Oxidation reactions historical perspectives

The [Co(CN)5]3 complex is an effective catalyst for some reactions, particularly the isomerization of alkenes. Newer and more efficient catalysts have been developed for some of the processes, but the catalytic behavior of the pentacyanocobalt(II) ion is also significant from a historical perspective. In reactions such as that shown in Eq. (22.10), two Co2+ ions increase one unit in oxidation state, instead of the more common situation in which one metal ion increases by two units in oxidation state. The cobalt complex also reacts with CIT3I, Cl2, and H202, which are indicated as X-Y in the equation... 

Historical Perspective on the Use of Benzoquinone and Dioxygen in Palladium-Catalyzed Oxidation Reactions... 

In view of the historical perspective and future requirements, it is important to reduce the amount of reductants for the coupling reactions. In the future, molecular hydrogen or electricity should be used in lieu of zinc in stoichiometric amounts for the reductive coupling reactions. In addition, catalytic transformations should be developed that may include oxidation of the resulting reductive coupling products so as to adjust the oxidation state. 

A number of good reviews of the oxidation of phenols have appeared " the most recent covers the literature to mid-1980. These offer historical perspective and coverage of the biosynthetic aspects of the area, both inappropriate in the present article. This chapter focuses entirely on synthetic uses of the reaction and sets out (i) to survey the main types of reaction stemming from oxidation of phenols and phenol ethers and (ii) to offer selected examples of reactions showing satisfactory yield and regioselectivity. 

In contrast to aromatic moieties, absence of w-resonance for aliphatic compounds results in very low oxidation rates even though the reactions may be favored thermodynamically. StabiUzation of free-radical products from aliphatic compounds can be achieved alternatively via their adsorption to the surface of noble metal electrodes. Unfortunately, adsorption of organic molecules and free radicals also has the consequence of fouling of the electrode and loss of its activity [57]. The historical perspective of nonreactivity for ahphatic compounds at noble metal electrodes can be attributed to surface fouling as a result of high, but transient, catalytic activity. An alternative approach is to combine electrochemical detection with on-hne cleaning. Hence, in order to maintain uniform and reproducible electrode activity at noble metal electrodes for polar aliphatic compounds. 

Succinate dehydrogenase and fumarate reductase catalyse the oxidation of succinate to fumarate and the reverse reaction, respectively. A structural comparison of the functionally related enzymes was performed for the E. coli species. One of the four units of each enzyme is an iron-sulfur subunit which contains three distinct [Fe4S4] clusters. A historical perspective of the spectroscopy of succinate dehydrogenase, which is also a part of mitochondrial complex II, has been published in which the development of the iron-sulfur clusters is described. "... 

First of all, note that the term "oxidation" is based on a historical premise that is not relevant from a more modem perspective namely, the combining of another element with oxygen to form a simple binary compounds i.e., an "oxide" similarly, the removal of oxygen atoms from an oxide molecule leaving the "reduced" element was the concept intended for the term "reduction". Although this idea works fairly well for many of the more simple interactions of oxygen with both metal and non-metal elements, a better, more comprehensive, definition that includes similar reactions with other elements, such as fluorine and chlorine, evolved that was based on the transfer of electrons from one atom (or ion) to another. 

Prediction of salt electrochemical stability in the context of Li-ion batteries has mainly involved predicting the Eox of novel lithium salt anions, frequently without any focus on the subsequent decomposition reaction products and mechanisms. However, with recent results on oxidation promoted solvent-anion reactions [57] and the rapid development of solvent-free ionic liquid (IL) electrolytes, investigations of both anion and cation decomposition products are foreseen by us to become more frequent and important - particularly in connection with the passivation phenomena at the negative electrode. As for solvents, we will here follow the historical development of studies and methods, followed by some more recent works that together with our remarks outline our perspective on the future. 

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