Cuprous chloride, preparation

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. 

Treat 0.25 gram of the product with 6 drops of water or enough to moisten it and then add 6 N HC1 a drop at a time noting the progressive change in the appearance of the residue. Finally see if a considerable amount (5-10 cc.) of the HC1 will dissolve the residue. Pour the clear solution into 500 cc. of cold water. Read the discussion of the cuprous chloride preparation and explain the observations made in this experiment. 

D) Formation of Metallic Acetylides. Pass acetylene gas for one minute into 5 ml of each of the solutions of ammoniacal silver nitrate and ammoniacal cuprous chloride, prepared according to directions given below. Note the character of the precipitate. Disconnect the flask, and dispose of the material in the flask, according to directions given by the instructor. 

Pour 800 mL of acidic cuprous chloride, prepared by the Winkler method, into about 4 L of water. Transfer the precipitate to a 250 mL graduate. After several hours, siphon off the liquid above the 50 mL mark and refill with 7.5% NH OH solution which may be prepared by diluting 50 mL of cone. NH.OH with 150 mL of water. The solution is well shaken and allowed to stand for several hours. It should have a faint odor of ammonia. 

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. 

Meanwhile, during the cooling of the cuprous chloride solution, prepare a solution of benzenediazonium chloride by dissolving 20 ml. (20-5 g.) of aniline in a mixture of 50 ml. of concentrated hydrochloric acid and 50 ml. of water, and after cooling to 5°, adding slowly a solution of 17 g. of sodium nitrite in 40 ml. of water. Observe carefully the general conditions for diazotisation given in the preparation of iodobenzene (p. 184). 

Allyl Chloride. Comparatively poor yields are obtained by the zinc chloride - hydrochloric acid method, but the following procedure, which employs cuprous chloride as a catalyst, gives a yield of over 90 per cent. Place 100 ml. of allyl alcohol (Section 111,140), 150 ml. of concentrated hydrochloric acid and 2 g. of freshly prepared cuprous chloride (Section II,50,i one tenth scale) in a 750 ml. round-bottomed flask equipped with a reflux condenser. Cool the flask in ice and add 50 ml. of concen trated sulphuric acid dropwise through the condenser with frequent shaking of the flask. A little hydrogen chloride may be evolved towards the end of the reaction. Allow the turbid liquid to stand for 30 minutes in order to complete the separation of the allyl chloride. Remove the upper layer, wash it with twice its volume of water, and dry over anhydrous calcium chloride. Distil the allyl chloride passes over at 46-47°. 

The procedure is not usually applicable to aminosulphonic acids owing to the interaction between the amino group and the phosphorus pentachloride. If, however, the chlorosulphonic acid is prepared by diazotisation and treatment with a solution of cuprous chloride in hydrochloric acid, the crystalline chlorosulphonamide and chlorosulphonanilide may be obtained in the usual way. With some compounds, the amino group may be protected by acetylation. Sulphonic acids derived from a phenol or naphthol cannot be converted into the sulphonyl chlorides by the phosphorus pentachloride method. 

In a 1 5 or 2-Utre rovmd-bottomed flask, prepare cuprous chloride from 105 g. of crystallised copper sulphate as detailed in Section 11,50,1. Either wash the precipitate once by decantation or filter it at the pump and wash it with water containing a httle sulphurous acid dissolve it in 170 ml. of concentrated hydrochloric acid. Stopper the flask loosely (to prevent oxidation) and cool it in an ice - salt mixture whilst the diazo-tisation is being carried out. 

Chlorobenzene. Prepare a solution of phenyldiazonium chloride from 31 g. (30 -5 ml.) of aniUne, 85 ml. of concentrated hydrochloric acid, 85 ml, of water, and a solution of 24 g. of sodium nitrite in 50 ml. of water (for experimental details, see Section IV,60). Prepare cuprous chloride from 105 g. of crystallised copper sulphate (Section 11,50,1), and dissolve it in 170 ml. of concentrated hydrochloric acid. Add the cold phenyl diazonium chloride solution with shaking or stirring to the cold cuprous chloride solution allow the mixture to warm up to room temperature. Follow the experimental details given above for p-chlorotoluene. Wash the chlorobenzene separated from the steam distillate with 40 ml. of 10 per cent, sodium hydroxide solution (to remove phenol), then with water, dry with anhydrous calcium chloride or magnesium sulphate, and distil. Collect the chlorobenzene (a colourless liquid) at 131-133° (mainly 133°), The yield is 29 g. 

Cuprous iodomercurate [13876-85-2] Cu2Hgl4, is a bright red water-insoluble compound prepared by precipitation from a solution of K Hgl with cuprous chloride. It is used in temperature-indicating paints because it reversibly changes color to brown at 70°C (see Chromogenic materials). 

