Solvent effects on the reactivity of solvated electrons with ions in tert-butanol/water mixtures

Abstract

Reactions of e; with the ions N H i V s , and H: showed different variations of rate with solvent composition in rerr-butanollwater mixtures from 0 to 100 mol% water. In pure rerr-butanol solvent at 298 K the respective values of k2 (lo6 m3 mol-I s-I) are 3.2, 13, and 42. The estimated value of reaction radius R, depends on the minimum number of solvent molecules needed between e; and the reactant ion to attain the static values of E of the bulk solvent used in the calculation of the Debye factor f ; R, is assumed to be larger in the alcohol-rich region than in the water-rich region, because the solvent molecules are larger. The Smoluchowski-Debye-Nernst-Einstein model is used to evaluate the effective reaction radius KR,, where K is the probability of reaction per encounter; KR, decreases from pure ferr-butanol to pure water. In the water-rich region the activation energies E2 of the efficient reactions, 11-24 kJ mol-I, are similar to EAo of the reactant electrolyes, 12-23 kJ mol-l. For the inefficient reactant NH: CIO;, E2 = 30 kJ mol-I. The high values of E2 = 43-53 kJ mol-I in pure rerr-butanol solvent are attributed to a high activation energy for diffusion of e; in this solvent.Ke.y words: rert-butanollwater solvents, solvated electron, ions, reactivity, solvent effects. RCsumC : Les vitesses de rtaction des e; avec les ions N H i T S et H l prtsentent des variationsdifferentes avec la composition des mtlanges de solvant rerr-butanolleau en allant de 0 B 100% en eau. Dans le tert-butanol pur, B 298 K, les valeurs relatives de k? (lo6 m h o l -I s-I) sont 3,2, 13 et 42.La valeur estimte du rayons de reaction R, dtpend du nombre minimal de moltcules de solvant requis entre le e; et I'ion rtactif pour atteindre les valeurs statiques de E de I'ensemble du solvant utiliste par le facteur f de Debye; comme les moltcules de solvant sont plus volumineuses que celles de I'eau, on considere que R, est plus Clevt dans la rtgion riche en alcool que dans la rtgion riche en eau. On a utilist le rnodttle de Smoluchowski-Debye-Nernst-Einstein pour tvaluer le rayon rtactionnelle efficace, KRI., dans lequel K est la probabilitt de rtaction par rencontre; KRr diminue en allant du rerr-butanol pur B l'eau pure.Dans la rtgion riche en eau, les energies d'activation E? des reactions efficaces, 11-24 kJ mol-l, sont semblables aux valeurs de EA0 des Clectrolytes qui rtagissent, 12-23 kJ mol-I. Pour le reactif inefficace N H ; CIO;, E? = 30 kJ mol-I. On attribue les valeurs tlevtes de E2 = 43-53 kJ rnol-' observtes dans le rerr-butanol B une Cnergie tlevte d'activation de la diffusion des e; dans ce solvant.

Solvated electron mobility in liquid tert-butanol

“…In support of them, our study of e; reactivity in tertbutanol (10) provides evidence that p, in tert-butanol is about (acid-base autodissociation) of alcohols produce a relatively high intrinsic conductivity, which means that relatively high 10 times higher than the mobility of a normal anion in this concentrations of e: must be used to obtain a sufficiently alcohol. The relevant data are presented below.…”

“…The purified alcohol contained 5 x lop4 mole fraction of equipment that is available at only two or three labs in the water (10). Up to 1 x mole fraction more water was world (1)(2)(3)(4)(5).…”

“…1, for temperatures 299.5-330.0 K; E2 = 50 kJ mol-I. The value of was taken as constant at 1.6 nm (10). The values of the Debye factor f calculated from known values of E (Table 1) are included in Fig.…”

Solvent effects on reactivity of solvated electrons with ammonium nitrate in 2-propanol/water mixed solvents

“…The values of f estimated from Eq. (7) were calculated from fixed values of R r , namely, R r ½e À s þ ðNO 3 À Þ s ¼ 1:5 nm, and R r ½e À s þ ðNH 4 þ Þ s ¼ 1:0 nm [12]. The values of f for the reaction of e À s with (NO 3 À ) s are 0.6-0.8, and those for the reaction of e À s with (NH 4 + ) s are 2.5-3.3.…”

“…All these studies showed that the reaction rate of e À s with solutes varied with solvent composition. Concerning, the reactivity tests of e À s with charged solutes in alcohol/water mixed solvents, there has been some more reports related with the transport properties of ions in solvent at different temperatures and compositions [11,12], where the reactivity of the solvated electrons is not only dependent on the properties of the solvent but also the nature of the coreactant. We have reported in previous article about the reactivity of solvated electrons with ammonium nitrate in 1-propanol/water mixed solvent system [13].…”