Synergistic Activities in the Ullmann Coupling of Chloroarenes at Ambient Temperature by Pd-Supported Calcined Ferrocenated La2O3

Chumkaeo, Peerapong,Poonsawat, Thinnaphat,Meechai, Titiya,Somsook, Ekasith

, (2019)

Novel palladium-doped nanoparticles have been explored to serve as the first metal oxide-derived heterogeneous catalyst for Ullmann reaction of chloroarenes under mild condition (34?°C). This heterogeneous catalyst exhibited high catalytic activity towards the Ullmann homocoupling of chloroarenes into a series of useful symmetrically biaryl products with good to excellent yields in the presence of ethanol and NaOH, thereby leading to green and economical Ullmann reaction. The produced nanoparticles were successfully characterized by various techniques including PXRD, XPS, HRTEM, SEM-EDS, BET, TGA techniques, elemental mapping analysis and ICP-OES. Interestingly, based on characterization and experimental data, a reasonable mechanism has been proposed. Also, the formation of aryl methyl ketone as a by-product has been further confirmed by isotopic labelling experiments that the acetyl moiety is derived from ethanol. Moreover, the catalyst was stable and could be easily reused up to 5 times under atmospheric air without suffering significant loss in catalytic activity.

A Zn4L6 Capsule with Enhanced Catalytic C?C Bond Formation Activity upon C60 Binding

Lu, Zhenpin,Lavendomme, Roy,Burghaus, Olaf,Nitschke, Jonathan R.

, p. 9073 - 9077 (2019)

A redox-switchable self-assembled ZnII4L6 cage was synthesized that contains naphthalenediimide (NDI) motifs. Its reduction lent these NDI panels persistent radical anion character. The redox activity of this cage allows it to act as a catalyst for the oxidative coupling of different tetraaryl borates to give biaryls. The catalytic activity of the cage was enhanced following its binding of C60, which implies a mechanism that does not involve encapsulation of the substrate.

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Bost, R. W.,Borgstrom, P.

, p. 1922 - 1925 (1929)

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Kinetic study of the reactions of chlorine atoms and Cl2·- radical anions in aqueous : Solutions. 1. Reaction with benzene

Martire,Bertolotti,Braun,Gonzalez,Alegre,Gerones,Rosso

, p. 3117 - 3125 (2000)

The photolysis of NaS2O8 aqueous solutions containing Cl- ions is a clean technique for kinetic studies of the species Cl./Cl2.- in the presence and absence of added aromatic substrates. Laser and conventional flash-photolysis methods were used to study the aqueous phase reactions of chlorine atoms and Cl2.- (340 nm) radical ions in the presence and absence of benzene. A mechanism that considers the decay of Cl2.- in aqueous solutions with chloride ion concentrations from 1 x 10-4 to 0.6 M, total radical (Cl. + Cl2.-) concentrations at (0.1-1.5) x 10-5 M, and 2.5-3 pH was proposed. Kinetic computer simulations supported interpretation of the experimental data. The rate constants 6 x 109/M-sec ≤ k ≤ 1.2 x 1010/M-sec and 5/M-sec were determined for the reactions of Cl. and Cl2.-, respectively, in the aqueous phase. The organic radicals produced from these reactions showed an absorption band with maximum at 300 nm that was assigned to a Cl-cyclohexadienyl radical (Cl-CHD). The kinetic analysis of the traces supported a reversible reaction between Cl-CHD and O2. A reaction mechanism leading to the formation of chlorobenzene was proposed.

Application of a dioxo-molybdenum(VI) complex anchored on TiO2 for the photochemical oxidative decomposition of 1-chloro-4-ethylbenzene under O2

Bakhtchadjian, Robert,Tsarukyan, Samvel,Barrault, Joel,Martinez, Fernando O.,Tavadyan, Levon,Castellanos, Nelson J.

