1- butanol water miscibility

The butanols are all colorless, clear Hquids at room temperature and atmospheric pressure with the exception of /-butyl alcohol which is a low melting soHd (mp 25.82°C) it also has a substantially higher water miscibility than the other three alcohols. Physical constants (1) of the four butyl alcohols are given in Table 1. 

To eliminate the need to recover the product by distillation, researchers are now looking at thermomorphic solvent mixtures. A thermomorphic system is characterized by solvent pairs that reversibly change from being biphasic to monophasic as a function of temperature. Many solvent pairs exhibit varying miscibility as a function of temperature. For example, methanol/cyclohexane and n-butanol/water are immiscible at ambient temperature, but have consolute temperatures (temperatures at which they become miscible) of 125°C and 49°C, respectively (3). 

This paper considers systems of lesser dimensionality than the previous study, namely, systems of two compounds, which (ignoring the vapor) can form only one or two phases. Specifically, excess enthalpies and phase compositions have been measured (at ambient pressure) by isoperibol calorimetry for n-butanol/water at 30.0 and 55.0 °C and for n-butoxyethanol/water at 55.0 and 65.0 °C. (Butanol, or C4E0, is C HgOH butoxyethanol, or C4E1, is C HgCX OH.) The miscibility... 

C. Each Figure shows titration data for compositions inside of the miscibility gap (where the "curve" is linear), as well as enthalpies in a single-phase region. Data from the literature are also shown for comparison with the present results (13-161. Table I shows values of the compositions of the aqueous and amphiphilic phases for n-butanol/water at 30.0 and 55.0 °C and for n-butoxyethanol/water at... 

The enzyme may be dissolved in a mixed aqueous-ionic liquid medium, which may be mono- or biphasic or it could be suspended or dissolved in an ionic liquid, with little or no water present. Alternatively, whole cells could be suspended in an ionic liquid, in the presence or absence of a water phase. Mixed aqueous-organic media are often used in biotransformations to increase the solubility of hydrophobic reactants and products. Similarly, mixed aqueous-ionic liquid media have been used for a variety of biotransformations, but in most cases there is no clear advantage over water-miscible organic solvents such as tert-butanol. 

A wide variety of organic solvents has been used to conduct bioconversions including nonpolar solvents such as isooctane, n-hexane, and toluene, in addition to methanol, acetone, and other water-miscible solvents. Dipolar aprotic solvents dimethylformamide (DMF) and dimethylsulfoxide (DMSO) are also compatible with many enzymes and are often used to enhance the solubility of substrates in combination with a nonpolar solvent. Tertiary alcohols such as f-butanol and t-amyl alcohol have been used for many lipase-mediated esterifications as the hindered tertiary alcohol is not typically a good substrate for most enzymes. It should be noted that the presence of small amounts of water is essential for the effective use of most biocatalysts in organic solvents. In some cases an enzyme may only require a monolayer of water molecules on its surface in order to operate. In other cases there may need to be enough water to form reverse micelles where the biocatalyst is contained within a predominantly aqueous... 

At atmospheric pressure, the n-butanol-water system exhibits a minimum boiling azeotrope and partial miscibility, and hence a binary heterogeneous azeotrope. Figure 1.8 shows the Tyx and Pyx phase diagrams for l-propanol(l)-water(2) azeotropic mixture obtained from the Aspen Plus simulator using the NRTL activity coefficient model. 

The catalytic cycle for the asymmetric dihydroxylation is shown in Figure 20. The reaction is carried out in a 1/1 t-butanol/water mixture to solubilize the potassium ferricyanide/potassium carbonate used as the oxidant. The solvent mixture, normally miscible, separates into two liquid phases upon addition of the inorganic reagents. 

The direct measurement of vapor-liquid equilibrium data for partially miscible mixtures such as 3-methyl-l-butanol-water is difficult, and although stills have been designed for this purpose (9, 10), the data was indirectly obtained from measurements of pressure, P, temperature, t, and liquid composition, x. It was also felt that a test of the validity of the NRTL equation in predicting the VLE data for the ternary mixtures would be the successful prediction of the boiling point. This eliminates the complicated analytical procedures necessary in the direct measurement of ternary VLE data. 

Methanol, acetonitrile, and 1- or 2-propanol have been the most popularly used solvents for peptide separations, although other water-miscible, UV-transparent solvents (e.g., methoxyethanol, ethanol, butanol, tet-rahydrofuran, and dioxane) have also been employed. The retention of peptide solutes generally follows an inverse relationship to the elutropic... 

Glycol ethers possess both alcoholic and ether functional groups and are milder in odor. They display water miscibility, strong solvency, and slow evaporation. N-Butanol and denatured alcohol are the most commonly used oxygenated solvents. 

In this project, distinguishing properties of the 10 organic liquids should be observed (Part A) and unknowns subsequently identified (Part B) according to an SOP which I wrote for this. The properties are (1) water miscibility, (2) density, (3) viscosity, (4) refractive index, and (5) odor. The 10 organic liquids are acetone, methanol, ethanol, isopropyl alcohol, heptane, cyclohexane, toluene, methyl ethyl ketone, butanol, and ethyl acetate. 

