118-75-2Relevant articles and documents
Oxidation using [bis(trifluoroacetoxy)]iodobenzene: A new and potentially practical approach to detection of polychlorinated phenols
Saby, Coralie,Luong, John H. T.
, p. 1197 - 1198 (1997)
A novel oxidation for pentachlorophenol, 2,4,6-trichlorophenol and 2,3,5,6-tetrachlorophenol using [bis-(trifluoroacetoxy)]iodobenzene has been developed, and the oxidation products from pentachlorophenol and 2,3,5,6-tetrachlorophenol have been identified as tetrachloro-1,4-benzoquinone; this novel reaction can be applied in electrochemistry using glucose oxidase for sensitive determination and identification of PCP, one of the most toxic polychlorinated phenols.
The chlorination of anthranilic acid.
ATKINSON,MITTON
, p. 3142 - 3142 (1947)
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Activation of electron transfer reduction of p-benzoquinone derivatives by intermolecular regioselective hydrogen bond formation
Fukuzumi, Shunichi,Kitaguchi, Hironori,Suenobu, Tomoyoshi,Ogo, Seiji
, p. 1984 - 1985 (2002)
Electron transfer reduction of p-benzoquinones by cobalt tetraphenylporphyrin is enhanced significantly by the presence of o-bis(phenylcarbamoylmethyl)benzene (o-L) due to the regioselective hydrogen bond formation between the corresponding semiquinone ra
Coexistence of Hydrogen Atom Transfer Reactions through and not through Triplet Ion Pair between p-Chloranil and Durene
Kobashi, Harumichi,Funabashi, Masa-aki,Kondo, Tomoyuki,Morita, Toshifumi,Okada, Tadashi,Mataga, Noboru
, p. 3557 - 3565 (1984)
Mechanism of hydrogen atom abstraction reactions by triplet state p-chloranil (3CA) from durene (DH) were studied by picosecond and nanosecond laser photolysis and transient photoconductivity measurements. 3CA was quenched by DH through diffusional encounter to form a triplet ion pair (IP) between CA and DH, p-chloranil semiquinone radical (CAH.), and 2,4,5-trimethylbenzyl radical (D.).Ionic dissociation of IP was observed in 1,2-dichloroethane (DCE) as well as in acetonitrile.However, no transient species was observed by direct excitation of a charge-transfer (CT) band of the electron donor-acceptor (EDA) complex between CA and DH.The H-atom transfer leading to production of CAH. was found to proceed through two distinct mechanisms; H-atom transfer via IP (Mechanism I) and a more rapid transfer competing with IP formation (Mechanism II).The quantum yields of CAH. produced by Mechanism I and II and the first-order rate constants for proton transfer, ionic dissociation, and intersystem crossing competing with one another in the IP state were estimated to be (0.1 and 0.2) and (2,5, and 13)X106 s-1, respectively, in DCE at room temperature.
Peroxidase-Catalyzed Oxidation of Pentachlorophenol
Samokyszyn, Victor M.,Freeman, James P.,Maddipati, Krishna Rao,Lloyd, Roger V.
, p. 349 - 355 (1995)
Pentachlorophenol (PCP) was shown to function as a reducing substrate for horseradish peroxidase (HRP) and to stimulate the HRP-catalyzed reduction of 5-phenyl-4-penten-1-yl hydroperoxide (PPHP) to 5-phenyl-4-penten-1-ol. HRP catalyzed the hydroperoxide-dependent oxidation of PCP, using H2O2, PPHP, or ethyl hydroperoxide as substrates, as evidenced by UV spectroscopic and reverse phase HPLC analysis of reaction mixtures. The major oxidation product was tetrachloro-1,4-benzoquinone which was identified on the basis of electronic absorption spectroscopy, mass spectrometry, and cochromatography with authentic standard. HRP-catalyzed oxidation of PCP yielded relatively stable, ESR-detectable pentachlorophenoxyl radical intermediates whose ESR spectra consisted of a symmetrical single line without hyperfine structure. Substitution of natural abundance isotopically-labeled PCP with 13C-labeled PCP resulted in broadening of the ESR signal line width from 6.1 G to 13.5 G. ESR spin trapping studies, with α-(1-oxy-4-pyridyl)-N tert-butylnitrone (4-POBN) as the spin trap demonstrated identical spectra using natural abundance isotopically-labeled PCP versus 13C-labeled PCP, suggesting oxyl addition, rather than carbon-centered radical addition to 4-POBN. The computer simulation of the observed spectra is consistent with two distinct 4-POBN adducts, with relative abundances of ca. 3:1, and hyperfine coupling constants of aN = (14.61 G)/aH = 1.83 G and aN = (14.76 G)/aH = 5.21 G, respectively. Mechanisms for the hydroperoxide-dependent, HRP-catalyzed oxidation of PCP are presented that are consistent with these results.
