RedOx characteristics

The requirements of a developer moiety for incorporation into a dye developer are well fulfilled by hydroquinones. Under neutral or acidic conditions hydroquinones are very weak reducing agents and the weakly acidic phenoHc groups confer tittle solubility. In alkali, however, hydroquinones are readily soluble, powerful developing agents. Dye developers containing hydroquinone moieties have solubility and redox characteristics in alkali related to those of the parent compounds. 

At greater depths, the redox characteristics are mainly determined by another mineral system fayalite (Fe2Si04), magnetite and quartz (Si02) (theFMQ system). The buffer properties of the two systems can be expressed in terms of the following equations ... 

Hagedoorn, P.-L., Hagen, W.R., Stewart, L.J., Docrat, A., Bailey, S., and Garner, C.D. 2003. Redox characteristics of the tungsten DMSO reductase of Rhodobacter capsulatus. FEBS Letters 555 606-610. 

In this review, the chemical properties of these electrophilic metabolites (i-XIIl) are discussed in terms of their metabolic formation and reactivity with nucleophiles, solvolysis and redox characteristics, reaction mechanisms, and their role as ultimate carcinogenic metabolites. 

Retain redox characteristics - no major changes to ligand backbone - mainly use exocyclic nitrogens. 

The redox characteristics, using linear sweep and cyclic voltammetry, of a series of (Z)-6-arylidene-2-phenyl-2,3-dihydrothiazolo[2,3-r][l,2,4]triazol-5(6//)-ones 155 (Figure 24) have been investigated in different dry solvents (acetonitrile, 1,2-dichloroethane, tetrahydrofuran (THF), dimethyl sulfoxide (DMSO)) at platinum and gold electrodes. It was concluded that these compounds lose one electron forming the radical cation, which loses a proton to form the radical. The radical dimerizes to yield the bis-compound which is still electroactive and undergoes further oxidation in one irreversible two-electron process to form the diradical dication on the newly formed C-C bond <2001MI3>. 

Deactivation of the Mediator Deactivation of the mediator is a commonly encountered event in the practice of homogeneous catalysis. Among the various ways of deactivating the mediator, the version sketched in Scheme 2.10 is particularly important in view of its application to the determination of the redox characteristics of transient free radicals (see Section 2.7.2).14 The current-potential responses are governed by three dimensionless parameters, 2ei = /F)(ke Cjl/v), which measures the effect of the rate-determining... 

In addition to the nature of the accompanying reactions the prediction that electron transfer chemistry triggers a radical chemistry or an acid-base chemistry depends on the redox characteristic of transient intermediates, such as unstable radicals. The methods that may be used to achieve this difficult task are described and illustrated by experimental examples. 

J.-M. Zen, A. S. Kumar and J.-C. Chen, Electrochemical Behavior of Lead-Ruthenium Oxide Pyrochlore Catalyst Redox Characteristics in Comparison with that of Ruthenium Dioxide, J. Mol. Catal. A Chem. 165 (2001) 177-188. 

Studies on the potential of the electrochemical approach to pyrazolotriazoles 117 showed that under the conditions of bicycle synthesis from 3-amino-4-hydrazonopyrazoles the N-l-unsubstituted triazole ring of 117 was further oxidized in a one-electron peak, followed by proton removal to yield the bis-(l,l )-2-phenylpyrazolo[3,4-i/][l,2,3]triazoles 118. This observation is significant, since in spite of pronounced pharmaceutical applications of pyrazoles, the redox characteristics of substituted pyrazoles have received limited attention (Scheme 13) <2001MI1022>. 

Physicochemical Properties of Biodiesel. - The redox characteristics of biodiesel make it a reducing agent for materials, such as brass, bronze, cooper, lead, tin and zinc. For this reason, contact of biodiesel with these materials must be avoided.Materials such as aluminum, steel, fluorinated polymers and Teflon do not react with biodiesel and can be used to handle it. In addition, biodiesel shows mild solvent properties hence, biodiesel contact with painted or varnished surfaces as well as rubber devices, such as hoses, seals and gaskets, may cause problems. 

