Organic compounds Oxidizability

Beilstein s test A method for detecting the presence of halogen in an organic compound. A piece of copper gauze is heated in an oxidiz-... 

Polarography is used extensively for the analysis of metal ions and inorganic anions, such as lOg and NOg. Organic compounds containing easily reducible or oxidizable functional groups also can be studied polarographically. Functional groups that have been used include carbonyls, carboxylic acids, and carbon-carbon double bonds. 

COD Chemical oxygen demand - the amount of oxygen in mg/1 required to oxidize both organic and oxidizable inorganic compounds. 

As has already been mentioned, during the iron(II)-hydrogen peroxide reaction a number of organic compounds which do not react, or react only slowly with hydrogen peroxide, are readily oxidizable. In the induced oxidation of organic compounds, hydrogen peroxide plays the role of the actor and iron(II) is the inductor. 

The type of enzyme sensor described above is highly selective and can be sensitive in operation. There are obvious applications for the determination of small amounts of oxidizable organic compounds. However, it is perhaps too early to give a realistic assessment of the overall importance of enzyme sensors to analytical chemistry. This is especially so because of parallel developments in other biochemical sensors which may be based upon a quite different physical principle. 

Chlorite ions and salts are strong oxidizers. Responsible care should be undertaken during disposal of chlorite ion solutions and salts. For example, solid sodium chlorite is unstable and can form explosive mixtures with oxidizable materials, such as organic compounds. Chlorite ion solutions should not be allowed to dry on textiles because this may result in a flammable combination (Kaczur and Cawlfield 1993 Vogt et al. 1986). No further information on the disposal of chlorite ions and chlorite salts were located. 

Still another compound of great interest is perchloryl fluoride (C103 F). It was described in Vol. II. Perchloryl fluoride is distinguished by its high stability it causes no corrosion of commonly used materials. It reacts vigorously with oxidizable organic compounds. 

As described in Section 4.1.2, nucleophilic organic compounds are oxidized at the electrode. Some oxidizable organic compounds are listed in Table 8.7 with the potentials of the first oxidation step in non-aqueous solvents. By using a solvent of weak basicity and a supporting electrolyte that is difficult to oxidize, we can expand the potential window on the positive side and can measure oxidations of dif-... 

Experiments in which the lysis of erythrocytes exposed to oxidizable organic compounds have also been performed 204-206.213,214) jjj some of these experiments O and H2O2 appear to be involved as shown by the inhibition of lysis by superoxide dismutase and catalase. However, the pathways leading to lysis in these experiments may be complex because of the effects of O and H2O2 on the rates of autoxidation of the organic compounds and because of the possibility that the oxidizable organic compounds or their products react with the red cells directly. 

Here AH2 is an oxidizable organic compound such as an alcohol or a pair of one-electron donor molecules. Catalases, which are found in almost all aerobic cells,194b may sometimes account for as much as 1% of the dry weight of bacteria. The enzyme catalyzes the breakdown of H202to water and oxygen by a mechanism similar to that employed by peroxidases. If Eq. 16-7 is rewritten with H202 for AH2 and 02 for A, we have the following equation ... 

Bare electrodes (particularly of gold and carbon) have been used for the determination of trace metals with oxidation potentials positive of that of mercury (e.g., Ag, Se, As, Au, and Te), and for adsorptive stripping measurements of oxidizable organic compounds. Gold film electrodes (on glassy carbon substrates) have been particularly useful for trace measurements of mercury. 

Liquid chromatography with electrochemical detection (LCEC) is in widespread use for the trace determination of easily oxidizable and reducible organic compounds. Detection limits at the 0.1-pmol level have been achieved for a number of oxidizable compounds. Due to problems with dissolved oxygen and electrode stability, the practical limit of detection for easily reducible substances is currently about 10-fold less favorable. As with all detectors, such statements of the minimum detectable quantity must be considered only with the proverbial grain of salt. Detector performance varies widely with the analyte and the chromatographic conditions. For example, the use of 100- m-diameter flow systems can bring attomole detection limits within reach, but today this is not a practical reality. 

Pure solid or liquid is highly explosive evaporation of a solution in liquid 02 results in explosion4 liquid explodes on contact with organic liquids and oxidizable materials2 safe handling techniques have been described,5"7 and interaction with organic compounds has been reviewed.8... 

Correspondingly, many toxic organic compounds (particularly halo-aromatics) have been shown to be oxidizable to innocuous compounds at Ti02 photoanodes with a counter-electrode of platinum (Bard, 1980 Fox, 1986). In 1980 Guruswamy suggested a design for a colloidal solar reactor for wastes that worked on photoelectro-chemical principles. 

The triplet sensitizer may react with the 02 triplet or an oxidizable reactant (Figure 6.10), eg with alkenes, dienes, and aromatic and other unsaturated organic compounds. For many sensitizers the reaction with oxygen is so efficient that the former process is favoured over the latter [125]. 

As noted above, in situ production of H2O2 within illuminated clouds and aquated aerosols is most likely a very important process governing the fate of oxidizable inorganic and organic compounds. Hydrogen peroxide is a potent thermal oxidant in its own right (i.e., = + 1.76 V H2O2 + 2 e +... 

Few reactions of electrically neutral organic compounds by photoelectro-chemical means have been reported, and reduction has been observed only when oxygen has been specifically removed [91]. Reduction of a cationic organic substrate by conduction band electrons can occur, as in the case of methyl-viologens, for example [91, 92]. Chlorinated organic acids which have no oxidizable hydrogen, such as trichloroacetic acid were found to degrade, albeit in small yields [90]. This was attributed to oxidation via the valence holes which is known as a photo-KoIbe process (Scheme 33). 

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