Organic compounds oxidation-reduction reactions

Chemoheterotrophs Organic compounds Oxidation-reduction reactions Organic compounds, e.g., glucose All animals, most microorganisms, nonphotosynthetic plant tissue such as roots, photosynthetic cells in the dark... 

In electroless deposition, the substrate, prepared in the same manner as in electroplating (qv), is immersed in a solution containing the desired film components (see Electroless plating). The solutions generally used contain soluble nickel salts, hypophosphite, and organic compounds, and plating occurs by a spontaneous reduction of the metal ions by the hypophosphite at the substrate surface, which is presumed to catalyze the oxidation—reduction reaction. 

An acidic bromate solution can oxidize various organic compounds and the reaction is catalyzed by species like cerous and manganous ions that can generate 1-equivalent oxidants with quite positive reduction potential. Belousov (1959) first observed oscillations in Celv]/[Cem] during Ce (III) catalysed oxidation of citric acid by bromate ion. Zhabotinskii made extensive studies of both temporal and spatial oscillations and also demonstrated that instead of Ce (III), weak 1- equivalent reductants like Mn(II) and Fe (II) can also be used. The reaction is called Belousov-Zhabotinskii reaction. This reaction, most studied and best understood, can be represented as... 

The transfer of phosphoryl groups is a central feature of metabolism. Equally important is another kind of transfer, electron transfer in oxidation-reduction reactions. These reactions involve the loss of electrons by one chemical species, which is thereby oxidized, and the gain of electrons by another, which is reduced. The flow of electrons in oxidation-reduction reactions is responsible, directly or indirectly, for all work done by living organisms. In nonphotosynthetic organisms, the sources of electrons are reduced compounds (foods) in photosynthetic organisms, the initial electron donor is a chemical species excited by the absorption of light. The path of electron flow in metabolism is complex. Electrons move from various metabolic intermediates to specialized electron carriers in enzyme-catalyzed reactions. 

The electron transfers in the oxidation-reduction reactions of organic compounds are not fundamentally different from those of inorganic species. In Chapter 7 we considered the oxidation of a reducing sugar (an aldehyde or ketone) by cupric ion (see Fig. 7-10a) ... 

Many organic compounds undergo reduction or oxidation at a DME. Consequently, polarographic techniques have been used extensively for determinations of organic compounds and for studying the mechanisms of their electrode reactions. In aqueous solution, the reduction of organic compounds is frequently a 2e process accompanied by protonation as in Equation 3.32 ... 

Reactions of Aldehydes and Ketones Aldehydes and ketones are central players in organic synthesis because of the wide variety of reactions they undergo. Likewise, their chemistry is important to biological systems. We will consider just two of the reactions involving these compounds oxidation/reduction and formation of acetals and ketals. 

Abiotic degradation transforms organic compounds by chemical reactions such as oxidation, reduction, hydrolysis, and photodegradation. Abiotic degradation processes do not usually achieve a complete breakdown of the chemical (mineralization). 

Transition metal nanoparticles supported on different substrates are used as catalysts for different reactions, such as hydrogenations and enantioselective-synthesis of organic compounds, oxidations and epoxidations, reduction, and decomposition [24,25], Among the supports that have been applied in the preparation of supported transition metal nanoparticles are active carbon, silica, titanium dioxide, and alumina. 

In true fermentation, the free energy drop between substrate (say glucose) and anaerobic end products is always modest by comparison with respiration, because fermentation is never based on electron transfer chains coupled to phosphorylation. Rather, true fermentations depend upon a variety of oxidation-reduction reactions involving organic compounds, C02, molecular hydrogen, or sulfur compounds. All these reactions are inefficient in terms of energy yield (moles ATP per mole substrate fermented), and, therefore, the mass of cells obtainable per mole of substrate is much smaller than with respiratory-dependent species. 

Interesting reactions occur when the charge transfer at the electrode is associated with homogeneous reactions in solution that can precede or follow the electron transfer reaction at the electrode. A selection of possible schemes is shown in Table 6.1. Note the presence of many organic compounds the reduction or oxidation of these compounds involves, in many cases, the addition or removal of hydrogen, which... 

Chemical/physical treatment processes are those in which a chemical reaction is used to alter or destroy a hazardous waste component. Chemical treatment techniques can be applied to both organic and inorganic wastes, and may be formulated to address specific target compounds in a mixed waste. Typical chemical treatment processes include oxidation-reduction reactions such as ozonation, alkaline chlorination, electrolytic oxidation and chemical dechlorination. Physical treatment processes separate waste component by either applying physical force or changing the physical form of the waste. Various physical processes include adsorption, distillation, or filtration. Physical treatment is applicable to a wide variety of waste streams but further treatment is usually required. 

Fig. 31 Preparation of optically active compounds employing HLADH and NADH, which are codeposited onto glass beads in a monophasic organic solvent, (a) Reduction reaction to produce chiral alcohols in the presence of ethanol for NADH regeneration, (b) Oxidation reaction to produce enantiomerically pure alcohol or a ketone out of the racemic mixture coupled with the reduction of isobutyraldehyde to regenerate NAD+...

It is well-known that the photocatalytic oxidation-reduction reaction of Ti02 irradiated with UV light can decompose organic compounds adsorbed on the surface. This photocatalytic oxidation-reduction reaction originated from the discovery of water-splitting on TiC>2 semiconductor electrodes irradiated with UV light, which is known as the Honda-Fujishima effect and was reported in Nature in 1972 [1], This effect attracted considerable attention after the first oil crisis. 

Experimental Observations. The nearest we have come to demonstrating the existence of N—F ions is in the electrochemical oxidation-reduction reactions of HNF2. The oxidation has been carried out in water and in various polar organic solvents under acid conditions (15). The first step of this reaction is formation of the NF2 radical. The NF2 radical undergoes combination processes on the surface of the electrode rather than diffusing into the body of the solution before being involved in further reactions. The combination process on the electrode surface has been used to prepare various NF2 compounds by simultaneously generating other radical species—e.g.,... 

Even though iron is the fourth most abundant element in the Earth s crust, only a small portion is available for biogeochemical cycling which consists largely of oxidation—reduction reactions of ferric to ferrous ions and vice versa. These reactions are important in organic and inorganic iron-containing compounds. 

Like other compounds, organic molecules undergo acid-base and oxidation-reduction reactions, as discussed in Chapters 2 and 4. Organic molecules also undergo substitution, elimination, and addition reactions. 

Combustion (Section 4.14B) An oxidation-reduction reaction, in which an alkane or other organic compound reacts with oxygen to form CO2 and H2O, releasing energy. 

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