Methanol acetone separation

Let us consider the minimum-boiling acetone/methanol separation discussed in Section 5.1, where extractive distillation was used. The first thing to find out is the pressure dependence of the azeotrope. Figure 5.26 gives Txy diagrams at two pressures 1 and 10 atm. The azeotropic compositions are 77.6 and 37.5 mol% acetone at these two pressures. This significant shift indicates that pressure swing should be feasible. 

Luyben W. L., Comparison of extractive distillation and pressure-swing distillation for acetone-methanol separation, Ind. Engng Chem. Res., 47, 2696-2707 (2008). 

Knapp and Doherty present the economic optimum design of an acetone-methanol separation using water as the extractive solvent. The design used in this chapter is based on their work. Kossack et al. presented a systematic synthesis framework for extractive distillation systems and the acetone-methanol system was considered. 

Steady-state and dynamic comparisons have been presented of an extractive distillation process using three different solvents. The numerical example examines the acetone-methanol separation using water, DMSO, or chlorobenzene solvents. 

TABLE 13.2 Summary of Operating Conditions for Steps 1 and 2 of Acetone-Methanol Separation. 

TABLE 13.3 Simulation Results for Step 3 of Acetone-Methanol Separation. 

Figure 13.5 Liquid compositions in the reflux drum and in the colunm bottoms for the acetone methanol separation.

Figure 13.7 Liquid composition profile at the end of each operating step for the acetone-methanol separation.

Fiaal purification of propylene oxide is accompHshed by a series of conventional and extractive distillations. Impurities ia the cmde product iaclude water, methyl formate, acetone, methanol, formaldehyde, acetaldehyde, propionaldehyde, and some heavier hydrocarbons. Conventional distillation ia one or two columns separates some of the lower boiling components overhead, while taking some of the higher boilers out the bottom of the column. The reduced level of impurities are then extractively distilled ia one or more columns to provide a purified propylene oxide product. The solvent used for extractive distillation is distilled ia a conventional column to remove the impurities and then recycled (155,156). A variety of extractive solvents have been demonstrated to be effective ia purifyiag propylene oxide, as shown ia Table 4. 

Fig. 7. Extractive distillation column profiles for the acetone—methanol—water separation (40). (a) Liquid composition versus theoretical tray location where...

FIG. 13-74 Extractive distillation cohunn composition profile for the separation of acetone-methanol with water. 

Bisethylenedioxypregn-5-ene. Method A. A mixture of progesterone (10 g), freshly distilled ethylene glycol (80 ml) and benzene (350 ml) is slowly distilled for 15 min to remove traces of water. p-Toluenesulfonic acid monohydrate (0.3 g) is added and the mixture is heated under reflux with stirring for 5 hr with a water separator. Saturated sodium bicarbonate solution is added to the cooled mixture and the benzene layer is separated. The organic layer is washed twice with water, dried and evaporated in vacuo. The residue is crystallized twice from acetone-methanol to give 4.15 g (32%) of bisketal, mp 178-181°. 

The isotopic method has been used in conjunction with a flow apparatus by Stranks, to measure the exchange between the cyclopentadienyl complexes of iron (III) and iron (II) in methanol. Separation was based on the insolubility of Fe(C5H5) in petroleum ether at —80 °C. Using Fe(II) and Fe(III) 10 M and short reaction times ( msec), a rate coefficient 8.7 x 10 l.mole .sec at — 75 °C was obtained. The rate of exchange in the presence of chloride ions and inert electrolytes was found to be more rapid. Calculations using Marcus Theory showed reasonable agreement with the experimental observations. In deuterated acetone, line broadening measurements have led to an estimate of this rate coefficient of > 10 l.mole . sec at 26 °C. 

Fig. 2.7. Separation of pigments of Capsicum annuum on a LiChrocart RP-18 column after 28 days of storage, using water-acetone-methanol gradient elution, detection wavelengh 450 nm, flowrate lml/min. Storage conditions a darkness, absence of oxygen, b light, absence of oxygen. Reprinted with permission from H. Morais et al. [31].

