- Synthesis of renewable C-C cyclic compounds and high-density biofuels using 5-hydromethylfurfural as a reactant
-
The major challenge in the synthesis of high-density biofuels is to identify the bio-based source for C-C cyclic compounds and C-C coupling reactions with a suitable selectivity. Herein, we selectively synthesize 1,2,4-benzenetriol (BTO) with a yield of 51.4% from cellulose-derived 5-hydromethylfurfural via a ring-rearrangement reaction. The cellulose-derived route is a more meaningful route for the C-C cyclic compounds compared to the traditional hemicellulose- and lignin-derived routes. Furthermore, BTO is very easily dimerized via a C-C oxidative coupling reaction, showing a yield of 94.4% and selectivity of nearly 100% under environmentally friendly reaction conditions. After hydrodeoxygenation, bicyclohexane is obtained with a yield of 87.4%. This work not only provides a promising route to produce C-C cyclic fine compounds based on a cellulose-derived route, but also shows a highly efficient synthesis route for high-density biofuels via the C-C oxidative coupling reaction.
- Cai, Taimei,Deng, Qiang,Deng, Shuguang,Gao, Rui,Peng, Hailong,Wang, Jun,Zeng, Zheling,Zhong, Jin,Zou, Ji-Jun
-
-
Read Online
- Reactions of 1,4-benzoquinones with s2 reducing centers
-
Aqueous solutions of Sn(II) and Ge(II) (in chloride media) and In(I) (in perchlorate media) react quantitatively with 1,4-benzoquinone and its 2,5-(OH)2 and 2,5-Cl2-3,6-(OH)2 derivatives, reducing the oxo-functions to 1,4-(OH)2. For Sn(II) and Ge(II), reaction is accelerated by incorporation of 2,5-(OH)2 substituents and by chloroanation of the s2 center. The most reactive reducing Sn(II) species are SnCl3- for benzoquinone and dihydroxyquinone but SnCl2(aq)x for the dichloroquinone. Reductions by Ge(II) proceed mainly through a species (probably GeCl 42-) having one more chloride than the predominant form. The activated complex for the (OH)2bzq-Ge(II) reaction features two germanium centers, only one of which is involved in the reduction act. Reductions of these quinones by In(I) proceed 102-103 times as rapidly as those by Sn(II) and Ge(II) and are not accelerated by hydroxylation of the quinone ring. The Royal Society of Chemistry 2003.
- Yang, Zhiyong,Gould, Edwin S.
-
-
Read Online
- Oxygen-vacancy-promoted catalytic wet air oxidation of phenol from MnO: X-CeO2
-
Catalytic oxidation can be effectively promoted by the presence of oxygen vacancies on the catalyst surface. In this study, the effect of oxygen vacancies on the catalytic wet air oxidation (CWAO) of phenol was investigated with CeO2 and MnOx-CeO2 as catalysts. CeO2 and MnOx-CeO2 catalysts with different amounts of oxygen vacancies were obtained via hydrothermal methods and applied for the CWAO of phenol. It was found that CeO2 and MnOx-CeO2 nanorods were much more active than the cubic nanorods. The physicochemical properties of the samples were characterized by TEM, XRD, BET, XPS, and H2-TPR techniques. The results revealed that the presence of oxygen vacancies in CeO2 and MnOx-CeO2 catalysts could increase the oxidizing ability of the catalysts surface. The addition of Mn could greatly improve the adsorption ability of CeO2 and more efficiently oxidize phenol and its intermediates. The synergy between Mn and Ce could further improve the catalyst redox properties and produce a larger amount of active oxygen species, which is the reason why MnOx-CeO2 nanorods are the most active catalysts among the catalysts investigated in this study.
- Ma, Changjian,Wen, Yaoyao,Yue, Qingqing,Li, Anqi,Fu, Jile,Zhang, Nouwei,Gai, Hengjun,Zheng, Jinbao,Chen, Bing H.
-
-
Read Online
- Self-decarboxylation of trichloroacetic acid redox catalyzed by trichloroacetate ions in acetonitrile solutions
-
In mixtures of trichloroacetate ion and trichloroacetic acid in acetonitrile, trichloromethyl radicals are produced as a result of the redox reaction between the acid and its conjugate base. The reaction follows a loop mechanism in which the trichloroacet
- Valencia, Drochss P.,Astudillo, Pablo D.,Galano, Annia,Gonzalez, Felipe J.
-
-
Read Online
- Purification and characterization of a naringinase from Aspergillus aculeatus JMUdb058
-
A naringinase from Aspergillus aculeatus JMUdb058 was purified, identified, and characterized. This naringinase had a molecular mass (MW) of 348 kDa and contained four subunits with MWs of 100, 95, 84, and 69 kDa. Mass spectrometric analysis revealed that the three larger subunits were β-d-glucosidases and that the smallest subunit was an α-l-rhamnosidase. The naringinase and its α-l-rhamnosidase and β-d-glucosidase subunits all had optimal activities at approximately pH 4 and 50 C, and they were stable between pH 3 and 6 and below 50 C. This naringinase was able to hydrolyze naringin, aesculin, and some other glycosides. The enzyme complex had a Km value of 0.11 mM and a kcat/Km ratio of 14 034 s-1 mM -1 for total naringinase. Its α-l-rhamnosidase and β-d-glucosidase subunits had Km values of 0.23 and 0.53 mM, respectively, and kcat/Km ratios of 14 146 and 7733 s -1 mM-1, respectively. These results provide in-depth insight into the structure of the naringinase complex and the hydrolyses of naringin and other glycosides.
