- Transformation of Aromatic Compounds under the Action of the Basidiomycetes Phanerochaete sanguinea and Coriolus villosus
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The pathways of the transformation of some aromatic compounds by the basidiomycetes Phanerochaete sanguinea and Coriolus villosus have been studied.It has been shown that the degradation of these compounds has an oxidative nature and depends on the type of substituents in the benzene ring and the propane chain.A differencew has been found in the mechanisms of the reactions of the two fungi that is a consequence of the different compositions of their enzyme complexes.
- Medvedeva, S. A.,Volchatova, I. V.,Babkin, V. A.,Antipova, I. A.,Kanitskaya, L. V.,et al.
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- Catechol 2,3-dioxygenase from Pseudomonas sp. strain ND6: Gene sequence and enzyme characterization
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The catechol 2,3-dioxygenase (C23O) gene in naphthalene catabolic plasmid pND6-1 of Pseudomonas sp. ND6 was cloned and sequenced. The C23O gene was consisted of 924 nucleotides and encoded a polypeptide of molecular weight 36 kDa containing 307 amino acid residues. The C23O of Pseudomonas sp. ND6 exhibited 93% and 89% identities in amino acid sequence with C23Os encoded by naphthalene catabolic plasmid NAH7 from Pseudomonas putida G7 and the chromosome of Pseudomonas stutzeri AN10 respectively. The Pseudomonas sp. ND6 C23O gene was overexpressed in Escherichia coli DH 5α using the lac promoter of pUC18, and its gene product was purified by DEAE-Sephacel and Phenyl-Sepharose CL-4B chromatography. The enzymology experiments indicated that the specific activity and thermostability of C23O from Pseudomonas sp. ND6 were better than those of C23O from Pseudomonas putida G7.
- Jiang, Yun,Yang, Xianglong,Liu, Bin,Zhao, Huabing,Cheng, Qiuxiang,Cai, Baoli
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- KINETICS AND MECHANISM OF THE REACTION OF OZONE WITH PHENOL IN ALKALINE MEDIA
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The kinetics of the reaction of O3 with PhOH in alkaline medium has been studied.The rate of oxidation of phenol by ozone is directly proportional to the concentrations of reactants and increases in a complex manner with increase in alkali content in aque
- Konstantinova, M. L.,Razumovskii, S. D.,Zaikov, G. E.
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- An isolated Candida albicans TL3 capable of degrading phenol at large concentration
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An isolated yeast strain was grown aerobically on phenol as a sole carbon source up to 24 mM; the rate of degradation of phenol at 30°C was greater than other microorganisms at the comparable phenol concentrations. This microorganism was further identified and is designated Candida albicans TL3. The catabolic activity of C. albicans TL3 for degradation of phenol was evaluated with the Ks and Vmax values of 1.7 ± 0.1 mM and 0.66 ± 0.02 μmol/min/mg of protein, respectively. With application of enzymatic, chromatographic and mass-spectrometric analyses, we confirmed that catechol and cis,cis-muconic acid were produced during the biodegradation of phenol performed by C. albicans TL3, indicating the occurrence of an ortho-fission pathway. The maximum activity of phenol hydroxylase and catechol-1,2-dioxygenase were induced when this strain grew in phenol culture media at 22 mM and 10 mM, respectively. In addition to phenol, C. albicans TL3 was effective in degrading formaldehyde, which is another major pollutant in waste water from a factory producing phenolic resin. The promising result from the bio-treatment of such factory effluent makes Candida albicans TL3 be a potentially useful strain for industrial application.
- Tsai, San-Chin,Tsai, Li-Duan,Li, Yaw-Kuen
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- Synthesis of muconic acids peracetic acid oxidation of catechols
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Monomeric and dimeric muconic acids were prepared in 30-83% yield by oxidation of catechols with peracetic acid in acetic acid.
- McKague, A. Bruce
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- Monitoring of phenol photodegradation by ultraviolet spectroscopy
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Advanced oxidation processes (AOPs) have been developed as an emerging technology for hazardous organic treatment in industrial wastewater. In this paper, the contribution of ultraviolet (UV) spectroscopy to follow phenol photodegradation was studied in a laboratory photochemical reactor equipped with a low pressure mercury lamp. It has been observed that a multicomponent approach is efficient for the evolution estimation of the initial product or intermediate compounds formed during the photodegradation.
