Anhydrous ethanol extractive distillation

Fig. 9. Extractive distillation sequence cost as a function of the feed ratio for the production of anhydrous ethanol from azeotropic ethanol using ethylene glvcol at reflux ratios of A, 1.15 r O, 1.2 r and 1.3 r (39). Point A represents a previously pubhshed design for the same mixture (37).

In a 1-1. round-bottomed flask equipped with a condenser are placed 78.0 g. (0.56 mole) of commercial anhydrous potassium arbonate, 45.0 g. (0.50 mole) of methallyl chloride (Note 1), 55.0 g. (0.55 mole) of 2,4-pentanedione (Note 1), and 300 ml. of anhydrous ethanol (Note 2). The mixture is refluxed on a steam bath for 16 hours. The condenser is replaced by a distilling head and condenser, and about 200 ml. of ethanol is distilled from the mixture (Note 3). Ice water (600 ml.) is added to dissolve the salts, and the mixture is extracted three times with ether. The... 

Diethyl phenyl ethyl malonate. 1 mole of benzyl cyanide is added dropwise to a solution of 1 mole of ethyl carbonate in 2 liters of anhydrous ethanol containing 5 g of clean sodium metal. This mixture is refluxed (preferably on a steam bath) for 5 hours. It is then cooled and to it is added a cooled mixture of 40 g of sulfuric acid in 100 ml of anhydrous ethanol. This alcoholic solution is refluxed for 5 hours, cooled, neutralized with sodium ethylate (use external indicator). The mixture is evaporated to half bulk, filtered from the sodium sulphate and to it is added 1 mole of clean metallic sodium. Reflux while adding 1 mole of ethyl bromide dropwise. Heat for another 2 hours after the addition is completed. Remove the alcohol by distillation and dissolve the remaining residue in water. Extract the substance from the water with benzene and after drying, the benzene is recovered and the ester should be purified by distilling in vacuo. 

Diethyl ethylphenylmalonate. In a dry 500-ml round-bottomed flask, fitted with a reflux condenser and guard-tube, prepare a solution of sodium ethoxide from 7.23 g (0.315 mol) of clean sodium and 150 ml of super-dry ethanol in the usual manner add 1.5 ml of pure ethyl acetate (dried over anhydrous calcium sulphate) to the solution at 60 °C and maintain this temperature for 30 minutes. Meanwhile equip a 1-litre three-necked flask with a dropping funnel, a sealed mechanical stirrer and a double surface reflux condenser the apparatus must be perfectly dry and guard-tubes should be inserted in the funnel and condenser respectively. Place a mixture of 74 g (0.315 mol) of diethyl phenylmalonate and 60 g (0.385 mol) of ethyl iodide in the flask. Heat the apparatus in a bath at 80 °C and add the sodium ethoxide solution, with stirring, at such a rate that a drop of the reaction mixture when mixed with a drop of phenolphthalein indicator is never more than faintly pink (1). The addition occupies 2-2.5 hours continue the stirring for a further 1 hour at 80 °C. Allow the flask to cool, and remove the ethanol under reduced pressure using a rotary evaporator. Add 100 ml of water to the residue in the flask and extract the ester with three 100 ml portions of toluene. Dry the combined extracts with anhydrous sodium sulphate, distil off the toluene at atmospheric pressure and the residue under diminished pressure. Collect the diethyl ethylphenylmalonate at 159-160 °C/8mmHg. The yield is 72 g (87%). 

II). trans-m-Bromocinnamic acid (14.8 g), ethanol (173 ml) and concentrated sulfuric acid (0.4 ml) were combined and heated at reflux for 15 hours. About 150 ml of the ethanol was distilled off, and the remaining solution was poured into ice/water (140 ml). The cold mixture was made strongly alkaline with 40% sodium hydroxide and extracted with methylene chloride (4x60 ml). The combined methylene chloride extract was dried over anhydrous potassium carbonate. The potassium carbonate was removed by filtration and the solvent stripped off under reduced pressure. trans-ethyl-3-Bromocinnamate, was obtained as a partially solidified oil. (IR spectrum was consistent with this compound). 