Both stabilizing and destabilizing effects of solvents on enzymes have been reported. A reasonably reliable measure of the compatibility of solvents with enzymes is the log P value, where P is defined as the distribution coefficient of a solvent between water and 1-octanol in a two-phase system[64> 791. Solvents with a log P value above 4 are suitable (e. g. aromatics, aliphatics) whereas water-miscible solvents with a log P value below 2 (short chain esters, DMF, short-chain alcohols) are not suitable for employment with biocatalysts. The latter solvents interfere with the water at the boundary of the protein itself and so disrupt the binding forces necessary to maintain an active form of the enzyme. Surprisingly, tert-butanol has a stabilizing effect on some oxidative enzymes(801, despite its low log P value (0.35). 

Commonly used water-immiscible solvents in industrial-scale processes include alcohols (isobutanol, -butanol), ketones (particularly methyl isobutyl ketone), acetates (butyl, ethyl, isopropyl), hydrocarbons (toluene, hexanes), and methylene chloride. These solvents are inexpensive, readily available, and exhibit physical properties of low viscosity and density significantly different from water. Common water-miscible solvents are the alcohols (particularly methanol). For laboratory-scale processes, the selection is greater since selection is not constrained by economics. Craig and Sogn (16) have prepared an extensive compilation of such solvents. 

In general, interfacial tensions are greater for liquid pairs with low mutual solubilities than for those with high ones. Thus, hexane-water (very low mutual solubility) has an interfacial tension two-thirds that of air-water, whereas butanol-water (reasonably large mutual solubility) has an interfacial tension only a few percent of that of air-water. For miscible liquid pairs such as ethanol-water, there can be no interfacial tension because there can be no interface. 

In laboratory, small amounts of metal alkyls may be destroyed by diluting the pure compounds or its more concentrated solutions to a concentration below 5% with a hydrocarbon solvent, such as hexane or toluene. Alternatively, a water-miscible solvent, such as ethanol or ferf-butanol may be used. Small volumes of such solutions are then slowly and cautiously added to water in wide-mouthed containers in a hood and swirled gently. The metal alkyls are converted into their oxides or hydroxides. The organic solvent, if immiscible in water, is separated and evaporated in a hood. The entire content may, alternatively, be placed in waste containers and labeled for disposal. The toxic oxides or hydroxides of the metals formed are disposed for landfill burial while the nontoxic metal oxides or hydroxides conld be flushed down the drain. Alternatively, the metal alkyl solution or its waste may be diluted to a concentration below 5% with toluene or heptane. The diluted solution is then placed in a labeled container under argon for waste disposal. 

Butanol by itself is not miscible in all proportions with water, but its water miscibility is unlimited in the presence of paint binders. Butanol is an extremely effective solvent in waterborne paints, although it has the disadvantage of a somewhat more pungent smell than glycol ethers. The auxiliary solvents in waterborne paints promote solubilization of the binder and water, reduce the viscosity maximum that occurs on dilution with water, and yield smooth-flowing, flawless paint surfaces [14.216]-[14.226]. 

Partially water-miscible organic solvents (PMOSs) may act as either cosolvents or cosolutes, and the research in the past has shown flic complexity of their effects. " It was demonstrated that in order to exert effects on solubility or sorption of HOCs, PMOSs must exist as a component of the solvent mixture in an appreciable amount Munz and Roberts suggested a mole fi action of greater than 0.005 and Rao and coworkers proposed a volume percent of 1% or a concentration above lO mg/L. Cosolvents with relatively high water solubility are likely to demonstrate observable effects on the solubilities of solutes, up to their solubility limits, in a similar manner to cosolvents of complete miscibility with water. A few experimental examples of the effects of PMOSs include 1 -butanol and... 

Higher molecular weight homologues are less water miscible than the lower molecular weight ones. Compare diisopropyl with diethylether, -butyl- with ethylacetate, -butanol with n-propanol and methyl-ethyl-ketone with acetone. 

For the system tert-butanol-water a miscibility gap is predicted, although tertiary butanol in contrast to 1-butanol, 2-butanol, and isobutanol forms a homogeneous mixture with water. 

CALB is an exceptionally robust protein which is deactivated only at 50-60°C, and thus also shows increased resistance towards organic solvents. In contrast to many other lipases, the enzyme appears to be rather rigid and does not show a pronounced effect of interfacial activation [430], which makes it an intermediate between an esterase and a lipase. This latter property is probably the reason why its selectivity could be predicted through computer modeling to a fair extent [431], and for the majority of substrates the Kazlauskas rule (Scheme 2.49) can be applied. In line with these properties of CALB, selectivity-enhancement by addition of water-miscible organic cosolvents such as t-butanol or acetone is possible - a technique which is rather common for esterases. All of these properties make CALB the most widely used lipase both in the hydrolysis [432-437] and synthesis of esters (Sect. 3.1.1). 

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