Ethanol/butanol equilibria

Butanol/ethanol equilibria, 375 Bufanol/wafer separation, 388 Butinediol reactor, 576... 

A. n-Butanol-ethanol-water (4 1 5), equilibrated at room temperature, upper phase in descending manner, in equilibrium with lower phase at 38°... 

Hull, A. Kronberg, B. Van Stamm, J. Golubkov, L Kristensson, J. Vapor-Uquid equilibrium of binary mixtures. 1. Ethanol + 1-butanol, ethanol -i- oetane, 1-butanol -I- octane. J. Chem. Eng. Data 2006, 51, 1996-2001. 

Many papers concerning salt effect on vapor-liquid equilibrium have been published. The systems formed by alcohol-water mixtures saturated with various salts have been the most widely studied, with those based on the ethyl alcohol-water binary being of special interest (1-6,8,10,11). However, other alcohol mixtures have also been studied methanol (10,16,17,20,21,22), 1-propanol (10,12,23,24), 2-propanol (12,23,25,26), butanol (27), phenol (28), and ethylene glycol (29,30). Other binary solvents studied have included acetic acid-water (22), propionic acid-water (31), nitric acid-water (32), acetone-methanol (33), ethanol-benzene (27), pyridine-water (25), and dioxane-water (26). 

Fig. 10. Equilibrium swelling curves of NIPA gel in aqueous solutions in the presence of organic compounds water (no additive) O methanol ethanol A 1-propanol A 1-butanol urea glycerol...

Two recent papers report the main features of the heterogeneously catalysed addition of alcohols to alkenes [364,365]. The reaction proceeds both in the liquid and gas phase [364], and the temperature must be kept well under 150°C with respect to the position of the equilibrium [364], The reactivity of isobutene and 2-methyl-l-butene is much higher than that of propene, 2-butene and 3-methyl-l-butene [364,365]. 2-Methyl-l-butene reacts faster than 2-methyl-2-butene [365]. The reactivity of alcohols with isobutene decreases in the order methanol > ethanol > 1-propanol > 1-butanol [365]. 

Azeotropic and Partially Miscible Systems. Azeotropic mixtures are those whose vapor and liquid equilibrium compositions are identical. Their x-y lines cross or touch the diagonal. Partially miscible substances form a vapor phase of constant composition over the entire range of two-phase liquid compositions usually the horizontal portion of the x-y plot intersects the diagonal, but those of a few mixtures do not, notably those of mixtures of methylethylketone and phenol with water. Separation of azeotropic mixtures sometimes can be effected in several towers at different pressures, as illustrated by Example 13.6 for ethanol-water mixtures. Partially miscible constant boiling mixtures usually can be separated with two towers and a condensate phase separator, as done in Example 13.7 for n-butanol and water. 

Differences in results can occur between tests in a liquid and a gaseous medium. This is often because different times are required to reach equilibrium temperature, and if crystallisation is occurring, for example, the stiffness will be dependent on time of conditioning. It is also essential that if a liquid medium is used the liquid does not affect the rubber by swelling it or removing extractables, as either process can have a considerable effect on low temperature behaviour. Ethanol is most widely used but acetone, methanol, butanol, silicone fluid and n-hexane are all suggested in ISO 2921. Not all of these will be suitable for all rubbers and the suitability of any proposed liquid must be checked by preliminary swelling tests. 

Boyer and Probecker [191] determined organic solvents in several pharmaceutical forms using a Perkin-Elmer HS-6 headspace sampler. Typically, the samples were heated at 90°C for 10 min to establish equilibrium. Head-space samples were injected onto a Chromosorb 102 column. Ten injections of a mixed ethanol-acetone standard using methanol as the internal standard gave better precision than manual injections as measured by the relative standard deviation 1.63% and 2.48% for ethanol and acetone, respectively, using the sampler as compared to 4.77% and 3.93% by manual injection, respectively. Methods were reported for acetone and ethanol in dry forms such as tablets and microgranules, ethanol of crystallization in raw materials, and ethanol in syrups. Denaturants such as n-butanol and isopropanol in ethyl alcohol were determined using ethyl acetate as the internal standard. 

The authors explain that there is a slight equilibrium between attractive (electrostatic and dispersive) and repulsive (steric) forces in the fundamental and excited state of the adducts, depending on solvent configuration and the chromophore structure. The homochiral complexes have been found to be more stable than their heterochiral counterparts. Another R2PI study by Speranza [113] used R-(+)-l-phenyl-1-propanol as model, to study the interaction with several solvents as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, S-(+)-2-butanol, R-(—)-2-butanol, 1-pentanol, S-(+)-2-pentanol, R-(—)-2-pentanol, and 3-pentanol. The experimental results had the support of theoretical calculations at the B3LYP/6-31G level. In all cases studied, the homochiral complexes were found to be more stable than the heterochiral ones, both in fundamental and excited states, as well as for the corresponding ionic adducts. 