Halophenols without 2,6-disubstitution do not polymerize under oxidative displacement conditions. Oxidative side reactions at the ortho position may consume the initiator or intermpt the propagation step of the chain process. To prepare poly(phenylene oxide)s from unsubstituted 4-halophenols, it is necessary to employ the more drastic conditions of the Ullmaim ether synthesis. A cuprous chloride—pyridine complex in 1,4-dimethoxybenzene at 200°C converts the sodium salt of 4-bromophenol to poly(phenylene oxide) (1) ... 

As a variation on the base-catalyzed nucleopbilic displacement chemistry described, polysulfones and other polyarylethers have been prepared by cuprous chloride-catalyzed polycondensation of aromatic dihydroxy compounds with aromatic dibromo compounds. The advantage of this route is that it does not require that the aromatic dibromo compound be activated by an electron-withdrawing group such as the sulfone group. Details of this polymerization method, known as the Ullmaim synthesis, have been described (8). 

The tri- or tetraamine complex of copper(I), prepared by reduction of the copper(II) tetraamine complex with copper metal, is quite stable ia the absence of air. If the solution is acidified with a noncomplexiag acid, the formation of copper metal, and copper(II) ion, is immediate. If hydrochloric acid is used for the neutralization of the ammonia, the iasoluble cuprous chloride [7758-89-6], CuCl, is precipitated initially, followed by formation of the soluble ions [CuClj, [CuCl, and [CuCl as acid is iacreased ia the system. 

Nitrophenylarsonic acid has been prepared by heating p-nitrobenzenediazonium chloride with arsenious acid in hydrochloric acid, by the action of -nitrobenzenediazonium chloride on sodium arsenite, by the action of sodium arsenite on sodium -nitrobenzeneisodiazo oxide, by the diazotization of -nitro-aniline in acetic acid in the presence of arsenic chloride and cuprous chloride, and by the reaction of -nitrobenzenediazonium borofluoride with sodium arsenite in the presence of cuprous chloride. ... 

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. 

Reaction.—a too c.c. flask to a short upright condenser (see Fig. 86) and to the upper end of the condensei attach a vertical delivery tube, dipping into an ammoniacal cuprous chloride solution. Pour 2—3 c.c. of ethylene bromide into the flask with 4 times its volume of strong methyl alcoholic potash, which is prepared by boiling methyl alcohol with excess of caustic potash on the water-bath with upright condenser. On gently heating, a rapid evolution of acetylene occurs and the characteristic brown copper compound (C2H,Cu,HjO) is precipitated from the cuprous chloride solution. 

Some of the cuprous chloride compounds of the diazonium salts have been isolated and analysed, and coirespond to the formula CoH.-.NjCl.CuoCIo (Hantzsch). The formation of a crystalline copper compound is rendeied very evident in the present preparation.. A modification of Sandmeyer s reaction IS the introduction of precipitated metallic copper in place of the cuprous salt (Gattermann). 

Aminocyclopropanes were prepared from enamines by the addition of Simmons-Smith reagent (688) or best through the cuprous-chloride-promoted decomposition of diazomethane (689). The reaction of an enamine with chloroform and base and opening of the resultant aminocyclopropane to an ynamine was reported (690). 

K has the value of about 1 x 10 at 298 K, and in solutions of copper ions in equilibrium with metallic copper, cupric ions therefore greatly predominate (except in very dilute solutions) over cuprous ions. Cupric ions are therefore normally stable and become unstable only when the cuprous ion concentration is very low. A very low concentration of cuprous ions may be produced, in the presence of a suitable anion, by the formation of either an insoluble cuprous salt or a very stable complex cuprous ion. Cuprous salts can therefore exist in contact with water only if they are very sparingly soluble (e.g. cuprous chloride) or are combined in a complex, e.g. [Cu(CN)2) , Cu(NH3)2l. Cuprous sulphate can be prepared in non-aqueous conditions, but because it is not sparingly soluble in water it is immediately decomposed by water to copper and cupric sulphate. 

The Ullman reaction has long been known as a method for the synthesis of aromatic ethers by the reaction of a phenol with an aromatic halide in the presence of a copper compound as a catalyst. It is a variation on the nucleophilic substitution reaction since a phenolic salt reacts with the halide. Nonactivated aromatic halides can be used in the synthesis of poly(arylene edier)s, dius providing a way of obtaining structures not available by the conventional nucleophilic route. The ease of halogen displacement was found to be the reverse of that observed for activated nucleophilic substitution reaction, that is, I > Br > Cl F. The polymerizations are conducted in benzophenone with a cuprous chloride-pyridine complex as a catalyst. Bromine compounds are the favored reactants.53,124 127 Poly(arylene ether)s have been prepared by Ullman coupling of bisphenols and... 

Treatment of diazonium salts with cuprous chloride or bromide leads to aryl chlorides or bromides, respectively. In either case the reaction is called the Sandmeyer reaction The reaction can also be carried out with copper and HBr or HCl, in which case it is called the Gatterman reaction (not to be confused with 11-16). The Sandmeyer reaction is not useful for the preparation of fluorides or iodides, but for bromides and chlorides it is of wide scope and is probably the best way of introducing bromine or chlorine into an aromatic ring. The yields are usually high. 

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