Mechanism of formation of 2-amino-3-cyano-4,5-diphenylfurane and some of its reactions

Prousek, Josef

doi:10.1135/cccc19833140

Cited by 11 publications

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“…All the reagents were chemically-pure grade and used without additional purification. The hydroxyl radicals were generated in an H 2 O 2 -Fe 3+ -H 2 O system similar to the Fenton reagent [2,11,12].…”

Section: Methodsmentioning

confidence: 99%

“…The behavior of these reactions in water may be attributed to a solvent cage effect.The reactions of hydrocarbons with hydroxyl radicals ( ⋅ OH) hold importance in the chemistry of the atmosphere and natural water sources [1,2]. OH Radicals are key oxidants of hydrocarbons (RH) in the troposphere as well as in surface, rainwater and cloud water [1,3], and in the ozonization of water [4].…”

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confidence: 99%

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Temperature dependence of the relative rate constants of the reactions of alkanes with oh radicals in aqueous solution

2009

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The values of k RH /k EtH decrease with increasing temperature in the gas phase but increase in water. The behavior of these reactions in water may be attributed to a solvent cage effect.The reactions of hydrocarbons with hydroxyl radicals ( ⋅ OH) hold importance in the chemistry of the atmosphere and natural water sources [1,2]. OH Radicals are key oxidants of hydrocarbons (RH) in the troposphere as well as in surface, rainwater and cloud water [1,3], and in the ozonization of water [4]. The kinetics of the reactions (1) RH + ⋅ OH ® [R…H…OH] ¹ ® R ⋅ + H 2 O and the temperature dependence of the rate constants for a broad range of alkanes have been studied extensively in the gas phase [1]. Considering the marked discrepancies in the values of the rate constants and activation parameters given by different workers, we shall subsequently use the values recommended by Atkinson [1]. Reactions (1) in aqueous solution have not been studied as extensively. The absolute rate constants have been measured only for methane by a method involving g-radiolysis of aqueous solutions [5, 6], while relative constants for the methane-butane series [7-9] and for cyclopentane [10] were measured by photolysis and radiolysis methods. There have been no data given for the temperature dependence of the rate constants.In previous work [11,12], we studied the kinetics and selectivity of reaction (1) in H 2 O 2 -Fe 2+ -Fe 3+ -H 2 O solutions at 25°C for broad range of normal, iso-, and cycloalkanes. We used a direct and most precise method for studying the activation kinetics of hydrocarbons based on measurement of the rate of consumption of trace amounts of RH under conditions of a large excess of the oxidizing agent [12]. The anomalously low substrate selectivity and kinetic isotope effect (KIE) for reaction (1) in aqueous solution in comparison with the gas phase were quantitatively attributed to the cage effect on diffusion [11,12]. Important additional information on mechanism can be obtained by studying the temperature dependence of the rate constant and substrate selectivity (rate constant ratios) for a broad range of hydrocarbons [13]. In recent work [14], we have shown that the temperature dependence of the KIE in gas-phase and liquid-phase reactions of cyclohexane (c-C 6 H 12 /C 6 D 12 ) with the OH radical at 5-55°C have opposite signs: the KIE values in the gas phase drop with increasing temperature, while these values increase in water. These discrepancies are presumably a consequence of the solvent cage effect. 0040-5760/09/4504-0239

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Section: Methodsmentioning

confidence: 99%

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confidence: 99%

Temperature dependence of the relative rate constants of the reactions of alkanes with oh radicals in aqueous solution

2009

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“…In previous work [13,14], we carried out a systematic study of the kinetics and selectivity of the reactions of OH radicals with a wide range of normal, iso, and cycloalkanes in the oxidative system containing H 2 O 2 , Fe 2+ , Fe 3+ , and water similar to Fenton's reagent [3]. We found unusually low substrate selectivity and hydrogen kinetic isotope effect (KIE) for reaction (1) in aqueous solution in comparison with the gas-phase reactions.…”

