Cuprous cyanide preparation

A solution of 20 g. (0.12 mole) of o-aminobiphenyl in hydrochloric acid is diazotized in the usual manner [Org. Syntheses Coll. Vol. 1, 170 (1941)], and the solution of the diazonium salt is added to a solution of cuprous cyanide prepared from 35 g. of copper sulfate [Org. Syntheses Coll. Vol. 1, 514 (1941)]. When evolution of nitrogen ceases, the mixture is warmed for 30 minutes on a water bath and then made alkaline with sodium hydroxide. The mixture is steam-distilled, and the distillate is agitated with stannous chloride solution. SuflBcient sodium hydroxide is added to precipitate the tin, and the mixture is extracted with ether. The ethereal solution is dried and distilled to give 11.0 g. (50%) of o-cyanobiphenyl boiling at 174°/13 mm., m.p. 37°. 

Potassium cupro-cyanide is the most convenient form in which cuprous cyanide can be used in Sandmeyer s Reaction. It is prepared by adding an excess of potassium cyanide to copper sulphate solution, whereby the cupric cyanide which is formed immediately breaks down to give cuprous cyanide and cyanogen, and the cuprous cyanide then dissolves in the excess of potassium... 

Cuprous cyanide solution. The most satisfactory method is to dissolve the cuprous cyanide (1 mol) in a solution of technical sodium cyanide (2 5-2-6 mols in 600 ml. of water). If it is desired to avoid the preparation of solid cuprous cyanide, the following procedure may be adopted. Cuprous chloride, prepared from 125 g. of copper sulphate crystals as described under 1 above, is suspended in 200 ml. of water contained in a 1-litre round-bottomed flask, which is fitted with a mechanical stirrer. A solution of 65 g. of technical sodium cyanide (96-98 per cent.) in 100 ml. of water is added and the mixture is stirred. The cuprous chloride passes into solution with considerable evolution of heat. As the cuprous cyanide is usually emplo3 ed in some modification of the diazo reaction, it is usual to cool the resulting solution in ice. 

The Sandmeyer reaction may also be applied to the preparation of nitriles. The solution of the diazonium salt is added to a solution of cuprous cyanide in excess of sodium or potassium cyanide solution (sometimes improved yields are obtained by substituting nickel cyanide for cuprous cyanide), for example CH3 CH, CH3... 

Benzonitrile (phenyl cyanide). Prepare a cuprous cyanide solution in a 500 ml. round-bottomed flask as above, but use the following quantities 65 g. of crystallised copper sulphate in 205 ml. of water, 18 g. of sodium bisulphite in 52 ml. of water, and 18 g. of potassium cyanide in... 

By the hydrolysis of nitriles. The nitriles may be easily prepared either from amines by the Sandmeyer reaction (Section IV,66) or by the action of cuprous cyanide upon aryl halides (compare Section IV,163). Benzyl cyanide... 

The patended method of preparation of the blue dye (120) [19187-01 -0] (81) involves treating the analogous dibromo substituted azo dye with cuprous cyanide in dimethylformamide or A-methylpyrrohdinone at 50°C to effect replacement of the two bromo substituents by cyano groups. 

The greenish-blue dye (117) (82) is prepared in a similar fashion, replacing bromo with cyano by using cuprous cyanide, pyridine, and 2-methoxyethanol as solvent at 85°C. 

Terephthalic acid has been obtained from a great many /)-disubstituted derivatives of benzene or cyclohexane by oxidation with permanganate, chromic acid, or nitric acid. The following routes appear to have preparative value from />-toluic acid, />-methylacetophenone,2 or dihydro-/)-tolualdehyde by oxidation with permanganate from f>-cymene by oxidation with sodium dichromate and sulfuric acid from />-dibromobenzene or from /i-chloro- or -bromobenzoic acid by heating at 250° with potassium and cuprous cyanides and from />-dibromo-benzene, butyllithium, and carbon dioxide. ... 

Methoxythiophene and 3-cyanothiophene have been prepared from 3-bromothiophene by means of a cupric oxide-catalyzed Williamson synthesis and by reaction with cuprous cyanide in quinoline, respectively. 

Halogeno compounds have been prepared by direct halogena-tion or by Sandmeyer reaction on 4-aminoisothiazoles. As expected from general considerations, a halogen atom in the 4-position is less reactive than one in the 5-position, but nitriles are obtained in good yield with cuprous cyanide at elevated temperatures. With butyllithium, lithiation occurs exclusively in the 5-position, and no evidence of halogen displacement has been obtained. ... 

A. Preparation of Cuprous Cyanide. (Note i)—In a 6-1. round-bottom flask fitted with a stopper carrying a mechanical stirrer, a separatory funnel, and a gas exit tube leading to a good hood (Note 2), is placed a solution of 650 g. (2.6 moles) of crystallized copper sulfate in 4 1. of water. The flask is surrounded by an oil bath and heated to about 8o°. The stirrer is started and a solution of 255 g. (5.2 moles) of sodium cyanide (Note 3) in 650 cc. of water is added from the separatory funnel over a period of about one-half hour. Then the mixture is boiled until no more cyanogen gas is evolved. This requires about five to ten minutes. 

