Poly electrochemical reaction

TaUe 4. Asymmrtric electrochemical reactions at poly-L-valine coated carbon electrodes... 

Hydrazones are transformed into gcw-difluoro compounds by treatment with a combination of 60% hydrogen fluoride/pyridine or 59% hydrogen fluoride/poly-4-vinylpyridine and N-bromosuccinimide yields are satisfactory.170 The electrochemical reaction of diarylketone hydrazones 1 in the presence of triethylamine trisfhydrogen fluoride) complex in dichloromethane solution (current density 1.3 mA cm"2) gives mainly the monofluorinated products 2 besides only very small amounts of difluorides 3.332... 

The adsorption of polymers, poly(vinyl pyridine) or poly(acrylonitrile) either to coordinate metal atoms or to adsorb biopolymers has been used to prepare chemically modified electrodes for immobihzation of enzymes either by physical or by chemical adsorption (carrier binding), cross-linking, and entrapping at lattice sites or in microcapsules [43]. A wide application of these types of electrodes has been made for electrochemical reactions of biological interest [44]. 

It has been demonstrated that hydrophobic, fluorinated, hyperbranched poly(acrylic acid) films can passivate and block electrochemical reactions on metal surfaces thus preventing surface corrosion [57]. Hyperbranched films can be synthesized on self-assembling monolayers on the metal surface via sequential grafting reactions to obtain thick and homogeneous films. 

Abbreviations HR hydrothermal reaction SP sonochemical process EC electrochemical reaction RT room temperature PEC-i-PPC poly(ethylene glycoljblock-poly (propylene glycol) PEC poly(ethylene glycol) PVP polyvinylpyrrolidone. 

The mechanism and kinetics of electrochemical reactions at electrodes covered with PT studied using the voltammetric behavior of PT films depend on the nature and concentration of mobile charge carriers within the polymer and therefore on the potential range [193,194]. The dependence of the processes during the electrochemical reduction and oxidation on the medium in contact with the PT film can be revealed by in situ Raman spectra [195]. The doped and neutral states of PMT and poly(3-thienylacetic acid) and the anion and cation dopants can be clearly identified by an improved specular reflectance IR spectroscopy. This method allows the use of the same electrode as that used in... 

Fig. 28 Scheme showing the stnictuie of poly-POM-dvb3,4-ZnOEP copolymer, obtained by electrochemical reaction of POM-dvb3,4 with ZnOEP... 

The Potential difference (m —< s) is determined [15] at = by the simultaneous occurrence of two different electrode reactions. The anodic current of the one reaction is equal to the absolute value of the cathodic current of the second reaction. An electrode that is the site of several electrochemical reactions with distinct values of U ev is called a poly-electrode. The steady-state condition 35 represents the relationship between 0 and /. The anodic partial currents are negligible. The coverage increases with rj. Only weak interaction is compatible with condition d. 

Electropolymerization is the electrochemically induced polymerization of monomers on a conductive surface. This is achieved by usually cyclically polarizing the electrode surface which is at the same time exposed to a solution of the monomer. The electrochemical reaction is rather irreversible the film formation can be followed by the current response. The best known example is probably poly (aniline), but also poly(pyrrole) or poly(thiophene) are popular (Fig. 18.5). 

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