Distillation, apparatus

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. ... 

When constructing a manometer of the type shown in Fig. 12(c), it is impor tant to apply a very high vacuum (e.g., with a Hy-Vac pump) to the manometer while the mercury in the left-hand (sealed) limb is heated until it boils unless this is done, traces of air will remain in this limb and cause inaccurate readings. During a distillation, the tap I should be kept closed except when a pressure reading is being taken if it is left open indefinitely, a sudden default by the distillation apparatus or by the pump may cause the mercury in the sealed limb of G to fly back and fracture the top of the limb. 

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... 

Fig. 23(D) shows a simple distillation apparatus with an adaptor fitted to the lower end of the condenser. This apparatus can also be used for the recovery of solvents, or for the concentration of a solution with collection of the distilled solvent.

Distillation. This process is carried out in the apparatus shown in Figs. 36, 37 and 38. The distillation apparatus (Fig. 36) is of very general application and is made in one piece. 

The hydrolysis of as little as 0 5 ml. of the ester can be carried out in the combined reflux-distillation apparatus shown in Fig. 38 (p, 63). Pass a stream of cold water through the vertical condenser. Place in the 10 ml. pear-shaped flask 0 5 ml. of the ester, 5 ml. of 10% NaOH solution and one or two minute fragments of unglazed porcelain and heat the mixture gently for 15 minutes so that the vapours do not rise more than about half-way up the vertical water ondenser. Now run the water out of the ver ical condenser, insert a thermometer at the top, and pass water through the inclined condenser. Heat the flask sufficiently strongly to collect 1--2 ml. of distillate. This is dilute ethanol. 

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. 

Meanwhile set up the ether distillation apparatus as used in the preparation of triethyl phosphite (p. 308). Distil off the ether and then fractionally distil the residue at water-pump pressure. The di-isopropyl hydrogen phosphite distils at 79Vi4 mm. other b.ps. are 8o°/i5 mm., 82-5°/i7 mm. Yield, 25 g., 89%. 

Oxidation, (i) Dissolve 5 g. of potassium dichromate in 20 ml. of dil. H2SO4 in a 100 ml. bolt-head flask. Cool and add 1 ml. of methanol. Fit the flask with a reflux water-condenser and warm gently a vigorous reaction soon occurs and the solution turns green. The characteristic pungent odour of formaldehyde is usually detected at this stage. Continue to heat for 3 minutes and then fit the flask with a knee-tube (Fig. 59, p. 100) and distil off a few ml. Test the distillate with blue litmus-paper to show that it is definitely acid. Then apply Test 3 p. 350) for formic acid. (The reflux-distillation apparatus (Fig. 38, p. 63) can conveniently be used for this test.)... 

Hydrolysis. Place 2 ml. of the ester in a 50 ml. round-bottomed flask fitted with a reflux water-condenser, or use the reflux-distillation apparatus shown in Fig. 38, p. 63. Add about 20 ml. of 10% aqueous NaOH solution, and some fragments of unglazed porcelain, and reflux gently for 20-30 minutes. (Note that methyl oxalate is hydrolysed rapidly by water alone. Phenyl esters on the other hand hydrolyse comparatively slowly even with hot NaOH solution, and should be heated... 

Steaming-out the steam distillation apparatus. After the cleaned steam -distillation apparatus (Fig. 88) has been assembled, it is essential to pass steam through it for some time to remove readily soluble alkali. All the taps on the apparatus are opened and the water in the steam generator boiled vigorously. The steam will gradually pass into the apparatus. After a few minutes, the tap of the tap-funnel C may be closed and soon afterwards the tap Ti of the steam-trap finally the tap Tj of the funnel G may be closed, Steaming-out should then be continued for not less than one hour, the receiver J not being in place. 

Before each experiment the steam-distillation apparatus should be steamed-out for about half an hour this may be carried out while the digestion is taking place. 

Ether. The most satisfactory method for the removal of (diethyl) ether is either on a steam bath fed from an external steam supply or by means of an electrically-heated, constant-level water bath (Fig. 77, 5, 1). If neither of these is available, a water bath containing hot water may be used. The hot water should be brought from another part of the laboratory under no circumstances should there be a free flame under the water bath. It caimot be too strongly emphasised that no flame whatsoever may be present in the vicinity of the distillation apparatus a flame 10 feet away may ignite diethyl ether if a continuous bench top lies between the flame and the still and a gentle draught happens to be blowing in the direction of the flame. 

