.gamma.-Ray and electron pulse radiolysis studies of aqueous peroxodisulfate and peroxodiphosphate ions

Levey, Gerrit; Hart, Edwin J.

doi:10.1021/j100583a006

Cited by 15 publications

(8 citation statements)

References 6 publications

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“…The persulfate reaction proceeded by a chain mechanism with chain lengths of 1800 a t 60°C for the thermal reaction and 1000 a t 60°C (500 a t 25OC) for the photooxidation reaction in contrast to a quantum yield of 2 for the photooxidation of 2-propanol by PZOg-. Levey and Hart [8] in a study of the gamma ray induced oxidation of by PzOi-+ eiq -PO:-+ POT] nor OH. radicals were effective in initiating a chain.…”

Section: Further Backgroundmentioning

confidence: 99%

Persulfate and perphosphate oxidation of 2‐propanol: A relative rate study

Levey

Bida

Edwards

1981

Int J of Chemical Kinetics

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A competitive reaction study for two isoelectronic peroxides (peroxodisulfate SzOi-and peroxodiphosphate P20:-) interacting with the free radical .C(CH&OH is described. The radical formation is initiated by photolysis, the amounts of peroxide remaining analyzed volumetrically. It is found that persulfate reacts with the organic radical over 100 times more rapidly than does perphosphate. Mechanistic consequences in relation to previous work are briefly discussed.

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Section: Further Backgroundmentioning

confidence: 99%

Persulfate and perphosphate oxidation of 2‐propanol: A relative rate study

Levey

Bida

Edwards

1981

Int J of Chemical Kinetics

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“…1, curve 2) can be due to the appearance of small amounts of peroxodiphosphate anions that interact with e aq -at rates constant higher than 1•10 9 L mol -1 s -1 . 23 At pH 9.6, the plot of the rate constant for e aq -decay vs. phosphate concentration (phosphate is present in the solution in the form of HPO 4 2-anions) is a curve with saturation (Fig. 2).…”

Section: Resultsmentioning

confidence: 99%

Kinetics of hydrated electron reactions with phosphate anions: a laser photolysis study

2007

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The decay kinetics of hydrated electron (e aq -) formed upon photolysis of aqueous solutions of sodium pyrene 1,3,6,8 tetrasulfonate at λ = 337 nm in the presence of phosphate anions (up to 2 mol L -1 ) was studied by nanosecond laser pulse photolysis in a wide range of pH (3.5-10) and ionic strength (I, up to 2 mol L -1 ) values. At high pH values, where the HPO 4 2-ions dominate, the e aq -decay kinetics depends only slightly on phosphate concentra tion (rate constant for the reaction is at most 2•10 5 L mol -1 s -1 ). The H 2 PO 4 -ions react with e aq -at a rate constant of 2.8•10 6 L mol -1 s -1 (I = 0), which increases linearly with the parameter exp( /(1 + ) in accordance with the Debye-Hückel theory. The rate constant for quenching of e aq -by H 3 PO 4 at pH ≤ 4 decreases linearly with the parameter exp( /(1 + ) due to the secondary salt effect and equals 1.6•10 9 L mol -1 s -1 at I = 0. The logarithm of the rate constant for quenching of e aq -by phosphates is linearly related to the number of the O-H bonds in the phosphate molecule.Key words: laser flash photolysis, hydrated electron, phosphate anions, kinetics, quench ing, salt effect.The kinetics and mechanisms of hydrated electron (e aq -) reactions with phosphate anions have been a sub ject of scientific research for more than four decades. The reactions can serve models in the studies of (i) mecha nisms of hydrated electron interactions with phosphate containing organic (including biologically important) sub stances and (ii) phosphorylation processes. 1-3 A great impetus to these investigations came from the fact of generation of H atoms in the reactions of e aq -with H 2 PO 4 -anions in aqueous media. 1,3,4 Earlier experi ments showed that radiolysis or photolysis of water with high energy UV radiation is accompanied by generation of H atoms as a result of the interaction of e aq -with protons of the medium or with the Brønsted acids, namely, e aq -+ HX → HX -→ H + X, where HX is a protic acid. 1,4-6 In this connection, orthophosphates are of par ticular interest, because they are substrates of many bio chemical reactions and can act as sources of H atoms at pH values similar to the physiological one (pH 7). The rate constants (k q ) for reactions of e aq -with phos phate anions and H 3 PO 4 were measured using pulsed ra diolysis and photolysis techniques. The rate constants, k q , for the H 2 PO 4 -reactions with e aq -in aqueous media vary in the range 3.1•10 6 -1.9•10 7 L mol -1 s - 1 . 3,4,7-12 The k q value reported 9 for the reaction of HPO 4 2-is relatively low (k q = 1.4•10 5 L mol -1 s -1 ). The fastest reaction oc curs between e aq -and H 3 PO 4 (k q = 1•10 9 L mol -1 s -1 ). 10Thus, successive addition of protons to the HPO 4 2-anion is accompanied by an increase in the k q value by two orders of magnitude. It was assumed 4-6 that the interaction of e aq -with phosphates produces H atoms.WThe generation and consumption of H atoms upon pulsed radiolysis and photolysis of aqueous solutions at λ < 200 nm can follow a number of channels inv...

