Alcohol rectification

Figure 2 illustrates the three-step MIBK process employed by Hibernia Scholven (83). This process is designed to permit the intermediate recovery of refined diacetone alcohol and mesityl oxide. In the first step acetone and dilute sodium hydroxide are fed continuously to a reactor at low temperature and with a reactor residence time of approximately one hour. The product is then stabilized with phosphoric acid and stripped of unreacted acetone to yield a cmde diacetone alcohol stream. More phosphoric acid is then added, and the diacetone alcohol dehydrated to mesityl oxide in a distillation column. Mesityl oxide is recovered overhead in this column and fed to a further distillation column where residual acetone is removed and recycled to yield a tails stream containing 98—99% mesityl oxide. The mesityl oxide is then hydrogenated to MIBK in a reactive distillation conducted at atmospheric pressure and 110°C. Simultaneous hydrogenation and rectification are achieved in a column fitted with a palladium catalyst bed, and yields of mesityl oxide to MIBK exceeding 96% are obtained. 

The term still is applied only to the vessel in which liquids are boiled during distillation, but the term is sometimes applied to the entire apparatus, including the fractionating column, the condenser, and the receiver in which the distillate is collected. If a water and alcohol distillate is returned from the condenser and made to drip down through a long column onto a series of plates, and if the vapor, as it rises to the condenser, is made to bubble through this liquid at each plate, the vapor and liquid will interact so that some of the water in the vapor condenses and some of the alcohol in the liquid vaporizes. The interaction at each plate is equivalent to a redistillation. This process is referred to by several names in the industry namely rectification, fractionation, or fractional distillation. 

Distillation is probably Ihe most widely used separation (mass transfer) process in the chemical and allied industries. Its applications range from the rectification of alcohol, which has been practiced since antiquity, lo the fractionation of crude oil. The separation of liquid mixtures by distillation is based on differences in volatility between the components. The greater the... 

Benzyl alcohols, including commercially available benzyl alcohol and 4-methylbenzyl alcohol, were purified through rectification, followed by recrystallization when the alcohols were solids. 

The best method for recovering the alcohol is to collect the 60-70% alcohol and rectify it and to collect the 80% alcohol separately and use it for the dehydration of the next batch of nitrocellulose. 1251. of 95% alcohol is consumed per 100 kg of dehydrated nitrocellulose of this 30-35 1. remain in the nitrocellulose and about 90 1. are recovered by rectification. 

Dehydration using this type of press precludes the recovery of dilute alcohol. Only 92-96% alcfhol is used for dehydration. The waste alcohol below a certain concentration (usually 50%) is discarded. Any of a higher concentration is sent to rectification. 

According to Ponchon 110 kg of 93% alcohol are used for the dehydration of 100 kg of nitrocellulose (dry weight). In French factories (1917) an average of 33 kg of 42-52% waste alcohol was recovered and returned for rectification. 

In addition to the charge of activated charcoal A, a thermal layer T of broken rock is laid in the adsorber to absorb heat should the charcoal layer ignite. The air plus solvent passes through fan V, valve (7), layers T, A and valve (2). When the charcoal is saturated with solvent both valves are closed, the steam is introduced through valve (3), valve (4) is opened and the alcohol and ether are distilled off and passed to the condenser (5). The condensed solvent and water is collected in the lower section (6), and from there conveyed by pump (7) for rectification. After the solvent has been distilled the inflow of steam is stopped and hot air is passed through the adsorber, with valves (i) and (2) open. When the charcoal is dry the air heater is shut off (it is not shown in the figure) and the charge is cooled by means of cold water, after which the adsorber is ready for another adsorption cycle. 

The water from the vat containing an average of 18.5% alcohol was recycled for rectification. 

Alcohol and Cabamel.—Alcohol,—The manufacture and rectification of alcohol have already been described in VoL I., pages 48-149. The Editor will only remark, that for ihe purposes of perfumery it should be wholly free from ihe odor of fousel oil, which is... 

The alcohol obtained after usual work up was heated at 170 °C in the presence of CuS04 (40 grams) for 5 hrs. The crude olefin was recovered by distillation and then purified by rectification under reduced pressure. ( + ) (S)-l-Phenyl-3-methyl-l-pentene (trans) (40 grams) was thus obtained (bp 113°C at 18 mm Hg, nD25 1.5242, D25 +44.95°) (21). 

