Rate Constants for Reaction of Hydrogen Atoms with Compounds of Biochemical Interest

Neta, P.; Schüler, Robert H.

doi:10.2307/3573354

Cited by 66 publications

(31 citation statements)

References 15 publications

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“…The reactions shown above in Eqs. (47)-(52) could also be initiated by hydrogen atom abstraction due to H radical [69] (k = 6.0 × 10 7 L mol −1 s −1 ) [74]. However, in basic solution H radical is also scavenged at a comparable rate [6]:…”

Section: The Radiation Chemistry Of Organic Chelating Agents In Aqueomentioning

confidence: 99%

Radiation chemical effects on radiochemistry: A review of examples important to nuclear power

Mincher¹,

Mezyk

2009

Radiochimica Acta

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Radiolysis / Linear energy transfer / Redox reactions / Ligand degradation / Free radicals / Solvent extractionSummary. Radiochemistry deals with the chemistry of the radioactive elements. In the nuclear industry successful fuel reprocessing, high-level waste treatment, and long-term storage of spent fuel depend on an understanding of the radiochemistry of actinides and fission products in these settings. Radiation chemistry is concerned with the chemical effects of ionizing radiation, with the most common types of radiation encountered by the radiochemist being low linear energy transfer (LET) β − and γ radiation, and higher LET α radiation. These radiations can have profound and important effects on radiochemistry, including changes in metal oxidation states and degradation of the organic ligands designed to complex radioelements. This may occur by direct action of the incident radiation on compounds present with high abundance or by reaction with radiolytically produced reactive species for trace components, such as the complexing agents. This review examines the role of reactive species created in irradiated aqueous and organic solution and their effects on radiochemistry. The sources and nature of these reactive species are discussed. Examples of radiation chemical effects are provided related to solvent extraction of the actinides from acidic solution, metal complexation and technetium redox chemistry in alkaline tank waste, and the corrosion of spent fuel stored in repository brine.

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Section: The Radiation Chemistry Of Organic Chelating Agents In Aqueomentioning

confidence: 99%

Radiation chemical effects on radiochemistry: A review of examples important to nuclear power

Mincher¹,

Mezyk

2009

Radiochimica Acta

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“…a Numbering scheme for rate constants based upon species index given in Table 3 b [26] c [27] (value at neutral pH was estimated from measured value at pH 1) d [28] e [29] f Estimated value based upon late chemistry calculations g Reactions (18 a) and (18 b) are estimated to occur at frequencies 55% (α) and 45% (1-α), respectively …”

Section: Computation Of the Early Chemistrymentioning

confidence: 99%

Product yields from irradiated glycylglycine in oxygen-free solutions: Monte Carlo simulations and comparison with experiments

Yoshida

et al. 1998

Radiation and Environmental Biophysics

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The radiation chemistry of photon-irradiated aqueous solutions of biological molecules may be considered under four distinct time regimes: physical transport (< or = 10(-15) s); prechemical conversion of H2O+, H2O*, and subexcitation electrons into free radicals and molecular products (10(-15) s to 10(-12) s); chemical reactions within individual electron tracks (10(-12) s to 10(-6) s); and chemical reactions within overlapping tracks (>10(-6) s). We have previously reported of the use of the Monte Carlo radiation transport/chemistry codes OREC and RADLYS to model the radiolysis of glycylglycine in oxygen-free solution to a time of 1 micros. These simulations successfully predicted the yields of free ammonia, an end product created solely in the reaction of the hydrated electron with the solute within individual tracks. Other measurable products are only partially created during intratrack reactions, and thus one must additionally consider the late, intertrack chemistry of this system. In this paper, we extend our simulations of glycylglycine radiolysis to model for the first time the events which occur during this late chemistry stage. The model considers the product rates of the reactants in bulk solution by using previously available microsecond intratrack yields given by single-track OREC/RADLYS simulations and an x-ray dose rate of 2.80 Gy min(-1) as used in a companion experimental program. These rates are then applied in a series of coupled, differential rate equations that describe the solution chemistry of glycylglycine radiolysis. Product yields are reported as a function of time over a total irradiation period of 10(4) s. Excellent overall agreement is seen between the theoretical predictions and measurements of five radiolysis end products: free ammonia, acetylglycine, diaminosuccinic acid, aspartic acid, and succinic acid. The model also gives the explicit contributions of intratrack and intertrack reactions to the various end products. For example, the model predicts that approximately 56% and 93% of succinic acid and aspartic acid, respectively, are produced during intertrack reactions at a solute concentration of 0.05 M; these contributions drop to 0.07% and 11%, respectively, at 1.2 M.

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“…Volkert and Kuntz (11) determined the order in amino acids to be NH3+ < H < COOH < OH. Also, Neta and Schuler (3) found that NH3+ has a strong deactivating effect on H-atoms in the a, ,6, and y positions of aliphatic compounds, whereas COOH produces a small deactivating influence and the amino acid group contributes very little to ease of abstraction from adjacent atoms. Reaction 4 is the predominant pathway for H-atom reactions with primary SH compounds in this study and accounts for 70-85% of the total rate.…”

Section: Introductionmentioning

confidence: 98%

“…The rates of H-atom reactions with a large number of species have been surveyed (1)(2)(3) and the effect of molecular structure on reactivity has been discussed (2,3). In reactions with sulfhydryl compounds, there is considerable evidence, based on esr studies (4,5) and kinetic data (S), the H-atoms attack the SH moiety exclusively.…”

Section: Introductionmentioning

confidence: 99%

The Reactions of Hydrogen Atoms in Aqueous Solutions: Thiols

Tung¹,

Kuntz²

1973

Radiation Research

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Rate Constants for Reaction of Hydrogen Atoms with Compounds of Biochemical Interest

Cited by 66 publications

References 15 publications

Radiation chemical effects on radiochemistry: A review of examples important to nuclear power

Radiation chemical effects on radiochemistry: A review of examples important to nuclear power

Product yields from irradiated glycylglycine in oxygen-free solutions: Monte Carlo simulations and comparison with experiments

The Reactions of Hydrogen Atoms in Aqueous Solutions: Thiols

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