Of superoxide ion

Contents Introduction and Principles. - The Reaction of Dichlorocarbene With Olefins. - Reactions of Dichlorocarbene With Non-Olefinic Substrates. -Dibromocarbene and Other Carbenes. - Synthesis of Ethers. - Synthesis of Esters. - Reactions of Cyanide Ion. - Reactions of Superoxide Ions. - Reactions of Other Nucleophiles. - Alkylation Reactions. - Oxidation Reactions. - Reduction Techniques. - Preparation and Reactions of Sulfur Containing Substrates. -Ylids. - Altered Reactivity. - Addendum Recent Developments in Phase Transfer Catalysis. 

It should be noted that dissociation of surface complexes of oxygen in polar solvents on semireduced ZnO films is presumably justified from the thermodynamic point of view as oxygen adsorption heat on ZnO and electron work function are [58] 1 and approximately 5 eV respectively while the energies of affinity of oxygen molecules to electron, to solvation of superoxide ion and surface unit charge zinc dope ions are 0.87, 3.5, and higher than 3 eV, respectively [43]. 

F. Matsumoto, K. Tokuda, and T. Ohsaka, Electrogeneration of superoxide ion at mercury electrodes with a hydrophobic adsorption film in aqueous media. Electroanalysis. 8, 648-653 (1996). 

T. Ohsaka, F. Matsumoto, and K. Tokuda, An electrochemical approach to dismutation of superoxide ion using a biological model system with a hydrophobic/hydrophilic interface, in Frontiers of Reactive Oxygen Species in Biological and Medicine (K. Asaka and T. Yoshikawa, eds), pp. 91—93. Elsevier Science B.V. Oxford (1994). 

He is the author of Superoxide Ion Chemistry and Biological Implications (Volumes 1 and 2, CRC Press, 1989 1990) and the co-author of several jointed books on free radicals. He has published about 100 works. 

Table 2 The reactivity of complexes [M(triphos)(catecholate)J+ (M=Co, Rh, Ir) with molecular oxygen as a function of the catecholate/ semiquinone oxidation potential. I=no reactivity 11= the oxygenated complex regenerates the initial complex in the quinone form by release of superoxide ion III = the oxygenated complex regenerates the initial complex in the quinone form by release of molecular oxygen...

The reaction of superoxide ion with carbon tetrachloride is important for olefin epoxidations. This reaction includes the formation of the trichloromethyl peroxide radical Oj" + CCI4 —> Cl + CI3COO. The trichloromethyl peroxide radicals formed oxidize electron-rich olefins. The latter gives the corresponding epoxides. This peroxide radical is a stronger oxidizing agent than the superoxide ion itself (Yamamoto et al. 1986). 

This complex was prepared from KOa with aluminiumtrimethyl and dibenzo[18]-crown-6 in benzene. In boiling toluene it is stable for more than 24 h S3). It depicts a new coordination type of the superoxide ion. The 1.47 A bond is the longest yet reported for an Of superoxide ion. 

Anderson, R. F. Flavin-oxygen complex formed on the reaction of superoxide ions with flavo-semiquinone radicals. In Flavins and flavoproteins (Massey, V., Williams, C. H. eds.) pp. 278-283, New York, Elsevier North Holland 1982... 

The major in situ process that results in the formation of H202 is undoubtedly photochemical (e.g., 12, 15, 49, 50). Photochemical formation of H202 in fresh and salt waters probably results from the disproportionation of the superoxide ion radical, 02 (8, 9, 15, 51, 52). The kinetics of superoxide disproportionation are well established (53), and its steady-state concentration can be calculated. Because of the known effects of superoxide ion in cells (47), its presence in surface waters may be important in biologically mediated processes. However, other sources, such as biological formation (e.g., 45, 54), redox chemistry (21, 24, 29, 31, 32), wet (e.g., 55) and dry (50, 56, 57) deposition, and surfaces (e.g., 58) may also be important. 