Phenyl ethyl selenide, C6H5.Se.C2H5.3—Phenyl selenide (10 grams) is dissolved in one equivalent of sodium hydroxide in the minimum of water, 50 c.c. of absolute alcohol then added, followed by 20 grams of ethyl bromide. The mixture is heated under reflux for fifteen minutes, then diluted with four times its volume of cold water, extracted three times with ether, the extract washed with water, dried over calcium chloride and distilled. Rectification of the oil obtained gives a 72 per cent, yield of the required selenide, boiling at 214° to 216° C. Treatment with bromacetic acid converts the selenide into phenyl-selenoglycollic acid.4... 

By rectification these impurities are almost completely eliminated, so that, whilst in rectified spirit of passable quality the coefficient of impurity is about 40 mgrms., in well rectified spirit containing 95-97% by volume of alcohol, the coefficient of impurity does not reach 10 mgrms. As a rule these spirits contain neither aldehydes nor higher alcohols, the low coefficient of impurity being constituted mostly Of acids and esters. 

These include a group of substances formed by secondary fermentations which accompany the alcoholic fermentation and separated during the rectification of raw spirit. 

The most important of these are whisky and gin. By whisky is meant the distillation product of the fermented worts obtained by diastatic saccharification of various cereals. Good whiskies are prepared by partial rectification of the first distillate. Gin is similarly prepared, but juniper berries are added to the still thus, it contains juniper oil as well as the prdinary impurities of alcohol. 

Out of collector 13 the base salve solution of trimethylborate is sent into tank 16, where at 200 °C trimethylborate is distilled. The distilled fraction, which contains 88-90% of trimethylborate, is collected into collector 6 and sent into the tank of rectification tower 7 the base salve from tank 16 is sent through container 17 back into batch box 5. During rectification all methyl alcohol is separated in the form of azeotropic mixture with trimethylborate and collected in collector 19 trimethylborate remains in the tower tank. The azeotropic mixture is sent through collector 11 for repeated extraction into tower 12 the ready product, 98.5-99.5% trimethylborate, is sent from the tank of tower 7 into collector 18. 

The process is carried out periodically, in the presence of OP-7 catalyst. The supplementaiy reactions are the flushing of the reactive mixture, the separation of the target product from the flush waters, the diying of the moist product and the rectification and absolution of ethyl alcohol. 

Distillation is an ancient unit operation, and has been widely practiced for thousands of years. Early applicetions used crude vaporization and condensation equipment, often for concentrating the alcoholic content of beverages, The first vertical columnar continuous distillation still was developed by Cellier-Blumenthal in France in 1813. Perrier introduced an early version of the bubble-cep tray in England in 1822, Packings were used as early as 1820 by a technologist named Clement who used glass balls in an alcohol still. Coffey developed the first sieve tray column in 1830. The first book on fundamentals of distillation was La Rectification de I alcohol by Ernest Sorel in 1893. 

The distillation of alcohol is perhaps the most frequent operation in herbal alchemy and this distillation is repeated anywhere from six to twelve times in order to make it pure enough. This process is called Rectification. However we cannot produce 100% alcohol by simple distillation no matter how often you repeat the process. The best we can do is about 95% unless we use some new tricks. Most often a drying agent is used such as potassium carbonate or calcium oxide (quicklime). These materials are not soluble in alcohol but have a voracious affinity for water, which they absorb from the alcohol. In many instances, the distillations are repeated not so much to increase the purity but to elevate or spiritualize the matter. 

One mole of the phenol is dissolved in 400 cc. water containing 1 mole of sodium hydroxide and 80 grams of soda ash. To this solution is added 500 cc. 90 per cent alcohol (ethyl or methyl) and the whole is cooled to 10°. Then 1.75 moles of ethyl or methyl chloride is added and the mixture is heated, with stirring or rotating, in an autoclave at 100°C. and 4 to 5 atmospheres pressure for 8 hours. The alkylation is then completed. The mixture is poured into water, and the alkyl ether is separated, recovering the alcohol by rectification. The product, which is washed with small amounts of sodium hydroxide and water, should now contain no nitrophenol. 

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