Azeotropic distillation ethyl acetate

Crude vinyl acetate is separated from acetic acid and water in an azeotropic distillation system. Acetic acid is recycled to the acetic acid vaporizer and the vinyl acetate product is separated from other by-products in a two-column recovery section. Light ends are removed in the first column followed by a heavy ends in the final column. The light ends, primarily methyl acetate, and the heavy ends, mostly ethyl acetate and acetaldehyde, are incinerated. The vinyl acetate product from the overhead of the heavy ends column is cooled and sent to storage. 

The formation of ethyl isopropylidene cyanoacetate is an example of the Knoevenagel reaction (see Discussion before Section IV,123). With higher ketones a mixture of ammonium acetate and acetic acid is an effective catalyst the water formed is removed by azeotropic distillation with benzene. The essential step in the reaction with aqueous potassium cyanide is the addition of the cyanide ion to the p-end of the ap-double bond ... 

If the molecular species in the liquid tend to form complexes, the system will have negative deviations and activity coefficients less than unity, eg, the system chloroform—ethyl acetate. In a2eotropic and extractive distillation (see Distillation, azeotropic and extractive) and in Hquid-Hquid extraction, nonideal Hquid behavior is used to enhance component separation (see Extraction, liquid—liquid). An extensive discussion on the selection of nonideal addition agents is available (17). 

Esters of medium volatility are capable of removing the water formed by distillation. Examples are propyl, butyl, and amyl formates, ethyl, propyl, butyl, and amyl acetates, and the methyl and ethyl esters of propionic, butyric, and valeric acids. In some cases, ternary azeotropic mixtures of alcohol, ester, and water are formed. This group is capable of further subdivision with ethyl acetate, all of the ester is removed as a vapor mixture with alcohol and part of the water, while the balance of the water accumulates in the system. With butyl acetate, on the other hand, all of the water formed is removed overhead with part of the ester and alcohol, and the balance of the ester accumulates as a high boiler in the system. 

Weichbrodt et reported on the use of focused open-vessel microwave-assisted extraction (EOV-MAE) for the determination of organochlorine pesticides in high-moisture samples such as fish. The results were comparable to those with closed-vessel microwave-assisted extraction (CV-MAE) and ASE. The main advantage of FOV-MAE is that the use of Hydromatrix is unnecessary as the solvent mixture of ethyl acetate and cyclohexane allows the removal of water from the sample matrix via azeotropic distillation. 

An equimolar mixture of ethanol and ethyl acetate is to be separated by distillation into relatively pure products. The mixture forms a minimum-boiling azeotrope, as detailed in Table 12.1. However, the composition of the azeotrope is... 

The concentration of acrylic acid by extraction with ethyl acetate is a rather different illustration of this technique. As shown in Figure 13.4, the dilute acrylic acid solution of concentration about 20 per cent is fed to the top of the extraction column 1, the ethyl acetate solvent being fed in at the base. The acetate containing the dissolved acrylic acid and water leaves from the top and is fed to the distillation column 2, where the acetate is removed as an azeotrope with water and the dry acrylic acid is recovered as product from the bottom. 

The catalytic esterification of ethanol and acetic acid to ethyl acetate and water has been taken as a representative example to emphasize the potential advantages of the application of membrane technology compared with conventional distillation [48], see Fig. 13.6. From the McCabe-Thiele diagram for the separation of ethanol-water mixtures it follows that pervaporation can reach high water selectivities at the azeotropic point in contrast to the distillation process. Considering the economic evaluation of membrane-assisted esterifications compared with the conventional distillation technique, a decrease of 75% in energy input and 50% lower investment and operation costs can be calculated. The characteristics of the membrane and the module design mainly determine the investment costs of membrane processes, whereas the operational costs are influenced by the hfetime of the membranes. 

Highest yields are obtained when the reaction is carried out in boiling toluene until all water and ethanol are eliminated by azeotropic distillation. Other /S-ketocarboxylic esters such as ethyl benzoyl acetate, o-methoxybenzoyl acetate and ethyl acetonedicarboxylate react similarly with aromatic amidoximes (50). 

