by Basheer et al. In this case they use a stirred-tank reactor as well as a hollow-fiber membrane reactor system. Moreover, in 2004 a new immobilization of lipase into microporous... 

Ohde, H., A. Uehara, Y. Yoshida, K. Maeda, and S. Kihara, Some factors in the vol-tammetric measurement of ion transfer at the micro aqueous I organic solution interface, 7 SecfroaraoZ Chem, Vol. 496, (2001) p. 110. 

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