Isopropanol-Water System

The purpose of the preconcentrator column is again to remove part of the water in the fresh feed (assume the fresh feed composition is 50 mol% IPA to agree with a true application of a waste IPA stream in the semi-conductor industry). The distillate composition of this preconcentrator column will approach the azeotropic composition of IPA-water. This distillate stream is fed into a heterogeneous azeotropic column. With the aid of adding another component (cyclohexane) into the system through an OR stream, the bottom composition will approach a pure IPA composition and the column top vapor will approach the lowest temperature of the ternary system, which is the ternary azeotrope. Note that this column is operated inside the upper distillation region (see Fig. 8.12). 

This azeotrope is heterogeneous, so by condensing and cooling the top vapor and feeding the condensate at 40°C to a decanter, natural hquid-liquid separation into an organic phase and an aqueous phase will occur. The organic phase, which is rich in entrainer, is designed 

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Isopropanolamines, 20 795, 812 2-Isopropanol-water system, evolving separation strategies for, 22 322-325. See also Water- IPA-hexane system Isopropenyl acetate, 7 148 74 596 m-Isopropenyl-a,a-dimethylbenzyl isocyanate (TMI), 25 463 Isopropenyl methyl ether, production from acetone, 7 163... 

Eor phospholipids separation, various HPLC columns, e.g., silica, - - NH2,"° diol, " and polyvinyl alcohol" have been used. Silica columns were most often used. Both isocratic and gradient" mobile phases have been used. The most often used mobile phases are chloroform-methanol-water and hexane-isopropanol-water systems. The phospholipid classes can be separated very well by carefully adjusting the composition and time schedule of mobile phases. 

There are many important industrial applications of azeotropic separations, which employ a variety of methods. In this book we discuss several of these chemical systems and demonstrate the application of alternative methods of separation. The methods presented include pressure-swing distillation, azeotropic distillation with a light entrainer, extractive distillation with a heavy entrainer (solvent), and pervaporation. The chemical systems used in the numerical case studies included ethanol-water tetrahydrofuran (THF)-water, isopropanol-water, acetone-methanol, isopentane-methanol, n-butanol-water, acetone-chloroform, and acetic acid-water. Economic and dynamic comparisons between alternative methods are presented for some of the chemical systems, for example azeotropic distillation versus extractive distillation for the isopropanol-water system. 

Selecting the analysis type as Txy, specifying the system pressure, specifying Valid Phases as Vapor-Liquid and clicking the Go button at the bottom of the dialog box produce the Txy plot shown in Figure 2.2. Tabulated binary analysis results like activity coefficients and K values are also shown. From the example Txy plot of isopropanol-water system, we can see that this system contains an azeotrope at isopropanol mole fraction between 0.6 and 0.8 and azeotropic temperature of about 80°C. To hnd the exact prediction of the azeotropic composition and temperature, the azeotrope search tool can be used. The use of this tool will be explained later in Section 2.5.2. 

Figure 2.1 Binary analysis dialog box of the isopropanol-water system.

We will start this chapter by explaining how the heterogeneous azeotropic distillation works in separating a mixture with an azeotrope. Three systems with different RCMs will be used as examples to illustrate the column sequence for the separation. After that, we will focus on the detailed design and control of the isopropanol-water system, which is a system that exhibits the most complex RCM. 

STEADY-STATE DESIGN OF AN ISOPROPANOL-WATER SYSTEM 227... 

STEADY-STATE DESIGN OE AN ISOPROPANOL-WATER SYSTEM... 

Example 9.1 From Table A.7 for the isopropanol-water system at 1 atm pressure the van Laar constants (log form) are... 

Because of the problems encountered with the water system, the use of aliphatic alcohols, ie.g., methanol, ethanol, and isopropanol, as modifiers of the adsorption strength has been recommended (44. 45. 50. 51). Usually, between 0.01 and 0.5% (v/v) alcohol is added to the eluent. As an example, the k values for the benzyl alcohols on a silica column are in the same range when eluted with dichloromethane containing either 0.1% water (50% water-saturated) or 0.15% methanol or 0.3% isopropanol (45). The preparation and preservation of these alcohol-eluent mixtures is accompanied by problems similar to those discussed with water-modified eluents. Also, column equilibration is slow (44). The efficiency of columns operated with alcohol-modified eluents is generally lower than that of water-modulated eluent system. At some alcohol concentrations, distorted peaks with tailing or frontal asymmetry have been observed 44), but olhei workers using another silica could not verify this observa tion (61). 

