- Electrocatalytic reduction of ROOH by iron porphyrins
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Electrocatalytic reduction of a series of chemical oxidants of different power (tert-butyl hydroperoxide, potassium peroxomonosulfate, peracetic acid, and m-chloroperbenzoic acid) at iron-porphyrin-modified graphite electrodes is studied in buffered aqueous solutions by rotating disk and ring-disk voltammetry. Both ferric and ferrous porphyrins are catalytically active. Turnover of ferric catalysts is slower than that of the ferrous analogues and involves competing catalytic reduction and disproportionation. The kinetic data are consistent with reactant binding being the rate-determining step in catalysis by Fe(III). In catalysis by Fe(II), the turnover is controlled by the first electron transfer. The covalently linked proximal imidazole ligand is found to be crucial for achieving the Fe(III) catalysis. Copyright
- Collman, James P.,Kaplun, Marina,Sunderland, Christopher J.,Boulatov, Roman
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Read Online
- The interaction of ozone with chlorobenzene
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The reaction of ozone with chlorobenzene was studied over the temperature range 77-305 K. Ozone was found to oxidize chlorobenzene starting with 77 K to produce a complex mixture of ozonides and peroxides of various compositions. The products of the reaction between chlorobenzene and ozone formed over the temperature range 77-305 K were analyzed by IR Fourier transform spectroscopy. Nauka/Interperiodica 2007.
- Vysokikh,Yagodovskaya,Savilov,Lunin
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- Benzene Hydroxylation by Bioinspired Copper(II) Complexes: Coordination Geometry versus Reactivity
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A series of bioinspired copper(II) complexes of N4-tripodal and sterically crowded diazepane-based ligands have been investigated as catalysts for functionalization of the aromatic C-H bond. The tripodal-ligand-based complexes exhibited distorted trigonal-bipyramidal (TBP) geometry (τ, 0.70) around the copper(II) center; however, diazepane-ligand-based complexes adopted square-pyramidal (SP) geometry (τ, 0.037). The Cu-NPy bonds (2.003-2.096 ?) are almost identical and shorter than Cu-Namine bonds (2.01-2.148 ?). Also, their Cu-O (Cu-Owater, 1.988 ? Cu-Otriflate, 2.33 ?) bond distances are slightly varied. All of the complexes exhibited Cu2+ → Cu+ redox couples in acetonitrile, where the redox potentials of TBP-based complexes (-0.251 to -0.383 V) are higher than those of SP-based complexes (-0.450 to -0.527 V). The d-d bands around 582-757 nm and axial patterns of electron paramagnetic resonance spectra [g∥, 2.200-2.251; A∥, (146-166) × 10-4 cm-1] of the complexes suggest the existence of five-coordination geometry. The bonding parameters showed K∥ > K∥ for all complexes, corresponding to out-of-plane πbonding. The complexes catalyzed direct hydroxylation of benzene using 30% H2O2 and afforded phenol exclusively. The complexes with TBP geometry exhibited the highest amount of phenol formation (37%) with selectivity (98%) superior to that of diazepane-based complexes (29%), which preferred to adopt SP-based geometry. Hydroxylation of benzene likely proceeded via a CuII-OOH key intermediate, and its formation has been established by electrospray ionization mass spectrometry, vibrational, and electronic spectra. Their formation constants have been calculated as (2.54-11.85) × 10-2 s-1 from the appearance of an O (π?σ) → Cu ligand-to-metal charge-transfer transition around 370-390 nm. The kinetic isotope effect (KIE) experiments showed values of 0.97-1.12 for all complexes, which further supports the crucial role of Cu-OOH in catalysis. The 18O-labeling studies using H218O2 showed a 92% incorporation of 18O into phenol, which confirms H2O2 as the key oxygen supplier. Overall, the coordination geometry of the complexes strongly influenced the catalytic efficiencies. The geometry of one of the CuII-OOH intermediates has been optimized by the density functional theory method, and its calculated electronic and vibrational spectra are almost similar to the experimentally observed values.
- Anandababu, Karunanithi,Mayilmurugan, Ramasamy,Muthuramalingam, Sethuraman,Velusamy, Marappan
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- Catalysis by Amberlite IR-120 resin: A rapid and green method for the synthesis of phenols from arylboronic acids under metal, ligand, and base-free conditions
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A clean process has been developed for the ipso-hydroxylation of aryl and heteroaryl boronic acids to the corresponding phenols using commercially available and recyclable Amberlite IR-120 resin and aqueous hydrogen peroxide as an oxidizing agent. The ion-exchange sulfonic acid resin catalyst could be readily recycled by filtration and directly reused at least four times without any significant loss of activity.
- Mulakayala, Naveen,Ismail,Kumar, Kottur Mohan,Rapolu, Rajesh Kumar,Kandagatla, Bhaskar,Rao, Pallavi,Oruganti, Srinivas,Pal, Manojit
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- Aryl phenol compound as well as synthesis method and application thereof
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The invention discloses a synthesis method of an aryl phenol compound shown as a formula (3). All systems are carried out in an air or nitrogen atmosphere, and visible light is utilized to excite a photosensitizer for catalyzation. In a reaction solvent, ArNR1R2 as shown in a formula (1) and water as shown in a formula (2) are used as reaction raw materials and react under the auxiliary action of acid to obtain the aryl phenol compound as shown in a formula (3). The ArNR1R2 in the formula (1) can be primary amine and tertiary amine, can also be steroid and amino acid derivatives, and can also be drugs or derivatives of propofol, paracetamol, ibuprofen, oxaprozin, indomethacin and the like. The synthesis method has the advantages of cheap and easily available raw materials, simple reaction operation, mild reaction conditions, high reaction yield and good compatibility of substrate functional groups. The fluid reaction not only can realize amplification of basic chemicals, but also can realize amplification of fine chemicals, such as synthesis of drugs propofol and paracetamol. The invention has wide application prospect and use value.
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Paragraph 0071-0074
(2021/05/12)
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- Nickel-catalyzed deallylation of aryl allyl ethers with hydrosilanes
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An efficient and mild catalytic deallylation method of aryl allyl ethers is developed, with commercially available Ni(COD)2 as catalyst precursor, simple substituted bipyridine as ligand and air-stable hydrosilanes. The process is compatible with a variety of functional groups and the desired phenol products can be obtained with excellent yields and selectivity. Besides, by detection or isolation of key intermediates, mechanism studies confirm that the deallylation undergoes η3-allylnickel intermediate pathway.