Azeotropic Distillation. The concept of azeotropic distillation is not new. The use of benzene to dehydrate ethyl alcohol and butyl acetate to dehydrate acetic acid has been in commercial operation for many years. However, it was only during World War II that entrainers other than steam were used by the petroleum industry. Two azeotropic processes for the segregation of toluene from refinery streams were developed and placed in operation. One used methyl ethyl ketone and water as the azeo-troping agent (81) the other employed methanol (1). 

In the chemical processing industry, extraction is used when distillation is impractical or too costly. Extraction may be more practical than distillation when the relative volatilities of two components are close. In other cases, the components to be separated may be heat sensitive like antibiotics or relatively nonvolatile like mineral salts. When unfortunate azeotropes form, distillation may be ineffective. Several examples of cost-effective liquid-liquid extraction processes include the recovery of acetic acid from water using ethyl ether or ethyl acetate and the recovery of phenolics from water with butyl acetate. 

Separation of n-hexane-ethyl acetate mixtures by azeotropic batch distillation with heterogeneous entrainers... 

Selection of a suitable entrainer for the separation of w-hexane-ethyl acetate mixtures by heterogeneous azeotropic batch distillation... 

Nitromethane shows the simplest residue curve map with one unstable curved separatrix dividing the triangle in two basic distillation regions. Methanol and acetonitrile give rise two binary azeotropic mixtures and three distillation regions that are bounded by two unstable curved separatrices. Water shows the most complicated residue curve maps, due to the presence of a ternary azeotrope and a miscibility gap with both the n-hexane and the ethyl acetate component. In all four cases, the heteroazeotrope (binary or ternary) has the lowest boiling temperature of the system. As it can be seen in Table 3, all entrainers except water provide the n-hexane-rich phase Zw as distillate product with a purity better than 0.91. Water is not a desirable entrainer because of the existence of ternary azeotrope whose n-hexane-rich phase has a water purity much lower (0.70). Considering in Table 3 the split... 

I. Rodriguez-Donis, U. Jauregui-Haza, E. Pardillo-Fondevila, Separation of -hexane-ethyl acetate mixtures by azeotropic distillation, Latin Am. Appl. Res. 29 (1999) 119-127. 

A mixture containing of 23 g of l-ethyl-3-hydroxypyrrolidine, 51.2 g of ethylbenzilate and 1.50 ml of benzene is subjected to azeotropic distillation to remove traces of water and then 250 mg of metallic sodium added to the residual solution. The mixture heated under reflux for about 8 hours while slowly drawing off the benzene-alcohol azeotrope formed. The reaction mixture is cooled, treated with 1 ml of acetic acid and washed with water. The benzene is removed by distillation and the residue distilled in vacuo to obtain the desired l-ethyl-3-pyrrolidinyl benzilate as a viscous oil yield 44 g,... 

Ester manufacture is a relatively simple process in which the alcohol and an acid are heated together in the presence of a sulfuric acid catalyst, and the reaction is driven to completion by removing the products as formed (usually by distillation) and employing an excess of one of the reagents. In the case of ethyl acetate, esterification takes place in a column that takes a ternary azeotrope. Alcohol can be added to the condensed overhead liquid to wash out the alcohol, which is then purified by distillation and returned to the column to react. 

Ethyl acetate is a clear, volatile, and flammable liquid with a pleasant, fruity odor. It has a pleasant taste when diluted. Ethyl acetate slowly decomposes by moisture, so it should be kept in air-tight bottles and in a cool dry place. It has a boiling point of 77 Celsius, and a melting point of-83 Celsius. Ethyl acetate is moderately soluble in water (1 milliliter in 10 milliliters of water), but is miscible with alcohol, acetone, chloroform, and ether. It forms a azeotropic mixture with water (6% by weight with a boiling point of 70 Celsius). Ethyl acetate can be prepared by distilling a mixture of ethanol and acetic acid in the presence of a few drops of sulfuric acid. Ethyl acetate is a valuable solvent for many chemical reactions. 

The fractionation should be carried out slowly to ensure complete alcoholysis of the bromoacetate. The boiling point during the collection of the first 500 ml. of distillate remains constant at around 72°, corresponding to the ethanol-ethyl acetate azeotrope. 

The polished product is passed to a distillation train (3) where a novel distillation arrangement allows the ethanol/ethyl acetate water azeotrope to be broken. Products from this distillation scheme are unreacted ethanol, which is recycled, and ethyl acetate product. 

---