- Roig, Benoit,Gonzalez,Thomas
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- Investigation of acid-base catalysis in the extradiol and intradiol catechol dioxygenase reactions using a broad specificity mutant enzyme and model chemistry
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The extradiol and intradiol catechol dioxygenase reaction mechanisms proceed via a common proximal hydroperoxide intermediate, which is processed via different Criegee 1,2-rearrangements. An R215W mutant of extradiol dioxygenase MhpB, able to produce a mi
- Brivio, Michela,Schlosrich, Janne,Ahmad, Mark,Tolond, Caroline,Bugg, Timothy D. H.
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- High-yield production of cis,cis-muconic acid from catechol in aqueous solution by biocatalyst
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A fed-batch process was used to produce cis,cis-muconic acid from catechol by recombinant Escherichia coli cells expressing the catA gene, which encodes the Pseudomonas putida mt-2 catechol 1,2-dioxygenase responsible for catalyzing ortho-cleavage of catechol, as biocatalysts. We succeeded in producing 415mM (59.0 g L-1) cis,cis-muconic acid in aqueous solution without generation of by-products in 12 h under the optimal conditions with successive addition of 10mM catechol. The molar conversion yield based on the amount of consumed catechol was the theoretical value of 100% (mol mol-1).
- Kaneko, Aya,Ishii, Yoshitaka,Kirimura, Kohtaro
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- Cloning and functional analysis of aniline dioxygenase gene cluster, from Frateuria species ANA-18, that metabolizes aniline via an ortho-cleavage pathway of catechol.
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Genes encoding an aniline dioxygenase of Frateuria sp. ANA-18, which metabolizes aniline via the ortho-cleavage pathway of catechol, were cloned and named tdn genes. The tdn genes were located on the chromosomal DNA of this bacterium and weren't clustered with catechol-degrading gene clusters. These results show that the ANA-18 aniline-degrading gene cluster is constructionally different from Pseudomonas tdn and Acinetobacter atd gene clusters, which degrade aniline via the meta-cleavage pathway of catechol and organize catechol-metabolic genes in the gene clusters. When cloned tdnQTA1A2B genes were expressed in Eschherichia coli, aniline dioxygenase activity was observed. Southern blot analysis revealed that homologues of the tdnA1A2B genes didn't exist in strain ANA-18. Disruption of the tdnA1A2 genes gave the parent strain ANA-18 a defect in aniline metabolism. On the basis of these results, we concluded that only the cloned tdn genes function as genes encoding aniline dioxygenase in strain ANA-18 although this bacterium had two catechol-degrading gene clusters.
- Murakami, Shuichiro,Hayashi, Teruhiko,Maeda, Tetsuya,Takenaka, Shinji,Aoki, Kenji
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- An EPR, thermostability and pH-dependence study of wild-type and mutant forms of catechol 1,2-dioxygenase from Acinetobacter radioresistens S13
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Intradiol dioxygenase are iron-containing enzymes involved in the bacterial degradation of natural and xenobiotic aromatic compounds. The wild-type and mutants forms of catechol 1,2-dioxygenase Iso B from Acinetobacter radioresistens LMG S13 have been investigated in order to get an insight on the structure-function relationships within this system. 4K CW-EPR spectroscopy highlighted different oxygen binding properties of some mutants with respect to the wild-type enzyme, suggesting that a fine tuning of the substrate-binding determinants in the active site pocket may indirectly result in variations of the iron reactivity. A thermostability investigation by optical spectroscopy, that reports on the state of the metal center, showed that the structural stability is more influenced by the type rather than by the position of the mutation. Finally, the influence of pH and temperature on the catalytic activity was monitored and discussed in terms of perturbations induced on the tertiary contact network of the enzyme. Springer Science+Business Media New York 2013.
