Capillary: for distillation

This tube is drawn out in the flame of a blow-pipe from glass tubing 4-8 mm. wide and is then drawn out again to sufficient fineness in a micro-flame. To make sure before use that the capillary is not closed, the tip is submerged in ether in a small test tube and air is blown in from the mouth. The bubbles should emerge separately and slowly. Capillaries for distillation in a high vacuum should emit air bubbles only on powerful blowing, and then with difficulty. 

The swan neck adapter of Fig. II, 56, 12 is useful for distillations as it permits the use of a capillary tube (held in position by a short length of heavy-walled rubber tubing) not sealed to a ground joint. It may also be used for inser tion of a thermometer or a gas-inlet tube in the narrow neck and a reflux condenser into the ground joint this device virtually converts a three-necked into a four-necked flask. Common sizes are cone fil9, 24, 29, or 34 socket 19, 24 or 29. 

The mercury reservoir is then lowered until the mercury flow just ceases (not further) and the electrode is allowed to stand in the air. It is good technique, at the beginning of each period of use, to immerse the capillary for ca 1 min. in 1 1-nitric acid while mercury is flowing, then wash it well with distilled water a further precaution is to allow the mercury drops to form in distilled water for about 15 minutes. 

Tn a 125-ml. Claisen flask, equipped with a capillary for vacuum distillation and a thermometer, are placed 50 g. (0.3 mole) of isodchydroacetic acid (p. 76) and 2 g. of copper powder (Note 1). A 125-ml. simple distilling flask, cooled by a water jet, is used as a vacuum receiver and is attached to a water aspirator. The Claisen flask is heated at atmospheric pressure in an oil bath at 230 235° for 45 minutes or until the decarboxylation has (eased. The pressure on the system is then slowly reduced, and... 

The flask is equipped with a short column, attached to which is a condenser set for distillation. A capillary is provided to prevent bumping. The water is then distilled at a pressure of 30-40 mm. by heating the flask in a water bath which is raised to the boiling point as rapidly as is consistent with smooth... 

Conversion to phenyl vinyl ketone. Place an intimate mixture of 21.4 g (0.1 mol) of //-dimethylaminopropiophenone hydrochloride and 0.2 g of hydroquinone in a 100-ml round-bottomed flask. Attach a Claisen still-head fitted with a stout capillary air leak and condenser arranged for distillation under reduced pressure place a few crystals of hydroquinone in the receiving flask. Pyrolyse the amine hydrochloride by heating the flask in an electric mantle at 2 mmHg (oil immersion pump), and collect the crude ketone which distils between 70 and 90 °C. On redistillation 7g (51%) of pure phenyl vinyl ketone, b.p. 72-73 °C/3 mmHg (115 °C/18 mmHg), are obtained. Characterise... 

Water is distilled from the mixture at atmospheric pressure until the temperature of the solution reaches 115° (Notes 2 and 3) whereupon the liquid is transferred to a 500-ml. round-bottomed flask. This flask is connected to the distillation apparatus used previously except that the thermometer is replaced by a capillary tube. Distillation is then continued under the reduced pressure obtainable from a water aspirator. The bath temperature is raised to 175° over a period of about an hour and is held there until the mixture solidifies (usually 30-60 minutes longer), and for 1 hour thereafter. The flask is cooled and broken to remove the product. 

The clear red-orange solution is cooled to 15°, and chilled glacial acetic acid (60-65 ml.) is added with stirring until the solution is just acid to litmus a mush of sodium acetate crystals precipitates. The dropping funnel is replaced by a capillary tube, and the condenser is set for distillation. About three-fourths of the ethanol is removed under reduced pressure while air is bubbled int<> the mixture through the capillary tube (Note 5). Care is taken that the internal temperature does not exceed 100°. 

Hydrogen fluoride can be handled in apparatus of suitable metals (copper, nickel, magnesium, or aluminum, which all form a protective fluoride coating, or platinum), or plastic materials [especially polypropylene. Teflon, and polyvinylidene fluoride (Viton)] polychlorotrifluoroethylene (Kel-F) can be made into transparent windows. A capillary for a dropping mercury electrode may be made from Teflon [307]. Hydrogen fluoride is obtained commercially in steel cylinders in a purity of 99.5%. The impurities may be removed by distillation [308] or electrolysis [309]. During the electrolytic removal of water the explosive FoO is formed, which must be taken into consideration [305]. 

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