Oxido-reduction, potentials reactions

The catalytic properties of copper during polyols conversion in aqueous phase may be drastically modified by some additives. Metals having a standard oxido-reduction potential higher than that of copper (Ir, Rh, Ru, Pd, Pt, Au) can be deposited on it by oxido-reduction reaction. The first atoms of second metal deposited exchange with hydroxylated... 

Other antioxidant species are synthesized by cells like uric acid, ubiquinol or thiols (cystein, homocystein, etc.). In addition, many compounds found in food display antioxidant properties retinol (vitamin A) and its precursor /(-carotene, and polyphenols (flavonoids, etc.). Figure 8.2 shows the apparent standard potential of some LMWA and ROS explaining the spontaneous oxido-reduction reactions at the origin of the antioxidant protection system. 

For each of the redox couples, the potential can be calculated using the Nernst equation. This equation correlates Gibb s free energy, known as AG, and the electromotive force provided by an oxido-reduction reaction (such a reaction acts as a galvanic cell). Given the following equation due to a chemical reaction ... 

The concept of oxido-reduction can be applied in inorganic chemistry as well as in organic chemistry. Otherwise, the majority of cellular synthesis is issued from redox reactions, which are only possible in media endowed with well-determined redox potential values. Furthermore, biological cells exhibit a noteworthy constancy in their redox potential courtesy of the redox buffers present in them. We can affirm that aU biochemical syntheses are governed by the concepts of proton and electron exchanges. 

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