Reduction reactions dissolving metal

In an amazing reaction, dissolving metal reduction of dichloro diester 859 generates dianion 860 which can be conventionally methylated (Scheme CIII) Irradiation of keto ester 861 introduces yet another framework bond. Dehydration of the newly... 

Other reactions at surfaces (catalytic hydrogenation and reduction by dissolving metals)... 

Free radical attack at ring carbon atoms. 6.3 Electrochemical reactions and reactions with free electrons. 6.4 Catalytic hydrogenation and reduction by dissolving metals Reactions with Cyclic Transition States. 7.1 Diels-Alder reactions and 1,3-dipolar additions. 7.2 Photochemical cycloadditions... 

In some situations, the oxygen or proton reduction reaction during metal corrosion will be mass transfer (diffusion) controlled, due to poor fluid agitation and/or a low concentration of H or dissolved oxygen in solution (this is especially trae for O2, which has a low solubility in water at... 

Usually, PET processes are preferred to other fragmentation processes in HMPA, but only dialkylthiocarbamates give satisfactory yields of R -H. Again a very good parallel can be drawn between the PET reaction of carbonic acid derivatives and their reduction by dissolving metals in primary amines or HMPA. ... 

Corrosion occurs at the anode, where metal dissolves. Often, this is separated by a physical distance from the cathode, where a reduction reaction takes place. An electrical potential difference exists between these sites, and current flows through the solution from the anode to the cathode. This is accompanied by the flow of electrons from the anode to the cathode through the metal (Fig. 8). 

This group was developed to prevent participation of the BnO bond during cationic reactions. It is formed from the bromide [C6H3F2CH2Br, Ba(0H)2 8H20, DMF, 25 h, 94% yield] and cleaved by dissolving metal reduction (Ca, NH3, 79% yield). ... 

The hydrogen evolution reaction (h.e.r.) and the oxygen reduction reaction (equations 1.11 and 1.12) are the two most important cathodic processes in the corrosion of metals, and this is due to the fact that hydrogen ions and water molecules are invariably present in aqueous solution, and since most aqueous solutions are in contact with the atmosphere, dissolved oxygen molecules will normally be present. 

The mechanism of the oxygen reduction reaction is by no means as fully understood as the h.e.r., and a major experimental difficulty is that in acid solutions (pH = 0) E02/H20 = 1 23, which means that oxygen will start to be reduced at potentials at which most metals anodically dissolve. For this reason accurate data on kinetics is available only for the platinum metals. In the case of an iridium electrode at which oxygen reduction is relatively rapid, a number of reaction sequences have been proposed, of which the most acceptable appear to be the following ... 

When dezincification occurs in service the brass dissolves anodically and this reaction is electrochemically balanced by the reduction of dissolved oxygen present in the water at the surface of the brass. Both the copper and zinc constituents of the brass dissolve, but the copper is not stable in solution at the potential of dezincifying brass and is rapidly reduced back to metallic copper. Once the attack becomes established, therefore, two cathodic sites exist —the first at the surface of the metal, at which dissolved oxygen is reduced, and a second situated close to the advancing front of the anodic attack where the copper ions produced during the anodic reaction are reduced to form the porous mass of copper which is characteristic of dezincification. The second cathodic reaction can only be sufficient to balance electrochemically the anodic dissolution of the copper of the brass, and without the support of the reduction of oxygen on the outer face (which balances dissolution of the zinc) the attack cannot continue. 

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