Vacuum apparatus distillation

It has already been pointed out that a liquid even when subjected to simple atmospheric distillation may become superheated and then bump violently in consequence this danger is greatly increased during distillation under reduced pressure and therefore a specially designed flask, known as a Claisen flask, is used to decrease the risk of superheating. In Fig. i2(a) a Claisen flask D is shown, fitted up as part of one of the simplest types of vacuum-distillation apparatus. ... 

Fractional Distillation under Reduced Pressure. One great disadvantage of the simple vacuum-distillation apparatus shown in Fig. 12(a) is that, if more than one fraction distils, the whole process has to be stopped after collecting each consecutive fraction, in order to change the receiver F. This may be overcome by replacing the simple receiving flask F by a pig (Fig. 13) which collects consecutive... 

If a vacuum-distillation apparatus is not available for the above preparation, the crude product may be distilled at atmospheric pressure and the acetoacetate collected as the fraction boiling at i75 -i85 . A pure preparation cannot be obtained in this way, however, because the ester decomposes slightly when distilled at atmospheric pressure. 

A satisfactory vacuum-distillation apparatus is one that resembles a vacuum desiccator with a tube ground into the cover and having a side arm. If the ground surface between vessel and cover is improved by grinding with the finest carborundum or emery flour and then with rouge, it will hold a vacuum sufficiently well without any lubricant—... 

Nitromethane. In the presence of alkali, nitromethane and formaldehyde react to produce 2-nitroethanol and di- and tri-condensation products. A flash explosion may result if air is admitted to the vacuum distillation apparatus after removal of the 2 nitroethanol unless the residue is adequately cooled.5... 

The following is the specific procedure for the preparation of levoglucosenone (2) by the pyrolysis of 5 g of cellulose (l).8 To a 50-mL round-bottom flask fitted with a vacuum distillation apparatus was added phosphoric acid (25 mg, 0.5 wt %), cellulose (5 g) and vegetable oil (15 g). The slurry was stirred for about 5 min under reduced pressure (20-30 mm Hg), and then heated by an appropriate heating mantle for 7 min to 270°C, as indicated by the internal thermometer. The reaction mixture began to turn black and water distillate appeared at about 140°C. Yellow distillate containing water and levoglucosenone (2) appeared on the flask wall around 270°C, and the temperature in the distillation head reached around 110-120°C. The reaction... 

Analytical Treatment of Hydrogenated Coal Liquids. Scheme A. Filtered coal liquids were distilled in a standard vacuum distillation apparatus to recover the gasoline (IBP-400°F) and gas-oil (400°-1000°F) cuts (see Figure 2). The treatment with anhydrous HC1 was applied to the composite of these cuts (IBP-1000°F) or to the gas-oil fraction, each diluted with an equal volume of n-hexane. 

Figure 014. Advanced setup, two-path vacuum distillation apparatus for collecting safrole Note in some cases, the safrole may... 

FIGURE 15 Closed-System Vacuum Distillation Apparatus for 1,4-Dioxane. 

Set up a vacuum distillation apparatus so that the container vessel is placed in a water bath and the receiver vessel is cooled in an acetone/C02 bath. 

One piece vacuum distillation apparatus (or head, condenser, and collection adaptor)... 

Allow the distillation flask to cool to room temperature, replace the vacuum distillation apparatus with the reflux condenser and nitrogen inlet adapter, and replace one stopper with the thermometer and adaptor. 

Vacuum distillation is another common method of distillation in modem labs. Figure 016 illustrates a common vacuum distillation apparatus. Vacuum distillation takes advantage of the volatility of liquids by reducing pressure. The boiling points of liquids decrease with decreasing pressure, so distillation of heat sensitive liquids can be carried out at lower temperatures. 22... 

Figure 016. A standard vacuum distillation apparatus. The bleed tube allows for pressure equalization, and allows for faster distillation as air passes through the mixture, it carriers away some of the solvent.

Procedure Prepare a sol ution by adding 21 grams of 2-methyl-2-ami no-1,3-propanediol, 30 grams of nitroform, and 17 milliliters of 37% formaldehyde sol ution into 70 milliliters of distilled water. After preparing the sol ution, place the sol ution into an ice bath, and chill to 0 Celsius for 3 hours with rapid stirring. After 3 hours, pi ace the mixture into a rotary evaporator or vacuum distillation apparatus, and remove the water under vacuum until no more water passes into the receiver flask. 

A typical vacuum distillation apparatus is shown in Fig. 11.10. The chief difference from the simple distillation apparatus is in the design of the receiver adapter. This must allow several fractions to be collected without needing to break the vacuum. The simplest design is the pig type shown in... 

A typical vacuum distillation apparatus is illustrated in Fig. 1. It is constructed of a round-bottomed flask (often called the pot ) containing the material to be distilled, a Claisen distilling head fitted with a hair-fine capillary mounted through a rubber tubing sleeve, and a thermometer with the bulb extending below the side arm opening. The condenser fits into a vacuum adapter that is connected to the receiver and, via heavy-walled rubber tubing, to a mercury manometer and thence to the trap and water aspirator. 

FIG. 4 Vacuum distillation apparatus with Vigreux column and fraction collector. 

Two 200-mL beakers, cooling bath, magnetic stirrer, reclosable polythene bottle, vacuum distillation apparatus, safety glasses, protective gloves. 

Apparatus for filtration under reduced pressure Buchner funnel, flask, and water aspirator Small-scale vacuum distillation apparatus Erlenmeyer flask (various sizes)... 

The pyrrole is separated using a separating funnel and poured into another round-bottomed flask and step 1 is repeated. This procedure is then repeated five times whereupon pyrrole should contain about 98% deuterium. The substitution level is checked by infrared (IR) spectroscopy. Finally, the pyrrole is dried with CaCl2 and then distilled at reduced pressure from CaH2 (in a small-scale vacuum distillation apparatus). 

---