- Ding, Guangni,Fan, Sijie,Wang, Jingyang,Wang, Yu,Wu, Xiaoyu,Xie, Xiaomin,Yang, Liqun,Zhang, Zhaoguo
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supporting information
(2021/09/28)
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- Non-Innocent Role of the Ceria Support in Pd-Catalyzed Halophenol Hydrodehalogenation
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The hydrodehalogenation (HDH) of halophenols is efficiently catalyzed by palladium supported on high-surface ceria (Pd/CeO2) under mild conditions (35 °C, 1 atm H2). A combination of NMR, diffuse reflectance infrared Fourier transform spectroscopy, Raman spectroscopy, and XPS studies and HDH kinetics of substituted halobenzenes suggests that the reaction proceeds mainly via a sequence of dissociative adsorption of phenolic hydroxyl onto the support, oxidative addition of the C-halogen bond to Pd, and reductive elimination to give phenol and hydrogen halide. The dissociative adsorption of the -OH group onto oxygen vacancies of the ceria support results in an electron-rich intermediate that facilitates the turnover-limiting reductive elimination step. In contrast, the direct pathway catalyzed by Pd without dissociative adsorption of the reactants on the support takes place at a slower rate. The mechanistic insights gained in this study were used to modify the reaction conditions for enabling HDH of recalcitrant halides such as fluorides and iodides.
- An, Yeongseo,Freppon, Daniel,Masching, Hayley,Naik, Pranjali J.,Sedinkin, Sergey L.,Slowing, Igor I.,Smith, Emily A.,Venditti, Vincenzo
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p. 10553 - 10564
(2021/09/04)
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- Highly recyclable Ti0.97Ni0.03O1.97catalyst coated on cordierite monolith for efficient transformation of arylboronic acids to phenols and reduction of 4-nitrophenol
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A stable Ni2+substituted TiO2catalyst (Ti0.97Ni0.03O1.97) has been synthesized by a solution combustion method with an average crystallite size of 7.5 nm. Ti1?xNixO2?x(x= 0.01-0.06) crystallizes in the TiO2anatase structure with Ni2+substituted in Ti4+ion sites and Ni taking a nearly square planar geometry. This catalyst is found to be highly active in the transformation of diverse arylboronic acids to the corresponding phenols. The catalyst coated cordierite monolith can even be recycled for up to 20 cycles with a cumulative TOF of 1.8 × 105h?1. In scale-up reactions, various phenols are synthesized by employing a single cordierite monolith. It also shows high performance in the reduction of 4-nitrophenol.
- Hegde, M. S.,Prasanna,Usha, K. M.
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supporting information
p. 14223 - 14234
(2021/10/25)
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- Catalyst-free rapid conversion of arylboronic acids to phenols under green condition
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A catalyst-free and solvent-free method for the oxidative hydroxylation of aryl boronic acids to corresponding phenols with hydrogen peroxide as the oxidizing agent was developed. The reactions could be performed under green condition at room temperature within very short reaction time. 99% yield of phenol could be achieved in only 1 min. A series of different arenes substituted aryl boronic acids were further carried out in the hydroxylation reaction with excellent yield. It was worth nothing that the reaction could completed within 1 min in all cases in the presence of ethanol as co-solvent.
- Dong, Zhenhua,Liu, Mengmeng,Pan, Hongguo
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- Coordination Polymers as a Functional Material for the Selective Molecular Recognition of Nitroaromatics and ipso-Hydroxylation of Arylboronic Acids
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We report the synthesis and structural characterization of two coordination polymers (CPs), namely; [{Zn(L)(DMF)4} ? 2BF4]α (1) and [{Cd(L)2(Cl)2} ? 2H2O]α (2) (where L=N2,N6-di(pyridin-4-yl)naphthalene-2,6-dicarboxamide). Crystal packing of 1 reveals the existence of channels running along the b- and c-axis filled by the ligated DMF and lattice anions, respectively. Whereas, crystal packing of 2 reveals that the metallacycles of each 1D chain are intercalating into the groove of adjacent metallacycles resulting in the stacking of 1D loop-chains to form a sheet-like architecture. In addition, both 1 and 2 were exploited as multifunctional materials for the detection of nitroaromatic compounds (NACs) as well as a catalyst in the ipso-hydroxylation of aryl/heteroarylboronic acids. Remarkably, 1 and 2 showed high fluorescence stability in an aqueous medium and displayed a maximum 88% and 97% quenching efficiency for 4-NPH, respectively among all the investigated NACs. The mechanistic investigation of NACs recognition suggested that the fluorescence quenching occurred via electron as well as energy transfer process. Furthermore, the ipso-hydroxylation of aryl/heteroarylboronic acids in presence of 1 and 2 gave up to 99% desired product yield within 15 min in our established protocol. In both cases, 1 and 2 are recyclable upto five cycles without any significant loss in their efficiency.
- Bhasin, K. K.,Husain, Ahmad,Kumar, Girijesh,Rani, Pooja
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- Highly efficient, recyclable and alternative method of synthesizing phenols from phenylboronic acids using non-endangered metal: Samarium oxide
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Oxidation of phenylboronic acid to phenol is one of the important industrial processes and it is generally employed in the plastic, explosive and drug manufacturing industries. Over the past decades, numerous efficient methods have been described for the generation of phenols from phenylboronic acids in the presence of oxidant. However, these methods suffered from various limitations, including the use of expensive, toxic reagents and sophisticated protocol to synthesise the phenols. Additionally, some of these reported literatures employed endangered metals, in which mankind is facing the risk of limited supply of these elements in 20 years’ time from now. As such, a viable alternative and green method for achieving organic synthesis is highly sought after by the chemists of today. Herein, we report for the first time a facile, efficient and alternative method in the preparation of phenols from phenylboronic acids using non-endangered metal as catalyst. In all cases, all phenols were afforded in satisfactory yields (81–96%) by employing column-free method. In the recyclability study, the Sm2O3 catalyst was found to possess good catalytic performance, even after being reused for five consecutive times (96–91%). In addition, SEM result revealed that the morphology of the recycled Sm2O3 catalyst was well preserved after five successive uses, which indicate no observable changes occurred in the recovered catalysts. As a final note, the current method is anticipated to be useful for industries manufacturing chemical intermediates as it provides an alternative method of catalysis by using a non-endangered metal in organic transformations.
