Binary azeotropes with water

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. 

Methyl Vinyl Ketone. Methyl vinyl ketone [78-94-4] (3-buten-2-one) is a colorless Hquid with a pungent odor. It is stable only below 0°C, and readily polymerizes on standing at room temperature. It can be inhibited for storage and transportation by a mixture of acetic or formic acid and hydroquinone or catechol (266). This ketone is completely soluble in water, and forms a binary azeotrope with water (85 MVK 15 H2O vol %) at 75.8°C. 

The physical piopeities of ethyl chloiide aie hsted in Table 1. At 0°C, 100 g ethyl chloride dissolve 0.07 g water and 100 g water dissolve 0.447 g ethyl chloride. The solubihty of water in ethyl chloride increases sharply with temperature to 0.36 g/100 g at 50°C. Ethyl chloride dissolves many organic substances, such as fats, oils, resins, and waxes, and it is also a solvent for sulfur and phosphoms. It is miscible with methyl and ethyl alcohols, diethyl ether, ethyl acetate, methylene chloride, chloroform, carbon tetrachloride, and benzene. Butane, ethyl nitrite, and 2-methylbutane each have been reported to form a binary azeotrope with ethyl chloride, but the accuracy of this data is uncertain (1). 

Formic acid can be dehydrated with propyl formate as entrainer. Small contents of formic acid and water in acetic acid can be entrained away with chloroform which forms binary azeotropes with water and formic acid but no other azeotropes in this system. 

Give minimum boiler ternary heterogeneous azeotrope with alcohol and water, or most preferably binary heterogeneous azeotrope with water. The entrainer must form also a minimum binary azeotrope with the alcohol. 

Because a large amount of water is entrained in the side stream, this is removed in the column C-3. Raw acetonitrile, namely a binary azeotrope with 20% water, separates in top. The bottom stream contains water with heavy impurities. Vacuum distillation at 0.5 bar is adequate to limit the bottom temperature. In the next step pure acetonitrile can be obtained by using pressure-swing distillation. 

The quantity of hexane necessary to entrain water, methanol, ethanol, acetone, and acetaldehyde dimethyl acetal to the top was estimated as the sum of the hexane quantities required to form the binary azeotropes with the quantities of water, methanol, ethanol, acetone, and acetaldehyde dimethyl acetal in the mixture. 

Properties Colorless liquid etherlike odor. Fp -88.68C, bp 63.2-65.6C, d 0.913 (20/4C), refr index 1.4320 (20C), flash p -22F (-30C). Insoluble in water 0.3 g/100 g water. Miscible with most organic solvents. Forms a binary azeotrope with methanol, a ternary azeotrope with methanol-water. 

Liquid with pungent odor. bp7 81.4. tig 1.4086. dj 0.8636 dj5 0 8407. Easily soluble in water, methanol, ethanol, ether, acetone, glacial acetic acid. Slightly sol in hydrocarbons. Forms a binary azeotrope with water, bp 75 (12% water), uv spectrum and electric moments Rogers, J. Am. Chem. Soc. 69, 2544 (1947). Polymerizes on standing, LDm in mioe and rats 35 mg/kg, C.A. 72, 124809b 0970). 

These layers are separated continuously in an automatic separator the upper layer is returned to the still, while the lower is taken off and measured. As the reaction nears completion, the amount of water that separates diminishes until there is none the temperature in the still, after rising steadily, flattens out at the refluxing temperature of l e butyl acetate. The crude ester is cooled and neutralized with aqueous sodium hydroxide. After separation of the water layer, the ester is ready for refining by distillation. The first fraction is the ester-water binary azeotrope which is caught in an automatic separator, from which the ester layer is returned to the still. The next is a smtdl fraction that contains some water, as shown by turlndity when it is mixed with 10 vol. of benzene. This is added to the next batch. The rest of the distillate is finished ester and goes to storage. 

These solvents have water azeotropes that are miscible with water in all proportions but can be dried by adding an entrainer. The entrainers are all Class 1 solvents and preferably they should form a binary azeotrope with water and no ternary with the solvent to be dried. 

In a situation in which fractionating power is known to be barely adequate, the two solvents (DIPE and chloroform) with low-boiling binary azeotropes including water rather than ethanol have the advantage that it is positively helpful to have their water binaries admixed with the ternary in the decanter (Table 7.6). 

Many investigations of the extraction of ethanol from water have postulated that a very high selectivity is needed to enrich the solvent-free extract to an ethanol content near or above the binary azeotrope with water. However, this degree of enrichment is not necessary. The extraction step can be followed by an extractive-distillation dewatering step similar to the process shown for acetic acid recovery in Fig. 15.2-3. 

However, there is a problem. Water and ethanol form an azeotrope, as mentioned before, but benzene also forms a binary azeotrope with ethanol. The benzene-ethanol binary azeotrope boils at 67.8°C and consists of 67.6% benzene and 32.4% ethanol. This means that as the benzene-water azeotrope is distilled, ethanol is also removed. An excess of ethanol is therefore essential. 

Water is the most common azeotropic component In the bible of azeotropic information, the reference given in Ref. 3, Appendix 2, there are 64 pages devoted to lists of binary azeotropes with water Each page has approximately 50 entries of different azeotropes with water as one component. For comparison, there are 30, 35, 10, and 13 pages for methanol, ethanol, n-propanol, and isopropanol, respectively... 

Water can form binary azeotropes with a few halogenated solvents, but none of them containing cleaning solvents are of consequence. 

The emerging biofuel processes typically have fermentation products that form azeotropes with flie water, which is present in large excess in the fermentor. The most important example is ethanol, which forms a minimum-boiling homogeneous binary azeotrope with water. Butanol is anoflier biofuel example that forms an azeotrope with water. The nonideality in this system is so large that the azeotrope is heterogeneous, forming two liquid phases. 

Ethanol prepared by distillation is only about 96% pure because it forms a low-boiling binary azeotrope with water. "100%" ethanol can be made by adding a specific amount of benzene to form a ternary azeotrope that boils at 54.9°C. However, this ethanol should not be ingested Why ... 

Regardless of the way fatty acids are incorporated, the main step of alkyd synthesis is the polyesterification. This process is quite similar to the process for saturated polyester resin production, and actually more or less the same equipment can be used (Figure 16.3). The polyesterification of the alkyd raw materials normally proceeds at 240°C with the aid of xylene as a mode of transportation of the water, by forming a binary azeotrope with it. The xylene and water vapors rise through the column on top of the reador and are condensed on top of a separator. The xylene is pumped back into the reador and the water is removed. Because of... 

Binary azeotropic systems are reported for all three derivatives (9). The solubiHties of benzyl chloride, benzal chloride, and ben zotricbl oride in water have been calculated by a method devised for compounds with significant hydrolysis rates (10). 

Esters of low volatility are accesible via several types of esterification. In the case of esters of butyl and amyl alcohols, water is removed as a binary azeotropic mixture with the alcohol. To produce esters of the lower alcohols (methyl, ethyl, propyl), it may be necessary to add a hydrocarbon such as benzene or toluene to increase the amount of distilled water. With high boiling alcohols, ie, benzyl, furfuryl, and P-phenylethyl, an accessory azeotroping Hquid is useful to eliminate the water by distillation. 

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