Free radical induced oxidation of phloroglucinol. A pulse radiolysis and EPR study

Wang, Degui; György, I.; Hildenbrand, Knut; Sonntag, Clemens von

doi:10.1039/p29940000045

Cited by 36 publications

(29 citation statements)

References 34 publications

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“…Sawicki [16] proposed phloroglucinol in two tautomeric forms depending on the pH of the medium. In free radical induced oxidation, a dimer of phloroglucinol can be produced [23]. Accordingly, it is deduced that the compounds might be electrochemically oxidized to quinone and ketone or their dimer and even polymer under different pHs.…”

Section: Mechanistic Discussionmentioning

confidence: 99%

Inhibition of Ru Complex Electrochemiluminescence by Phenols and Anilines

Cui

Shi

et al. 2005

Electroanalysis

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The effect of 30 phenols and anilines on typical Ru complex electrochemiluminescence (ECL) was systematically investigated under different conditions. It was found that all the tested compounds showed an ECL inhibiting signal. The magnitude of ECL inhibition was related to the position of the substituting group in the benzene ring and decreased in the following order: meta-> ortho-> para-. The oxidation potential of the tested compounds, the ECL spectra and UV-visible absorption spectra of Ru(bpy) 2þ 3 /tripropylamine (TPrA) in the presence of phenols and anilines, and the direct ECL between Ru(bpy) 2þ 3 and phenols/aniline were studied. The mechanism of ECL inhibition has been proposed due to energy transfer from the excited state Ru(bpy) system, respectively.

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Section: Mechanistic Discussionmentioning

confidence: 99%

Inhibition of Ru Complex Electrochemiluminescence by Phenols and Anilines

Cui

Shi

et al. 2005

Electroanalysis

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“…[20] Detailed insight into the thermal conversion of phenol/ phenoxy is a prerequisite for understanding the behaviour of (poly)chlorinated analogues. The latter are demonstrated precursors of the notorious family of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), (often toxic) by-products of the combustion and other thermal processes involving chlorine-containing materials.…”

Section: Scheme 1 Formation Of Dibenzofuran Through the Dimerisationmentioning

confidence: 99%

Products, Rates, and Mechanism of the Gas-Phase Condensation of Phenoxy Radicals between 500-840 K

Wiater¹,

Born

Louw

2000

Eur. J. Org. Chem.

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Phenols are demonstrated precursors of “dioxins” ‐ polychlorinated dibenzo‐p‐dioxins (DDs) and dibenzofurans (DFs) ‐ in thermal processes, especially incineration. Heterogeneous catalysis, depending on conditions, can play an important role, but mere gas‐phase combination of phenolic entities to ultimately DD and/or DF is always possible. The present paper addresses the fundamental role of phenol itself. Phenol has long been known to give DF upon pyrolysis and in similar thermal reactions. In the liquid phase under oxidative conditions it yields five condensation products (A‐E); this clearly occurs through the dimerization of two phenoxy (PhO) radicals, followed by enolisation/rearomatisation. Our study shows that in the gas phase, at the lower T end, such dimers are also formed, but still with very little DF. That DF, indeed, is almost the only condensation product at elevated temperatures is substantiated by thermochemical‐kinetic analysis (favouring the pathway of ortho‐C/ortho‐C combination of two PhO radicals), as well as by results obtained with two plausible intermediates, viz. 2,2′‐dihydroxybiphenyl (A) and 2‐phenoxyphenol (C). Mechanisms for the requisite enolisation and dehydration steps leading to DF are discussed.

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“…At pH 2 11 .O, there were two absorption bands (350 and 415 nm), and purpurogallin was further oxidized. Phloroglucinol had an absorption band at 275 nm at pH 8.0, and phloroglucinol dissociated partly to monodeprotonated anion (15,16). At pH 1 11.0, there were two absorption bands at 250 and 350 nm, and phloroglucinol existed in keto-dianion form (l5, 16).…”

Section: Uv-visible Absorption Spectramentioning

confidence: 99%

Effect of pH on Inhibition and Enhancement of Luminol–H2O2–Co2+ Chemiluminescence by Phenolic Compounds and Amino Acids

Cui

Shi

Rong

et al. 2004

Photochem Photobiol

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The effect of pH on inhibition and enhancement of luminol-H2O2-Co2+ chemiluminescence (CL) by 18 phenolic compounds and 20 amino acids was studied. It was found that most of the tested compounds showed an inhibiting effect at lower pH and an enhancing effect at higher pH. At a midrange pH, for some phenolic compounds with two ortho-position -OH, both an inhibiting and an enhancing peak were simultaneously observed. UV-visible spectra of the tested phenolic compounds at different pH values were studied. The mechanism for CL inhibition and enhancement was proposed. It is likely that the competition of the -OH or the -NH2 group and other reducing groups in the molecules with luminol for O2*- led to the CL inhibition. A reaction of -COO(-) and quinone or ketone formed by phenolic compounds at higher pH via deprotonation with O2*- also resulted in the CL enhancement.

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Free radical induced oxidation of phloroglucinol. A pulse radiolysis and EPR study

Cited by 36 publications

References 34 publications

Inhibition of Ru Complex Electrochemiluminescence by Phenols and Anilines

Inhibition of Ru Complex Electrochemiluminescence by Phenols and Anilines

Products, Rates, and Mechanism of the Gas-Phase Condensation of Phenoxy Radicals between 500-840 K

Effect of pH on Inhibition and Enhancement of Luminol–H2O2–Co2+ Chemiluminescence by Phenolic Compounds and Amino Acids

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