- Yusoff, Hanis Mohd,Bala Chandran, Prasana Devi,Sayuti, Fatin Amira Binti,Kan, Su-Yin,Mohd Radzi, Siti Aisha,Yong, Fu-Siong Julius,Lee, Oon Jew,Chia, Poh Wai
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- An efficient Ti0.95Cu0.05O1.95 catalyst for ipso – hydroxylation of arylboronic acid and reduction of 4-nitrophenol
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A stable, active and selective Ti0.95Cu0.05O1.95 catalyst, crystallized in anatase TiO2 structure with 5% Cu2+ ions substituted for Ti4+ ions with 5% oxide ion vacancy has been synthesized by solution combustion method. The catalyst was coated over a cordierite monolith (Mg2Al4Si5O18) by solution combustion method. By the first principle density functional theory (DFT) calculations, 48 atoms bulk structure has been optimized and density of states (DOS) has been calculated. Ti – O bond distribution in Ti0.95Cu0.05O1.95 has been compared with pure TiO2. Bond distribution analysis has shown longer Cu – O and Ti – O bonds compared to those in CuO and TiO2 creating Cu2+ and oxide ion vacancy as electrophilic and nucleophilic active sites, respectively. This catalyst was found to be very active for ipso – hydroxylation of arylboronic acid and 4-nitrophenol reduction reactions at room temperature. Catalyst coated cordierite monolith was used in the recycling process of the reaction for 20 cycles and cumulative turnover frequency was found to be 184,840 h?1. Ti0.95Cu0.05O1.95 catalyst coated on cordierite monolith enhanced the rate of the reaction compared to powder catalyst and made the handling and recycling of the catalyst very easy. Graphic abstract: [Figure not available: see fulltext.]
- Bhat, Shrikanth K,Dasappa, Jagadeesh Prasad,Hegde, M. S.,Prasanna
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- Cu(I)/sucrose-catalyzed hydroxylation of arenes in water: The dual role of sucrose
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A protocol for the hydroxylation of aryl halides catalyzed by copper(I) and sucrose in neat water has been developed. The dual role of sucrose, the reaction pathway, and the high selectivity for hydroxylation were investigated using a combination of experimental and theoretical techniques. This journal is
- Murata, Shigeo,Takagi, Mio,Takita, Ryo,Watanabe, Ayako,Watanabe, Kohei
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supporting information
p. 7827 - 7831
(2020/11/02)
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- Method for preparing alcohol and phenol through aerobic hydroxylation reaction of boric acid derivative in absence of photocatalyst
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The invention discloses a method for preparing alcohol and phenol through aerobic hydroxylation reaction of a boric acid derivative in the absence of a photocatalyst, wherein the boric acid derivativeis aryl boronic acid or alkyl boronic acid, and the corresponding target compounds are respectively a phenol-based compound and an alcohol-based compound. According to the method, by using a boric acid derivative as a reaction substrate, an additive is added under a solvent condition, and a hydroxylation reaction is performed under aerobic and illumination conditions to obtain a corresponding target compound. According to the invention, the new strategy is provided for the synthesis of phenols through aerobic hydroxylation of aryl boronic acid without a photocatalyst; the catalyst-free aerobic hydroxylation method for photocatalysis of aryl boronic acid or alkyl boronic acid by using triethylamine as an additive is firstly disclosed; and the new method has advantages of photocatalyst-freecondition, wide substrate range and good functional group compatibility.
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Paragraph 0025-0028; 0030-0032
(2020/01/25)
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- Hydroxylation of Aromatics by H2O2 Catalyzed by Mononuclear Non-heme Iron Complexes: Role of Triazole Hemilability in Substrate-Induced Bifurcation of the H2O2 Activation Mechanism
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Rieske dioxygenases are metalloenzymes capable of achieving cis-dihydroxylation of aromatics under mild conditions using O2 and a source of electrons. The intermediate responsible for this reactivity is proposed to be a cis-FeV(O)(OH) moiety. Molecular models allow the generation of a FeIII(OOH) species with H2O2, to yield a FeV(O)(OH) species with tetradentate ligands, or {FeIV(O); OH.} pairs with pentadentate ones. We have designed a new pentadentate ligand, mtL42, bearing a labile triazole, to generate an “in-between” situation. Two iron complexes, [(mtL42)FeCl](PF6) and [(mtL42)Fe(OTf)2]), were obtained and their reactivity towards aromatic substrates was studied in the presence of H2O2. Spectroscopic and kinetic studies reflect that triazole is bound at the FeII state, but decoordinates in the FeIII(OOH). The resulting [(mtL42)FeIII(OOH)(MeCN)]2+ then lies on a bifurcated decay pathway (end-on homolytic vs. side-on heterolytic) depending on the addition of aromatic substrate: in the absence of substrate, it is proposed to follow a side-on pathway leading to a putative (N4)FeV(O)(OH), while in the presence of aromatics it switches to an end-on homolytic pathway yielding a {(N5)FeIV(O); OH.} reactive species, through recoordination of triazole. This switch significantly impacts the reaction regioselectivity.
- Rebilly, Jean-No?l,Zhang, Wenli,Herrero, Christian,Dridi, Hachem,Sénéchal-David, Katell,Guillot, Régis,Banse, Frédéric
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p. 659 - 668
(2019/12/27)
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- Nickel-catalyzed removal of alkene protecting group of phenols, alcohols via chain walking process
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An efficient nickel-catalyzed removal of alkene protection group under mild condition with high functional group tolerance through chain walking process has been established. Not only phenolic ethers, but also alcoholic ethers can be tolerated with the retention of stereocenter adjacent to hydroxyl group. The new reaction brings the homoallyl group into a start of new type of protecting group.