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confidence: 99%

“…Values for the KIE and k 6 /k 5 decrease with increasing temperature from 5 to 55°C in the gas phase, while these values increase in solution. We propose that this phenomenon is a consequence of a solvent cage effect.The reactions of hydroxyl radicals with hydrocarbons play an important role in biochemical processes and the chemistry of the atmosphere and natural water supplies [1][2][3][4]. The kinetics of the reactions of OH radicals with saturated hydrocarbons (RH)…”

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Kinetics and anomalous temperature dependence of the kinetic isotope effect of reactions of cycloalkanes C5H10, C6H12 and C6D12 with OH radicals in aqueous solutions

et al. 2008

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in aqueous solution and in the gas phase has opposite signs. Values for the KIE and k 6 /k 5 decrease with increasing temperature from 5 to 55°C in the gas phase, while these values increase in solution. We propose that this phenomenon is a consequence of a solvent cage effect.The reactions of hydroxyl radicals with hydrocarbons play an important role in biochemical processes and the chemistry of the atmosphere and natural water supplies [1][2][3][4]. The kinetics of the reactions of OH radicals with saturated hydrocarbons (RH)including cycloalkanes, has been studied extensively in the gas phase [1]. The absolute rate constants for reaction (1) have been measured in aqueous solution only for methane [5,6], while relative rate constants in the methane series have been measured for butane [7-10] and cyclopentane [11,12].In previous work [13,14], we carried out a systematic study of the kinetics and selectivity of the reactions of OH radicals with a wide range of normal, iso, and cycloalkanes in the oxidative system containing H 2 O 2 , Fe 2+ , Fe 3+ , and water similar to Fenton's reagent [3]. We found unusually low substrate selectivity and hydrogen kinetic isotope effect (KIE) for reaction (1) in aqueous solution in comparison with the gas-phase reactions. These findings were qualitatively explained by diffusion complications for the reactions in solution related to the cage effect [13].A new approach toward the study of the mechanisms for activation of C-H bonds of saturated hydrocarbons by oxidizing agents, metal complexes, and electrophiles developed in previous work [13,15] involves study of the temperature dependence of the KIE for cyclohexane/cyclohexane-d 6 pairs and the ratios of the reaction rates for the cyclopentane/cyclohexane pair and analysis of the compensation ratios obtained. There have been no data on the temperature dependence of the rate constants of the reactions of alkanes with OH radicals in aqueous solution.

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Identification and characterization of Fenton oxidation products of surfactants by electrospray mass spectrometry and by solid phase microextraction gas chromatography mass spectrometry. 2. Fatty alcohol polyethoxy sulphates

Cuzzola

Raffaelli

Salvadori

2000

Rapid Commun. Mass Spectrom.

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The Fenton reaction for the degradation of surfactants has been investigated and partial degradation products have been identified and characterized by mass spectrometry for the case of fatty alcohol polyethoxy sulphates. The polar water-soluble products were investigated by liquid chromatography/mass spectrometry (LC/MS) with electrospray ionization (ESI), and the volatile products leaving the mixture during the reaction were trapped by means of solid phase microextraction (SPME) and investigated by gas chromatography/mass spectrometry (GC/MS) with electron and chemical ionization. The oxidation leads to the formation of products with hydroxyl and epoxide groups due to insertion of oxygen atoms or with terminal ethoxylic moieties deriving from the loss of the hydrophilic sulphate group. The formation of volatile aldehydes is also observed, corresponding to the fragmentation between hydrocarbon and ethoxylic chains. The extent of mineralization is dependent on peroxide and iron(II) concentrations. Copyright 2000 John Wiley & Sons, Ltd.

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Mechanism of formation of 2-amino-3-cyano-4,5-diphenylfurane and some of its reactions

Cited by 11 publications

References 0 publications

Temperature dependence of the relative rate constants of the reactions of alkanes with oh radicals in aqueous solution

Temperature dependence of the relative rate constants of the reactions of alkanes with oh radicals in aqueous solution

Kinetics and anomalous temperature dependence of the kinetic isotope effect of reactions of cycloalkanes C5H10, C6H12 and C6D12 with OH radicals in aqueous solutions

Identification and characterization of Fenton oxidation products of surfactants by electrospray mass spectrometry and by solid phase microextraction gas chromatography mass spectrometry. 2. Fatty alcohol polyethoxy sulphates

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