Reductions copper sulfate

Pentafluorobenzene. Pentafluoroben2ene has been prepared by several routes multistage saturation—rearomati2ation process based on fluorination of ben2ene with cobalt trifluoride reductive dechlorination of chloropentafluoroben2ene with 10% pabadium-on-carbon in 82% yield (226,227) and oxidation of penta uorophenylbydra2ine in aqueous copper sulfate at 80°C in 77% yield (228). Its ioni2ation potential is 9.37 V. One measure of toxicity is LD q = 710 mg/kg (oral, mouse) (127). 

Of course, as time goes on the copper sulfate solution in the cell has to be replaced because it collects undesirable ions such as Fe+2, which have not been reduced because the voltage used is favorable to the reduction of Cu+2 only. 

Fig. 4. Current density for the reduction of copper and the double layer capacity of a copper electrode in an acidic copper sulfate solution vs. applied overpotential (adapted from ref. 50).

Zinc. Next to sodium, zinc is the most used reductant. It is available in powder, dust, and granular (mossy) forms. Zinc gets coated by a l er of zinc oxide which must be removed to activate it before it can reduce effectively. It can easily be activated by shaking 3 to 4 min. in a 1% to 2% hydrochloric acid solution. This means for every 98 ml of water volume, add 2 ml of coned hydrochloric acid. Then wash this solution with water, ethatiol, acetone, and ether. Ot activation can be accomplished by washing zinc in a solution of anhydrous zinc chloride (a very small amount) in ether, alcohol, or tetrahydrofuran. Another way is to stir 180 g of zinc in a solution of 1 g copper sulfate pentahydrate. Personally, I like the HCl acid method. 

The behavior of dienes and polyenes - both open chain and cyclic - toward reduction depends especially on the respective positions of the double bonds. Carbon-carbon double bonds separated by at least one carbon atom behave as independent units and can be partly or completely reduced by catalytic hydrogenation or by diimide. cis, trans, /rani-l,5,9-Cyclododecatriene treated with hydrazine and air in the presence of copper sulfate (diimide in situ) gave cij-cyclododecene in 51-76% yield [269]. It appears as if the trans double bonds were reduced preferentially. 

Refluxing of 9-fluorenone-l-carboxylic acid with zinc dust and copper sulfate in aqueous potassium hydroxide for 2.5 hours afforded 9-fluorenol-1-carboxylic acid in 94% yield [1004]. Reduction with sodium borohydride in aqueous methanol at 0-25° converted 5-ketopiperidine-2-carboxylic acid to /ra j-5-hydroxypiperidine-2-carboxylic acid in 54-61% yield [1005], On the other hand, reduction of V-benzyloxycarbonyl-5-ketopiperidine-2-carboxylic acid gave 89% yield of V-benzyloxycarbonyl-cis-5-hydroxypiperidine-2-car-boxylic acid under the same conditions [1005],... 

One more example demonstrates how to use standard reduction potentials to determine the standard potential of a cell. Let s say you wanted to construct a cell using silver and zinc. This cell resembles the Daniell cell of the previous example except that a silver electrode is substituted for the copper electrode and a silver nitrate solution is used in place of copper sulfate. From Table 14.2, it is determined that when silver and copper interact silver is reduced and copper oxidized. The two relevant reactions are... 

Aminopyridine has been prepared by heating nicotinamide in an alkaline potassium hypobromite solution at 70° by hydrolysis of 8-pyridylurethan with oleum by heating 3-amino-pyridine-2-carboxylic acid at 250° by reduction of 3-nitro-pyridine with zinc and hydrochloric acid and by heating 3-bromopyridine with ammonia and copper sulfate in a sealed tube. ... 

The dehalogenation of naphthyridines with hydrogen over palladium on calcium carbonate in a weakly basic alcoholic solution gives excellent yields (90-95%) of reduced compounds.38,45,134,137,138 This method for removal of halogens has been extensively used and generally surpasses the classic hydrazine-copper sulfate reduction method. 

Copper from the reduction of ores must be purified for use in making electrical wiring because impurities increase its electrical resistance. The method used is electrorefining (Figure 18.19), an electrolytic process in which copper is oxidized to Cu2+ at an impure copper anode, and Cu2+ from an aqueous copper sulfate solution is reduced to copper at a pure copper cathode. The process is described in Section 18.12. 

Reduction - Carbon dioxide evolved when coal is heated with a suitable catalyst (such as copper carbonate or copper sulfate) is a measure of carboxyl groups. 

Sulfide (S ) is a bivalent monoanion produced from the decomposition of metal sulfide salts. It occurs in groundwaters, hot springs, and wastewaters. It is also formed from the bacterial reduction of sulfate. Sulfide salts in solid wastes in contact with an acid can produce hydrogen sulfide. H2S, which is highly toxic. In an aqueous sample, sulfide may be present as dissolved H2S and HS , dissolved metallic sulfide, and acid-soluble metallic sulfide contained in suspended particles. All these soluble and insoluble sulfides and dissolved H2S and HS together are termed as total sulfide. The sulfide remaining after the removal of suspended solids is termed the dissolved sulfide. Copper and silver sulfides are insoluble even under acidic conditions. Therefore, these two sulfides are not determined in the following tests. 

The only way we can get the oxidation of the metal to continue is to couple it with some other process that restores electroneutrality to the two phases. A simple way to accomplish this would be to immerse the zinc in a solution of copper sulfate instead of pure water. As you will recall if you have seen this commonly-performed experiment carried out, the zinc metal quickly becomes covered with a black coating of finely-divided metallic copper. The reaction is a simple oxidation-reduction process, a transfer of two electrons from the zinc to the copper ... 

Oxidation and reduction reactions, also known as redox reactions, involve the transfer of electrons from one substance that is being oxidized (losing electrons) to another that is being reduced (gaining electrons). A very common example of a redox reaction, one that you may very well have done in the lab, is the reaction that occurs when you place clean, iron nails into a copper sulfate solution. In this reaction, shown below, iron is oxidized and copper is reduced ... 

Since the corrosion of iron in copper sulfate solution involves an oxidation and reduction reactions with exchange of electrons, the reaction must involve an electrochemical potential difference, related to the equilibrium constant. This relationship may be written as ... 

Although copper sulfate aftertreatments are designed mainly to enhance lightfastness, the reduction in water solubility that accompanies Cu-complex formation can have a beneficial effect on washfastness. This treatment also dulls the fabric shade and causes a shift in dye color, so that the resultant color must be the one the dyer is seeking. 

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