Acetone azeotropes

A liquid-phase isophorone process is depicted in Figure 4 (83). A mixture of acetone, water, and potassium hydroxide (0.1%) are fed to a pressure column which operates at head conditions of 205°C and 3.5 MPa ( 500 psi). Acetone condensation reactions occur on the upper trays, high boiling products move down the column, and unreacted acetone is distilled overhead in a water—acetone azeotrope which is recycled to the column as reflux. In the lower section of the column, water and alkali promote hydrolysis of reaction by-products to produce both isophorone and recyclable acetone. Acetone conversion is typically in the range 6—10% and about 70% yield of isophorone is obtained. Condensation—hydrolysis technology (195—198), and other liquid-phase production processes have been reported (199—205). 

As a result of the study of these systems, it has been found that the methanol-acetone azeotrope exhibits the unusual phenomenon of becoming nonazeotropic at both low and high pressures—that is, below 200-mm. pressure the system is nonazeotropic with methanol as the more volatile product, while above 15,000 mm. the system is nonazeotropic with acetone the more volatile component. 

The chloroform-acetone azeotrope (52% chloroform-48% acetone) is an example of the much rarer maximum-boiling azeotrope. Its boiling point is higher than that of the components (Fig. 179). At compositions off the... 

Isoprene [78-79-5] (2-methyl-1,3-butadiene) is a colorless, volatile Hquid that is soluble in most hydrocarbons but is practically insoluble in water. Isoprene forms binary azeotropes with water, methanol, methylamine, acetonitrile, methyl formate, bromoethane, ethyl alcohol, methyl sulfide, acetone, propylene oxide, ethyl formate, isopropyl nitrate, methyla1 (dimethoxymethane), ethyl ether, and / -pentane. Ternary azeotropes form with water—acetone, water—acetonitrile, and methyl formate—ethyl bromide (8). Typical properties of isoprene are Hsted in Table 1. 

Fig. 5. The acetone—2-propanol—water system where I represents the 2-propanol—water azeotrope, (a) Residue curve map (34) (b) material balance lines...

FIG. 13-12 Liq iiid boiling points and vapor condensation temperatures for maximum-boiling azeotrope mixtures of chloroform and acetone at 101.3 kPa (1 atm) total pressure. 

Schematic DRD shown in Fig. 13-59 are particularly useful in determining the imphcations of possibly unknown ternary saddle azeotropes by postulating position 7 at interior positions in the temperature profile. It should also be noted that some combinations of binary azeotropes require the existence of a ternaiy saddle azeotrope. As an example, consider the system acetone (56.4°C), chloroform (61.2°C), and methanol (64.7°C). Methanol forms minimum-boiling azeotropes with both acetone (54.6°C) and chloroform (53.5°C), and acetone-chloroform forms a maximum-boiling azeotrope (64.5°C). Experimentally there are no data for maximum or minimum-boiling ternaiy azeotropes. The temperature profile for this system is 461325, which from Table 13-16 is consistent with DRD 040 and DRD 042. However, Table 13-16 also indicates that the pure component and binary azeotrope data are consistent with three temperature profiles involving a ternaiy saddle azeotrope, namely 4671325, 4617325, and 4613725. All three of these temperature profiles correspond to DRD 107. Experimental residue cui ve trajectories for the acetone-...

FIG. 13-60 Residue curves for acetone-chloroform-methanol system suggesting a ternary saddle azeotrope. 

Acetone-methanol Minimum-hoiling azeotrope Water, aniline, ethylene glycol ... 

Methanol and acetone boil at 64.5°C and 56.1°C, respec tively and form a minimum-boihng azeotrope at 55.3°C. The natural volatility of the system is acetone > methanol, so the favored solvents most likely will be those that cause the acetone to be recovered in the distillate. However, for the purposes of the example, a solvent that reverses the natural volatility vi l also be identified. First, examining the polarity of... 

This example clearly shows good distribution because of a negative deviation from Raonlt s lawin the extract layer. The activity coefficient of acetone is less than 1.0 in the chloroform layer. However, there is another problem because acetone and chloroform reach a maximum-boiling-point azeotrope composition and cannot be separated completely by distillation at atmospheric pressure. 

Although less common, azeotropic mixtures are known which have higher boiling points than their components. These include water with most of the mineral acids (hydrofluoric, hydrochloric, hydrobromic, perchloric, nitric and sulfuric) and formic acid. Other examples are acetic acid-pyridine, acetone-chloroform, aniline-phenol, and chloroform-methyl acetate. 

Ethanol [64-17-5] M 46.1, b 78.3 , d 0.79360, d 0.78506, n 1.36139, pK 15.93. Usual impurities of fermentation alcohol are fusel oils (mainly higher alcohols, especially pentanols), aldehydes, esters, ketones and water. With synthetic alcohol, likely impurities are water, aldehydes, aliphatic esters, acetone and diethyl ether. Traces of benzene are present in ethanol that has been dehydrated by azeotropic distillation with benzene. Anhydrous ethanol is very hygroscopic. Water (down to 0.05%) can be detected by formation of a voluminous ppte when aluminium ethoxide in benzene is added to a test portion. Rectified... 

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