Pulse radiolysis and product analysis of 1,1-diphenyl-ethylene and related compounds in methanol

Getoff, N.; Ritter, A.; Schwörer, F.

doi:10.1039/f19837902389

Cited by 26 publications

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“…19 The molecular hydrogen (G(H 2 ) neat ) 5.8 × 10 -7 mol J -1 ) originates directly from excited molecule dissociation and indirectly from scavenging of H-atoms by methanol:…”

Section: Resultsmentioning

confidence: 99%

“…9 Silver ions released in the corrosion cascade (reactions 14-16) are adsorbed through reaction 18 and are also included in the development. This second cascade of reactions (eqs [17][18][19] corresponds to the delayed bleaching at 600 nm of the MV + blue color after 2 ms in the pulse radiolysis study (Figures 11 and inset b). The clusters now grow mostly by successive additions of supplementary reduced atoms (alternate reactions of electron transfer (eqs 17 and 19) and adsorption of surrounding metal ions (eq 18)), making the redox potential of Ag n + more and more favorable to the electron transfer.…”

Section: G(nag Nmentioning

confidence: 99%

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Transient and Stable Silver Clusters Induced by Radiolysis in Methanol

et al. 2002

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The optical absorption spectra of Ag 0 , Ag 2 + , transient oligomers, and stable clusters were studied in deaerated methanol by pulse and γ-radiolysis methods and compared with data obtained from studies using other solvents. From the decay of esolv at 620 nm, the formation rate constant of Ag 0 was determined to be k(esolv + Ag + ) ) (2.6 ( 0.6) × 10 10 M -1 s -1 . The coalescence rate of transient oligomers is particularly slow and the growth process is not completed within 2 s after the pulse. The surface plasmon band of stable clusters obtained by γ-radiolysis in methanol is intense and sharp ( 385 nm ) 1.8 × 10 4 M -1 cm -1 ). The clusters are readily oxidized by oxygen. By adding methyl viologen MV 2+ to the solution containing stable silver clusters, the blue color of MV +• is transitorily observed, and the small clusters are developed into larger ones. Similarly, by pulse radiolysis of a mixture of silver cations and MV 2+ , silver atoms and MV +• are formed immediately through solvated electron scavenging, but subsequently additional MV +• are produced by reduction of MV 2+ by Ag 0 and small oligomers. In a further step, MV +• radicals reduce Ag + cations adsorbed on large clusters and let them develop eventually to larger sizes. The general mechanism of the methanol radiolysis is revisited on the basis of electron and radical scavenging by Ag + and silver clusters, and values of the yields of methanol radiolysis species are discussed in detail.

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“…19 The molecular hydrogen (G(H 2 ) neat ) 5.8 × 10 -7 mol J -1 ) originates directly from excited molecule dissociation and indirectly from scavenging of H-atoms by methanol:…”

Section: Resultsmentioning

confidence: 99%

Section: G(nag Nmentioning

confidence: 99%

Transient and Stable Silver Clusters Induced by Radiolysis in Methanol

et al. 2002

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“…These results are interpreted on the basis of reaction (16). From the slope of the plot in Figure 2 A plot of the conductivity change taken 300 p after the pulse as function of pH is shown in Figure 3.…”

Section: The Reaction Of the @Imethylamino)methyl Radical A' With Oxygenmentioning

confidence: 99%

The production of the superoxide radical anion by the OH radical‐induced oxidation of trimethylamine in oxygenated aqueous solution. The kinetics of the hydrolysis of (hydroxymethyl)dimethylamine

Das

Schuchmann

et al. 1987

Chem. Ber.

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The radiolysis of trimethylamine in N20/02 (4: 1 v/v) saturated basic solutions eventually gives rise to dimethylamine, formaldehyde, and hydrogen peroxide. Pulse radiolysis using conductivity and opfical detection permits the observation of the chemical transformations following the generation of the (dimethylamino)methyl radical from trimethylamine upon attack by the hydroxyl radical. The (dimethy1amino)methyl radical reacts rapidly with oxygen ( k = 3.5 x lo9 M-' s-') to give 0 , ' and dimcthylimonium, possibly via a short-lived ( c~.~ < s) pcroxyl radical. The dimethylimonium ion adds O H ~ to form (hydroxymcthyl)dimcthylaminc (k = 2.8 x 10' M ' s '). This is hydroly7cd to dimethylamine and formaldehyde hydrate (kObs = 4.0 0.6 s I). A mechanism incorporating these reactions is shown to be in good accordance with the experimental data in the pH range from 9 to 11.3.The reactions of hydroxyl radicals with trimethylamine in deoxygenated aqueous solutions ' -' ) have been extensively studied recently ' ) using pulse radiolysis, combined with ESR and product analysis. Aqueous trimethylamine exists in both the protonated and the unprotonated forms (pKa 9.76), and hydroxyl radical attack leads to the formation of three radicals, the aminoalkyl radical (CH3hNCH; (A*), its conjugated acid (CH,),HN+CH; (AH+'), and the alkylamine radical cation (CH&N+' (N+'). Under such conditions 'OH is the major radical (go%,, 0.57 pmol J-'), with a small contribution of the H atom (lo%, 0.057 pmol J-I). Hydroxyl radicals react with trimethylamine thirty times faster (k7,* = 1.2 x 1O'O M-' s-') than with its protonated form (k = 4 x lo8 M-' s-' ) 6, . In the present study we deal only with the pH range above 9. This simplifies the situation, because then we may restrict ourselves essentially to the consideration of A' and N+' as the primary amine radicalsn [reactions (7) and (8)

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“…With increasing the concentration of oxygen the yield of glycol is reduced up to nil. The rate constant (k) for the reac tion of solvated electrons with oxygen is very high, k(e~ + 0 2) = 2.0 x 1010 dm3 m ol"1 s~1 [4]. Just so react the H-atoms in acidified methanol (0.5 vol.% aqueous lm o ld m " 3 HC104), /c(H + 0 2^H 0 2) ~2 x 1010 dm3 m ol"1 s " 1 [5].…”

Section: Introductionmentioning

confidence: 99%

“…Just so react the H-atoms in acidified methanol (0.5 vol.% aqueous lm o ld m " 3 HC104), /c(H + 0 2^H 0 2) ~2 x 1010 dm3 m ol"1 s " 1 [5]. The resulting peroxyradicals show absorption maxima at 240 nm (assigned to Ö 2 and HÖ2) and 265 nm (assumed to be Ö 2CH2OH) [4],…”

Section: Introductionmentioning

confidence: 99%

Radiation Induced Oxidation of Methanol

Jung

Getoff

1991

Zeitschrift Für Naturforschung A

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The radiolysis of methanol in the presence of air as well as of pure oxygen (1 to 5 atm) was investigated. The yields of the major products: carboxylic acids (by far predominantly formic acid), oxalic acid, formaldehyde and glycolaldehyde were determined as a function of the absorbed dose. In addition small amounts (G<0.05) of glyoxal, glyoxalic acid and glycolic acid were also detected. Based on the results a possible reaction mechanism is presented.

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Pulse radiolysis and product analysis of 1,1-diphenyl-ethylene and related compounds in methanol

Cited by 26 publications

References 0 publications

Transient and Stable Silver Clusters Induced by Radiolysis in Methanol

Transient and Stable Silver Clusters Induced by Radiolysis in Methanol

The production of the superoxide radical anion by the OH radical‐induced oxidation of trimethylamine in oxygenated aqueous solution. The kinetics of the hydrolysis of (hydroxymethyl)dimethylamine

Radiation Induced Oxidation of Methanol

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