Technical cuprous cyanide dried at iio° gives as good results as the specially prepared substance. 

Allyl cyanide has been found in oil of mustard 1 and has been prepared from allyl chloride and potassium cyanide,2 allyl bromide and potassium cyanide,3 allyl iodide and potassium cyanide4 and silver cyanide.5 The method described in the procedure is essentially that of Bruylants, who has shown that the yields are much better when dry cuprous cyanide is treated with allyl bromide.6... 

The method described is essentially that of La Forge.2 Nicotinonitrile has also been prepared from nicotinic acid by heating with ammonium acetate and acetic acid,3 from 3-pyridinesulfonic acid by fusion of the sodium salt with sodium cyanide,4 and from 3-bromopyridine and cuprous cyanide.6... 

Thenoic acid has been prepared in low yield by oxidation of 3-methylthiophene with potassium permanganate,2-4 dilute nitric acid, chromic acid, and hydrogen peroxide,4 and by reductive dechlorination of chloro-3-thenoic acid.4 Starting with 3-iodothiophene, which is difficult to obtain, good yields are obtained by the Grignard procedure 6 or with cuprous cyanide and potassium cyanide in a sealed tube.6... 

While the cuprous cyanide solution is warmed gently (to 60°-70°) on the water bath, a solution of p-tolyldiazonium chloride is prepared as follows Heat 20 g. of p-toluidine with a mixture of 50 g. of concentrated hydrochloric acid and 150 c.c. of water until dissolution is complete. Immerse the solution in ice-water and stir vigorously with a glass rod so that the toluidine hydrochloride separates as far as possible in a microcrystalline form. Then cool the mixture in ice and diazotise with a solution of 16 g. of sodium nitrite in 80 c.c. of water, added until the nitrous acid test with potassium iodide-starch paper persists. The diazonium chloride solution so obtained is poured during the course of about ten minutes into the warm cuprous cyanide solution, which is meanwhile shaken frequently. After the diazo-solution has been added the reaction mixture is heated under an air condenser on the water bath fox a further quarter of an hour, and then the toluic nitrile is separated by distillation with steam (fume chamber, HCN ). The nitrile (which passes over as a yellowish oil) is extracted from the distillate with ether, the p-cresol produced as a by-product is removed by shaking the ethereal extract twice with 2 A-sodium hydroxide solution, the ether is evaporated,... 

The preparation described is based on the method of de Wolf and van de Straete. Fumaronitrile has also been prepared by the reaction of diiodoethylene with cuprous cyanide. ... 

Diazotise 223 g. of 2-naphtliylamine-l-sulphonic acid as detailed under fi-Bromonaphthalene in Section IV,62. Prepare cuprous cyanide from 125 g. of cupric sulphate pentahydrate (Section IV,66) and dissolve it in a solution of 65 g. of potassium cyanide in 500 ml. of water contained in a 1-litre three-necked flask. Cool the potassium cuprocyanide solution in ice, stir mechanically, and add the damp cake of the diazonium compound in small portions whilst maintaining the temperature at 5-8°. Nitrogen is soon evolved and a red precipitate forms gradually. Continue the stirring for about 10 hours in the cold, heat slowly to the boiling point, add 250 g. of potassium chloride, stir, and allow to stand. Collect the orange crystals which separate by suction filtration recrystallise first from water and then from alcohol dry at 100°. The product is almost pure potassium 2-cyanonaphthalene-l-sulphonate. Transfer the product to a 2-litre round-bottomed flask, add a solution prepared from 400 ml. of concentrated sulphuric acid and 400 g. of crushed ice, and heat the mixture under reflux for 12 hours. Collect the -naphthoic acid formed (some of which sublimes from the reaction mixture) by suction filtration... 

Mesitylacetonitrile can be prepared by the action of potassium cyanide on < 2-chloroisodurene4 or by treating a. 2-chloroisodurene with cuprous cyanide in the presence of pyridine.5 The procedure described is based upon the method for the preparation of benzyl cyanide from benzyl chloride. 

If several runs are to be made it may be more convenient to prepare a large quantity of cuprous cyanide solution, since this appears to be stable for several days. 

The methods used for preparing cyanobenzo[6]thiophenes are merely summarized in the present section they are discussed in more detail elsewhere in this review. Cyanobenzo[6]thiophenes are most conveniently prepared by heating a halobenzo[6]thiophene with cuprous cyanide in a suitable solvent (Section VI, D, 2), or by means of a Sandmeyer reaction of the appropriate diazotized amine (Section VI, F, 4 and 5). Less commonly they are prepared from aldehydes or aldoximes, by methods described in Section VI, L, 1, or from carbox-... 

---