- Caglio, Raffaella,Pessione, Enrica,Valetti, Francesca,Giunta, Carlo,Ghibaudi, Elena
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- Study of the paracetamol degradation pathway that generates color and turbidity in oxidized wastewaters by photo-Fenton technology
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This study aims determining the effect that certain kind of water contaminants have on the changes of turbidity during their oxidation. Phenol is considered by its frequent presence in industrial discharges; meanwhile paracetamol is representative of emerging pollutants of pharmaceutical origin. Quite different results are observed in the turbidity changes during the oxidation of both pollutants that evolve following the kinetics of a reaction intermediate. The analysis of paracetamol and phenol degradation pathways reveals that operating conditions are important in the formation of intermediates that cause turbidity. The maximum turbidity levels are achieved operating at the ratios 12?mol HO? per 100?mg contaminant. However the turbidity generated during the paracetamol oxidation only reaches a third of the intensity achieved with phenol. During the paracetamol degradation, the intermediates causing turbidity are similar to the ones found during the phenol decomposition. These species are generated during the initial minutes of oxidation and possess structures of large size and molecular weight. At the máximum turbidity point, muconic acid and hydroquinone are identified and found to coexist with other compounds such as pyrogallol and resorcinol. Therefore, the path involving metasubstitution would be the main originator of turbidity. It is noteworthy the rapid formation of muconic acid that coexists with resorcinol-like species. These compounds enable the establishment of hydrogen bond interactions that yield supramolecular structures.
- Villota, Natalia,Lomas, Jose M.,Camarero, Luis M.
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- Oxidation of catechol and of 2,6-di-tert butylphenol by dioxiranes
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In a biomimetic transformation, the selective oxidation of catechol (2) to Z,Z-muconic acid (3) has been achieved under extremely mild conditions using methyl(trifluoromethyl)dioxirane (1b). Both dioxirane 1b and dimethyldioxirane (1a) have been applied to the oxidation of 2,6-di-tert-butylphenol (4); the product natures suggest the incursion of radical pathways.
- Altamura,Fusco,D'Accolti,Mello,Prencipe,Curci
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- Mechanism of the Fe(III)-Catalyzed Peracetic Acid Oxidation of Catechol. A Biomimetic Reaction for Pyrocatechase
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The Fe(III)-catalyzed peracetic acid (HOOAc) oxidation of catechol to cis,cis-muconic acid (MA) is proposed as a model for the action of the Fe(III)-containing dioxygenase pyrocatechase (catechol 1,2-dioxygenase).The yield of MA is a function of the reaching a maximum of 75 percent when the ratio / is 1000.No appreciable quantity of MA is formed in the absence of Fe(III).Evidence is presented that implicates peracetic acid and hydrogen peroxide as the active oxidants and o-benzoquinone as an intermediate in the reaction.Substrate binding to Fe(III) represents an important part of the reaction.The proposed mechanism for the model involves formation of an Fe(III)-catechol complex which is oxidized to an Fe(III)-o-benzoquinone species.The Fe(III)-quinone complex then undergoes nucleophilic attack at carbonyl by H2O2 to give a peroxide addition product which undergoes intramolecular nucleophilic addition at the adjacent carbonyl to give a dioxetane intermediate.Spontaneous opening of the dioxetane gives MA.
- Pandell, Alexander J.
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- Ionization Shifts in 1H-NMR Spectra of α,β-Unsaturated Carboxylic Acids
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Changes in chemical shifts of olefinic protons in a number of α,β- and α,β,γ,δ-unsaturated carboxylic acids caused by ionization of the COOH group were investigated.The ionization shifts of α-H-atoms are -0.09 to 0.07 ppm, those of β-H-atoms are 0.32-0.47 ppm.The ionization shifts of δ-H-atoms are substantially larger than those of γ-H-atoms.The ionization shifts can be used for immediate determination of the esterification site in monoesters of (2E,4Z)-2,4-hexadienedioic (muconic) acid, which are of interest in connection with synthetic studies on verrucarins.Thus, isomerization by heating in aqueous solution of monoesters of (2Z,4Z)-2,4-hexadienedioic acid yields 1-monoesters rather than 6-monoesters of (2E,4Z)-2,4-hexadienedioic acid, in accordance with the isomerization mechanism involving anchimeric assistance of the free COOH group.Solutions of the ABXY spectra of olefinic protons of monomethyl (2E,4E)- and (2Z,4Z)-2,4-hexadienedioate are reported.
- Jaroszewski, Jerzy W.,Grossen, Peter,Mohr, Peter,Tamm, Christoph
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- Multi-Enzymatic Cascade Reactions for the Synthesis of cis,cis-Muconic Acid
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Lignin valorization allows the generation of a number of value-added products such as cis,cis-muconic acid (ccMA), which is widely used for the synthesis of chemicals for the production of biodegradable plastic materials. In the present work, we reported the first multi-enzymatic, one-pot bioconversion process of vanillin into ccMA. In details, we used four sequential reactions catalyzed by xanthine oxidase, O-demethylase LigM (and the tetrahydrofolate-regeneration enzyme methyl transferase MetE), decarboxylase AroY (based on the use of E. coli transformed cells) and catechol 1,2-dioxygenase CatA. The optimized lab-scale procedure allowed to reach, for the first time, the conversion of 5 mM vanillin into ccMA in ～30 h with a 90% yield: this achievement represents an improvement in terms of yields and time when compared to the use of a whole-cell system. This multi-enzymatic system represents a sustainable alternative for the production of a high value added product from a renewable resource. (Figure presented.).