, p. 897 - 900 (2011)

The catalytic activity of dioxo-molybdenum(VI)- dichloro[4,4'- dicarboxylato-2,2'-bipyridine] covalently anchored through the carboxylate function to the surface of TiO2 has been tested for the oxidative degradation of 1-chloro-4- ethylbenzene in MeCN solution under argon and UV irradiation (λ = 254 nm). After 4-5 h of photochemical reaction, the Mo complex was reoxidized in the presence of O2 in the dark, and then the reaction was continued under argon. The reaction proceeds by the intermediate formation of 40-chloroacetophenone that undergoes further decomposition to chlorobenzene, plus small amounts of oxygen-containing organochlorine compounds, CO2 and H2O. Similar results were obtained for the decomposition of 4'-chloroacetophenone under the same conditions, which also gave chlorobenzene as one of the main products. The ratio of [final product]/ [Mo complex] increases during the decomposition of 1-chloro-4-ethylbenzene (up to 350-400% for 30-35 h of reaction), which provides evidence of a catalytic process. The probable photochemical reactions are discussed. Springer Science+Business Media B.V. 2011.

Oxychlorination and combustion of propene on fly-ash. Formation of chlorinated benzenes, dibenzodioxines and mono- and dibenzofurans

Jarmohamed, W.,Mulder, P.

, p. 1911 - 1918 (1994)

Heterogenous gas phase reactions of propene on fly ash in the presence of hydrochloric acid and air between 300-580 deg C have been investigated. At mild conditions only the formation of polychlorinated C1, C2 and C3 species takes place. At the high tempe

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Le Fevre

, p. 1745,1746 (1932)

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Transformation of chemical contaminants by biotic and abiotic processes in water and soil

Mansour,Feicht

, p. 323 - 332 (1994)

In contrast to biological processes, which can give rise to only a limited amount of transformation because of the biostability of many persistent organic chemicals, abiotic environmental factors (solar radiation) make an appreciable contribution to the transformation of these substances in the environment. In this context, abiotic transformation of organic chemicals should be investigated with particular consideration to the dynamic and catalytic effects due primarily to the state of the molecule and its interaction with the environment. Our investigation demonstrate that selected chemical substances can be degraded and mineralized within relatively short periods if irradiated with light of wavelenghts λ ≥ 290 nm. The present investigations deals with the fate of selected s-triazines in soil and under simulated solar light in the presence of TiO2 and soil suspension.

Formation of complex organochlorine species in water due to cavitation

Kruus, Peeter,Beutel, Lise,Aranda, Rocio,Penchuk, Jaan,Otson, Rein

, p. 1811 - 1824 (1998)

Sonication at 900 kHz was carried out on aqueous solutions of chloroform in the concentration range 25 to 500 mg/L. The formation of chlorinated hydrocarbons was detected by means of GC/MS analyses. For instance, carbon tetrachloride, chlorinated ethanes, and chlorinated ethenes were formed after 10 min of sonication. The greatest concentration of any product was 6 mg/L. Sonication of aqueous chloroform with phenol present produced chlorophenols, and with benzene present produced phenol, chlorobenzene and chlorophenols. These results are significant for the evaluation of sonication as a method of eliminating chlorinated organic compounds from water. They also have significance in supporting the notion that some complex organochlorines may be formed naturally in the environment. Some chloroform and methyl chloride are produced in nature and could react with other organic compounds to form more complex organochlorines through natural processes which have an action similar to cavitation, e.g. waterfalls and breaking waves.

Catalytic alkane oxidation by homogeneous and silica-supported cobalt(II) complex catalysts with a triazoly group-containing tetradentate ligand

Nakazawa, Jun,Yata, Akinori,Hori, Tomoaki,Stack, T. Daniel P.,Naruta, Yoshinori,Hikichi, Shiro

, p. 1197 - 1199 (2013)

Homogeneous and heterogeneous cobalt complex catalysts with bis(pyridylmethyl)(triazolylmethyl)amine ligand were prepared. Although simple cobalt salts catalyze cyclohexane oxidation with mCPBA, the cyclohexane selectivity increases upon coordination of tetradentate ligands. In the heterogeneous catalysis, the yield and selectivity of cyclohexanol are improved with an increase in the ligand density on the silica support due to the suppression of metal leaching.

