Organic electron acceptors oxidants

Organisms with anaerobic mitochondria can be divided into two different types those which perform anaerobic respiration and use an alternative electron acceptor present in the environment, such as nitrate or nitrite, and those which perform fermentation reactions using an endogenously produced, organic electron acceptor, such as fumarate (Martin et al. 2001 Tielens et al. 2002). An example of the first type is the nitrate respiration that occurs in several ciliates (Finlay et al. 1983), and fungi (Kobayashi et al. 1996 Takaya et al. 2003), which use nitrate and/or nitrite as the terminal electron acceptor of their mitochondrial electron-transport chain, producing nitrous oxide as... 

Hydrogenation of n-AIkenes. - The activity of oxides with alkali metals in the hydrogenation of alkenes is similar to the activity of EDA complexes of alkali metals with organic electron acceptors described by Tamam. Hydrogenation of alkenes occurs at 423-473 K under normal pressure. In Table 5 are given the initial rates of hydrogenation reactions of alkenes in the presence of oxides doped with sodium and potassium vapours. 

Kang and coworkers76 have also used organic electron acceptors such as 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) and chloranil. A solvent effect was observed when polymerization was carried out using DDQ. Polymerization in acetonitrile gave the lowest conductivity, and in water it was slightly better. A similar solvent dependence was observed for chloranil oxidations. 

Redox potential of soils is affected by (i) the activities of electron donors (biodegradable organic matter and rednced inorganic snbstances), (ii) the activities of electron acceptors (oxidants snch as O2, NO3, Mn02, FeOOH, SO4, and HCO3), and (iii) the temperatnre. 

ET Kang, KG Neoh, TC Tan, YK Ong. Polymerization and oxidation of pyrrole by organic electron acceptors. J Polym Sci A Polym Chem 1987 25 2143-2153. 

In higher organisms, the oxidation of pyruvate takes place in subcellular, membranous organelles known as mitochondria. Because mitochondria are responsible for the synthesis of most of the ATP in nonphotosynthetic tissue, they are often referred to as the powerhouses of cells. Mitochondrial ATP synthesis is called oxidative phosphorylation since it is linked indirectly to oxidative reactions. In the complete oxidation of pyruvate, there are five oxidation-reduction reactions. Three of these reactions are oxidative decarboxylations. The electron acceptor (oxidizing agent) for four of the reactions is NAD+ the oxidizing agent for the fifth is flavin adenine dinucleotide, or FAD. 

Oxidizing Properties. Nitric acid is a powerful oxidizing agent (electron acceptor) that reacts violentiy with many organic materials (eg, turpentine, charcoal, and charred sawdust) (19,20). The concentrated acid may react explosively with ethanol (qv). Such oxidizing properties have had military appHcation nitric acid is used with certain organics, eg, furfuryl alcohol and aniline, as rocket propellant (see Explosives AND PROPELLANTS). 

Chemical and biological sensors (qv) are important appHcations of LB films. In field-effect devices, the tunneling current is a function of the dielectric constant of the organic film (85—90). For example, NO2, an electron acceptor, has been detected by a phthalocyanine (or a porphyrin) LB film. The mechanism of the reaction is a partial oxidation that introduces charge carriers into the film, thus changing its band gap and as a result, its dc-conductivity. Field-effect devices are very sensitive, but not selective. 

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