The Non-Random, Two Liquid Equation was used in an attempt to develop a method for predicting isobaric vapor-liquid equilibrium data for multicomponent systems of water and simple alcohols—i.e., ethanol, 1-propanol, 2-methyl-l-propanol (2-butanol), and 3-methyl-l-butanol (isoamyl alcohol). Methods were developed to obtain binary equilibrium data indirectly from boiling point measurements. The binary data were used in the Non-Random, Two Liquid Equation to predict vapor-liquid equilibrium data for the ternary mixtures, water-ethanol-l-propanol, water-ethanol-2-methyl-1-propanol, and water-ethanol-3-methyl-l-butanol. Equilibrium data for these systems are reported. 

Ternary System. The values of all binary parameters used in predicting the ternary data are shown in Table IV. The predicted values of the vapor-liquid equilibrium data—i.e.9 the boiling point, and the composition of the vapor phase, y, for given values of the liquid composition, x, are presented in Tables V, VI, and VII. Also shown are the measured boiling points for the given values of the liquid composition. The RMSD value between the predicted and measured boiling points for the systems water-ethanol-l-propanol, water-ethanol-2-methyl-l-propanol, and water-ethanol-2-methyl-l-butanol are 0.23°C, 0.69°C, and 2.14°C. It seems therefore that since the NRTL equation successfully predicts temperature, the predicted values of y can be accepted confidently. 

Table VII. Vapor—Liquid Equilibrium Data at 760 mm Hg Water (1)—Ethanol (2)-3-Methyl-1-Butanol (3)...

All cell potentials reached equilibrium in 1 or 2 hr, except when the solvent was anhydrous terf-butanol, in which the electrodes reached equilibrium only in dilute soltuions of HBr and even then only in a sluggish manner. This sluggish behavior has been reported (27) for the silver-silver bromide electrode in anhydrous ethanol when the acid was concentrated. In the dilute hydrobromic acid solutions used here, this phenomena was not observed in anhydrous ethanol. It is estimated that the standard electrode potential of the silver-silver bromide electrode in anhydrous terf-butanol is accurate to only d=l mV. However, these data are reported to the same degree of precision found in the other tert-buta-nol-water solvents in order to facilitate comparisons of the emf s in the various dilutions of tert-butanol used. 

The hydrazone (XI) is the predominant form, and in acid and neutral solution no indication of either the azo- (X) or the ene-hydrazine form (XII) has been found. In alkaline solution, however, studies with tritium [56] have shown exchange both of the aldehyde hydrogen and of hydrogen atoms at the a-carbon, indicating the presence of both the forms (X and XII). The equilibrium constant in 0.1 M ethanolic KOH for the equilibrium benzyl phenyldiazene — benzaldehyde phenylhydrazone is about 10, but for monoalkylhydrazones of aliphatic carbonyl compounds a higher proportion of the azo form is found. Acetaldehyde propylhydrazone is thus in r-butanol containing 0.02 M potassium -butylate at 100°C in equilibrium with 3.7% of the azo form [57]. 

In this laboratory, attempts (G6, G8) have been made to purify and crystallize human placental alkaline phosphatase enzyme by a number of procedures involving homogenization with 0.05 M Tris buffer (pH 8.6), extraction with butanol, ammonium sulfate precipitation, exposure to heat, ammonium sulfate fractionation, dialysis, repeated ethanol fractionation, gel filtration with Sephadex G-200 (Fig. 18), continuous curtain electrophoresis on paper (Beckman Model CP), multiple TEAE-cellulose anion exchange chromatography, and equilibrium dialysis. Variant A (electrophoretically fast-moving) of human placental alkaline... 

The diffusion and equilibrium adsorption of aqueous alcohols in silicalite crystals have been studied using a novel HPLC technique. With a nonlinear mathematical model, the adsorption isotherms and intracrystalline diffusivities have been determined at 10, 30, 50, 70°C for ethanol, i-propanol, i-butanol, and at 30°C for n-propanol and n-butanol. The liquid intracrystalline diffusivities are found to be in the range of 10- to 10 11 cm /s and decrease in the folowing order n-butanol> n-propanol> ethanol >i-propanol> i-butanol. 