- Di Nardo, Giovanna,Gazzola, Silvia,Gilardi, Gianfranco,Pollegioni, Loredano,Rosini, Elena,Valetti, Francesca,Vignali, Elisa
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p. 114 - 123
(2021/10/07)
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- Sustainable oxidative cleavage of catechols for the synthesis of muconic acid and muconolactones including lignin upgrading
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Muconic acid and muconolactones are attracting high interest as platform molecules for the synthesis of a variety of compounds, especially in the domain of materials. Although several technologies have been described for their synthesis, there is still a lack of performance, especially regarding green chemistry principles. In this study, we describe the development of an optimized catechol oxidative cleavage to muconic acid using performic acid in an intriguingly safe fashion. Common iron salts were used as catalysts to a level as low as 0.005 mol%, for a maximum turnover number of 13?200. Maximum muconic acid yield reached 84% after isolation by simple filtration. This procedure optimized on catechol was also efficient over a wide range of substituted catechols, providing access to muconolactones in a domino reaction. Noticeably, biobased catechols produced by a proven technology of lignin depolymerization were cleaved into muconolactones of high functional value. Applying this supplementary cleavage step to catechols obtained by lignin depolymerization was thus an ultimate way to maximize the economical value created from lignin. In contrast to other studies, lignin was not only depolymerized, but also depolymerization products were further transformed to take as much value from biomass as possible.
- Coupé, Florentin,Petitjean, Laurène,Anastas, Paul T.,Caijo, Frédéric,Escande, Vincent,Darcel, Christophe
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supporting information
p. 6204 - 6211
(2020/10/18)
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- A cobalt-substituted Keggin-Type polyoxometalate for catalysis of oxidative aromatic cracking reactions in water
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Efficient detoxification of harmful benzene rings into useful carboxylic acids in water is indispensable for achieving a clean water environment. We report herein that oxidative aromatic cracking (OAC) reactions in water were achieved using a catalytic system with a cobalt-substituted Keggin-Type polyoxometalate (Co-POM) as a catalyst, an Oxone monopersulfate compound as a sacrificial oxidant and sodium bicarbonate as an additive under mild conditions. Sodium bicarbonate plays a crucial role in the selective OAC reactions by Co-POM using ethylbenzenesulfonate as a model substrate. The reactive species was characterized to be a cobalt(iii)-oxyl species based on 31P NMR, UV-vis spectroscopic, kinetic, and theoretical analyses. The electrophilicity of the cobalt(iii)-oxyl species was demonstrated by a linear relationship with a negative slope in the Hammett plots of initial rates obtained from the OAC reactions of m-xylenesulfonate derivatives. Besides, we have verified the degradation pathway of the OAC reactions using benzene as a model substrate in the catalytic system. The degradation was initiated by an electrophilic attack of the cobalt(iii)-oxyl species on benzene to yield phenol followed by producing catechol, muconic acid, maleic/fumaric acid, tartaric acid derivatives and formic acid on the basis of 1H NMR spectroscopic analysis.
- Hong, Dachao,Kitagawa, Yasutaka,Kon, Yoshihiro,Shimoyama, Yoshihiro,Tamura, Satoru
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p. 8042 - 8048
(2020/12/28)
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- Sustainable production of dimethyl adipate by non-heme iron(iii) catalysed oxidative cleavage of catechol
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Adipic acid and its esters are important bulk chemicals whose principal use is in the production of the nylon-6,6 polymer. There is considerable interest in finding novel green routes from sustainable feedstocks towards these important intermediates. Herein, we describe the catalytic oxidative cleavage of catechol to muconic acids using a catalyst prepared in situ from iron(iii) nitrate, tris(2-pyridylmethyl)amine and ammonium acetate. An investigation of catalyst loading, temperature and oxygen pressure, allowed a turnover frequency of 120 h-1 to be obtained. The subsequent hydrogenation and transesterification of the obtained muconic acid products were shown to proceed well over commercially available supported catalysts. After vacuum distillation, dimethyl adipate could be isolated in 62% yield from catechol, thus demonstrating a green and sustainable route to this important bulk chemical.