Liquid-Phase Hydrogenation of Halobenzenes in the Presence of Palladium-Containing Nanodiamonds

Kalmykov,Magdalinova,Klyuev

, p. 1206 - 1212 (2018)

Abstract: The catalytic activity of palladium-containing nanodiamonds (Pd/ND) is studied in the model reaction of liquid-phase hydrodehalogenation of monohalobenzenes (chlorobenzene, bromobenzene, and iodobenzene) and ortho-, meta-, and para-isomers of dichlorobenzene under mild conditions (Т = 45°С, (Formula presented.)?= 1 atm). The obtained results are compared with the catalytic behavior of the palladium-containing activated carbon (Pd/C) under identical conditions. It is found that catalyst Pd/ND is more active than Pd/C and is more stable against the poisonous effect of hydrogen halide forming during the reaction. Study of the effect of HCl and NaOH additives on the catalyst activity shows that, in the presence of HCl, poisoning of the catalyst occurs: the rate of reaction decreases; in the presence of NaOH, the catalyst activity grows; the rate of reaction increases as a result of hydrogen chloride neutralization by an alkali. For both catalysts the rate of reaction decreases in the sequence Cl > Br > I for monohalobenzenes and in the sequence para- > ortho- > meta-isomer in the case of dichlorobenzenes. The obtained dependences are explained using the quantum-chemical modeling of substrates of model reactions.

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Baird et al.

, p. 1173 (1969)

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Erickson et al.

, p. 461 (1966)

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Oxidative radical arylation of anilines with arylhydrazines and dioxygen from air

Hofmann, Josefa,Jasch, Hannelore,Heinrich, Markus R.

, p. 2314 - 2320 (2014)

Substituted 2-aminobiphenyls have been prepared from arylhydrazine hydrochlorides and anilines in biphasic radical arylation reactions with dioxygen from air as a most simple and readily available oxidant. Under optimized conditions, the free amino functionality of the aniline leads to high ortho:meta regioselectivities, now even for anilines bearing a donor substituent in the para position. Finally, the mild and metal-free new access to aminobiphenyls was shown to be applicable on a gram scale.

Molecule-induced homolysis of N-hydroxyphthalimide (NHPI) by peracids and dioxirane. A new, simple, selective aerobic radical epoxidation of alkenes

Minisci, Francesco,Gambarotti, Cristian,Pierini, Monica,Porta, Ombretta,Punta, Carlo,Recupero, Francesco,Lucarini, Marco,Mugnaini, Veronica

, p. 1421 - 1424 (2006)

Evidences are reported concerning the molecule-induced homolysis of NHPI by peracids and dioxirane; their combination can be utilized for the aerobic free-radical epoxidation of alkenes with selectivity quite different from the well-known epoxidation by peracids.

Hazardous air pollutants formation from reactions of raw meal organics in cement kilns

Sidhu, Sukh,Kasti, Nabil,Edwards, Phil,Dellinger, Barry

, p. 499 - 506 (2001)

Thermally induced chlorination, condensation, and formation reactions of raw meal organic surrogates were investigated on different types of surfaces. The System for Thermal Diagnostic Studies provided a powerful tool to study these reactions under defined reaction conditions, which were related to typical conditions in the preheater zone of cement kiln. Experiments were conducted with benzene and benzene/myristic acid (C6H6/C13H27COOH) mixtures in a quartz reactor containing different chlorinating catalysts/reagents over a temperature range of 300-500°C. Reaction products were trapped in-line and analyzed by GC-MS. A mixture of chlorides of calcium, potassium, aluminium and iron was highly effective for chlorination/condensation reactions of benzene and benzene/myristic acid mix at temperatures above 300°C. The same behavior was observed only when calcium chloride and potassium chloride were used as chlorinating catalyst/reagent. This result showed that transition metal chlorides like FeCl3 are not necessary for chlorination/condensation of organics under post-combustion conditions. Methylene chloride was the major chlorinated product followed by chloroform and various other C1, C2 and C6 chlorinated products. Yields of chlorinated aliphatics were highest at 400°C for both benzene and benzene/myristic acid mix. C6 products were mainly mono- to hexa-chlorinated benzenes with trace amounts of chlorinated phenols. The major chlorinated products observed in this study (i.e., methylene chloride, chloroform, chloroethanes and monochlorobenzene) were also present as major chlorinated hydrocarbons in the cement kiln field emission data.

