Dehydration apparatus

The dehydration process is based primarily on the ability of alcohol to displace water. Since, however, the water is not always perfectly displaced the alcohol becomes partly mixed with water. In addition, some of the water is adsorbed by the nitrocellulose and cannot readily be removed, which causes a further dilution of the alcohol. The subsequent portions of fresh alcohol displace the dilute alcohol, the residual alcohol adsorbed by nitrocellulose is mixed with concentrated alcohol, the latter is displaced by fresh alcohol etc. This course of the operation is illustrated by variations in the concentration of alcohol in the liquid flowing out of the dehydration apparatus (Figs. 203-205). 

Figure 1. (a) The zeolite dehydration apparatus (b) the zeolite reduction apparatus... 

Schievelbein, V. H. and Piglia, T. J. 1992. Glycol dehydration apparatus for natural... 

Accidental addition of 6500 1 of cone, hydrochloric acid to a bulk sulfuric acid storage tank released sufficient hydrogen chloride gas by dehydration to cause the tank to burst violently [1], Complete dehydration of hydrochloric acid solution releases some 250 volumes of gas. A laboratory apparatus for effecting this safely has been described [2], which avoids the possibility of layer formation in unstirred flask generators [3],... 

Phosphorus pentoxide has been used as dehydrating agent but the pentachloride method is much superior. With the pent-oxide method there is always trouble due to the formation of a black, sticky mass which swells up during the latter part of the experimentand often disrupts the apparatus. 

Sodium 4-hydroxybenzenesulfonate dihydrate (2.37 g, 0.01 mol) was dehydrated by distillation with benzene using Dean-Stark apparatus and then dissolved in 20 mL of acetone in a lOOmL round-bottomed flask with a reflux condenser. Ethyl bromoacetate (2.04 g, 0.012 mol), potassium carbonate (2.79 g, 0.02 mol) and dibenzo-18-crown-6 (74 mg, 0.2 mmol) were added, and the mixture was heated at reflux for 48 h. After cooling to room temperature, the crystals were collected on a Buchner funnel, washed with acetone (2 x 60 mL), and dried under reduced pressure to yield 2 as a white powder (2.68 g, 95 %). m.p. > 300 °C. 

Preparation of Manganese(ll) Oxide. Dehydrate 1 g of manganese oxalate by heating in a porcelain bowl at not over 200 °C. Transfer the salt into a porcelain boat and roast it in a tubular furnace in a stream of dry hydrogen at 300-400 °C (see Fig. 115). Preliminarily check the tightness of the apparatus and the purity of the hydrogen ... 

After analysis each form of nitrocellulose (guncotton, collodion cotton, pyror collodion cotton) is batched separately into a linen bag which for convenience and safety is stored in an air-tight iron vessel (to protect the nitrocellulose from drying up and becoming dusty). Nitrocellulose is batched by charges, the size of which depends on the dimensions and the type of apparatus used. In France, for instance, a total charge of nitrocellulose (CPt and CP2) is 20 kg when dehydrated in a hydraulic press or 30 kg when dehydrated in a centrifuge. 

Zinc bromide, ZnBr2, used as a desiccant Zinc chloride, ZnCl2, used as a dehydrating condensing agent in org synthesis Commercial dehydration operations are best performed on solids by an apparatus that provides air to catty off water vapor on its release Some of the equipment is convertible from heat removal to heat supply by simply changing the temp level of the fluid or air (Ref 3)... 

Fatty Substances.—5 grams of flour previously dehydrated at 1050 are mixed with an equal amount of siliceous sand and treated in one or the other ordinary extraction apparatus with anhydrous ether or petroleum ether the fat is calculated on either the dry or moist flour. 

Sanple Preparation. Copper Y zeolite was prepared by ion exchange of sodium Y (Linde SK-40) zeolite with aqueous Cu(N03)2 solution. CuigNa24Y(Cu Y) (11) was obtained by stirring a slurry of 50g of NaY in 1 dm of 0.1 M Cu Oj at 25° for 4 h. The copper content was determined by spectrophotometry of Cu + after dissolution of exchanged sieve. The Cu Y zeolite was washed, air dried, and 2g samples were dehydrated in an apparatus (Fig. la) under vacuum first at room temperature and then at 100°C, 200°C, 300°C, and 400°C, being held at each temperature for one hour. 

In a 50-ml three-necked flask are placed the carboxylic acid (0.01 mol), ethyl polyphosphate (6g, PPE) and purified chloroform (5 ml). The mixture is cooled in an ice bath and the flask is connected to a balloon containing ammonia gas ( 3 litres). Air in the flask is replaced with ammonia and the mixture is mechanically stirred at 0-5 °C for 30 minutes and then at room temperature for one and a half hours whereupon the mixture turns very viscous (1). The balloon is removed and PPE (10 g) is added. The stirring is continued at 80 °C until the reaction is complete (usually within several hours) the dehydration is monitored by t.l.c. analysis (1). The mixture is stirred with aqueous 25 per cent sodium carbonate solution (150 ml), and then extracted with benzene (3 x 40 ml CAUTION). The combined organic extracts are dried with sodium sulphate and evaporated. The residual oil is passed through a short column packed with silica gel ( 20g) and the product eluted with benzene. The eluate is evaporated and the residue purified by short path distillation under reduced pressure (Kugelrohr apparatus). 

Acetic Acid-Acetic Anhydride Solution. One kilogram of glacial acetic acid is dehydrated in a 3-1.. flask over phosphorus pentoxide. The supernatant liquid is then fractionally distilled in an all-glass apparatus, and the portion boiling between 118 to 118.5° is collected. This procedure is repeated until the product has a melting point of 15.6°C. corresponding to that of 99.5 per cent acetic acid.f To the pure acetic acid 10 per cent acetic anhydride is now added. This solution should be kept in a stoppered container protected from moisture. 

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