S-Isomer was prepared the next way. To a solution of 160 parts of dibenzoyl d-tartaric acid in 1600 parts of anhydrous ethanol were added for 15 minutes 80 parts of dl-l-(3-trifluoromethylphenyl)-2-ethylaminopropane. After 15 additional minutes, 90.5 parts of crystalline solid were isolated. When this product was recrystallized from 1300 parts of anhydrous ethanol, there was obtained 70 parts of dibenzoyl d-tartarate acid salt of L-l-(3-trifluoromethylphenyl)-2-ethylaminopropane. This salt was treated with 500 parts of 4 N NaOH. The mixture was extracted with 2x200-part portions of diethyl ether and the ether extract was re-extracted with 100 parts of 4 N hydrodiboric acid. After treatment with 120 parts of 4 N NaOH, the free amine amounting to 25 parts distills at 105°-107°C (17.5 mm.). [a]D25 - 9.6° (c=8% in ethanol). 

Dihydro-l//-2-benzotelliirin (Kongalite Method)2 34 g (0.17 mol) of sodium formaldehyde sulfoxylate, 26 g (0.65 mol) of sodium hydroxide, and 100 ml of water are placed in a flask fitted with a stirrer, a reflux condenser, and a nitrogen inlet tube. The flask is flushed with nitrogen, 15 g (0.12 mol) of fine tellurium powder is added, and the mixture is stirred and heated on a water bath for 30 min. 100 ml of ethanol and a solution of 25 g (0.09 mol) of 2-(2 -bromoethyl)benzyl bromide dissolved in 150 mi of hot ethanol are added. The mixture is stirred and heated under reflux for 2 h, the ethanol is distilled off, and the residue is ground, then extracted with a mixture of 300 ml of water and 300 ml of diethyl ether. The diethyl ether layer is separated, washed with water, dried with anhydrous sodium sulfate, filtered, and fractionally distilled yield 8.5 g b.p. 116-12670.3 torr. The residue from the extraction is boiled with 50 m/of ethanol, the mixture is filtered hot, and the filtrate allowed to cool. The crystals are collected (3.8 g) and the combined product fractions are recrystallized from methanol whereby the methanol solution is cooled in dry ice yield 12.3 g (54%) m.p. 64°. 

Other industrial processes that have taken advantage of the process intensification deriving from the introduction of reactive (catalytic) distillation are (i) production of high purity isobutene, for aromatic alkylation (ii) production of isopropyl alcohol by hydration of propylene (iii) selective production of ethylene glycol, which involves a great number of competitive reactions and (iv) selective desulfurization of fluid catalytic cracker gasoline fractions as well as various selective hydrogenations. Extraction distillation is also used for the production of anhydrous ethanol. 

The imidic ester hydrochloride (1 mole) is dissolved in an eight- to ten-fold weight of anhydrous ethanol, treated with 2-(diethylamino)ethylamine (1.05 moles), and stirred for 8 h at 40-45°. The alcohol is then removed in a vacuum and the residue is dissolved in water and acidified to Congo Red by hydrochloric acid. After short warming the mixture is cooled and all non-basic material is removed by filtration or by extraction with ether. The solution is then evaporated to dryness at 40° in a vacuum and the last traces of water are distilled off azeotropically with benzene-ethanol. The yield is 75-80%. 

Extractive distillation with liquid solvent is used commercially for the production of anhydrous ethanol from ethanol-water mixtures. This method uses a relatively nonvolatile liquid solvent, such as ethylene glycol, which is fed into a distillation column some trays above the ethanol feed tray. The presence of the solvent at relatively high concentration in the liquid on the trays alters the volatility of one of the feed components more than the other, so a separation of the feed components can be made in the column. 

Alvarez, V. H., P. Alijo, D. Serrao, R. M. Filho, M. Aznar and S. Mattedi (2009). Prcxluction of anhydrous ethanol by extractive distillation of diluted alcoholic solutions with ionic hquids. Computer Aided Chemical Engineering 27 1137-1142. 

Method 1. Reflux a mixture of pure nicotinic acid (Section V,22), 84 g. (105 ml.) of absolute ethanol and 90 g. (50 ml.) of concentrated sulphuric acid in a flask for 4 hours on a steam bath. Cool the solution and pour it slowly and with stirring on to 200 g. of crushed ice. Add sufficient ammonia solution to render the resulting solution strongly alkaline generally, some ester separates as an oil but most of it remains dissolved in the alkaline solution. Extract the solution with five 25 ml. portions of ether, dry the combined ethereal extracts with anhydrous magnesium sulphate, remove the ether and distil under reduced pressure. The ethyl nicotinate passes over at 117-118°/ 6 mm. the yield is 34 g. The b.p. under normal pressure is 222-224°. 

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