- Jastrzebski, Robin,Van Den Berg, Emily J.,Weckhuysen, Bert M.,Bruijnincx, Pieter C. A.
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p. 2103 - 2109
(2015/04/14)
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- Methods for producing isomers of muconic acid and muconate salts
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A method for producing cis,trans- and trans,trans-isomers of muconate by providing cis,cis -muconate produced from a renewable carbon source through biocatalytic conversion; isomerizing cis,cis-muconate to cis,trans-muconate under reaction conditions in which substantially all of the cis,cis-muconate is isomerized to cis,trans -muconate; separating the cis,trans-muconate; and crystallizing the cis,trans-muconate. The cis,trans-isomer can be further isomerized to the trans,trans-isomer. In one example, the method includes culturing recombinant cells that express 3-dehydroshikimate dehydratase, protocatechuate decarboxylase and catechol 1,2-dioxygenase in a medium comprising the renewable carbon source and under conditions in which the renewable carbon source is converted to 3-dehydroshikimate by enzymes in the common pathway of aromatic amino acid biosynthesis of the cell, and the 3-dehydroshikimate is biocatalytically converted to cis,cis-muconate.
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Paragraph 0095
(2014/09/03)
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- Oxidative degradation of phenol by corona dielectric barrier discharge at gas-liquid interphase
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In this study, corona gas-liquid dielectric barrier discharge reactor for phenol degradation was investigated. The discharge was formed between two needle metal electrodes and an aqueous solution surface where the counter electrode was submerged and separated by a quartz dielectric tube. Effects of solution conductivity, pH and gas composition on the degradation were examined. Experimental results showed that the degradation of phenol proceeded perfectly in a wide range of solution conductivity. In the process of degradation of phenol, ozone was additionally formed. The removal of phenol increased with the order: argon air oxygen. Increasing pH was favorable for phenol removal. When using argon as the discharge gas, the major degradation products were catechol, hydroquinone, hydroxyhydroquinone, acetic acid, formic acid and oxalic acid. In oxygen or air discharges, 1,4-benzoquinone and muconic acid were additionally formed. The energy efficiency of removal of phenol has been compared with other competitive processes.
- Wang, Lei,Yu, Xin,Li, Guoxin,Li, Dailin
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p. 853 - 859
(2014/06/09)
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- Biodegradation of aromatic hydrocarbons and phenols by bacteria isolated from caspian waters and soils
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Experimental studies have been carried out on the degradability of monoaromatic hydrocarbons (benzene, toluene, and ethylbenzene) and phenols (phenol, pyrocatechol, hydroquinone, tetrachloropyro- catechol) by bacteria isolated from coastal waters and soil
- Veliev,Salmanov,Babashly,Alieva,Bektashi
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p. 426 - 430
(2014/02/14)
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- Catalytic oxidative cleavage of catechol by a non-heme iron(iii) complex as a green route to dimethyl adipate
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The catalyst system prepared in situ from iron(iii) salts, tris(2-pyridylmethyl)amine and a base readily catalyses the intradiol dioxygenation of pyrocatechol in methanol, to primarily afford the half-methyl ester of muconic acid. Dimethyl adipate is obtained by the subsequent, one-step catalytic hydrogenation/esterification, thus providing a green route to this important nylon precursor.
- Jastrzebski, Robin,Weckhuysen, Bert M.,Bruijnincx, Pieter C. A.
