Ethanol activity, water comparison

Bamwenda GR, Tsubota S, Nakamura T, Haruta M (1995) Photoassisted hydrogen production from a water-ethanol system a comparison of activities of Au-Ti02 and Pt-Ti02. J Photochem Photobio A 89 177-189... 

Solvent system does play very important role in the isolation and extraction of psilocybin. It is quite evident from the early phase of research activities that very polar solvent, such as methanol or mixtures of ethanol and water, is most suitable for the isolation of psilocybin. The polar properties of the phosphate group make psilocybin soluble in water and methanol (polar solvent), and as a result solubility decreases with the decrease in polarity, i.e., less soluble in polar solvent. In comparison, psilocin is less polar and thus readily soluble in polar solvent, such as 1-chlorobutane. For thin layer chromatography, solvent systems comprising of n-butanol + acetic acid + water (20 10 10) or methanol + con. ammonia solution (100 1.5) may be used to develop the plates, and visualization of the blue spots on fluorescent background can be made using ultraviolet (UV) light at 254 and 365 nm. The absorption characteristics of both... 

The use of lead oxide (PbO) for the conversion of ethyl carbamate (EC) to form diethyl carbonate (DEC) using ethanol has been reported this reaction is the second step in the conversion of urea to DEC by alcoholysis (Scheme 22.15). Of interest is that the catalytic species appears to be a mixture of metallic Pb and PbOj, generated under the reactions conditions from the initially added PbO by reaction with ethanol to generate ethane, acetaldehyde, carbon dioxide and water. This lead oxide catalyst exhibited excellent activity in comparison other metals and high conversion yield (16%), and could be reused up to five times without significant loss in activity. ... 

The reverse reaction is catalysed by copper sulphate in an ethanol/water (50 50) mixture297 298. Indium(III) chloride catalysis of Diels-Alder reactions was also reported, but the effects were poor and comparison to uncatalysed reactions was made only in a few cases299,300. A very versatile Lewis acid catalyst for such reactions is methylrhenium trioxide (MTO)300. This catalyst can be used without a solvent, in pure organic solvents like chloroform and even in pure water. While the catalyst is active in the latter two solvents (Table 22), it gives the best results in water (Table 23). 

Palytoxin is a white, amorphous, hydroscopic solid that has not yet been crystallized. It is insoluble in nonpolar solvents such as chlorophorm, ether, and acetone sparingly soluble in methanol and ethanol and soluble in pyridine, dimethyl sulfoxide, and water. The partition coefficient for the distribution of palytoxin between 1-butanol and water is 0.21 at 25°C based on comparison of the absorbance at 263 nm for the two layers. In aqueous solutions, palytoxin foams on agitation, like a steroidal saponin, probably because of its amphipathic nature. The toxin shows no definite melting point and is resistant to heat but chars at 300°C. It is an optically active compound, having a specific rotation of -i-26° 2° in water. The optical rotatory dispersion curve of palytoxin exhibits a positive Cotton effect with [a]25o being -i-700° and [a]2,j being +600° (Moore and Scheuer 1971 Tan and Lau 2000). 

FIGURE 4-1 Comparison of the mean coeflBdents for the salt effect and the overall activity coeflScient for hydrochloric acid in several solvents at 2S°C I, water 2, 80% 2-methoxyethanol S, ethanol 4, 82% dioxane S, methanol. From Bates, Pool and Bates, and Thun, Stt les, and Bates. °)... 

Fig. 2. Comparison between experimental (O) (Romero et al., 1996) and calculated (solid lines) solubilities of paracetamol (S is the mole fraction of paracetamol) in the mixed solvent water/ethanol (xet is the mole fraction of ethanol) at room temperature. The solubility was calculated using Eq. (6) combined with Eqs. (9) and (12) (1) the activity coefficients expressed via the Flory-Huggins equation, (2) the activity coefficients expressed via the Wilson equation.

There has been a relatively small number of clinical trials with kava, a majority of them conducted in Germany. Although kava is a herbal anxiolytic drink that is prepared in the South Seas as a water extract, most of the trials have been performed on commercially produced preparations that contain kavalactones extracted using organic solvents, such as ethanol and acetone. The kavalactone content of these formulations usually is between 30 and 70%. In addition, a number of studies have used individual synthetic preparations [e.g., (+)-kavainl rather than kava extracts which contain a mixture of at least six major active kavalactones. Thus, comparisons across studies in terms of clinical efficacy and adverse side-effects should not be made across studies unless they have used similar, standardized kava preparations. 

By nature ILs are polar compounds, a property that is easily studied with solvatochromic compounds such as Reichardt s dye [4]. On the normalized polarity scale ( ) from 0.0 (tetramethylsilane, TMS) to 1.0 (water), most ILs can be foimd around 0.6-0.7. By comparison, for ethanol is 0.654 [4]. In general, the polarity is largely controlled by the nature of the cahon, whereas the ability of the ILs to parhcipate in hydrogen bonding seems to depend on the anion. On the other hand, the miscibility of ILs with water seems unpredictable. A well-known example is [BMIMjjBFJ which is water-miscible, while [BMIM][PFj] is not. Regarding biocatalysis, it has been pointed out that even trace amoimts of ionic impurihes can significantly affect the properties of the IL as well as the activity of added enzyme. 

The accuracy of the predicted thermodynamic data depends on the type of system and also on the thermodynamic properties. Group predictive models often predicted activity coefficients at infinite dilution with less accuracy. A comparison between a UNIFAC prediction and values measured by Atik et al. [38] shows relative deviations of 2.4, 8, 15, 17, and 29% for activity coefficients at infinite dilution [x = 10 ) of ethanol, acetone, benzene, 2-butanone, and 2-pentanone in water, respectively. 

A dry elixir is a novel dosage form developed by spray-drying actives and excipients dissolved or suspended in ethanol/water mixtures. One example is a dry elixir in which the feed solution contained actives, dextrin, and sodium lauryl sulfate in a mixture of ethanol/water (48). The spray-dried product was spherical in shape with a smooth surface and a mean diameter of 13 pm. A comparison with the active in powder form revealed a major decrease in dissolution time from >60 to 2 min. 

Meziani, A., Touraud, D., Zradba, A., Pulvin, S., Pezron, I., Clausse, M., and Kunz, W. (1997). Comparison of enzymatic activity and nanostructures in water/ ethanol/Brij 35 and water/l-pentanol/Brij 35 systems. J. Phys. Chem. B, 101, 3620-3625. 

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