Bimolecular rate constants, hydrated electron

Table 1. A compilation of specific bimolecular rate constants (/tc) for the reaction of hydrated electrons with Li battery related materials (61,62]...

The absolute rate constants were determined for a variety of reactions of the solvated electron in ethanol and methanol. Three categories of reaction were investigated (a) ion-electron combination, (b) electron attachment, and (c) dissociative electron attachment. These bimolecular rate constants (3, 27, 28) are listed in Table III. The rate constants of four of these reactions have also been obtained for the hydrated electron in water. These are also listed in the table so that a comparison may be made for the four rate constants in the solvents ethanol, methanol, and water. 

Anbar, M., and Neta, P A compilation of specific bimolecular rate constants for the reactions of hydrated electrons, hydrogen atoms and hydroxyl radicals with inorganic and organic compounds in aqueous solution. Ini. J. Appl. Radiat. Isot. 18, 493 (1967). 

Hydrogen peroxide, cuprum perchloride, and perchloric acid were used as acceptors in aqueous solutions. The experimentally observed process of hydrated electron decay in solutions of these three substances obeyed the first-order reaction law. Kinetic characteristics of observed processes were calculated by the method of the least squares using 15-20 photo-oscillograms. Values of rate constants of corresponding pseudo-first order reactions are shown in Table I. There one can see also values of bimolecular rate constants calculated on the basis of above data. The rate constant does not vary occasionally within some limits but it changes monotonously with the variation of concentration. This may mean that some process of the decay of the intermediates was not taken into consideration. It was shown in earlier work (J), that we had satisfactory agreement with the experiment supposing that the process was the mono-molecular intermediates decay. 

From the first-order rate constant versus concentration dependency a bimolecular rate constant of 2.9 x lO M s was derived for reaction 29. All bisfunctionalized fullerene derivatives investigated were successfully reduced by means of hydrated electrons ((0.75 - 3.4) x lO M s ) and (CH3)2 COH radicals ((0.9 - 2.2) x 10 IvT s ) (Table 6). These values are, however, significantly lower than those for the reduction of Ceo/surfactant (C6oC(COO )2)/surfactant and the respective y-CD encapsulated complexes. Such an effect reflects the perturbation of the fullerene tt-system caused by placing two functional negatively charged appendices onto the fullerene core. 

C(io(OH)i8 (10) Poly hydroxy lation (Scheme 4) of the hydrophobic [60]fullerene core enhances the water solubility of this carbon allotrope up to 4.0 x 10 M (67). The tt-radical anion, (Ceo )(OH)ig, generated by electron transfer from hydrated electrons and (CH3)2 C0H radicals, absorbs with maxima at 870, 980 and 1050 nm. The bimolecular rate constant for a reaction with hydrated electrons is 4.5 x 10 M s . Based on electron transfer studies with suitable electron donor / acceptor substrates, the reduction potential of the C6o(OH)ig/(C6o )(OH)i8 couple was estimated to be in the range between -0.358 V and -0.465 V versus NHE. 

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