Ketones solubility

The use of the following constituents is described in Ref.5) water, glycerol (or its solution), wax solution in water-soluble ketones, aliphatic (stearic) alcohol and ethanol mixtures, urea-formaldehyde solution, aqueous solutions of urea, vinacryl, impregnating urea-formaldehyde resin, polyoxyethylene, etc. 

C. Wandrey, 1998, A novel reactor concept for the enzymatic reduction of poorly soluble ketones, J. Mol. Catal. B ... 

In addition to this, that an interesting novel emulsion membrane reactor concept overcomes the difficulties of the large solvent volume otherwise required for the reduction of poorly soluble ketones [30]. 2-Octanone was reduced by a carbonyl reductase from Candida parapsilosis to (S)-2-octanol with > 99.5 % ee and total turnover number of 124 - the 9-fold value of that obtained in a classical enzyme reactor. 

As a new option, for the bioconversion of poorly soluble substrates the classical EMR-concept can be extended to an Emulsion Membrane Reactor , comprising a separate chamber for emulsification (with a hydrophilic ultrafiltration membrane), an EMR-Ioop with a normal ultrafiltration module, and a circulation pump. This approach has been successfully demonstrated for the enzymatic reduction of poorly soluble ketones [107]. Using this device, e.g., for the enantioselective reduction of 2-octanone to (S)-2-octanol (e.e. >99.5%) with a carbonyl reductase from Candida parapsilosis under NADH-regeneration with FDH/for-mate, the total turnover number was increased by a factor 9 as compared with the classical EMR. 

In summary, the conversion of acetyl-CoA molecules into acetoacetate and P-hydroxybutyrate transforms acetyl groups into water-soluble ketone bodies which readily diffuse from the liver into the bloodstream and then into the peripheral tissues. The brain, in particular, uses ketone bodies as a source of energy, reducing its reliance on glucose. 

Epoxidation of methyl vinyl ketone (1). This ,/3-unsaturated water-soluble ketone is epoxidized most satisfactorily with 5% aqueous NaOCl (clorox) at 10° at pH 8.5 maintained with HCl. The by-produet (3) arises from the halo-form reaction. 

Much of the endogenous lipid that is eventually used by peripheral tissues is transported in the form of water-soluble ketone bodies, the two most important being jS-hydroxybutyrate and acetoacetate. The metabolic pathway of ketone body formation and its relationship to cholesterol biosynthesis is shown in Fig. 4.10. Four enzymes are Involved in the formation of ketone bodies, namely acetyl-CoA transferase (also known as thiolase), hydroxymethylglutaryl-CoA synthase (HMG-CoA synthase), hydroxymethyl-glutaryl-CoA lyase (HMG-CoA lyase) and jS-hy-droxybutyrate dehydrogenase. Tbe last of these catalyses the interconversion of the two principal ketone bodies. All four enzymes are present in liver, the principal site of ketone body formation. Acyl-CoAs are unable to pass through the plasmalemma, and HMG-CoA lyase thus controls the release of ketone... 

Treatment of the 8elenlum(IV) polymer with 30% H2O2 results In rapid loss of the color, presumably due to formation of the peracldi In a trlphase system at room temperature 1.5 mol X of the polymer and 1.5 - 1.8 equivalents of H2O2 were effective for oxidation of both olefins and ketones. Unlike the arsonated system, olefins opened readily to the trans dlols only In the case of tetramethylethylene could the epoxide be Isolated. Such a result may be due to partial oxidation to the selenonlc acid, a more powerful acid, or to a more aqueous microenvironment. The Baeyer-Vllllger reactions of ketones could be carried out In a similar fashion In a trlphase system some ester hydrolysis could be observed. Water soluble ketones and aromatic ketones were both unreactlve. The polymer can be recycled readily but becomes unstable If elevated temperatures are used In the reaction. Use of the catalyst under reaction conditions for 150h led to loss of less than 5% of the Initial selenium content. 