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supporting information
p. 6912 - 6914
(2013/07/26)
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- Catalytic properties of catechol 1,2-dioxygenase from Acinetobacter radioresistens S13 immobilized on nanosponges
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Catechol 1,2-dioxygenases are iron containing enzymes able to convert catechol into cis,cis-muconate, a precursor of the industrially important compound adipic acid. Catechol 1,2-dioxygenase from Acinetobacter radioresistens S13 was immobilized on β-cyclodextrins cross-linked with carbonate groups (nanosponges) with a yield of 29 mg of enzyme per gram of support. This support was chosen for its low cost and its ability to offer different types of interactions with the enzyme. The activity profiles at different pH and temperatures showed a shift of the optimal pH from 8.5, for the free protein, to 9.5, for the immobilized protein and, similarly, a shift in optimal temperature from 30 °C to 50 °C. The Michaelis-Menten constant, KM, increased from 2.0 ± 0.3 μM, for the free form, to 16.6 ± 4.8 μM for the immobilized enzyme, whereas the rate constant, kcat, values were found to be 32 ± 2 s-1 and 27 ± 3 s -1 for the free and immobilized forms respectively. The immobilization process also increased the thermostability of the enzyme with 60% residual activity after 90 min at 40 °C for the immobilized protein versus 20% for the free enzyme. A residual activity of 75% was found after 15 min at 60 °C for the immobilized enzyme while the free form showed a total loss of activity under the same conditions. The activity toward other substrates, such as 3- and 4-methylcatechol and 4-chlorocatechol, was retained by the immobilized enzyme. A small scale bioreactor was constructed and was able to convert catechol into cis,cis-muconic acid with high efficiency for 70 days. The Royal Society of Chemistry 2009.
- Di Nardo, Giovanna,Roggero, Carlo,Campolongo, Simona,Valetti, Francesca,Trotta, Francesco,Gilardi, Gianfranco
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experimental part
p. 6507 - 6512
(2010/02/16)
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- Ozonolysis of phenols in aqueous solution
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In the ozonolysis of phenol in aqueous solution at pH 3, 7 and 10 the following products were quantified: catechol, hydroquinone, 1,4-benzoquinone, cis,cis-muconic acid, H2O 2, 2,4-dihydroxybiphenyl and 4,4-dihydroxybiphenyl. At pH 10, material balance (products vs. phenol consumption) is obtained. Singlet dioxygen, O2(1Δg), and OH are formed as short-lived intermediates. The precursor of the latter, O3-, and a phenoxyl radical is suggested to arise from electron transfer from phenol/phenolate to ozone. Addition of OH to phenol gives rise to dihydroxyclohexadienyl radicals which add dioxygen and eliminate HO2 thereby forming catechol/hydroquinone. In competition and catalysed by H+ and OH-, the dihydroxycyclohexadienyl radical eliminates water yielding a phenoxyl radical. At pH 10, they readily oxidise catechol and hydroquinone. This reforms phenol (accounting for the low phenol consumption) and yields higher-oxidised products, eventually 1,4-benzoquinone, cis,cis-Muconic acid can be accounted for by the Criegee mechanism, while O2(1Δg) is released on the way to (some of the) catechol and hydroquinone. Similar reactions proceed with hydroquinone (products: 1,4-benzoquinone, 2-hydroxy-1,4-benzoquinone and H2O2, with high yields of O2(1Δg) and OH) and with catechol (products: 2-hydroxy-1,4-benzoquinone, cis,cis-muconic acid, H2O2 with high yields of O2(1Δg) and OH). Material balance is not obtained for these two systems. Pentachlorophenolate, pentabromophenolate and 2,4,6-triiodophenolate ions give rise to halide ions, O2(1Δg) (58%/48%/10%) and OH (27%/2%/0%). It is suggested that together with O2(1Δg) the corresponding ortho- and para-quinones plus a halide ion are formed. Further halide ion is released upon the hydrolysis of these and other products. For pentachlorophenolate the material balance with respect to the short-lived intermediates is 85%. With the bromo- and iodophenolates the O2(1 Δg) yields are substantially lowered, most likely due to release of triplet (ground state) dioxygen induced by the heavy atom effect.
- Mvula, Eino,Von Sonntag, Clemens
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p. 1749 - 1756
(2007/10/03)
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- Degradation of Phenol and Salicylic Acid by Ultraviolet Radiation/Hydrogen Peroxide/Oxygen
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Based on the oxidation reactions of u.v. radiation/hydrogen peroxide/oxygen with either phenol or salicylic acid a spectra library was established. The reaction products contain hydroxylated phenols, benzoquinone and aliphatic acids with up to six carbon atoms. Many of the substances have been identified by means of chromatography and spectra comparison. From the observed concentrations of the substances and the known reaction mechanisms the following course of reaction has been postulated. The first reaction step is the hydroxylation of the aromatic ring. Further oxidation occurs via abstraction of a hydrogen atom to form 1,2-benzoquinone which is cleaved to form muconic acid. The cleavage of the muconic acid by u.v. radiation/hydrogen peroxide/oxygen leads to maleic acid, fumaric acid and oxalic acid. The degradation of oxalic acid leads to formic acid and finally to carbon dioxide. The hydroxylation of the double bond of the maleic or fumaric acid and the abstraction of a hydrogen atom produces malic acid. The reactions can be seen as essential step in the photochemical transformation of refractory substances into biodegradable ones.