Synthesis and spectral properties of iron(III) tetra-tert-butylphthalocyanine complexes

Burtsev, Ivan D.,Dubinina, Tatiana V.,Platonova, Yana B.,Kosov, Anton D.,Pankratov, Denis A.,Tomilova, Larisa G.

, p. 466 - 469 (2017)

Two tetra-tert-butylphthalocyanine complexes of iron(III) were synthesized in high yields from the phthalocyanine ligand and iron(III) salts; the oxidation state of iron was confirmed by M?ssbauer and EPR spectroscopy. The existence of an acid–base equilibrium during spectrophotometric titration was revealed. The ButPcFeCl complex catalyzed chlorination of benzene.

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Beringer,Bodlaender

, p. 1981 (1969)

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Kinetics and mechanism of the reaction of Cl atoms with nitrobenzene

Froosig,Nielsen,Bilde,Wallington,Orlando,Tyndall

, p. 11328 - 11331 (2000)

The kinetics and mechanism of the reaction of Cl atoms with nitrobenzene in 10-700 torr of N2, or air, at 296 K were studied using smog chamber/FTIR methods. The reaction of Cl atoms with nitrobenzene proceeded with a rate constant of 9.3 × 10-13 cc/molecule-sec to give C6H5Cl and NO2 products in essentially 100% yield. The UV-visible spectrum of nitrobenzene was measured. The dominant atmospheric fate of nitrobenzene was photolysis, which occurred at a rate of 3 × 10-5/sec for a solar zenith angle of 25° representative of a typical summer day at 40°N.

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Jenner

, p. 1031 (1962)

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Kochi

, p. 2500,2501 (1965)

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Ichikawa et al.

, p. 169 (1971)

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Erlenmeyer,Leo

, p. 897,903 (1933)

The importance of copper placement in chiral catalysts supported on heteropolyanions: Lacunary vs external exchanged

Fraile, José M.,Mansilla, Daniela S.,Mayoral, José A.,Torviso, M. Rosario

, (2020)

Lacunary [PCuW11O39]5? species modified with chiral bis(oxazoline) leads to very poor results as catalyst in the enantioselective cyclopropanation, in contrast with the Cu-bis(oxazoline) complex exchanged on the Keggin [PW12O40]3? species. The incomplete neutralization and/or exchange of the Keggin species produces a loss in symmetry that leads to spectra in solid phase (IR and NMR) similar to those obtained for the lacunary species. The symmetry is averaged in solution, but additional characterization methods are necessary to determine the true nature of the solid heteropolyanionic species. These results demonstrate that the efficiency of copper-bis(oxazoline) complexes is related to its placement in an external exchange position, whereas the copper included in the heteropolyanion structure is not active for cyclopropanation reactions.

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Milligan et al.

, p. 158,161 (1962)

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Iron-mediated desulphurization approach: synthesis of cyanamides and their conversions

Nannapaneni, Madhavi,Pendem, Venkata Bhavanarushi,Tamminana, Ramana

, (2022/01/12)

The iron-mediated efficient multi-component method has been demonstrated for the synthesis of substituted cyanamides from isothiocyanates under mild reaction conditions. Subsequent nucleophilic addition and desulfurization are involved in this proposed synthetic methodology. All the reactions are rapid, facile, and accomplished at room temperature. A variety of substrates readily underwent the optimized reaction conditions to provide their respective target products in good to excellent yields. Furthermore, we have confirmed that no other by-products could be identified during our experimental reaction process. Graphical abstract: Iron-mediated efficient multi-component method has been demonstrated for the synthesis of substituted cyanamides from isothiocyanates under mild reaction conditions. Subsequent nucleophilic addition and desulfurization are involved in this proposed synthetic methodology.[Figure not available: see fulltext.].