The telomerization of 1,3-butadiene with glucose was first reported in a patent awarded to Henkel and Zucker AG [96]. Using a Pd/PPh3 system (0.07 mol% Pd relative to glucose P/Pd = 2) in isopropanol/water, a glucose conversion of >90% was observed after 12 h at 85°C. Telomers with an average degree of substitution of 2 were obtained. 

The enantiomer excess depends on the solvent system isopropanol-water < ethanol-water methanol-water. The best values are 42% in 75% ethanol-water at 25°C and 40% in 75% methanol-water. The reaction mechanism was investigated kinetically. In general, photoreaction takes place via either a dynamic quenching mechanism or a static quenching mechanism, as shown in Scheme 23. 

For heterogeneous batch distillation a new double column configuration operating in closed system is suggested. This configuration is investigated by feasibility studies based on the assumption of maximal separation and is compared with the traditional batch rectifier. The calculations are performed for a binary (n-butanol - water) and for a ternary heteroazeotropic mixture (isopropanol - water + benzene as entrainer). Keywords heteroazeotrope, batch distillation, feasibility studies. 

Five solvent systems useful for the chromatographic separation of 32 PTH-amino acids on silica gel G thin layers with one-dimensional runs are listed in Table 44 of the textbook by Pataki (P7). According to Cherbuliez et al. (C3, C3a, C5), when three chromatograms are run simultaneously in one dimension on silica gel G plates with the following solvent systems (a) chloroform isopropanol water (28 8 1),... 

Equilibrium data for the system isopropanol-water are given in Problem 8.34. The usual simplifying assumptions may be made. 

Beside isopropanol/water, there are many other systems that are conventionally achieved by distillation, which is inferior to membrane separation both in operating... 

If you do not know what happened to the equipment before you got to work on it, you should flush it (without the column) at a flow rate of 1 ml/min with a 50/50 mixture isopropanol/water for about 10 min. You should also inject the mobile phase a few times in order to ensure that the old eluent or impurities are removed from the sample injection system. Now you can bring the mobile phase recommended for your method into the system. Again, do not forget the injection system. 

The pervaporation dehydration study of isopropanol-water and ethanol-water mixtures was carried out by Moon et al. [90]. The two-ply dense composite membranes were prepared using successive castings of sodium alginate and CS solutions. The membranes showed improved mechanical strength, flux, and separation factor. The three factors like polymer type contacting the feed stream, NaOH treatment, and type of cross-linking agent decide the flux and separation factor of the two-ply membrane system. 

Two recent studies have examined the selective monoalkylation and polyaUcylation of sucrose (Scheme 17, 52). Using Pd(acac)2/Ph3P, sucrose was efficiently polyalkylated with butadiene in 4 1 isopropanol/water to give a mixture of 2,7-octadienyl ethers averaging 4-5 ether linkages per sucrose.While conditions for polyalkylation were found, Mortreux and co-workers also reported an alternative set of conditions that favor selective monoaUcylation.t Treatment of sncrose (52) with Pd(OAc)2/3 TPPTS (TPPTS = tris(m-sulfonatophenyl)phosphine) in 5 2 isopropanol/1 M NaOH (80 °C, 30 min, 73% conversion) afforded a 2 1 mixture of mono- and diethers, from which monoethers 53a (65%) and 53b (18%) were isolated. The reaction is of interest for its selective alkylation, the use of a water-soluble catalyst system, and the observation that NaOH acts as a strong activator for the reaction. 

The azeotropic composition of a binary system is not only influenced by recycled third components added to the mixture and by the operating pressure, but also by the presence of an insoluble inert gas, which is favorable for the separation if the volatile components of the mixture diffuse at different velocities across the regions of inert gases. Figure 2-31 a shows an example using the binary isopropanol/water mixture. Steam diffuses faster across an air bolster than isopropanol vapor, and thus, the distillate of isopropanol mole fraction is more water-rich due to the presence of air between the liquid and the condensation surfaces (point A2), compared with the distillation under air exclusion (point A,). 

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