Another HPTLC method has been developed for the separation of kaempferol and quercetin in the extract of Ginkgo biloba leaves showing beneficial effect in brain diseases. Leaves were refluxed with methanol for 30 min then filtered. The filtrate was refluxed with 25 per cent HC1 for 60 min then neutralized with ammonia and the clear supernatant was applied for HPTLC. Silica plates were predeveloped in chloroform-methanol (1 1, v/v). Separation was performed with toluene-acetone-methanol-formic acid (46 8 5 1, v/v) as the mobile phase using incremental multiple development. A densitogram illustrating the good separation charactersitics of the system is shown in Fig. 2.42. The relative standard deviation (RSD) of the method was low (1.37 and 1.40 for kaempferol and quercetin,... 

The classical solvent precipitation fractionation technique provides reproducible fractionations for determining molecular weight distributions of CTPB and almost 100% recovery of the sample from the column. A solvent-nonsolvent combination which has been used effectively is the toluene—acetone-methanol system, where acetone and methanol are used as the nonsolvents. The precipitating fractions are required to stand approximately 24 hours to ensure complete separation. Each fraction is vacuum stripped of solvent at approximately 30 °C., and the molecular weight of each fraction is then determined by either VPO or intrinsic viscosity. 

The contents of the Carius tube should appear as a brown solid. This is extracted with 50-mL portions of ethyl acetate each brought to boil in the Carius tube by heating it in an oil bath under stirring. When the solvent is pale pink in color, all the neutral clusters will have been extracted. The residue contains a mixture of high nuclearity osmium anions of which [Os10C(CO)24]2- and [OsnC(CO)27]2 have been fully characterized.3 These can be extracted with a methanol-acetone (1 1) solution of [PPN]C1, (/i-nitrido-bis(triphenylphosphorus)(l +)] chloride (Ventron) and separated by fractional crystallization from acetone-methanol. 

A second procedure uses acetone as the extracting solvent followed by partition with chloroform (Timberlake and Bridle, 1971 Wrolstad and Heatherbell, 1974 Abers and Wrolstad, 1979 Wrolstad et al., 1990). Timberlake and Bridle (1971) compared this extraction procedure with the usual acidified methanol extraction and concluded that the use of acetone with separation of the aqueous phase by addition of chloroform gave much cleaner and better-defined bands and enabled a better... 

Plattner (82) briefly examined the effects of solvent composition upon TG separations. Mixtures of acetone/methanol and acetone/acetonitrile were examined. In this work, acetone/ acetonitrile mobile phases were reported to give less complex chromatograms of TG mixtures than acetone/methanol mixtures. 

Solid foods can be extracted by means of partition into organic solvents (133). The samples are macerated with aqueous acetone, methanol, or ethanol. The extract is made alkaline with sodium tetraborate, and the solids are separated by filtration or centrifugation after the addition of Celite 545 (135). Foods can also be ground with Celite and 0.1 N hydrochloric acid and washed with chloroform (156). 

Method. The amino acid derivatives are prepared by adding disyl chloride (1 mg/ml in acetone) to an equal volume of a solution of the amino acid (ca. 5 10 4 jumoles/ml in 0.1 M sodium bicarbonate solution). The reaction is allowed to proceed for 3 h at room temperature. The solvent is evaporated and the residue is dissolved in 1 ml of acetone-methanol (1 1) for application to a thin-layer plate of silica gel. A number of solvent systems used for the separation of amino acid derivatives is given in Table 4.14. After chromatography, the plates are dried at 10S °C for S min, cooled to room temperature and dipped in a solution of sodium ethoxide (S g of sodium per 100 ml of 96% ethanol). The plate is observed immediately under UV light at 365 nm. The amino acid derivatives appear yellow-green. 

Lyle and Tehrani (103) have separated several vitamins, including vitamin Bg, by TLC, using anhydrous acetic acid - acetone - methanol -benzene (1 1 4 14). 

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