Potassium surface desiccant

A mixture of acetamide (30 g. = 0-5 mole) and bromine (80 g. = 26 c.c.) in a half-litre flask is kept well cooled with water while enough of a solution of 50 g. of potassium hydroxide in 350 c.c. of water is added to change the initially red-brown colour into a pale yellow this requires most of the alkali. The solution is now run from a dropping funnel in an unbroken jet into a solution of 80 g. of potassium hydroxide in 150 c.c. of water, maintained at 70°-75° in a litre flask. The operation lasts for several minutes. Until the reaction mixture becomes colourless (one quarter to half an hour) the temperature is maintained at 70°-75°, and then the methylamine is distilled with steam. An adapter is fixed to the lower end of the condenser and dips 1 cm. below the surface of the liquid in the receiver (100 c.c. of approximately 5 N-hydrochloric acid2). As soon as the liquid which forms in the condenser is no longer alkaline the distillation is discontinued and the contents of the receiver are evaporated to dryness in a porcelain basin on the water bath. The last traces of water are removed by allowing the basin to stand over night in a vacuum desiccator. The dried material is boiled with absolute alcohol, which dissolves the methylamine hydrochloride but not the ammonium chloride with which it is mixed. The clear filtrate obtained when the ammonium chloride is removed by filtration is concentrated to a small volume and the methylamine hydrochloride is allowed to crystallise out in the cold. The salt is filtered with suction, washed with a little alcohol, and dried in a desiccator. Yield 15-20 g. 

A solution of 13,5g of mercuric chloride in 200ml of water is mixed with 16.% of potassium Iodide In 160ml of water and the red precipitate of mercuric iodide is filtered off, washed with two 25ml portions of water, and drained diy, It is then dissolved in a hot solution of 16g more of potassium iodide in 10ml of water, the yellow supernatant liquid is decanted from the small residue of undissolved mercuric iodide, and allowed to crystallize in vaciw over concentrated sulphuric add, The crystalline crusts on the surface should be broken up from time to time. The final paste of light-yellow crystals is completely dried in an ordinary desiccator. Based on the mercuric chloride taken, the yield is almost quantitative. The product is deliquescent and should be stored in tightly stoppered vessels to avoid absorption of moisture from the air. 

Naphthylacetonitrile. Place a mixture of 56g (0.32mol) of l-(chloro-methyl)naphthalene, 29 g (0.45 mol) of potassium cyanide, 125 ml of ethanol and 50 ml of water in a 500-ml round-bottomed flask fitted with a double surface reflux condenser, and reflux for 1 hour. Distil off the alcohol, transfer the residue to a separatory funnel, wash it with water, filter from a small amount of solid, transfer to a dish and dry under reduced pressure (vacuum desiccator charged with anhydrous calcium chloride). Distil under diminished pressure and collect the 1-naphthylacetonitrile at 155-160°C/9 mmHg (1) the yield is 38 g (72%). 

Xylene (150 g. or 1.41 moles) is heated to 130° in an oil bath while 252. g. (3.15 moles) of bromine is added slowly through a tube passing below the surface of the o-xylene. (Hood.) After the addition of the bromine, the reaction mixture is poured into an evaporating dish and placed in a vacuum desiccator over potassium hydroxide until the hydrogen bromide has been removed. The product is distilled, and the a-bromo-o-xylene is collected at 215-218° in 80% yield. 

Anhydrobisdibenzylsilicanediol is formed when 2 mols. of dibenzylsilicanediol condense with loss of 1 mol of water. Though the yield is not good, the best method of preparation is as follows Dibenzylsilicanediol (3 grams) is dissolved in 20 c.c. of dry ether, acetyl chloride (30 drops) added, and the solution in a beaker is kept in a desiccator over potassium hydroxide for three hours. It is then connected to the pump and evacuated to remove most of the acid chloride. After six hours, crystals of termolecular silicone usually appear on the surface. The solution is then poured into excess of cooled, dilute ammonium hydroxide and shaken. After extraction with ether and evaporation, the oily residue is treated with a little alcohol, which precipitates the silicone. The filtered alcoholic solution is diluted with water, and vigorous rubbing of the beaker with a glass-rod causes... 

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