Indirect electrochemistry

The most abundant rate data concern the reductive cleavage of aryl chlorides and bromides, obtained by either direct or indirect electrochemistry (Section 2.2) or by pulse radiolysis. They show (Figures 3.19 and 3.20), a rough linear... 

The experimental kinetic data obtained with the butyl halides in DMF are shown in Fig. 13 in the form of a plot of the activation free energy, AG, against the standard potential of the aromatic anion radicals, Ep/Q. The electrochemical data are displayed in the same diagrams in the form of values of the free energies of activation at the cyclic voltammetry peak potential, E, for a 0.1 V s scan rate. Additional data have been recently obtained by pulse radiolysis for n-butyl iodide in the same solvent (Grim-shaw et al., 1988) that complete nicely the data obtained by indirect electrochemistry. In the latter case, indeed, the upper limit of obtainable rate constants was 10 m s", beyond which the overlap between the mediator wave and the direct reduction wave of n-BuI is too strong for a meaningful measurement to be carried out. This is about the lower limit of measurable... 

Integration of Indirect Electrochemistry and Separation by Supercritical Fluids... 

Other important alternate electrochemical methods under study for pCO rely on measuring current associated with the direct reduction of CO. The electrochemistry of COj in both aqueous and non-aqueous media has been documented for some time 27-29) interferences from more easily reduced species such as O2 as well as many commonly used inhalation anesthetics have made the direct amperometric approach difficult to implement. One recently described attempt to circumvent some of these interference problems employs a two cathode configuration in which one electrode is used to scrub the sample of O by exhaustive reduction prior to COj amperometry at the second electrode. The response time and sensitivity of the approach may prove to be adequate for blood ps applications, but the issue of interfering anesthetics must be addressed more thorou ly in order to make the technique a truly viable alternative to the presently used indirect potentiometric electrode. 

The MOR is a surface-sensitive reaction [Clavilier et al., 1981a]. The influence of surface crystallography on the partitioning between the direct and the indirect pathways was investigated by Housmans and co-workers using electrochemistry, mass spectrometry, and modeling [Housmans et al., 2006 Housmans and Koper, 2003]. 

The term direct electrochemistry of proteins means the possibility to detect the direct exchange of electrons between the active site(s) of a protein and a (metallic or inert material) electrode without the help of redox mediators, which might favour an indirect interaction between the electrode and the protein (see the discussion on Electrocatalysis in Chapter 2, Section 1.4.4). This aspect of electrochemistry is not yet as widely explored as it deserves, but the relevant results are now analysed in a rather comprehensive fashion.1 ... 

Different strategies of electrochemical sensing have been used for DNA electrochemical detection (1) direct DNA electrochemistry, (2) indirect DNA electrochemistry, (3) DNA-specific redox indicator detection, (4) DNA-mediated charge transport, and (5) nanoparticle-based electrochemistry amplification. 

In addition to the direct conversions shown above, electrochemistry is often used in an indirect fashion, e.g. for the in situ generation of (harmful) reagents such as bromine or iodine by oxidation of bromide and iodide ion, respectively, or of Ce4+ by oxidation of Ce3+ [28]. Also, the regeneration of oxidation products such as dichromate, Equations 6.1a and 6.3, has been put to use [28] ... 

The preparative aspects of organic electrochemistry are presented in the fundamental review by Lund and Baizer.4 An earlier review5 includes the technical aspects of electroorganic synthesis. Indirect methods in preparative organic electrochemistry also have been summarized 6 these methods are used in the production of fine chemicals and pharmaceuticals. Electroenzymatic synthesis also has been reviewed.7... 

In the third part of the book areas in which there are important applications of electrochemistry are described. Chapters 13 and 14 look at potentiometric and amperometric/voltammetric sensors respectively, focusing particularly on recent developments such as new electrode materials and miniaturization. Electrochemistry in industry, which produces many materials used directly or indirectly in everyday life, as well as batteries, is described in Chapter 15. The electrochemical phenomenon... 

Free radicals are well known to add on activated olefins [241], Thus, in electrochemistry, the indirect formation of a free radical in solution may happen concomitantly by reaction on the mediator inside a solvent cage. Two examples follow. First is the indirect reduction of RX types compounds by the radical anion of a spin marker [242] such as a nitroso derivative. In this case the reaction is monoelectronic, since the nitroxyde radical is totally electroinactive (note that a nucleophilic action of the radical anion cannot be totally excluded (Scheme 46). 

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