Reaction with hydrated electrons

REACTIONS OF THE OXIDES OF NITROGEN 5.17 REACTIONS WITH HYDRATED ELECTRONS 

Gordon ei have estimated the rate of reaction of hydrated electrons with nitric oxide by subjecting a water solution of nitric oxide to a 0.4 /isec pulse of 15 MeV electrons from a linear accelerator, and following the decay of the hydrated electron photometrically. The reaction 

These values are constant with the findings of Knight and Sutton, who studied the effect of NOJ ions on the radiolysis of nitric oxide-water solutions buffered at pH 7 and estimated that kj 52/ 153 6. 

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A. Shafferman and G. Stein, The effect of aromatic amino acids on the photochemistry of a disulfide Energy transfer and reaction with hydrated electrons, Photochem. Photobiol. 20, 399-406 (1974). 

Fig. 98. Lower parr, difference spectra of Q-CdS after the reaction with hydrated electrons (full line) and after the reaction with OH radicals (dashed line, lOx magnified). Upper part absorption spectrum of the investigated sample [576]...

Visscher KJ, de Haas MP, Loman H, Vojnovic B, Warman JM (1987) Fast protonation of adenosine and of its radical anion formed by hydrated electron attack a nanosecond optical and dc-conduc-tivity pulse radiolysis study. Int J Radiat Biol 52 745-753 Visscher KJ, Spoelder HJW, Loman H, Hummel A, Horn ML (1988) Kinetics and mechanism of electron transfer between purines and pyrimidines, their dinucleotides and polynucleotides after reaction with hydrated electrons a pulse radiolysis study. Int J Radiat Biol 54 787-802 von Sonntag C (1980) Free radical reactions of carbohydrates as studied by radiation techniques. Adv Carbohydr Chem Biochem 37 7-77... 

A number of inorganic compounds have been investigated for their rates of reaction with hydrated electrons. For purposes of later discussions, we divide them into two groups compounds which approach the diffusion controlled rate and compounds which react much slower. The data of the first group are presented in Table I which includes a number of cobalt complexes, and in Table II which contains the remaining fast reacting compounds. Here they are presented in the order of increasing atomic number of their central atom. In addition to the experimental conditions and the observed specific rate constants (kohs), these tables... 

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. 

Two findings are particularly noteworthy. First, the experiments in which the reactivity of water-soluble fullerene derivatives in aqueous media was probed (62-64) Not only, that the intermolecular reactions with hydrated electron and various radicals provided unequivocally evidence for the presence of fullerene clusters. But, furthermore, these investigations helped, in reference to the kinetics of the fullerene monomers, to estimate the agglomeration number for, for example, the mono pyrrolidinium salt in the respective fullerene cluster. Secondly, the intermolecular electron transfer reactions between radiolytically generated arene tt-radical cations and higher fullerenes (25,51) The noted parabolic dependence of the rate constants on the thermodynamic driving force is one of the rare confirmations of the existence of the Marcus-Inverted region in forward electron transfer. 

Electron scavenging is often carried out using N2O additive. At room temperature it dissolves in water in 0.025 mol dm concentration. In reaction with hydrated electrons, N2O transforms to N2 and OH (Schuler and Albarran 2002) ... 

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

Anbar, M. and Neta, P. (1967). A compilation of specific biomolecular rate constants for the reaction of hydrated electrons, hydrogen atoms and hydroxyl radicals with inorganic and organic compounds in aqueous solutions. Int. J. Appl. Radiat. Isot. 18, 493-497. 

In the presence of 10 pM peroxide, the yields of H2, H202, and of H + eh are about the same in neutral and 0.4 M acid solutions. Since H atoms produced by the reaction of acid with hydrated electrons have different reaction rates and sequences of reaction, a much greater difference of the... 

The most simple case of a electron-transfer chemiluminescence has been realized recently by the reaction of hydrated electrons with tri-(bipyridyl)ruthenium(III) (J. E. Martin, E. J. Hart, A. W. Adamson, H. Gafney, and J. Halpern 212>) ... 

It is known that more than 30 reactions are needed to reproduce the radiation-induced reactions occurring in pure water. Intensive measurements with a pulse radiolysis method have been done at elevated temperature up to 300°C [25 2], and the temperature dependence of some reactions does not exhibit a straight line but a curved one in Arrhenius plot. These examples are the reactions of the hydrated electron with N2O, NOJ, NO2, phenol, Se04, 8203 , and Mn [33,35], and two examples, egq + NOJ and ejq -i- NOJ, are shown in Fig. 2. The rate constant for the reaction of hydrated electron with NOJ is near diffusion-controlled reaction at room temperature and is increasing with increasing temperature. Above 100°C, the rate does not increase and reaches the maximum at 150°C, and then decreases. Therefore the curve is concave upward in Arrhenius plot. 

Benzophenone solution was taken because it is stable in supercritical water at 400 °C. It is known that the reaction of hydrated electron with benzophenone produces an anion,... 

In deoxygenated aqueous solutions, the decay of eh (Fig. la), besides other reaction pathways, involves the reaction of hydrated electrons with 2AP... 

Oxidative reactions of 2AP(-H) have been studied in oxygen-saturated solutions because 2AP(-H) radicals do not exhibit observable reactivities towards O2 [10]. In contrast, O2 rapidly reacts with hydrated electrons (rate constant of 1.9x10 ° s ) [51] and hydrated electrons do not interfere in... 

An ingenious application of reactions of hydrated electrons with divalent cations was developed by Jonah et al. [126]. They increased the cation concentration in the presence of a polyvinyl sulphate. At low concentrations of cation, the rate of reaction of hydrated electrons was low, but above a well-defined concentration, the pseudo-first-order rate coefficient increased linearly and rapidly with concentration. Providing it is reasonable to assume that divalent cations bound to the polymer display much lower reactivitiy with hydrated electrons, it is possible to deduce... 

Finally, the comparison between experimentally measured rate coefficients for reactions of hydrated electrons with strong oxidants and the... 

There are also certain data on electron tunneling in electron transfer reactions in liquids. The ideas about electron tunneling have been used by Anbar and Hart [75] to interpret the anomalously large rate constants for the diffusion controlled reactions of hydrated electrons with some inorganic anions in aqueous solution. Table 5 represents the data on the largest values of the rate constants, ke, observed for the reactions of eaq with various inorganic anions and cations. Theoretical diffusion rate constants, kA, for... 

The rate constants of reactions of hydrated electrons with some accep-tors-anions substantially exceed the diffusion rate constants calculated with the help of the Debye equation [Chap. 2, eqn. (45)l(see Chap. 2, Sect. 4). This excess is usually attributed to the capture of electrons by acceptors via tunneling at distances exceeding the sum of the reagents [28,89,111,1201- In this case, the tunneling distance can be estimated from experimental rate constants for reactions of eaq with acceptors [109] by means of the expression... 

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