Substrate recycling scheme for tetrachloro-p-benzoquinone using bilirubin oxidase and NADH: Application for pentachlorophenol assay
Cybulski, David,Male, Keith B.,Scharer, Jeno M.,Moo-Young, Murray,Luong, John H. T.
, p. 796 - 800 (1999)
A novel assay for tetrachloro-p-benzoquinone (TCBQ), the main oxidation product of pentachlorophenol (PCP), was developed using bilirubin oxidase (BOX) in the presence of excess NADH. TCBQ was easily and rapidly reduced by NADH to 1,4-tetrachlorohydroquinone (TCHQ), which was then recycled back to TCBQ by the enzyme. BOX exhibited no reactivity toward NADH while its catalytic activity for the oxidation of TCHQ was very high. Under an optimized condition (250 μM NADH, 0.3 U/mL BOX, and 25 mM sodium phosphate at pH 5.5), the rate of NADH consumption determined by measuring the absorbance decrease at 340 nm yielded a detection limit for TCBQ of 110 nM. Fluorescence detection of the NADH using a lower enzyme concentration (0.1 U/mL) with excitation and emission wavelengths of 345 and 450 nm, respectively, allowed for a TCBQ detection limit of 30 nM. PCP was oxidized to TCBQ with high yield using bis(trifluoroacetoxy)iodobenzene in 0.05 M trichloroacetic acid. Coupling this oxidation reaction to the BOX/NADH assay attained PCP detection limits of 170 and 50 nM using absorbance and fluorescence measurements, respectively. When tested on PCP-contaminated soil samples, the BOX assay compared very well with HPLC measurements. Chlorophenols constitute a major group of pollutants having been widely used as wood preservatives, pesticides, and herbicides. They are also formed as byproducts of many industrial activities including chlorination of potable water and paper bleaching. A novel assay for tetrachloro-p-benzoquinone (TCBQ), the main oxidation product of pentachlorophenol (PCP), was developed using bilirubin oxidase (BOX) in the presence of excess NADH. TCBQ was easily and rapidly reduced by NADH to 1,4-tetrachlorohydroquinone (TCHQ), which was then recycled back to TCBQ by the enzyme. BOX exhibited no reactivity toward NADH while its catalytic activity for the oxidation of TCHQ was very high. Under an optimized condition (250 μM NADH, 0.3 U/mL BOX, and 25 mM sodium phosphate at pH 5.5), the rate of NADH consumption determined by measuring the absorbance decrease at 340 nm yielded a detection limit for TCBQ of 110 nM. Fluorescence detection of the NADH using a lower enzyme concentration (0.1 U/mL) with excitation and emission wavelengths of 345 and 450 nm, respectively, allowed for a TCBQ detection limit of 30 nM. PCP was oxidized to TCBQ with high yield using bis(trifluoroacetoxy)iodobenzene in 0.05 M trichloroacetic acid. Coupling this oxidation reaction to the BOX/NADH assay attained PCP detection limits of 170 and 50 nM using absorbance and fluorescence measurements, respectively. When tested on PCP-contaminated soil samples, the BOX assay compared very well with HPLC measurements.
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Shteingarts,V.D. et al.
, p. 1264 - 1265 (1969)
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Pollak,Gebauer-Fluenegg
, p. 115,537 (1926)
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Kinetics of photodegradation and ozonation of pentachlorophenol
Benitez, F. Javier,Acero, Juan L.,Real, Francisco J.,Garcia, Juan
, p. 651 - 662 (2003)
The oxidation of 2,3,4,5,6-pentachlorophenol (PCP) has been carried out by a photodecomposition process using a polychromatic UV irradiation, and by an ozonation process. In the photodegradation process, the pH accelerated the decomposition rate and the approximate first-order rate constants were evaluated, with values between 0.16 ± 0.005 min-1 at pH = 3 and 0.26 ± 0.007 min-1 at pH = 9. A more rigorous kinetic study led to the determination of the quantum yields of the reaction, with values of 200 ± 7 x 10-3 mol/Eins for pH = 3 and 22 ± 1.1 x 10-3 mol/Eins for pH = 9. In the ozonation process, the rate constants for the reaction between ozone and PCP were determined by means of a competition kinetics, with values in the range from 0.67 x 105 to 314 x 105 l/mol s. The specific rate constants for the un-dissociated and dissociated forms of PCP were also calculated. Finally, in both processes, the intermediate reaction products were identified, the most important being tetrachlorocatechol, tetrachlorohydroquinone and tetra-p-chlorobenzoquinone. Free chloride ion released, which was favored at high pHs, was also followed in both processes.
