Acid dissociation constant of the carboxyl radical. Pulse radiolysis studies of aqueous solutions of formic acid and sodium formate

Buxton, George V.; Sellers, Robin M.

doi:10.1039/f19736900555

Cited by 113 publications

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“…The corresponding pKcooH is not well established: 3.9k0.3 [27] and 1.4 [28]. However for the pH Overview of relevant spectra of transients and copper species as given in Table 2 range studied, the concentration of the COOH radical is negligible.…”

Section: System C Without Coppermentioning

confidence: 90%

O⁻₂ Decay Catalyzed by Cu²⁺ and Cu⁺ Ions in Aqueous Solutions: A Pulse Radiolysis Study for Atmospheric Chemistry

Piechowski

Nauser

Hoigné

et al. 1993

Ber Bunsenges Phys Chem

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Atmospheric Chemistry / Chemical Kinetics / Pulse Radiolysis / Thansition Metals IonsThe catalytic decay of 0; radicals due to Cu+ and Cu2+ ions in 0, saturated solutions of low ionic strength was studied by pulse radiolysis and computer simulation of the entire reaction mechanism. Phosphate was used as buffer and formate was used to convert OH radicals into 0;. At pH = 6, the very low solubility products of Cu2+ with OH-and PO:-limited the copper concentration to the order of wM. In experiments with [Cu*+]>[O,], the rate constant k(Cu2+ +OF) = (8.0rt0.5).109M-'s-1 was determined. In systems with[O?] * [CuItot, steady state for the copper ions is attained with apparent first-order kinetics, which correlates k(Cu2+ +OF) with k(Cu+ +OF). The 0, decay rate decreased with increasing pH due to Cu2+ complexation with HPOZ-. Correspondingly the pK(CuHP04) was found to be -4.Ok0.2 under the assumption that k(CuHP04+O;)S0.01 *k(Cu2+ +O;). With this value, k(Cu+ +O;) could be determined as (9.4k0.8).lo9 M -' s-' by an iterative procedure. The consequences for the chemistry of atmospheric waters are discussed.

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Section: System C Without Coppermentioning

confidence: 90%

O⁻₂ Decay Catalyzed by Cu²⁺ and Cu⁺ Ions in Aqueous Solutions: A Pulse Radiolysis Study for Atmospheric Chemistry

Piechowski

Nauser

Hoigné

et al. 1993

Ber Bunsenges Phys Chem

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“…While the strongly reducing radical C02; reduces Fc+ with 100% efficiency, even though the rate constant for its dimerization is quite high (24), other reducing radicals such as C H~~( O H ) C O~-and ~H ( O H ) C O~-reacted more slowly (1) with Fc+. Clearly in this system high efficiency in reducing Fc+ requires that the redox reaction is virtually diffusion controlled.…”

Section: Methodsmentioning

confidence: 99%

Redox reactions with ferrocene/ferricenium species of radicals derived by H atom abstraction from alcohols and diols

Logan¹

1991

Can. J. Chem.

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. Can. J. Chem. 69, 540 (199 1). The effect of various alcohols and diols in diminishing the extent of the photo-oxidation of 4-ferrocenylbutanoate ion in the presence of N20 has been investigated. Where the hydroxyl radical generated in the photo-initiated electron transfer reacts with an alcohol by H atom abstraction at the a-position, the resulting radical is capable of reducing the ferricenium zwitterion to the ferrocenyl anion. Abstraction at other positions produces radicals that are essentially inert in this system and rate constants are derived for the reaction of OH with some such compounds. Non-vicinal diols behave similarly to the corresponding alcohols. With vicinal diols, a dehydratipn process, which occurs the more slowiy the more highly substituted the diol, converts the radical -CR(OH)C(OH)-into -CRCO-, which is an oxidizing species. The behaviour of pinacol was found to be anomalous.Key words: radical reactions, redox behaviour, alcohols.S. R. LOGAN. Can. J. Chem. 69, 540 (1991). On a CtudiC 1'habilitC de divers alcools et diols a diminuer le taux de photo-oxydation de l'ion 4-ferrocCnylbutanoate en prCsence de N20. Lorsque le radical hydroxyle gCnCr6 lors du transfert de charge photo-initiC rCagit avec un alcool par l'enlevement d'un atome de H en position a , le radical qui en rCsulte est capable de rCduire le zwitterion femcCnium en anion ferrocCnyle. Des ablations a d'autres positions foumissent des radicaux qui sont essentiellement inertes dans ce systtme; on a aussi CvaluC les constantes de vitesse des rkactions du OH avec quelques composCs de ce type. Les diols qui ne sont pas vicinaux se comportent comme les alcools correspondants. Avec les diols yicinaux, il ;e produit une dkshydratation d'autant plus lente que le diol est plus substituC; elle transforme le radical -CR(OH)C(OH)-en -CRCO-qui est une espece oxydante. On a trouvC que le comportement du pinacol est anormal.

