Cuprous salts, derivatives chloride

Treatment of diazonium salts with cuprous, Cu(I), salts generates aryl halides. When 398 reacts with CuCl (cuprous chloride) or CuBr (cuprous bromide), the products are chlorobenzene or bromobenzene via what is probably a radical reaction.29l jhis conversion is known as the Sandmeyer reaction. 2 The use of copper powder rather than cuprous salts for this transformation is often called the Gattermann reaction. 93,292b,c Aryl iodides are also produced from diazonium salts by reaction with potassium iodide (KI) but the actual reactive species may be l3-.294,295 Treatment of aniline derivative 403 with sodium nitrite and HCl followed by treatment with KI, for example, gave a 89% yield of 404.Aryl nitriles are generated under Sandmeyer conditions using cuprous cyanide (CuCN), as in the conversion of 405 to benzonitrile derivative 407 via diazonium chloride, 406. 

Metallic Derivatives, (a) Cuprous Acetylide. CujCg. Prepare an ammoniacal solution of cuprous chloride by first adding dilute ammonia to 2-3 ml. of dilute copper sulphate solution until the initial precipitate just redissolves and a clear deep-blue solution is obtained now add an aqueous solution of hydroxylamine hydrochloride drop by drop with shaking until the solution becomes first green and then completely colourless, the cupric salt being thus reduced to the cuprous derivative. 

Aniline [62-53-3] M 93.1, f -6.0", b 68.3/lOmm, 184.4"/760mm, d 1.0220, n 1.585, n s 1.5832, pK 4.60. Aniline is hygroscopic. It can be dried with KOH or CaH2, and distd at reduced pressure. Treatment with stannous chloride removes sulfur-containing impurities, reducing the tendency to become coloured by aerial oxidn. Can be crystd from Et20 at low temps. More extensive purifications involve preparation of derivatives, such as the double salt of aniline hydrochloride and cuprous chloride or zinc chloride, or A -acetylaniline (m 114") which can be recrystd from water. 

Acetylene and its derivatives of the type R-C=C-H form organo-metallic derivatives with ammoniacal cuprous chloride or with ammoniacal silver nitrate. R-C=C-Ag and R-CsC-Cu. These precipitates although explosive when dry, have been used for quantitative determinations. (Ber. 20, 3081 (1887).) An alcoholic silver nitrate solution precipitates a double salt. 

Acetylene derivatives can be coupled rapidly at room temp, with Og or air in the presence of a catalytic amount of an amine complex of a Cu(I)-salt in an organic solvent. Pyridine can serve as both ligand and solvent.—E Og bubbled through a vigorously stirred mixture of phenylacetylene, cuprous chloride, and pyridine at 30-40° until the reaction subsides after 40 min. diphenyldiacety-lene. Y 86%. A. S. Hay, J. Org. Chem. 25, 1275 (1960). 

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