Single electron transfer reaction

Cumulative Subject Index Single electron transfer reactions... 

There are in principle two types of charge-transfer processes at ITIES, a single ion and a single electron transfer reaction. The first one can be described as the transfer of an ion Xf< with charge number z. ... 

AG° for the single electron-transfer reaction can be obtained from the redox potentials of the systems involved in the process and is given by ... 

In single-electron-transfer reactions from carbanions where charge transfer is essentially complete, is near-unity, while for Sat2 reactions / nu ranges from 0.2 to 0.5. In SjvAr processes, where the size of /Jnu is determined by the bonding between the... 

Although the above reactions are written in terms of the global species, no specific mention has been made about how the reaction proceeds. For example, each reaction can be broken down into single electron-transfer reactions, and the gas probably dissolves into the membrane that is covering the electrocatalyst sites (e.g., platinum on carbon). Some more comments about this can be found in section 4.4. Adding eqs 1 and 2 yields the overall reaction... 

The boron substructure was eliminated from the imidazo[4,5-i/][l,3,2]diazaborolidine framework 56 following ultrasonic reduction with metallic lithium in THE and anions of the imidazoles 90 formed. The observed reactivity mled out the possibility of isolating the intermediates from these single-electron-transfer reactions <2004CC1860>. 

The most reactive Michael acceptors, such as alkylidene malonates, gem-dicyanoalkenes and nitroalkenes, react with a-halozinc esters in a conjugate fashion. Beautiful examples were offered by two stereocontrolled conjugate additions to piperidinone 102 and pyrro-lidinone 104 leading to optically active bicyclic lactams 103147 (equation 60) and 105 (equation 61)148. With these electron-poor alkenes a Grignard two-step protocol is to be adopted in order to avoid the single electron transfer reactions from the metal to the Michael acceptor, which should afford olefin dimers. The best solvent is found to be a... 

Equation (7.144) is the most general form of the Butler-Volmer equation it is valid for a multistep overall electrodic reaction in which there may be electron transfers in steps other than the rds and in which the rds may have to occur V times per occurrence of the overall reaction. This generalized equation is seen to be of the same form as the simple Butler-Volmer equation for a one-step, single-electron transfer reaction ... 

Fluorinated radicals play a significant role in synthetic organo-fluorine chemistry, for example, in electrophilic radical addition to alkenes, single-electron transfer reactions (SET), telomerization of fluoroalkenes with perfluoroalkyl iodides, polymerization to fluoropolymers and copolymers, and thermal, photochemical and radiation destruction of fluorocarbons. Furthermore, such free radicals are of interest for studying structures, reaction kinetics and ESR spectroscopic parameters.38... 

A further significant mechanistic pathway for aromatic nitration can involve a single electron-transfer reaction to an initial radical ion intermediate ... 

At the equilibrium potential, both anodic and cathodic processes of a single electron transfer reaction take place at the same exchange rate (exchange current density) and no net current is observed through the external circuit. The exchange rate reflects the kinetics of the overall reaction and, in many cases, the electrocatalytic properties of the electrode surface. The open circuit potential, in this case, is the equilibrium potential and is therefore a thermodynamic quantity independent of kinetic factors and is related to the activities in solution through the Nemst law. 

SINGLE ELECTRON-TRANSFER REACTIONS, ELECTRON-TRANSFER SERIES AND LINKED 493 REDOX CENTRES... 

A single electron-transfer reaction of a coordination compound may result in the generation of an unstable or reactive species which decays to a more stable product, i.e. the primary species generated by electron transfer undergoes further chemistry. 

Treatment of aiylimine (22) with alkyllithiums results in a range of single-electron-transfer reactions, substitution on die phenyl ring, and nucleophilic addition to the imine bond.43... 

It is evident that a single electron transfer photoproduct is transformed into a doubly reduced charge relay in two phase systems. The primary processes in the natural photosynthetic apparatus involve single electron transfer reactions that proceed in hydrophobic-hydrophilic cellular microenvironment. Thus, we suggest similar induced disproportionation mechanisms as possible routes for the formation of multi-electron charge relays, effective in the fixation of CO2 or N2. 

The fixation reaction involves eight single electron-transfer reactions, consistent with the apparent limiting stoichiometry [Eq. (85)]. However, this does not exclude the possibility that the electrons are transferred to dinitrogen within the enzymes in groups of two or more. 

With very few exceptions, organic compounds do not form stable products following single-electron transfer reactions thus, as a rule, the primary products are unstable organic radical anions or radicals. The final products of the e q reactions will therefore be the result of subsequent reactions of these primary products. 

The reaction of 3,3-dichloro-2-methoxyazetidine 35 with lithium aluminium hydride in ether afforded 3-chloro-azetidine 36 (Equation 8). The substitution of the methoxy group by hydride via an azetinium intermediate and subsequent conversion of the geminal dichloro derivative to the monochloroazetidine via a single electron transfer reaction yielded this compound <1998JOC6>. Treatment of 1-benzyl-3-hydroxyazetidine 37 with triphenylphos-phine in carbon tetrachloride yielded l-benzyl-3-chloroazetidine 38 (Equation 9) <2004JOC2703>. 

From a kinetic point of view, the single electron transfer reaction is described by the second-order rate law [i],... 

The measurement of ket for single electron-transfer reactions is of particular fundamental interest since it provides direct information on the energetics of the elementary electron-transfer step (Sect. 3.1). As for solution reactants, standard rate constants, k t, can be defined as those measured at the standard potential, E, for the adsorbed redox couple. The free energy of activation, AG, at E°a is equal to the intrinsic barrier, AG t, since no correction for work terms is required [contrast eqn. (7) for solution reactants] [3]. Similarly, activation parameters for surface-attached reactants are related directly to the enthalpic and entropic barriers for the elementary electron-transfer step [3],... 

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