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“…Since the ESR parameters coincide exactly with those of the hydroxyl radical adduct to fumaric acid8,15 and maleic acid,23 this ESR spectrum is ascribed to OOCCH(OH)CHCOO-. 24 The hydroxyl radical could be produced originally in strongly alkaline solution by the reaction P04=" + OH"-» OH + P043" (2) the rate constant being 6.2 X 105 M-1 s-1 estimated by optical pulse radiolysis.13 There is another possible source of hydroxyl radical adduct II; i.e., alkaline hydrolysis of the phosphate group in radical I:…”

Section: Resultsmentioning

confidence: 99%

“…Peroxodiphosphate like peroxodisulfate reacts very efficiently with eaq~p roducing phosphate radicals. 2 In a recent paper,3 the results of the reactions of a number of organic compounds with the three acidbase forms4 of phosphate radicals H2P04 -a* pKa = 5.9 HPCV -H + pKa = 10.7 P042" have been reported.…”

Section: Introductionmentioning

confidence: 99%

An in situ photolysis-electron spin resonance study of some reactions of phosphate radicals

Maruthamuthu¹,

Taniguchi²

1977

J. Phys. Chem.

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19) Reference 11, p 103. (20) For a discussion of uncertainties and significant figures in the parameters see ref 15. (21) G. Orlandi and W. Siebrand, Chem. Phys. Lett., 30, 352 (1975). ( 22) T. M. Stachelek, T. A. Pazoha, and W. M. McClain, submitted for publication. We are grateful to these authors for a preprint of their paper.(23) Actually, if oxygen quenched 1t* and 1p* with equal efficiency the expected ,°/ , ratio according to the fluorescence distribution in Table IV would be 1.16 rather than 1.03, suggesting that the calculated parameters still overestimate the contribution of the slow component to the fluorescence yield. (24) A correction for dihydrophenanthrene formation would be required.9 c/s-Stllbene , measurements are planned as an extentlon of this work. (25) The observed value, 0.046, was rounded off in the publication. (26) R.

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.gamma.-Ray and electron pulse radiolysis studies of aqueous peroxodisulfate and peroxodiphosphate ions

Cited by 15 publications

References 6 publications

Persulfate and perphosphate oxidation of 2‐propanol: A relative rate study

Persulfate and perphosphate oxidation of 2‐propanol: A relative rate study

Kinetics of hydrated electron reactions with phosphate anions: a laser photolysis study

An in situ photolysis-electron spin resonance study of some reactions of phosphate radicals

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