Cuprous chloride, III

OXIDATIVE COUPLING Cuprous chloride. Ferric chloride-Dimethylformamide. Manganese dioxide. Palladium(II) chloride. Potassium ferricyanide. Silver carbonate-Celite. Thallium(III) trifluoroacetate. 

Cuprous Chloride System. Cuprous chloride (0.05-0.8 gram) was dissolved in 4N hydrochloric acid (10 ml.) and added steadily (15 sec.) to a vigorously stirred suspension of the aromatic reactant (1 ml.) in aqueous phosphate buffer (200 ml., pH 7) through which oxygen was bubbled (30 ml./min.). Bubbling and stirring were continued for 10 minutes after addition was complete. The concentrations of cuprous chloride used are given in Tables I-III. 

When we consider the elements in Period 4, in which the transition elements appear, the situation becomes more complex because these elements can form ions of more than one charge type. For example, iron can form ions of 2 + and 3 +, and copper can form ions of 1+ and 2+, so that the chlorides of these metals can have the compositions FeCl2, FeClj, CuCl, and CUCI2. The older, and sometimes commonly used names of these compounds are ferrous chloride, ferric chloride, cuprous chloride, and cupric chloride, respectively. The modern systematized method is simply iron(II) chloride, iron(III) chloride, copper(I) chloride, and copper(II) chloride, respectively. Given the names of these compounds, and knowing the charge of the anion, one can deduce the combining ratios, and hence their formulas. 

Reduction of a nitro compound to a hydroxylamine. Dissolve 0-5 g. of the compound in 10 ml. of 50 per cent, alcohol, add 0-5 g. of solid ammonium chloride and about 0 5 g. of zinc powder. Heat to boiling and allow the ensuing chemical reaction to proceed for 5 minutes. Filter from the excess of zinc powder and test the filtrate with ToUen s reagent see Section III,70,(i). An immediate black or grey precipitate or a silver mirror indicates the presence of a hydroxylamine formed by the reduction of the nitro compound. Alternatively, warm the filtrate with Fehling s solution a hydroxylamine will precipitate red cuprous oxide. (A blank test should be performed with the original compound.)... 

By a procedure analogous to that described in the preceding experiment, octalone-2 (12 g, 0.08 mole, Chapter 9, Section III) in ether is added to methylmagnesium iodide in the presence of cuprous bromide (0.2 g). After decomposition with ice-acetic acid, extraction with ether, and washing of the ether extract, the ethereal solution is shaken with an equal volume (50-60 ml) of saturated aqueous sodium bisulfite for 3 hours. The mixture is filtered and the filtrate is reserved. The crystals are washed with ether. The filtrate is separated and the aqueous phase is combined with the filtered solid. The combination is acidified (dilute hydrochloric acid) and heated under reflux for 30 minutes. The product thus liberated is extracted into ether, the ether is washed with bicarbonate, then with saturated aqueous sodium chloride solution, and then dried and evaporated. The residual oil is the desired product, bp 250-254°. 

Aryl Halides from Diazonium Ion Intermediates. Replacement of diazonium groups by halides is a valuable alternative to direct halogenation for the preparation of aryl halides. Aryl bromides and chlorides are usually prepared by a reaction using the appropriate Cu(I) salt, which is known as the Sandmeyer reaction. Under the classic conditions, the diazonium salt is added to a hot acidic solution of the cuprous halide.99 The Sandmeyer reaction occurs by an oxidative addition reaction of the diazonium ion with Cu(I) and halide transfer from a Cu(III) intermediate. 

One general method for acyl silane synthesis particularly successful for a-cyclopropyl examples (and even an a-cyclobutyl example) involves treatment of acid chlorides with lithium tetrakis(trimethylsilyl) aluminum or lithium methyl tris(trimethylsilyl) aluminium and cuprous cyanide (vide supra, Section III.A.3)77. For example, cyclopropyl acyl silane (23) was obtained in 89% yield by this process. Improved procedures use lithium t-butyldimethylsilyl cuprate78 and a dimethylphenylsilyl zinc cuprate species79,80 as reagents. 

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