There are a number of ways to determine HLB. The general rule is to determine the ratio of lipophilic functional groups to the whole surfactant molecular. Surfactants with a strong lipophilic character have a low HLB, while the ones with a stronger hydrophilic character have a high HLB. The surfactants for perfumes can be also characterized by the solubility of spices in the surfactants. Alcohol type spices have higher solubility, ketone type spices have less and ester t5q)e spices have the lowest of the three. 

Orlich, B., Schomaecker, R. 1999. Enzymatic reduction of a less water soluble ketone in reverse micelles with NADH regeneration. Biotech. Bioeng. 65, 357-362. Orlich, B., Berger, H., Lade, M., Schomacker, R. 2000. Stability and activity of alcohol dehydrogenases in w/o-microemulsions Enantioselective reduction including cofactor regeneration. Biotech. Bioeng. 70, 638-646. 

Biphasic reaction media, which are advantageous for poorly water-soluble ketones and for reactions at higher substrate concentrations, have been developed for the... 

So far, some oxidoreductase-catalyzed reactions have been examined in reversed micelles. The enzyme activity and stability that depend largely on the microemulsion composition, mostly the water-to-stirfactant ratio (ivo), are often comparable to values in aqueous media. Orlich et al. reported the application of reverse micelles for ADH-catalyzed reduction of less water-soluble ketones in an FDHcontained water, cyclohexane, and Marlipal 013-16 as the surfactant. The reaction rate of ADH for the reduction of 2-heptanone in reverse micellar medium was increased up to 12 times compared to aqueous medium [84], The improved enzymes stability was observed at optimal Wq. Finally, it was possible to perform successful semibatch experiments reducing 2-butanone with full conversion and enantioselectivity [85]. 

Kohlmarm, C., Roberta, N., Leuchs, S., Dogan, Z., Liitz, S., Bitzer, K., Na amnieh, S., and Greiner, L. (2011) Ionic liquid facilitates biocatalytic conversion of hardly water soluble ketones./. Mol. Catal. B. Enzym., 68,147-153. 

Orlich, B. and Schomaecker, R. (1999) Enzymatic reduction of a less water-soluble ketone in reversed micelles with NADH regeneration. Biotechnol Bioeng., 65, 357-362. 

Mutated Rhodococcus phenylacetaldehyde reductase (PAR) or Leifsonia alcohol dehydrogenase (LSADH) were applied to water-soluble ketone substrates. For example, 4-hydroxy-2-butanone was reduced to (S)/(R)-l,3-butanediol, with a high yield and stereoselectivity. Intact E coli cells overexpressing mutated PAR (Sar268) or LSADH were directly immobilized with polyethyleneimine or 1,6-hexanediamine and glutaraldehyde and evaluated in a batch reactor. This system produced (S)-l,3-butanediol (87% ee) with a space-time yield (STY) of 12.5 mg/h/mL catalyst or (R)-l,3-butanediol (99% ee.) with an STY of 60.3 mg/h/mL catalyst. The immobilized cells in a packed bed reactor continuously produced (R)-l,3-butanediol with a yield of 99% (about 49.5 g/L) from 5% (w/v) 4-hydroxy-2-butanoate over 500 h. The concentration of PEI used for immobilization influenced the operational stability of immobilized cells, and the cells treated with 3% PEI showed better stability than those treated with lower PEI concentrations The immobilized E. coli biocatalyst could be used more than 30 times (for about 500 h) with no decrease in conversion [54]. 

C. Kohlmann, N. Robertz, S. Leuchs, Z. Dogan, S. Liitz, K. Bitzer, S. Na amnieh, L. Greiner, Ionic liquid facilitates biocatalytic conversion of hardly water soluble ketones, J. Mol. Cat. B Enz. 68 (2011) 147-153. 

For substrates and products with low solubility in aqueous buffer the ttn that can be reached is somewhat lower. Two examples for sparingly soluble ketones are shown in Fig. 

Figure 15 Total turnover number (ttn) as a function of the ratio substrate/coenzyme concentration and coenzyme retention of the enzymatic reduction of poorly soluble ketones. The data points are experimental values (compare Table 5) and indicate the increase of the ttn compared to the operation without additional means for coenzyme retention. (A) Synthesis of (S)-l-pheny 1-2-propanol (B) synthesis of (iS)-2-octanol.

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