- Meng, Chenkai,Niu, Haolin,Ning, Juehan,Wu, Wengang,Yi, Jun
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- Quaternary ammonium hydroxide-functionalized g-C3N4 catalyst for aerobic hydroxylation of arylboronic acids to phenols
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A new and efficient metal-free approach toward the synthesis of phenols via an aerobic hydroxylation of arylboronic acids by using a novel quaternary ammonium hydroxide g-C3N4 catalyst has been described. The functionalized quaternary ammonium hydroxide (g-C3N4-OH) has been prepared from graphitic carbon nitride (g-C3N4) scaffold by converting the residual –NH2 and –NH groups to quaternary methyl ammonium iodide by performing a methylation reaction with methyl iodide followed by ion-exchange with 0.1 N KOH or anion exchange resin Amberlyst A26 (OH- form) by post-synthetic modification. The resultant g-C3N4-OH was characterized by XRD, FTIR, field-emission scanning electron microscope (FESEM), high-resolution transmission electron microscope (HRTEM), N2 adsorption/desorption isotherms, and acid–base titration. Tested as solid-base catalysts, the g-C3N4-OH showed excellent catalytic activity in the aerobic hydroxylation reaction by converting a variety of arylboronic acids to the corresponding phenols in high yields. More importantly, the g-C3N4-OH solid-base has been successfully reused four times with the minor loss of initial catalytic activity (10.5percent).
- Muhammad, Ibrahim,Mannathan, Subramaniyan,Sasidharan, Manickam
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p. 1470 - 1476
(2020/07/13)
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- Bimetallic photoredox catalysis: Visible light-promoted aerobic hydroxylation of arylboronic acids with a dirhodium(ii) catalyst
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We report the use of a rhodium(II) dimer in visible light photoredox catalysis for the aerobic oxidation of arylboronic acids to phenols under mild conditions. Spectroscopic and computational studies indicate that the catalyst Rh2(bpy)2(OAc)4 (1) undergoes metal-metal to ligand charge transfer upon visible light irradiation, which is responsible for catalytic activity. Further reactivity studies demonstrate that 1 is a general photoredox catalyst for diverse oxidation reactions.
- Campbell, Michael G.,Chuang, Gary Jing,Liu, Ming-Lun,Miura-Stempel, Emily,Tu, Jing-Wen,Yang, Hsiang-Ming
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p. 2040 - 2047
(2020/03/13)
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- Selective oxidative hydroxylation of arylboronic acids by colloidal nanogold catalyzed in situ generation of H2O2 from alcohols under aerobic conditions
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Selective hydroxylation of arylboronic acids was achieved through PVP (polyvinylpyrrolidone)-stabilized nanogold catalyzed in situ generated H2O2 formed by the oxidation of an alcoholic solvent under aerobic conditions. The synthetic application of in situ generated H2O2 was investigated through aerobic epoxidation of (E)-chalcone.
- Sakurai, Hidehiro,Vinsen, Yuta Uetake
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p. 299 - 301
(2020/04/27)
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- Optimizing the crystallization process of conjugated polymer photocatalysts to promote electron transfer and molecular oxygen activation
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Photocatalytic reactive oxygen species (ROS)-induced reactions provide an appealing method to solve the environmental and energy issues, whereas the current oxidation reaction generally suffered from low efficiency and poor selectivity due to uncontrollable O2 activation process. In view of the existence of competitive electron and energy transfer pathway, we propose that highly efficient superoxide radical anion (·O2?) generation can be achieved by optimizing the order degree of the photocatalyst. Herein, by taking carbon nitride polymer as an example, we optimized the crystallization process of carbon nitride polymer by selecting precursors of different polymerization degrees with a molten salt method. Benefiting from the high crystallinity, extended π-conjugated system and strong van der-Waals interactions between interlayers, the modified carbon nitride polymer exhibited accelerated charge transport and enhancement in electron induced molecular oxygen activation reactions under visible light. Consequently, the CCN-P exhibits about 1.5 times higher conversion rate in hydroxylation of phenylboronic acid and over 6-fold faster degradation rate in Rh B organic pollutants photodegradation with respect to pristine carbon nitride. This study provides an in-depth understanding on the optimization of the O2 activation process and the design of advanced photocatalysts.
- Anpo, Masakazu,Cheng, Jiajia,Huang, Caijin,Ou, Honghui,Ren, Wei,Wang, Xinchen
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p. 636 - 645
(2020/07/27)
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- Regioselectivity of Hydroxyl Radical Reactions with Arenes in Nonaqueous Solutions
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The regioselectivity of hydroxyl radical addition to arenes was studied using a novel analytical method capable of trapping radicals formed after the first elementary step of reaction, without alteration of the product distributions by secondary oxidation processes. Product analyses of these reactions indicate a preference for o- over p-substitution for electron donating groups, with both favored over m-addition. The observed distributions are qualitatively similar to those observed for the addition of other carbon-centered radicals, although the magnitude of the regioselectivity observed is greater for hydroxyl. The data, reproduced by high accuracy CBS-QB3 computational methods, indicate that both polar and radical stabilization effects play a role in the observed regioselectivities. The application and potential limitations of the analytical method used are discussed.
- Moores, Lee C.,Kaur, Devinder,Smith, Mathew D.,Poole, James S.
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supporting information
p. 3260 - 3269
(2019/03/11)
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- A preparation method of m-chlorophenol
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The present invention provides a preparation method of m-chlorophenol, silica gel load sulfuric acid catalyst and water in the mixture, adding between chloroaniline and sodium nitrite solution, cooling, diazo reaction to obtain the diazonium salt solution, wherein inter-chloroaniline, sodium nitrite solution, silica gel load sulfuric acid catalyst and the weight of the water parts are in a ratio of 2: (3 - 4): (6.5 - 8): (7 - 8); adjusting the pH value of the filtrate and filtering; silica gel load sulfuric acid catalyst and water added in the mixture of filtrate, hydrolytic reaction, wherein the filtrate, silica gel load sulfuric acid catalyst and water in the ratio by weight of (9 - 13): (2 - 3): 1; through the extraction layered, distillation or coring chlorophenol. The preparation method to yield m-chlorophenol reached 80% or more and easy industrialized large-scale use; silica gel load sulfuric acid catalyst in the reaction process is released slowly in the adsorption of the silica gel in vivo concentrated sulfuric; its silicon colloid can be repeatedly absorbing and utilizing the catalytic reaction of the remainder of the concentrated sulfuric acid, recycling, waste acid generation is obviously reduced.