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“…At pH 5, the oxalate exists essentially as the dianion, which has a lower rate constant (reaction 1181) than at lower pH's where the oxalic acid is in the mono-anion form (reaction [17]). …”

Section: Radiolysis Of Uranyl Sulphate Solutionsmentioning

confidence: 99%

Free-radical redox reactions of uranium ions in sulphuric acid solutions

Elliot¹,

Padamshi²,

Pika³

1986

Can. J. Chem.

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A. JOHN ELLIOT, SHAHSULTAN PADAMSHI, and JANA PIKA. Can. J. Chem. 64, 314 (1986).The radiolytic reductio? of uranyl ions in degassed sulphuric acid solutions containing various organic solutes was studied. It was shown that while COOH, C02-, and a-hydroxy-alkyl radicals reduced uranyl ions, the P-hydroxy-alkyl radicals and those derived from gluconic acid could not affect the reduction. The oxidation of uranium(1V) by hydrogen peroxide at pH 0.7 involves hydroxyl radicals in a chain mechanism but at pH 2.0 the oxidation proceeds by a non-radical reaction pathway. From the enhancement of the rate of oxidation of uranium(1V) by oxygen in the presence of 2-propanol, a mechanism involving the perhydroxyl radical, which reconciles earlier published data on kinetics and oxygen tracer studies, is proposed for the oxygenuranium(1V) reactions.A. JOHN ELLIOT, SHAHSULTAN PADAMSHI et JANA PIKA. Can. J. Chem. 64, 314 (1986). On Ctudie la reduction radiolytique des ions uranyles dans des solutions dCgazCes d'acide sulfurique contenant divers solutks organiques. On montre que, contrairement aux radicaux COOH, COz-et a-hydroxy-alkyles qui rCduisent les ions uranyles, les radicaux P-hydroxy-alkyles et ceux provenant de l'acide gluconique ne peuvent effectuer la rkduction. L'oxydation de I'uranium(1V) par le peroxyde d'hydrogtne i un pH de 0,7 fait intervenir des radicaux hydroxyles dans un mCcanisme en chaine; toutefois, i un pH de 2,0, la rCaction d'oxydation s'effectue par une voie non-radicalaire. En se basant sur le fait que la vitesse d'oxydation de l'uranium(1V) par l'oxygtne est plus grande en presence de propanol-2, on propose pour cette rCaction un mCcanisme qui implique le radical perhydroxyle. Ce mkcanisme permet de concilier les donntes publites anttrieurement tant sur la cinCtique que sur les Ctudes par marqueurs d'ox>g' ene.[Traduit par le journal]

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Acid dissociation constant of the carboxyl radical. Pulse radiolysis studies of aqueous solutions of formic acid and sodium formate

Cited by 113 publications

References 0 publications

O⁻₂ Decay Catalyzed by Cu²⁺ and Cu⁺ Ions in Aqueous Solutions: A Pulse Radiolysis Study for Atmospheric Chemistry

O⁻₂ Decay Catalyzed by Cu²⁺ and Cu⁺ Ions in Aqueous Solutions: A Pulse Radiolysis Study for Atmospheric Chemistry

Redox reactions with ferrocene/ferricenium species of radicals derived by H atom abstraction from alcohols and diols

Free-radical redox reactions of uranium ions in sulphuric acid solutions

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Acid dissociation constant of the carboxyl radical. Pulse radiolysis studies of aqueous solutions of formic acid and sodium formate

Cited by 113 publications

References 0 publications

O−2 Decay Catalyzed by Cu2+ and Cu+ Ions in Aqueous Solutions: A Pulse Radiolysis Study for Atmospheric Chemistry

O−2 Decay Catalyzed by Cu2+ and Cu+ Ions in Aqueous Solutions: A Pulse Radiolysis Study for Atmospheric Chemistry

Redox reactions with ferrocene/ferricenium species of radicals derived by H atom abstraction from alcohols and diols

Free-radical redox reactions of uranium ions in sulphuric acid solutions

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O⁻₂ Decay Catalyzed by Cu²⁺ and Cu⁺ Ions in Aqueous Solutions: A Pulse Radiolysis Study for Atmospheric Chemistry

O⁻₂ Decay Catalyzed by Cu²⁺ and Cu⁺ Ions in Aqueous Solutions: A Pulse Radiolysis Study for Atmospheric Chemistry