Stepwise oxidation

Primary amino groups are oxidized stepwise by ozone to hydroxylamine, nitroso, and nitro (54,58) tertiary amines are oxidized to amine oxides. 

The situation in the pteridine series is somewhat more complex. Pteridine, 2-, 4-, and 7-hydroxypteridine, and some of the dihydroxy-pteridines are oxidized, stepwise and quantitatively, in the presence of xanthine oxidase to a single substance, 2,4,7-trihydroxypteridine. Notably, 6-hydroxypteridine, which readily forms a covalent hydrate, is not attacked. 

The electrochemistry of Ti2+ in 66.7 m/o AlCl3-NaCl has been investigated wherein the electroactive Ti2+ was prepared by the oxidation of Ti metal with liquid A1C13 [176, 185] and by the electrochemical dissolution of titanium metal [120, 177], The authors of both studies concluded that Ti2+ may be oxidized stepwise to Ti3+ and Ti4+ and that both processes are reversible at platinum and tungsten electrodes. However, anomalous voltammetric behavior at high Ti2+ concentrations (greater than 50 mmol L ) suggests the formation of polymeric Ti2+ species in the melt. The reduction of Ti2+ to the metal was not observed at potentials more positive than that required for aluminum deposition. 

Oxidation of the ligand by external agents. In Ir(dppe)2(82)Cl, for instance, the 82 ligand can be oxidized stepwise (on the metal) to form 82O and 82O2 (165,166). Complexes with bridging 82O ligands are also known (57) (a more reasonable classification is as 8, 0, ligands). 

About 10% of products derived from methyl oxidation. Stepwise addition of the peroxide. 

Phenothiazine derivatives and compounds with two or three thiazine rings conjugated to each other, such as 98 and 99 <2004JA1388>, 159, 160, and 161 <2003EJO3534>, have interesting electronic properties (see also Section 12.2) and their cyclic voltammetry has been studied. These compounds are oxidized stepwise until each phenothiazine moiety has lost an electron. 

In this study a cobalt(I) carbonyl complex serves as the catalyst. The complex [Co(CO)(CN)2(PEt3)2r is oxidized stepwise by two equivalents of Fe(CN)g" leading to formation of the Co(III) carbonyl species (19) which is readily attacked by water or hydroxide in the pH range 6-12.5. This attack produces the hydroxycarbonyl intermediate (20) which is identified as the main species in solution. 

The WOC is oxidized stepwise by a nearby tyrosine residue (Tyrz), which is itself oxidized by the chlorophyll cation radical P680+ (formed by light-induced charge separation). The electrons are eventually used by PSII for the reduction of plastoqui-none. After the WOC has lost four electrons, the accumulated oxidizing power drives the formation of molecular oxygen from two substrate water molecules, and the catalytic system is reset. The sequence of the four electron-transfer steps is summarized in the Kok cycle [32] of Figure 4.5.3, where the most probable spectroscopically derived oxidation states of the Mn ions [33] are shown for each of the five redox state intermediates S (n - 0-4). 

Figure 6 Pathway of conifer diterpene resin acid biosynthesis. Bifunctional di-TPS convert geranylgeranyl diphosphate to various diterpenes, which are oxidized stepwise by multisubstrate and multifunctional cytochromes P450 to the corresponding diterpene acid. The oxidation of (-)-abietadiene to (-)-abietic acid is shown as an example.

Polyhydroxy compounds can be considered to be oxidized stepwise, the first step giving an a-hydroxy carbonyl compound, which is oxidized to a carboxylic acid. If each carbon atom has a hydroxyl group, the final products are formic acid and formaldehyde ... 

The activity of the bicyclic chelates are higher than those of polymeric and monocyclic (115 Co) 60%, (117 Cm) 16%, (113 Co) 5% acetophenone after 6h at 409 K using 10-2 mol% of the catalyst. Ethylbenzene is oxidized stepwise. The high activity of 115) may correlate with the bifunctional contact center of such a process. The lower activity of the polymer may be due to smaller solubility. 

Phoq)horus trichloride (but not the pentachloride) also reacts smoothly with ethylene oxide stepwise thus ... 

To oxidize H2O to O2, PSII must catalyze the breaking of four O—bonds and the formation of an O—O bond. To achieve this, the Mn4 cluster is oxidized stepwise by PCET reactions involving Yz. The thermodynamics and kinetics of these steps may reveal the mechanism of H2O oxidation and O—O bond formation. 

Fung and Mamantov studied the electrochemical oxidation of Ti + [added as Ti(AlCl4)2] in AlCl3-NaCl (50-65 mole % AICI3) melts by linear sweep voltammetry, voltammetry, and chronopotentiometry at solid electrodes. TF" is oxidized stepwise to Ti " and TF " both processes are electro-chemically reversible at a platinum electrode. The lower oxidation states were found to be more stable at lower temperatures and in more acidic melts. The diffusion coefficient for Ti + was reported. 

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