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Paragraph 0006; 0021-0040
(2019/07/08)
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- One step phenol synthesis from benzene catalysed by nickel(ii) complexes
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Nickel(ii)complexes of N4-ligands have been synthesized and characterized as efficient catalysts for the hydroxylation of benzene using H2O2. All the complexes exhibited Ni2+ → Ni3+ oxidation potentials of around 0.966-1.051 V vs. Ag/Ag+ in acetonitrile. One of the complexes has been structurally characterized and adopted an octahedral coordination geometry around the nickel(ii) center. The complexes catalysed direct benzene hydroxylation using H2O2 as an oxygen source and afforded phenol up to 41% with a turnover number (TON) of 820. This is unprecedentedly the highest catalytic efficiency achieved to date for benzene hydroxylation using 0.05 mol% catalyst loading and five equivalents of H2O2. The benzene hydroxylation reaction possibly proceeds via the key intermediate bis(μ-oxo)dinickel(iii) species, which was characterized by HR-MS, vibrational and electronic spectral methods, for almost all complexes. The formation constant of the key intermediate was calculated to be 5.61-9.41 × 10-2 s-1 by following the appearance of an oxo-to-Ni(iii) LMCT band at around 406-413 nm. The intermediates are found to be very short-lived (t1/2, 73-123 s). The geometry of one of the catalytically active intermediates was optimized by DFT and its spectral properties were calculated by TD-DFT calculations, which are comparable to experimental spectral data. The kinetic isotope effect (KIE) values (0.98-1.05) support the involvement of nickel-bound oxygen species as an intermediate. The isotope-labeling experiments using H218O2 showed 92.46% incorporation of 18O, revealing that H2O2 is the key oxygen supplier to form phenol. The catalytic efficiencies of complexes are strongly influenced by the geometrical configuration of intermediates, and stereoelectronic and steric properties, which are fine-tuned by the ligand architecture.
- Muthuramalingam, Sethuraman,Anandababu, Karunanithi,Velusamy, Marappan,Mayilmurugan, Ramasamy
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p. 5991 - 6001
(2019/11/11)
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- Method of removing protective groups of olefins under catalytic action of nickel
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The invention relates to a method of removing protective groups of olefins under the catalytic action of nickel. The method comprises following steps: dissolving olefin containing compounds into an organic solvent, carrying out reactions in the presence of a catalyst, organic ligands, bis(pinacolato)diboron, alkalis, alcohols, and water, wherein the catalyst contains nickel; after reactions, adding excess hydrochloric acid solution (1M) to adjust the pH to the acidic region, stirring the solution until the solution becomes clear; adding water and ethyl acetate to carry out extraction; washing the organic phase by saturated brine, drying the organic phase by anhydrous sodium sulfate, carrying out condensation, and adopting a 200-300 mesh silica gel column to carry out chromatographic separation to obtain compounds that contains alcohols or phenol. The provide method has the advantages that the adopted chemical reagents are common, the primary alkyl halide protective groups of olefins can be removed efficiently, and the method has a good application prospect in the field of organic synthesis and good industrial potential.
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Paragraph 0172-0175
(2019/10/04)
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- Room-Temperature Ionic Liquids (RTILs) as Green Media for Metal- and Base-Free ipso -Hydroxylation of Arylboronic Acids
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The oxidative hydroxylation of arylboronic acids to the corresponding phenolic compounds under metal- and base-free aerobic conditions is successfully demonstrated on a greener media. Hydrogen peroxide, as an eco-friendly oxidant, is compatible with green mediates room-temperature ionic liquids (RTIL)s, providing hydroxylation products of arylboronic acids in an efficient manner. The RTIL support is particularly interesting for its reusability.
- Kim, Seung-Hoi,Kwon, Gyu-Tae,Shin, Eun-Jae
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supporting information
p. 1815 - 1819
(2019/09/09)
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- Heterogeneous Palladium–Chitosan–CNT Core–Shell Nanohybrid Composite for Ipso-hydroxylation of Arylboronic Acids
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Abstract: A novel palladium-nanohybrid (Pd–Chitosan–CNT) catalytic composite has been developed using CNT–chitosan nanocomposite and palladium nitrate. The prepared catalytic platform displays excellent catalytic reactivity for the ipso-hydroxylation of various arylboronic acids with a mild oxidant aqueous H2O2 at room temperature, affording the corresponding phenols in excellent yields. Significantly, the easy recovery and reusability by simple manipulation demonstrate the green credentials of this catalytic platform. Graphical Abstract: [Figure not available: see fulltext.]
- Shin, Eun-Jae,Kim, Han-Sem,Joo, Seong-Ryu,Shin, Ueon Sang,Kim, Seung-Hoi
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- Potassium: Tert -butoxide mediated aerobic hydroxylation of arylboronic acids: An application towards the synthesis of (E)-phenoxy acrylates
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The first example of potassium tert-butoxide mediated aerobic hydroxylation of arylboronic acids is described. A variety of arylboronic acids bearing both electron donating and withdrawing substituents successfully participated in the reaction and furnished phenols in good yields. This strategy also provides access to one pot synthesis of (E)-3-phenoxy acrylates from arylboronic acids and propiolates. The solvent plays an important role and a binary solvent system comprising CH3CN/THF is found to be the best.
- Muhammad, Ibrahim,Balakrishnan, Madasamy Hari,Sasidharan, Manickam,Mannathan, Subramaniyan
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supporting information
p. 11065 - 11068
(2019/07/31)
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- Photoinduced hydroxylation of arylboronic acids with molecular oxygen under photocatalyst-free conditions
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Photoinduced hydroxylation of boronic acids with molecular oxygen under photocatalyst-free conditions is reported, providing a green entry to a variety of phenols and aliphatic alcohols in a highly concise fashion. This new protocol features photocatalyst-free conditions, wide substrate scope and excellent functional group compatibility.