The present study reports the measurements of intracrystalline diffusion and adsorption equilibrium for ethanol, propanols and butanols from aqueous solution in silicalite using a modified HPLC technique. The unique feature of the present work is the use of a mathematical model with a nonlinear adsorption isotherm equation to obtain the intracrystalline diffusivity and adsorption isotherm parameters. The adsorption equilibrium data for alcohols from aqueous solution in silicalite measured by the conventional batch method are also reported and compared with the results measured by the HPLC technique. 

In the measurements of the adsorption equilibrium and intracrystalline diffusion data, the injection sample loop was first filled with a sample solution (water as solvent) of a known sorbate concentration by a syringe. The sample was then injected into the column after a stable base line in the recorder had been obtained. For each adsorbate at a given temperature, about 4 to 6 samples of different adsorbate concentration (CG from about 0.015 to 0.06 g/ml) and at different carrier flow rate (Q from 0.5 to 2.0 ml/min) were injected to give the corresponding response peaks at the outlet of the column. The response peaks were recorded and then directly read from the recording chart and input to a DEC-20 computer for further analysis. Figure 2 shows some recorded response peaks from the silicalite LC column for ethanol, n-propanol and n-butanol. 

The effect of temperature on equilibrium for liquid adsorption is generally much more complex than that for pure vapor phase adsorption due, partially, to the involvement of a solvent in liquid adsorption systems (22). The amount of an adsorbate adsorbed in liquid adsorption may decrease or increase with increasing temperature, depending mainly on the difference of the heats of immersion for the adsorbate (solute) and solvent (22). In the present study, the saturation adsorption capacity n for ethanol, i-propanol and i-butanol are insensitive to temperature, while the parameter b for the three alcohols decreases as the temperature increases. Bui et al. (4) reported a similar temperature dependence of n and b for the adsorption of ethanol from an aqueous solution in silicalite. 

Reaction temperature is another important variable. If the reaction is kept cold, all reactions (including the forward and reverse reactions that constitute the equilibrium) are slowed. If there is enough energy at low temperatures to convert 42 to 43, the subsequent acid-base reactions (that will promote the equilibrium) will be slower and this favors kinetic control. The common reaction temperatures are -78°C (CO2 in acetone or 2-propanol) and -100°C. (ether in C02). Conversely, high reaction temperatures promote the equilibrium process. In most cases, the temperatures observed with thermodynamically controlled reactions are the reflux temperatures of the solvent (refluxing ethanol, water, methanol, tert-butanol). 

Concerning tris(L-leucinato) complex, Denning and Piper refluxed an -butanol solution of A —) mer isomer until no further change in the CD spectrum was observed. A very small amount of red insoluble fac isomer was removed by filtration, the solution was evaporated, and the residue was chromatographed in 85 % ethanol-water on an alumina column. Two determinations of the equilibrium constant were made by CD measurements, and the following equilibrium constant was obtained. 

Problem 8.16 The system 3-methyl-i-butanol (i)/ethanol (2)/water (3) exhibits partial miscibility. The data below give the equilibrium composition of the two phases at 20 °C (Kadir et al., J. Chem. Eng. 

If the top temperature is too cold and the bottom tenperature is too hot to allow sandwich conponents to exit at the rate they enter the column, they become trapped in the center of the column and accumulate there fKister. 20041. This accumulation can be quite large for trace conponents in the feed and can cause column flooding and development of a second liquid phase. The problem can be identified from the simulation if the engineer knows all the trace conponents that occur in the feed, accurate vapor-liquid equilibrium (VLE) correlations are available, and the simulator allows two liquid phases and one vapor phase. Unfortunately, the VLE may be very nonideal and trace conponents may not accumulate where we think they will. For example, when ethanol and water are distilled, there often are traces of heavier alcohols present. Alcohols with four or more carbons (butanol and heavier) are only partially miscible in water. They are easily stripped from a water phase (relative volatility 1), but when there is litde water present they are less volatile than ethanol. Thus, they collect somewhere in the middle of the column where they may form a second liquid phase in which the heavy alcohols have low volatility. The usual solution to this problem is to install a side withdrawal line, separate the intermediate component from the other components, and return the other components to the column. These heterogeneous systems are discussed in more detail in Chapter 8. 

A, B, C. Define, explore, plan. With five conponents, there are a huge number of possibilities thus, we will use heuristics to generate possible configurations. Equilibrium data can be approximated as constant relative volatilities fKing. 19811 with n-propanol as the reference conponent ethanol, a = 2.09, isopropanol, a = 1.82, n-propanol, a = 1.0 isobutanol, a = 0.677 n-butanol, a = 0.428. 

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