Zinc cyanide, anhydrous

Zinc cyanide. Solutions of the reactants are prepared by dis solving 100 g. of technical sodium cyanide (97-98 per cent. NaCN) in 125 ml. of water and 150 g. of anhydrous zinc chloride in the minimum volume of 50 per cent, alcohol (1). The sodium cyanide solution is added rapidly, with agitation, to the zinc chloride solution. The precipitated zinc cyanide is filtered off at the pump, drained well, washed with alcohol and then with ether. It is dried in a desiccator or in an air bath at 50°, and preserved in a tightly stoppered bottle. The yield is almost quantitative and the zinc cyanide has a purity of 95-98 per cent. (2). It has been stated that highly purified zinc cyanide does not react in the Adams modification of the Gattermann reaction (compare Section IV,12l). The product, prepared by the above method is, however, highly satisfactory. Commercial zinc cyanide may also be used. 

In order to avoid the preparation and handling of anhydrous hydrocyanic acid the passage of the gas direct from a generator (Am. Soc., 43, 348) and the use of zinc cyanide (Am. Soc., 45, 2373) have been tried with very satisfactory results. 

Anisaldehyde (p-methoxybenzaldehyde). Use the apparatus described for fi-resorcylaldehyde. Place 30 g (30 ml, 0.28 mol) of anisole, 75 ml of sodium-dried benzene (CAUTION) and 52 g (0.44 mol) of powdered zinc cyanide in the flask. Cool the mixture in a bath of cold water, start the stirrer and pass in a rapid stream of hydrogen chloride for 1 hour. Remove the gas inlet tube, and without stopping the stirrer, add 45 g of finely powdered anhydrous aluminium chloride slowly. Replace the gas inlet and pass in a slow steam of hydrogen chloride while heating the mixture at 40-45 °C for 3-4 hours. Allow... 

Hydroxy-1-naphthaldehyde has been prepared from /3-naphthol, zinc chloride, and hydrogen cyanide 1 from /3-naphthol, zinc cyanide, and anhydrous hydrogen chloride 2 and from /3-naphthol, chloroform, and sodium hydroxide (Reimer-Tiemann reaction).3... 

A modified Gattermann synthesis introduced by R. Adams avoids the use of anhydrous hydrogen cyanide. By passing hydrogen chloride into a mixture of the phenol and zinc cyanide in ether, the effective reagent and catalyst are produced in the reaction mixture in the presence of the substrate. 

Dihydroxybenzaldehyde 5 9 0 A reaction flask (500-ml capacity) is fitted with an efficient stirrer, a reflux condenser, and a wide gas-inlet tube the end of the condenser is connected to, successively, a wash-bottle containing sulfuric acid, an empty safety flask, and a tube that passes over the surface of a sodium hydroxide solution. Resorcinol (20 g) and anhydrous ether (150-200 ml) are placed in the reaction flask, and anhydrous zinc cyanide (1.5 equivalents) is added. Then a rapid stream of dry gaseous hydrogen chloride is passed in. The zinc cyanide disappears as a milky mixture is formed and as the hydrogen chloride dissolves, the imide hydrochloride condensation product separates as a thick oil which solidifies in 10-30 min. The ether is usually saturated in 1.5 h, after which hydrogen chloride is passed in slowly for a further 0.5 h. Then the ether is decanted, water (100 ml) is added to the imide hydrochloride, and the solution is heated to the boiling point, filtered and allowed to cool. About half the aldehyde separates. After this has been collected the remainder of the aldehyde crystallizes in 10-15 h. The total yield is about 95 %, and the m.p. is 135-136° after recrystallization with charcoal from water. 

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