- Xu, Yu-Ting,Li, Chen-Yuan,Huang, Xiao-Bo,Gao, Wen-Xia,Zhou, Yun-Bing,Liu, Miao-Chang,Wu, Hua-Yue
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supporting information
p. 4971 - 4975
(2019/09/30)
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- Search for a photoinduced (site-selective) cleavage of the Ar-Cl bond in dichloroanisoles
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The site-selective cleavage of an Ar-X bond in polyhalogenated aromatics is an important tool in synthetic planning especially when more than one identical halogen atom is present. An alternative to the usual metal-catalyzed cleavage is represented by photochemistry although only a few examples have been reported. We then investigated the feasibility of the site-selective photodechlorination of some dichloroanisoles through a combined experimental and computational study. In the case of 2,4-dichloroanisole, selective detachment of the chlorine atom at the ortho position with respect to the OMe group was observed upon photohomolysis (in cyclohexane) or photoheterolysis (in MeOH) of the Ar-Cl bond. In the latter case, 5-chloro-2-methoxy-1,1′-biphenyl was exclusively formed upon reaction of the resulting phenyl cation with benzene. The substitution of an OH group for a OMe group was detrimental since a lower photoreactivity resulted with no improvement in the selectivity.
- Raviola, Carlotta,Fagnoni, Maurizio
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p. 107 - 117
(2018/02/06)
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- Green Photoorganocatalytic Synthesis of Phenols from Arylboronic Acids
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A green and cheap protocol for the photocatalytic hydroxylation of arylboronic acids is presented. 2,2-Dimethoxy-2-phenylacetophenone proved to be the best photoinitiator, among a range of organocatalysts in promoting this reaction. This photocatalytic protocol can be expanded into a wide substrate scope of aromatic boronic acids bearing various functional groups, leading to the corresponding phenols in good to high yields under mild reaction conditions, which include water as solvent, light irradiation provided from standard light-bulbs at room temperature.
- Sideri, Ioanna K.,Voutyritsa, Errika,Kokotos, Christoforos G.
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supporting information
p. 1324 - 1328
(2017/12/06)
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- Synthesis of phenols by using aryldiazonium silica sulfate nanocomposites
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The hydrolysis of a new type of diazonium salt immobilized on the surface of silica sulfuric acid was studied in this work. By using diazonium salt nanocomposites, a number of phenol derivatives were synthesized in good yields. In contrast to the previous works, the present procedure was conveniently carried out under mild and solvent-free conditions. The effects of solvent and temperature were studied on the dediazoniation products. The notable advantages of this methodology were operational simplicity, availability of reactants, short reaction time and easy work-up.
- Zarei, Amin,Khazdooz, Leila,Aghaei, Hamidreza,Gheisari, Mohammad Mehdi,Alizadeh, Shahrzad,Golestanifar, Laleh
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supporting information
p. 6954 - 6961
(2017/11/16)
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- Reagent Design and Ligand Evolution for the Development of a Mild Copper-Catalyzed Hydroxylation Reaction
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Parallel synthesis and mass-directed purification of a modular ligand library, high-throughput experimentation, and rational ligand evolution have led to a novel copper catalyst for the synthesis of phenols with a traceless hydroxide surrogate. The mild reaction conditions reported here enable the late-stage synthesis of numerous complex, druglike phenols.
- Fier, Patrick S.,Maloney, Kevin M.
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supporting information
p. 3033 - 3036
(2017/06/07)
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- METHOD FOR SYNTHESIZING PHENOL USING METAL CATALYST
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The present invention relates to a method for synthesizing phenol using a metal catalyst and, more specifically, to a method for preparing phenol, which is a product of cross-coupling reaction by performing reaction of aryl halide and 2-dimethylaminoethanol in the presence of a metal catalyst. According to the present invention, phenol, as a product of cross-coupling reaction by performing reaction of aryl halide and 2-dimethylaminoethanol in the presence of a metal catalyst, can be synthesized with high yield. Also, various phenols having substituents can be synthesized.COPYRIGHT KIPO 2017
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Paragraph 0058; 0061
(2017/10/26)
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- METHOD FOR PREPARING P-HYDROXYMANDELIC COMPOUNDS IN STIRRED REACTORS
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The process allows the preparation of a p-hydroxymandelic compound, comprising at least one step of condensation of at least one aromatic compound bearing at least one hydroxyl group and whose para position is free, with glyoxylic acid, the condensation reaction being performed in at least one reactor equipped with at least one mixing means, the specific mixing power being between 0.1 kW/m3 and 15 kW/m3. In addition, the invention also relates to a process for preparing a 4-hydroxyaromatic aldehyde by oxidation of this p-hydroxymandelic compound.
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- N-Substituted 3(10H)-Acridones as Visible-Light, Water-Soluble Photocatalysts: Aerobic Oxidative Hydroxylation of Arylboronic Acids
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We disclosed a novel water-soluble photocatalyst that could promote aerobic oxidative hydroxylation of arylboronic acids to furnish phenols in excellent yields. This transformation uses visible-light irradiation under environmentally friendly conditions, that is, water-soluble catalyst, metal-free, green oxidant, room temperature.
- Xie, Hong-Yan,Han, Li-Shuai,Huang, Shan,Lei, Xiantao,Cheng, Yong,Zhao, Wenfeng,Sun, Hongbin,Wen, Xiaoan,Xu, Qing-Long
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p. 5236 - 5241
(2017/05/24)
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- Copper-Catalyzed Hydroxylation of (Hetero)aryl Halides under Mild Conditions
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The combination of Cu(acac)2 and N,N′-bis(4-hydroxyl-2,6-dimethylphenyl)oxalamide (BHMPO) provides a powerful catalytic system for hydroxylation of (hetero)aryl halides. A wide range of (hetero)aryl chlorides bearing either electron-donating or -withdrawing groups proceeded well at 130 °C, delivering the corresponding phenols and hydroxylated heteroarenes in good to excellent yields. When more reactive (hetero)aryl bromides and iodides were employed, the hydroxylation reactions completed at relatively low temperatures (80 and 60 °C, respectively) at low catalytic loadings (0.5 mol % Cu).
- Xia, Shanghua,Gan, Lu,Wang, Kailiang,Li, Zheng,Ma, Dawei
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supporting information
p. 13493 - 13496
(2016/10/31)
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- A Mild Strategy for the Preparation of Phenols via the Ligand-Free Copper-Catalyzed O-Arylation of para -Toluenesulfonic Acid
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A facile and simple ligand-free copper-catalyzed reaction to synthesize substituted phenols is reported. The reaction presumably proceeds via an O-arylsulfonate intermediate that is hydrolyzed to afford good to excellent yields of up to 88%. This protocol provides an alternative to existing reports which use strong hydroxide salts as the direct hydroxylation partner. Demonstrating a wide substrate scope and functional group tolerance, this protocol can also be applied to inexpensive and commercially available carboxylic acids to yield phenols.