One should not gain the impression from the foregoing that redox excitation is restricted to reactions between aromatic radical ions in aprotic solvents. Studies of such reactions have indeed dominated research because the optical and electrochemical properties of many aromatics are well known, but there are numerous cases of redox excitation outside this chemical domain. For example, singlet oxygen seems to arise from oxidations of superoxide ion in acetonitrile [94]. Similarly, luminescent tris(2,2 -bipyridyl)ruthenium(II) can arise in at least three ways (1) from a kind of ion annihilation in CH3CN [95] or DMF,... 

The reactions of 1-hydroxy- and 1-aminonapthoquinones with 02 open one significant feature of superoxide ion formation. This ion forms a van der Waals complex with another product, a semiquinone. Namely, hydrogen bonds are formed between 02 and the OH and NH2 groups of the corresponding semiquinone. As a result, the reaction equilibrium is shifted to the right (Liwo et al. 1997). 

Kitajima, N., Fukuzumi, S., and Ono, Y., Formation of superoxide ion during the decomposition of hydrogen peroxide on supported metal oxides, /. Phys. Chem., 82, 1505, 1978. 

Rate constants for superoxide ion (02 ) and its conjugate acid HOz as oxidant, reductant, and nucleophile have been measured in several solvents (Hendry and Schuetzle, 1976 Sawyer et al., 1978 Bielski et al., 1985), but few SARs have been developed. Moreover, the reactivity of superoxide ion generally is too low for the oxidant to be important in surface waters. Solvated electrons (e Aq) also form on insolation of DOM (Fischer et. al., 1985 Zepp et. al., 1988), but its concentration is very low, and target compounds are too few to make e (Aq) an important redox agent in surface waters (Buxton et al., 1988). One possible exception is nitroaromatics such as 2,4,6-trinitrotoluene (TNT), which exhibit strong acceleration of photolysis rates in the presence of DOM (Mabey et al., 1983). 

The superoxide dismutases (SODs) catalyze the disproportionation of superoxide ion (Eq. 1) [5] into peroxide and molecular oxygen ... 

This is a convenient system for the synthesis of HOOH and may be similar to the mechanistic path for HOOH synthesis in biology via dihydroflavin proteins. Aniline (PhNH2) and phenylhydrazine (PhNHNH2) in combination with HO-and 02 are effective reagents for the in situ synthesis of superoxide ion 16... 

Generation of CIII from GS occurs when the enzyme acts as an oxidase in the presence of superoxide ion. This reaction has been observed in horseradish peroxidase isoenzymes C and A2 [28, 53, 63], lignin peroxidase [46], myeloperoxidase [69], and bovine liver catalase [64], The rate constant for the reaction of GS with superoxide increases with a decrease of pH suggesting that the reacting species is HO2 instead of C - [64], The physiological relevance of the hydroxyperoxyl radical has been recently reassessed [70],... 

HP here is great interest in the biochemistry and relevant coordination chemistry of copper-containing proteins (1,2, 3, 4, 5). They are widely distributed in both plants and animals and are often involved in oxygen metabolism, transport, and use. One of the most actively studied copper proteins is bovine erythrocyte superoxide dismutase (SOD) (6,7,8). This enzyme catalyzes the dismutation of superoxide ion, Reaction 1. 

The reaction products of superoxide ions are believed to be partly responsible for the removal and destruction of bacteria and damaged cells [1]. In view of its low reactivity it is unlikely that superoxide itself is responsible for killing the invading material, but the hydrogen peroxide formed from dismutation by superoxide dismutase can kill some strains of bacteria. Once the phagocytic... 

In the effort to find confirmation on Foote s original mechanistic proposal [84] and discriminate among these two different pathways, a great deal of experimental proofs were achieved. First of all, the DCA and/or 9-cyanoanthracene (CNA)-sensitized reactions on aryl-olefins were studied under inert atmosphere by flash spectroscopic techniques obtaining clear evident for the formation of both olefin radical cations and cyanoaromatic radical anions [95]. In the presence of oxygen, the cyanoaromatic radical anions were rapidly removed, supporting the very rapid formation of superoxide ion and so its direct involvement in these photoinduced oxygenations. 

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