Another precision fiaetioiial distillation apparatus is depicted in Fig. 11, 17, 4. The main features, worthy of special mention, are —... 

In order to protect the oil in the oil pump from contamination, some form of trap must be interposed between the distillation apparatus and the pump in order to prevent vapours from the distilling flask, etc. passing... 

Assemble the simple fractional distillation apparatus shown in Fig. II, 16, 1 the round-bottomed flask should have a capacity of 200 or 250 ml. and the conical flask 100 ml. (Alternatively, a long all-glass... 

Iodine monochlorlde may be prepared as follows. Pass dry chlorine into 127 g. of iodine contained in a 125 ml. distilling flask until the weight has increased by 34-6 g. The chlorine should be led in at or below the surface of the iodine whilst the flask is gently shaken it is essential to have an excess of iodine. Distil the iodine chloride in an ordinary distillation apparatus use a filter flask, protected from atmospheric moisture by a calcium chloride (or cotton wool) guard tube, as a receiver. Collect the fraction b.p. 97-105° the jdeld is 140 g. Preserve the iodine monochloride in a dry, glass-stoppered bottle. 

Small scale apparatus with interchangeable ground glass joints (compare Section 11,56) are available commercially. One set of apparatus ( A) is based largely upon BlO and B14 joints, although occasionally a larger size joint is used as in the steam distillation apparatus shown in Fig. XII, 3, 1. 

Alternatively, use the following procedure in which triethylamine replaces potassium acetate as the basic catalyst. Place 2 1 g. (2-0 ml.) of purified benzaldehyde, 2 0 ml. of anhydrous triethylamine and 5 0 ml. of A.R. acetic anhydride in a 200 ml. round-bottomed flask, equipped with a short reflux condenser and a calcium chloride drying tube. Boil the solution gently for 24 hours—heating may be interrupted. Incorporate a steam distillation apparatus in the flask and steam distil until the distillate is no longer cloudy (about 100 ml.) and then collect a further 50 ml. of the distillate di ard the steam distillate. Transfer the residue in the flask to a 400 ml. beaker, add water until the vplume is about 200 ml., then 0 2 g. of decolourising carbon, and boil for a few minutes. Filter the hot solution, and acidify the hot filtrate with 1 1 hydrochlorioiaoid... 

People with or without distillation apparatuses can take advantage of this fact. Just boil or distill off most of the oil up to the temperature of your preferred allylbenzene and stop. There is a very good chance that what is left will be a majority of what is wanted. 

Distillation is always the most reliable way of separating things from complex mixtures such as relieving our P2P from its annoying black contaminants just like what was done above. But wouldn t it be nice if there was another way to do it for those without a distillation apparatus or who Just didn t have the time to distill Well, there actually is such a way, and it works fabulously ... 

With brisk stirring 75mL Everclear (ethanol) is poured into the reaction flask then 75mL concentrated sulfuric acid is slowly added until incorporated. The rest of the distillation apparatus is connected and the solution slowly heated to about 140°C. Next, 150mL Everclear is dripped in slowly so as to match the approximate distillation output that one can see condensing over into the collection flask. The temperature must remain between 140-150 C. After all the ethanol has been added (which should have taken approximately 90 min) the distillate that has collected is washed with 5% NaOH solution then with water (remember that the ether will form the top layer here). The ether can then be dried through sodium sulfate and used or can be distilled to purify. 

H2C=CH-C=CH-C3h7. All glassware of the distillation apparatus was rinsed AcHi with a dilute solution of diethylamine in diethyl ether. 

Note 1. This addition is to ensure that no traces of acids are present which cause isomerization to H2C=CH-C(0CH3)=CH-C5Hi i. All glassware of the distillation apparatus was therefore rinsed with a dilute solution of... 

Note. 3. All glassware of the distillation apparatus must be rinsed before use with a dilute solution of triethylamine Or another volatile amine in diethyl ether. Traces of acid on the glass walls may cause isomerization to H2C=CH-C(OCH3)=C(CH3)(OC2H5). 

Note 2. The allenic ether is extremely sensitive towards oxygen. All operations during the work-up must be carried out under nitrogen. After termination of the distillation nitrogen should be admitted to the distillation apparatus. Too strong heating during the distillation involves the risk of an explosion. 

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