- Tan, Bryan Yong-Hao,Teo, Yong-Chua
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supporting information
p. 1814 - 1819
(2016/07/16)
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- Visible-Light Photoredox Borylation of Aryl Halides and Subsequent Aerobic Oxidative Hydroxylation
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Efficient and practical visible-light photoredox borylation of aryl halides and subsequent aerobic oxidative hydroxylation were developed. The protocols use readily available aryl halides and bis(pinacolato)diboron as the starting materials, fac-Ir(ppy)3 as the photocatalyst, and corresponding arylboronic esters and phenols were obtained in good yields. The methods show some advantages including simple equipment, mild conditions, easy operation, and wide substrate scope. Therefore, they should provide a valuable strategy for chemical transformations.
- Jiang, Min,Yang, Haijun,Fu, Hua
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p. 5248 - 5251
(2016/11/02)
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- PROCESSES FOR PREPARING 2,5-DICHLOROPHENOL
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Processes for producing 2,5-dichlorophenol and 3,6-dichloro-2-methoxybenzoic acid are described. Various processes for isomerizing 2,4-dichlorophenol over a zeolite catalyst to form 2,5-dichlorophenol are provided. Processes for preparing 2,5-dichlorophenol including hydroxylating 1,4-dichlorobenzene are also described. The present invention also relates to processes for producing 3,6-dichloro-2-methoxybenzoic acid.
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- Selective hydroxylation of benzene derivatives and alkanes with hydrogen peroxide catalysed by a manganese complex incorporated into mesoporous silica-alumina
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Selective hydroxylation of benzene derivatives and alkanes to the corresponding phenol and alcohol derivatives with hydrogen peroxide was efficiently catalysed by a manganese tris(2-pyridylmethyl)amine (tpa) complex ([(tpa)MnII]2+) incorporated into mesoporous silica-alumina with highly acidic surfaces in contrast to the reactions in a homogeneous solution where [(tpa)MnII]2+ was converted catalytically to a much less active bis(μ-oxo)dimanganese(iii,iv) complex. This journal is
- Aratani, Yusuke,Yamada, Yusuke,Fukuzumi, Shunichi
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supporting information
p. 4662 - 4665
(2015/05/27)
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- Reaction of 1,2-difunctionalized ethanes with aryl iodides in copper-catalyzed cross-coupling: Application to synthesis of phenols
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A series of 1,2-difunctionalized ethanes, such as ethylene glycol, 2-aminoethanol, 1,2-diaminoethane, 2-dimethylaminoethanol N',N'-dimethylethane-1,2-diamine, were investigated to test the reactivity with aryl iodides in the presence of copper catalysts. Under the reaction conditions, they produce the various Cheteroatom cross-coupled products. Interestingly, ethylene glycol and 2-dimethylaminoethanol afforded mainly the phenolic compounds while the others produced different cross-coupled products. Although ethylene glycol and 2-dimethylaminoethanol resulted in the same product, their behaviors in the reaction were quite different: ethylene glycol appears to mostly act as the ligand and 2-dimethylaminoethanol appears to serve as both the ligand and reactant. This finding led to a copper-catalyzed synthesis of phenols using either ethylene glycol or 2-dimethylaminoethanol, which can be applied to a variety of aryl iodides, providing an alternative synthetic route to phenols.
- Kim, Jihye,Battsengel, Oyunsaikhan,Liu, Yajun,Chae, Junghyun
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supporting information
p. 2833 - 2840
(2016/02/05)
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- Porphyrin-Metalation-Mediated Tuning of Photoredox Catalytic Properties in Metal-Organic Frameworks
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Photoredox catalytic activation of organic molecules via single-electron transfer processes has proven to be a mild and efficient synthetic methodology. However, the heavy reliance on expensive ruthenium and iridium complexes limits their applications for scale-up synthesis. To this end, photoactive metal-organic frameworks (MOFs) exhibit unique advantages as novel heterogeneous photocatalytic systems, yet their utilization toward organic transformations has been limited. Here we describe the preparation and synthetic applications of four isostructural porphyrinic MOFs, namely, UNLPF-10a, -10b, -11, and -12, which are composed of free base, InIII-, SnIVCl2-, and SnIV-porphyrin building blocks, respectively. We demonstrate that the metalation with high valent metal cations (InIII and SnIV) significantly modifies the electronic structure of porphyrin macrocycle and provides a highly oxidative photoexcited state that can undergo efficient reductive quenching processes to facilitate organic reactions. In particular, UNLPF-12 exhibits both outstanding photostability and efficient photocatalytic activities toward a range of important organic transformations including aerobic hydroxylation of arylboronic acids, amine coupling, and the Mannich reaction.
- Johnson, Jacob A.,Luo, Jian,Zhang, Xu,Chen, Yu-Sheng,Morton, Martha D.,Echeverría, Elena,Torres, Fernand E.,Zhang, Jian
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p. 5283 - 5291
(2015/09/15)
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- Ligand- and base-free synthesis of phenols by rapid oxidation of arylboronic acids using iron(III) oxide
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Fe2O3 catalyzed rapid oxidation of arylboronic acids to obtain phenols in excellent yields (90-95%) in the presence of atmospheric oxygen under solar VIS-light irradiation using α-Fe2O3 as a catalyst in ligand- and base-free conditions is presented.
- Sawant, Sanghapal D.,Hudwekar, Abhinandan D.,Aravinda Kumar,Venkateswarlu, Vunnam,Singh, Parvinder Pal,Vishwakarma, Ram A.
