together in a dry round-bottomed flask of capacity, the flask being well cooled.* to 3 litre The flask, to which a reflux condenser is now attached, is heated to about 40° on the water-bath.* When the evolution of hydrochloric acid gas has nearly ceased, the contents of the flask are distilled on the waterbath, the receiver being cooled in ice and provided with a calcium chloride tube to prevent absorption of moisture. Acetyl chloride collects in the receiver as a colourless liquid, which, after redistillation, is nearly pure, and should be kept in sealed vessels. 3CH CO2H+ PC13 = 3CH COC1+ P(OH)3 Acetyl Chloride. Properties.-Colourless liquid; b. p. 55°; sp. gr. 11305 at 0°; decomposes with water, forming hydrochloric acid and acetic acid, and therefore fumes in moist air. The same arrangement of apparatus is employed as shown in Fig. 25. For the preparation of chlorine a mixture of broken pieces of pyrolusite and comm. conc. hydrochloric acid (heated preferably in an earthenware vessel in the water-bath) or a mixture of equal parts of powdered salt (600 grms.) and powdered manganese dioxide (600 grms.) may be employed. The latter is introduced into a round-bottomed flask of about 6 litres capacity, and a cooled mixture of 1440 grms. conc. sulphuric acid and 720 grms. water added. When the evolution of chlorine slackens the flask is heated on the sand-bath. Properties.-Colourless liquid; b. p. 74°; sp. gr. 1.616 at 0°; fumes in moist air, decomposes into phosphorus acid and hydrochloric acid. PREPARATION LVII. = CH,CO ACETIC ANHYDRIDE, CH2OCH CO. (Acetyl Oxide.) LITERATURE.-Gerhardt (1853), Ann. Ch. Phys. (3) 37, 311; Kanonikoff, Saytzeff (1877), Ann. Ch. Pharm. 185, 192. 100 grms. sodium acetate (fused). One hundred grms. anhydrous and powdered sodium acetate are introduced into a retort of about litre capacity, connected with a condenser and receiver, 100 grms. acetyl chloride are then slowly added, drop by drop, from a tap-funnel, the retort being well cooled.* When the reaction, which proceeds at the ordinary temperature, has ceased, the vessel is first heated on the water-bath and the anhydride is then distilled off on the sand-bath. The distillate is rectified, and the portion passing over at 135-140° collected. By a further distillation the pure anhydride is obtained, which must be kept in well-stoppered bottles. CH CO2Na+ CH,COCI = (CH,CO)2O + NaCl Properties.-Colourless liquid, having an irritating smell; b. p. 138°; sp. gr. 1'097 at 0°; decomposes rapidly in presence of water into acetic acid. PREPARATION LVIII. ACETAMIDE, CH2NO=CH,CO.NH2 LITERATURE.-Dumas (1847), Compt. rend. 25, 657; Kündig (1858), Ann. Ch. Pharm. 105, 277; Smit (1875), Bull. Soc. Chim. 24, 540; Hofmann, Buckton (1856), Ann. Ch. 100, 131; Hofmann (1882), Ber. 15, 981. Pharm. 200 grms. ammonium acetate. Two hundred grms. ammonium acetate (prepared by passing ammonia gas, dried through quicklime (see Fig. 29) into about 160 grms. glacial acetic acid, and neutralising if necessary with conc. ammonia) are heated for from 5 to 6 hours in sealed tubes to 230°. Tubes made from the usual thick-walled tubing may be filled half full of the salt without risk of bursting. The tubes then contain an oily-looking liquid, consisting of an aqueous solution of ammonium acetate, together with a large quantity of acetamide. The contents are distilled, and the portion boiling above 180° collected apart. This distillate, on standing, almost completely solidifies to a colourless crystalline mass. It is freed from mother-liquor by draining at the filter-pump, and purified by a second distillation. The acetamide has then a nearly constant boiling point. CH3. COONH1 = CH3CONH2 + H2O Properties. Colourless rhombohedral crystals having a peculiar smell; m. p. 82°; b. p. 222°; easily soluble in water and alcohol. PREPARATION LIX. METHYLAMINE HYDROCHLORIDE, CH,NCI = LITERATURE.-Wurtz (1848), Compt. rend. 28, 223; Hofmann (1849), Ann. Ch. Pharm. 73, 91; Mendius (1862), Ann. Ch. Pharm. 121, 129; Hofmann (1882), Ber. 14, 2725 and (1883) Ber. 15, 407 and 762; Tafel (1886), Ber. 19, 1924. A 10 per cent. solution of caustic potash (about 20 grms.) is added in the cold to 20 grms. acetamide, previously dissolved in 54 grms. bromine, until the dark brown liquid changes to a deep yellow colour. The solution, which now contains potassium bromide and acetmonobromamide, is slowly added from a tap-funnel inserted, together with a thermometer, into the tubulus of a retort (litre capacity) which contains a concentrated solution of 56 grms. caustic potash heated to 60-70°. Heat is evolved, and care must be taken that the rise of temperature does not greatly exceed the above limits. The reaction goes on quietly, and the yellow solution is gradually decolourised. The mixture is then digested for a short. time at the above temperature until the yellow colour completely disappears, and the liquid distilled with a naked flame. The vapours of methylamine and ammonia which are evolved are passed into dilute hydrochloric acid contained in the receiver. When the methylamine has been driven over, the hydrochloric acid solution is evaporated to dryness on the water-bath, and the colourless crystalline residue extracted repeatedly with small quantities of absolute alcohol, which dissolves out the methylamine salt from the ammonium chloride. From the hot alcoholic solution foliated crystals separate out on cooling. CH,CONH2+ 2Br + KOH Acetamide = CH3. CONHBr + KBr + H2O CH,CONHBr + KOH = CN CON+KBr + H2O CHN:C:0+ H,O = CH,NH, + CO, Methyl Carbimide Methylamine. Properties.-Large deliquescent tablets, which melt at 200°, and sublime above 220° with slight decomposition. The base is liberated, on warming with caustic soda, as an inflammable gas. K |