- Scheck, Christoph K.,Frimmel, Fritz H.
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p. 2346 - 2352
(2007/10/03)
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- Environmentally compatible synthesis of adipic acid from D-glucose [16]
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An environmentally compatible synthesis has been established using a microbial catalyst to enzymatically convert D-glucose into cis,cis-muconic acid. Subsequent catalytic hydrogenation affords adipic acid. Ozone-depleting gases and greenhouse gases are not generated.
- Draths,Frost
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p. 399 - 400
(2007/10/02)
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- MECHANISM OF THE REACTION OF OZONE WITH PHENOLS
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An investigation has been carried out into the composition of the products of the O3 reaction with PhOH in different solvents and into the kinetics of their build-up.A scheme is proposed for the reaction in which the first stage, which limits the rate of
- Konstantinova, M. L.,Razumovskii, S. D.,Zaikov, G. E.
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p. 271 - 275
(2007/10/02)
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- Photocatalytic Reactions of Hydrocarbons and Fossil Fuels with Water. Hydrogen Production and Oxidation
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Photocatalytic H2 production from several aliphatic and aromatic compounds with water was investigated with powdered Pt/TiO2 catalyst suspended in solution.Various fossil fuels such as coal, tar sand, and pitch also reacted with water, producing both H2 and CO2 from an early stage of irradiation.The photocatalytic oxidations of their model compounds, especially a linear hydrocarbon and benzene, were studied in the presence of silver ion as an electron acceptor.For aliphatic hydrocarbons, they are oxidized to alcohols, aldehydes, and carboxylic acids, successively.CO2 was found to be formed through the photo-Kolbe type of reaction of carboxylic acids produced, which explained well the result of the complete decomposition of n-hexadecane.For benzene, we could detect phenol, catechol, hydroquinone, and muconic acid.On the basis of these results, the possibility of the direct oxidation of benzene by photogenerated holes and its ring-opening process peculiar to the photocatalytic reaction are discussed.The main reaction path for CO2 production was suggested in which the benzene ring opens not by way of phenol and catechol, but by way of the intermediates whose reactivities are much larger than that of benzene.
- Hashimoto, Kazuhito,Kawai, Tomoji,Sakata, Tadayoshi
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p. 4083 - 4088
(2007/10/02)
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- Rapid Biodegradation of Aniline by Frateuria species ANA-18 and Its Aniline Metabolism
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A bacterial strain, ANA-18, was isolated from soil, when aniline was provided as a sole source of carbon and nitrogen at pH 5.5.The isolate belongs to a Frateuria species.Frateuria sp.ANA-18 was able to grow on aniline at pH 4.0 to 7.0 and readily degrated it.This bacterium decomposed aniline more rapidly than Rhodococcus erythropolis AN-13 reported previously.Resting cells of aniline-grown Frateuria sp.ANA-18 had 9-fold the oxidizing activity for aniline of those of R. erythropolis AN-13.The metabolic pathway for mineralization of aniline by Frateuria sp.ANA-18 was the same as that proposed for R. erythropolis AN-13.
- Aoki, Kenji,Ohtsuka, Kotaro,Shinke, Ryu,Nishira, Hiroshi
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p. 865 - 872
(2007/10/02)
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- REACTION OF SUBSTITUTED γ-CROTONOLACTONES UNDER THE CONDITIONS OF THE MICHAEL ADDITION
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Under the conditions of the Michael addition γ-lactone of ethyl 4-hydroxy-6-oxo-2-octenedioate (II) isomerizes to γ-lactone of ethyl 4-hydroxy-6-oxo-4-octenedioate (VIII).The addition of an excess of ethyl acetate anion to γ-lactone of ethyl 4-hydroxy-2-hexenedioate (I) affords γ-lactone of ethyl 3-ethoxycarbonylmethyl-4-hydroxy-6-oxo-octanedioate (XI).The dimers IX and X are formed during the usual performance of the same addition.The mechanism of isomerization of II and the factors affecting the addition of the ethyl acetate anion are discussed.
- Janda, Miroslav,Koerblova, Eva,Stibor, Ivan
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