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p. 811 - 814
(2015/03/03)
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- Nanoscale Fe0particles for pentachlorophenol removal from aqueous solution: Temperature effect and particles transformation
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Pentachlorophenol (PCP), as an important contaminant which was toxic and intractable, has received extensive attention. In this paper, the temperature effect during the transformation of PCP using nanoscale Fe0particles was studied, and the transformation processes of PCP and iron particles was explained. The results revealed that the removal processes of PCP followed pseudo first-order kinetics. The scale of dechlorination to the transformation of PCP increased with the increase of temperature, though the transformation rate decreased after reacting for 2 h under the experimental condition. However, the initial apparent transformation rate constants were calculated to be 0.312-0.536 h-1at the temperature of 20-50°C, which showed an increase of transformation rate along with the increase of temperature. And the surface-area-normalized rate constants were calculated to be 9.50 × 10-3- 1.63 × 10-2L·h-1· m-2. The experimental activation energy was calculated to be 15.0 kJ · mol-1from these rate constants using Arrhenius equation. A phenomenon observed at 50°C indicated that more than one chlorine atom was removed from PCP and suggested β-elimination might be the major pathway for transformation. Sorption experiments showed that the sorption process on the surface of particles could be ignored in the kinetics and thermodynamics models. The changes of morphologies of nanoparticles before and after reaction indicated the transformation process of iron particles, and could be used to explain the changes of activity of nanoparticles. Magnetite (Fe3O4) and/or maghemite (Fe2O3) and lepidocrocite (γ-FeOOH) were corrosion products of iron. And along with the increase of temperature, the increased intensity of XRD peaks revealed the related a better crystallizing. Copyright
- Cheng, Rong,Zheng, Xiang,Liu, Peng,Wang, Jian-Long
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p. 6941 - 6949
(2015/02/18)
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- Metal-free synthesis of substituted phenols from arylboronic acids in water at room temperature
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A convenient, efficient and practical metal-free method for the synthesis of substituted phenols from arylboronic acids has been developed. The protocol uses hydrogen peroxide as a hydroxylating agent, ammonium bicarbonate as an additive, and the reactions were conveniently performed in water at room temperature. The method shows an excellent tolerance of functional groups, so it will find a wide variety of applications in academic and industrial research.
- Jiang, Min,Yang, Hai-Jun,Li, Yong,Jia, Zhi-Ying,Fu, Hua
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supporting information
p. 715 - 719
(2014/06/09)
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- Continuous-flow hydroxylation of aryl iodides promoted by copper tubing
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A simple and ligand-free synthesis of phenols from the corresponding aryl iodides in a continuous-flow system is described. The reaction is complete in only 4 to 20 minutes when heated between 150 to 165 °C in a reactor consisting of a commercially available copper coil. An example of trapping of the phenoxide in situ is also shown.
- Cyr, Patrick,Charette, André B.
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supporting information
p. 1409 - 1412
(2014/06/23)
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- Copper(ii)-catalyzed C-O coupling of aryl bromides with aliphatic diols: Synthesis of ethers, phenols, and benzo-fused cyclic ethers
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A highly efficient copper-catalyzed C-O cross-coupling reaction between aryl bromides and aliphatic diols has been developed employing a cheaper, more efficient, and easily removable copper(ii) catalyst. A broad range of aryl bromides were coupled with aliphatic diols of different lengths using 5 mol% CuCl2 and 3 equivalents of K2CO3 in the absence of any other ligands or solvents to afford the corresponding hydroxyalkyl aryl ethers in good to excellent yields. In this newly developed protocol, aliphatic diols have multilateral functions as coupling reactants, ligands, and solvents. The resulting hydroxyalkyl aryl ethers were further readily converted into the corresponding phenols, presenting a valuable alternative way to phenols from aryl bromides. Furthermore, it was demonstrated that they are useful intermediates for more advanced molecules such as benzofurans and benzo-fused cyclic ethers. This journal is
- Liu, Yajun,Park, Se Kyung,Xiao, Yan,Chae, Junghyun
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p. 4747 - 4753
(2014/06/24)
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- Structure-reactivity Relationships as Probes to Acetylcholinesterase Inhibition Mechanisms by Aryl Carbamates. II. Hammett-Taft Cross-interaction Correlations
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Substituted phenyl-N-butyl carbamates (1) and p-nitrophenyl-N-substituted carbamates (2) are characterized as "pseudo-pseudo-substrate" inhibitors of acetylcholinesterase. Since the inhibitors protonate in pH 7.0 buffer solution, the virtual inhibition co
- Lin, Gialih
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p. 423 - 429
(2015/02/05)
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- A mechanistic study on the α-N-acetylgalactosaminidase from E. meningosepticum: A family 109 glycoside hydrolase
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A recombinant glycoside hydrolase family 109 α-N- acetylgalactosaminidase from the pathogenic bacteria E. meningosepticum catalyses the hydrolysis of aryl 2-acetamido-2-deoxy-α-d- galactopyranosides. The sensitivities to leaving group abilities (βlg values) on V and V/K are -0.08 ± 0.06 and -0.31 ± 0.12, respectively. These results are consistent with an E2 elimination following hydride transfer from C3. This journal is the Partner Organisations 2014.
- Chakladar, Saswati,Shamsi Kazem Abadi, Saeideh,Bennet, Andrew J.
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p. 1188 - 1192
(2014/08/05)
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- A novel sustainable strategy for the synthesis of phenols by magnetic CuFe2O4-catalyzed oxidative hydroxylation of arylboronic acids under mild conditions in water
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A novel sustainable strategy for the synthesis of phenols has been developed using inexpensive, readily available, air-stable, and recyclable CuFe2O4 nanoparticles as the catalyst, and the corresponding substituted phenols were obtained in moderate to good yields by oxidative hydroxylation of arylboronic acids in water. Importantly, a ligand or an additive was not necessary. The catalyst was completely recoverable with an external magnet and could be reused six times without significant loss of catalytic activity.
- Yang, Daoshan,An, Baojuan,Wei, Wei,Jiang, Min,You, Jinmao,Wang, Hua
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supporting information
p. 3630 - 3634
(2014/05/20)
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- Preparation of phenolic compounds through catalyst-free ipso-hydroxylation of arylboronic acids
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A novel method for the preparation of phenolic compounds through ipso-hydroxylation of the corresponding widely available arylboronic acid precursors is described. Through application of a novel PEG400-H 2O2 reactant system, a variety of substituted phenols and other aromatic analogues have been prepared in excellent yields at room temperature in the absence of any catalyst.
- Gohain, Mukut,Du Plessis, Maretha,Van Tonder, Johannes H.,Bezuidenhoudt, Barend C.B.
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p. 2082 - 2084
(2014/04/03)
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