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Hofmann,A. W.
, p. 62 (1844)
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GEOMETRIC FACTOR IN PHOTOTROPIC REACTIONS OF NEUTRAL AND CHARGED RADICALS
Petrushenko, K. B.,Vokin, A. I.,Turchaninov, V. K.
, p. 23 - 26 (1989)
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Optimization and characterization of a flow injection electrochemical system for pentachlorophenol assay
Male, Keith B.,Saby, Coralie,Luong, John H. T.
, p. 4134 - 4139 (1998)
A flow injection (FI) electrochemical detection system has been developed and optimized for the determination of pentachlorophenol (PCP) in contaminated soil. PCP was oxidized to tetrachloro-1,4-benzoquinone (1,4- TCBQ) with a high yield using bis(trifluoroacetoxy)iodobenzene in 0.1 M tartaric acid, pH 2.0, at ambient temperature. Upon rapid reaction with immobilized glucose oxidase, the detection and amplification scheme was completed as the reduced form of 1,4-TCBQ or tetrachloro-1,4-hydroquinone was reoxidized to 1,4-TCBQ at the surface of the glassy carbon electrode (+ 0.40 V vs Ag/AgCl). Rapid electron exchange between the enzyme and its glucose substrate provided a non-rate-limiting current toward the electrode. The FI electrochemical system was linear up to 1 μM oxidized PCP with a detection limit of 10 nM and exhibited a reproducibility of ±0.6% over 165 repeated analyses during 14 h of continuous operation. When applied to PCP- contaminated soil samples, the results obtained from the FI electrochemical system compared well with those of the HPLC standard method.
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Luebbecke,Boldt
, p. 1577 (1978)
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Substituent effects in oxime radical cations. 1. Photosensitized reactions of acetophenone oximes
De Lijser, H.J. Peter,Kim, Jason S.,McGrorty, Suzanne M.,Ulloa, Erin M.
, p. 575 - 585 (2003)
A variety of ortho-, meta-, and para-substituted (-H, -F, -Cl, -CF 3, -CN (meta and para only), -CH3, -OCH3, and -NO2) acetophenone oximes were synthesized and studied using laser flash photolysis (LFP) and steady-state photolysis experiments in acetonitrile with chloranil as the photosensitizer. In addition, semi-empirical (AM1) calculations were performed on the neutral species, the radical cations, and the corresponding iminoxyl radicals. The data was analyzed in terms of the electrochemical peak potentials of the oximes, the quenching rates of triplet chloranil (LFP), the calculated ionization potentials, and the measured conversions of the oximes in the steady-state photolysis experiments. Photolysis of the oximes in the presence of chloranil results in the formation of the chloranil radical anion, which reacts rapidly with the oxime radical cation to form the semiquinone radical and an iminoxyl radical. Evidence for the formation of the chloranil radical anion and the semiquinone radical was obtained from LFP studies. The measured quenching rates from the LFP studies represent the rates of electron transfer from the oximes to triplet chloranil. This data was correlated to various radical and polar substituent constants. The Hammett studies suggest that steric, polar, and radical effects are important for ortho-substituted acetophenone oximes, polar effects are important for parasubstituted oximes, and radical stabilization is more important than polar effects for the meta-substituted substrates. The calculated ionization potentials of the oximes show an excellent correlation with the measured quenching rates supporting the electron transfer pathway. On the basis of calculated charge densities, we conclude that the measured substituent effects are transition state effects rather than ground state effects. At this point all of the available data suggests that the conversion of the oximes is controlled by two energetically opposing reactions, namely oxidation of the neutral oxime, which is favorable for oximes with electron-donating substituents, and deprotonation of the oxime radical cation, which is favorable for oximes with electron-withdrawing substituents. The overall result is a reaction with little selectivity as far as substituent effects are concerned.
Photochemical mechanisms responsible for the versatile application of naphthalimides and naphthaldiimides in biological systems
Aveline, Béatrice M.,Matsugo, Seiichi,Redmond, Robert W.