Homogeneous oxidation of C–H bonds with m-CPBA catalysed by a Co/Fe system: mechanistic insights from the point of view of the oxidant

Kuznetsov, Maxim L.,Nesterov, Dmytro S.,Nesterova, Oksana V.,Pombeiro, Armando J. L.,Shul'pin, Georgiy B.

, p. 282 - 299 (2022/01/19)

Oxidations of C–H bonds with m-chloroperoxybenzoic acid (m-CPBA) catalyzed by transition metal complexes are known to proceed through a number of routes, from the non-selective free radical to selective concerted and metal-mediated ones. However, there is a lack of understanding of the m-CPBA oxidative behavior, reaction mechanisms and factors that trigger its activity. An experimental and theoretical investigation of sp3 C–H bond oxidation with m-CPBA in the presence of the heterometallic pre-catalyst [CoIII4FeIII2O(Sae)8]·4DMF·H2O (1) (H2Sae = salicylidene-2-ethanolamine) and HNO3 promoter has been performed herein. The catalytic system 1/HNO3/m-CPBA allows mild hydroxylation of tertiary C–H bonds with 99% retention of stereoconfiguration of model alkane substrates, supported by high TOFs up to 2 s?1 (for cis-1,2-dimethylcyclohexane) and TONs up to 1.4 × 104 (at 50 °C). The catalytic effect of 1 is seen at the ppm level, while 1000 ppm (0.1 mol%) loading allows 1000-fold increase of the initial reaction rate up to 9 × 10?5 M s?1. The reaction mechanism was investigated by means of combined kinetic studies (including isotope effects), isotopic labeling (18O2, H218O, D2O), ESI-MS spectroscopy and DFT theoretical studies. The results suggest that the main oxidation pathway proceeds through a concerted mechanism involving a cobalt-peroxo C–H attacking species or via a cobalt–oxyl species (rebound process), rather than a free-radical pathway. Remarkably, the Co(iii) catalyst does not change its oxidation state during the most energetically favored pathway, consistent with a metal–ligand cooperativity. The chlorobenzene radical is responsible for H abstraction in the non-selective side route, which is efficiently suppressed by the acidic promoter. Finally, signs for slow direct oxygen exchange between m-CPBA and water in the presence of a proton or a metal complex are found, suggesting that the results of 18O-tests should be treated cautiously when m-CPBA is used as the oxidant.

Photoredox-catalyzed reduction of halogenated arenes in water by amphiphilic polymeric nanoparticles

Eisenreich, Fabian,Kuster, Tom H. R.,Palmans, Anja R. A.,van Krimpen, David

supporting information, (2021/10/05)

The use of organic photoredox catalysts provides new ways to perform metal-free reactions controlled by light. While these reactions are usually performed in organic media, the application of these catalysts at ambient temperatures in aqueous media is of considerable interest. We here compare the activity of two established organic photoredox catalysts, one based on 10-phenylphenothiazine (PTH) and one based on an acridinium dye (ACR), in the light-activated dehalogenation of aromatic halides in pure water. Both PTH and ACR were covalently attached to amphiphilic polymers that are designed to form polymeric nanoparticles with hydrodynamic diameter DH ranging between 5 and 11 nm in aqueous solution. Due to the hydrophobic side groups that furnish the interior of these nanoparticles after hydrophobic collapse, water-insoluble reagents can gather within the nanoparticles at high local catalyst and substrate concentrations. We evaluated six different amphiphilic polymeric nanoparticles to assess the effect of polymer length, catalyst loading and nature of the catalyst (PTH or ACR) in the dechlorination of a range of aromatic chlorides. In addition, we investigate the selectivity of both catalysts for reducing different types of aryl-halogen bonds present in one molecule, as well as the activity of the catalysts for C-C cross-coupling reactions. We find that all polymer-based catalysts show high activity for the reduction of electron-poor aromatic compounds. For electron-rich compounds, the ACR-based catalyst is more effective than PTH. In the selective dehalogenation reactions, the order of bond stability is C-Cl > C-Br > C-I irrespective of the catalyst applied. All in all, both water-compatible systems show good activity in water, with ACR-based catalysts being slightly more efficient for more resilient substrates.