In certain solids such as titanium dioxide or cadmium sulfide, the energy of the band gap corresponds to that of light (visible, ultraviolet, or infrared), with the result that the solid, when illuminated, may become electrically conducting or acquire potent chemical redox characteristics because of the promotion of electrons to the conduction band (which is normally unoccupied). These properties have obvious practical significance and are considered at length in Chapter 19. 

Nishihata et al. (2002) reported the re-dispersion of Pd in a Perovskite-type oxide. They investigated the oxidation state and the local structure of Pd by using X-ray absorption analysis. Pd occupies the -site in La2PdCo06 in the oxidized sample. For the reduced catalyst, the XAD and XANES measurements suggested the segregation of metallic Pd from the perovskite crystal. They imply that Pd also moves back and forth between the -site in the perovskite structure and sites within the lattice of Pd metal clusters dispersed on perovskite surface when the catalyst is exposed to fluctuations in the redox characteristics of the emission exhaust. 

Azo derivatives of indolizines are readily prepared since the arenediazonium ion is a good electrophile. Compounds of this type are sometimes used as dyes (73AC(R)95>. Another method of preparing azobisindolizines is by reaction of indolizines with tosyl or picryl azides thus compound (33) has been obtained from 2-methylindolizine by this route. Redox characteristics of such compounds have been studied (71LA(752)182, 71LA(752)196). 

Another method of preparing azobisindolizines is by reaction with tosyl or picryl azide.191-193 2-Methylindolizine is converted into the 3,3 -bisazo compound after 2 minutes. The product yields the radical ion 130 (detected by EPR) when treated with 1 mole of silver perchlorate.194,195 The redox characteristics of such compounds have been studied by Hiinig and co-workers.196,197 In view of the instability of aminoindolizines, they have not been used to prepare diazonium salts. 1-Nitrosoindolizines, however, yield diazonium nitrates in good yield when treated with dry nitric oxide.182,198 The products are stable both in... 

Dehydroascorbic Acid and Ascorbic Acid. The oxidized and reduced forms of vitamin C (dehydroascorbic acid and ascorbic acid, respectively) have redox characteristics that are similar to those for o-quinone/catechol systems.13 Al-... 

The redox characteristics of these azaviolenes and of analogs with polyene linkages between the heterocycles have been determined by Hiinig and co-workers.462,596 The rate constant for the comproportionation reaction yielding 180 (X = CH) was evaluated as (6.5 2.0) x 108 M l sec-1 by Bennion et al.597 using the temperature-jump technique. 

In a pulse radiolysis study of CS2 Roebke and co-workers identified several derivative species (258). SC(OH)S, its conjugate base, and the pKa (4.4) that relates them were determined from the reaction of CS2 with OH. SCSH and its pKa (1.6) were determined by the reactions of eaq and H with CS2. The redox characteristics of these species remain unexplored. A subsequent pulse radiolysis study has not contributed any additional thermochemical information (56a). 

Carbodiimides with a ferrocene group in the molecule are synthesized because the reversible redox characteristic of ferrocene is useful as an electron-transfer indicator. Such molecules are used as biosensors (see 13.3.2). 

Organovanadinm compounds exhibit unique reactivity on the basis of the redox characteristics of the vanadium. For example, treatment of VCI3 in THF with a stoichiometric amount of n- or 5-alkyhnagnesium halides affords alkanes, alkenes, and dimers. The organovanadinm compounds generated... 

Gulino, A., Casarin, M., Conticellio, V.P. etal. (1988) Efficient synthesis, redox characteristics, and electronic structure of a tetravalent tris(cyclopentadienyl)cerium alkoxide complex. Organometallics, 1, 2360. 

Ground Water Geochemistry. Ground water from the lower aquifer in the lower Perch Lake Basin at the Chalk River Nuclear Laboratories, Figure 2, was used for field elution studies to provide water of different redox characteristics. Water from piezometer "0" in the transition area, and from KNEW in the discharge area was used as being representative of "neutral" and... 

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