, p. 11785 - 11795 (1997)
Despite the number and variety of their biological applications, the mechanisms of action of the photoactive naphthalenic imides have not yet been fully elucidated. In order to provide mechanistic insight, the photochemistry of several N-substituted 1,8-naphthalimides (NT) and 1,4,5,8-naphthaldiimides (NDI) has been studied using absorption and fluorescence spectroscopy and by laser flash photolysis (λ(exc) = 355 nm). The lowest singlet state (S1) is mainly ππ* in nature for NI whereas nπ* character predominates for the NDI. This difference exerts a profound effect on subsequent reaction mechanisms: upon irradiation, only the NDI molecules can undergo intramolecular γ hydrogen abstraction. In the case of NP-III, a bishydroperoxy NDI derivative, this photoprocess (Φ = 0.03) leads to concomitant formation of an oxygen-centered radical (ε = 21,600 M-1 cm-1 at 465 nm in acetonitrile) and release of the hydroxyl radical (.OH). All the compounds studied produce the triplet state (in acetonitrile, ε(T) ~ 10,500-11,500 M-1 cm-1 at 470 nm for NI and 485 nm for NDI). The quantum yield of intersystem crossing was determined to be close to unity except where intramolecular γ hydrogen abstraction was possible (Φ(isc) 0.8 for NI and > 0.5 for NDI). In the absence of quenchers, the triplet states react with the ground-state of starting material via electron-transfer with a high rate constant [k = (4-6) x 109 and 5 x 108 M-1 s-1 for NDI and NI, respectively] to give the radical anion and radical cation of the corresponding naphthalenic derivative. The high reactivity of the triplet states toward electron donors such as DABCO and their low ability for hydrogen abstraction are typical of a ππ* configuration. These mechanistic photochemistry results are discussed with regard to the photobiological effects observed for these compounds and show that the actual reaction leading to biological damage will depend on the microenvironment of the naphthalenic molecule.
Homolytic vs heterolytic C-H bond cleavage in alkylaromatic radical cations. Formation of diarylmethyl cation in the photoinduced electron transfer reaction of bis(4-methoxyphenyl)methane sensitized by chloranil [3]
Baciocchi,Del Giacco,Elisei,Lanzalunga
, p. 11800 - 11801 (1998)
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Generation and reactivity of the radical cations of coniferyl alcohol and isoeugenol in solution
Schepp,Rodriguez-Evora
, p. 799 - 806 (2003)
Nanosecond laser flash photolysis of coniferyl alcohol and isoeugenol in acetonitrile leads to the formation of transient species that are identified as the corresponding radical cations. These radical cations decay with rate constants of ca. 1 × 106 s-1 in dry acetonitrile. Both radical cations react rapidly with hydroxylic solvents like water and alcohols to give 4-vinylphenoxyl radicals, indicating that these reagents behave as bases rather than nucleophiles. In addition, anionic reagents (acetate, cyanide, and chloride) react rapidly with the radical cations with second-order rate constants that are close to diffusion controlled. The main products generated in the presence of the anionic reagents are again the 4-vinylphenoxyl radicals, suggesting that these reagents also behave as bases. The lifetime of the radical cations in acidic acetonitrile was found to increase dramatically due to a shift in the radical cation - vinyl phenoxyl radical acid-base equilibrium to the side of the radical cation. An estimate of the pKa of the radical cation in acetonitrile of 4.0 was obtained from the data.
Synthesis of 2,4-Diarylquinoline Derivatives via Chloranil-Promoted Oxidative Annulation and One-Pot Reaction
Cheng, Dongping,Pu, Yueqi,Shen, Jing,Xu, Xiaoliang,Yan, Jizhong,Yan, Xianhang
supporting information, p. 1833 - 1840 (2020/06/08)
An oxidative annulation for the synthesis of 2,4-diarylquinolines from o -allylanilines is disclosed that uses recyclable reagent Chloranil as the oxidant. The corresponding products are obtained in moderate to excellent yields. Furthermore, a one-pot access to 2,4-di aryl quinolines from easily available anilines and 1,3-diarylpropenes is described as a highly atom-efficient protocol that involves oxidative coupling, rearrangement, and oxidative annulation.
Synthetic method for ethyleniminoquinone drug intermediate chloranil
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Paragraph 0013; 0018; 0019; 0022; 0023; 0024; 0026; 0027, (2018/07/30)
The invention discloses a synthetic method for the ethyleniminoquinone drug intermediate chloranil. The synthetic method comprises the following steps: adding 2,3,5,6-tetrachloro-1,4-dimethoxybenzeneand a potassium chloride solution into a reaction vessel, controlling a solution temperature, adding aluminum acetylacetonate powder in batches, controlling a stirring speed and carrying out a reaction; and adding a tributyl borate solution, raising the temperature, then adding a sodium nitrate solution, carrying out a reaction, subjecting the obtained solution to layering, lowering the temperature, carrying out washing with a hexyl ether solution a plurality of times, then carrying out washing with a 3-methylpyridine solution a plurality of times, then carrying out recrystallization in a chloroacetyl chloride solution, and carrying out dehydration with a dehydrating agent so as to obtain the finished chloranil.