- Chen, Yuelong,Ni, Hui,Chen, Feng,Cai, Huinong,Li, Lijun,Su, Wenjin
-
-
Read Online
- Kinetics and mechanistic studies of Ru(III) catalyzed oxidation of p-hydroxy benzoic acid by sodium N-chloro-p-toluene sulphonamide in acidic media
-
Kinetics studies of the oxidation of p-hydroxy benzoic acid by sodium N-chloro-p-toluene sulphonamide (chloramine-T or CAT) have been carried out in aqueous perchloric acid medium at 35 °C. The reaction follows almost similar kinetics, being first order with respect to chloramine-T, p-hydroxy benzoic acid and Ru(III). The reaction exhibits inverse first order depedence on the concentration of medium [HClO4]. Variation of ionic strength by adding NaClO4have no significant effect on the reaction rate. The addition of p-toluene sulphonamide, which is one of the reaction products, had no significant effect on the reaction rate. Thermodynamic parameters were computed by studying the reactions at different temperature (303-318 K). The rate laws derived are in excellent agreement with the experimental results. A mechanism consistent with the above kinetic result has been suggested.
- Singh, Kamini,Singh
-
-
Read Online
- A highly selective photooxidation approach using O2 in water catalyzed by iron(II) bipyridine complex supported on NaY zeolite
-
A new photocatalytic system involving iron(II) bipyridine supported on NaY zeolite (FeBY) shows excellent reactivity and selectivity in the oxidation of organic compounds. This approach allows highly controlled oxidation reaction to occur but avoids undesirable mineralization into CO2 and H 2O.
- Li, Jing,Ma, Wanhong,Huang, Yingping,Cheng, Mingming,Zhao, Jincai,Yu, Jimmy C.
-
-
Read Online
- Photohydroxylation of 1,4-Benzoquinone in Aqueous Solution Revisited
-
In water, photolysis of 1,4-benzoquinone, Q gives rise to equal amounts of 2-hydroxy-1,4-benzoquinone HOQ and hydroquinone QH2 which are formed with a quantum yield of ψ=0.42, independent of pH and Q concentration. By contrast, the rate of decay of the triplet (λmax=282 and ～ 410 nm) which is the precursor of these products increases nonlinearly (k= (2→3.8)×106 s-1) with increasing Q concentration ((0.2→10) mM). The free-radical yield detected by laser flash photolysis after the decay of the triplet also increases with increasing Q concentration but follows a different functional form. These observations are explained by a rapid equilibrium of a monomeric triplet Q* and an exciplex Q2* (K=5500±1000m-1). While Q* adds water and subsequent enolizes into 1,2,4-trihydroxybenzene Ph(OH) 3, Q2* decays by electron transfer and water addition yielding benzosemiquinone .QH and .OH adduct radicals .QOH. The latter enolizes to the 2-hydroxy-1,4-semiquinone radical .Q(OH)H within the time scale of the triplet decay and is subsequently rapidly (microsecond time scale) oxidized by Q to HOQ with the concomitant formation of .QH. On the post-millisecond time scale, that is, when .QH has decayed, Ph(OH)3 is oxidized by Q yielding HOQ and QH2 as followed by laser flash photolysis with diode array detection. The rate of this pH- and Q concentration-dependent reaction was independently determined by stopped-flow. This shows that there are two pathways to photohydroxylation; a free-radical pathway at high and a nonradical one at low Q concentration. In agreement with this, the yield of Ph(OH)3 is most pronounced at low Q concentration. In the presence of phosphate buffer, Q* reacts with H2PO4-giving rise to an adduct which is subsequently oxidized by Q to 2-phosphato-1,4-benzoquinone QP. The current view that .OH is an intermediate in the photohydroxylation of Q has been overturned. This view had been based on the observation of the .OH adduct of DMPO when Q is photolyzed in the presence of this spin trap. It is now shown that Q*/Q2* oxidizes DMPO (k ≈1×108M -1S-1) to its radical cation which subsequently reacts with water. Q*/Q2* react with alcohols by H abstraction (rates in units of M-1S-1): methanol (4.2×10 7), ethanol (6.7×107), 2-propanol (13×10 7) and tertiary butyl alcohol (～0.2×107). DMSO (2.7×109) and O2 (～2×109) act as physical quenchers.
- Von Sonntag, Justus,Mvula, Eino,Hildenbrand, Knut,Von Sonntag, Clemens
-
-
Read Online
- High-pressure Kinetics of the Reaction of p-Benzoquinone with Di-n-butylamine in Some Aprotic Solvents
-
The kinetics and the volume of activation of the title reaction to form 2-dibutylamino-p-benzoquinone in 1,2-dichloroethane and acetonitrile, -54 +/- 2 and -67 +/- 2 cm3/mol respectively, strongly support a reaction scheme in which ionic species are formed prior to the rate-determining step which is the second attack by the amine.
- Sasaki, Muneo,Bando, Masaichi,Inagaki, Yoh-ichi,Amita, Fujitsugu,Osugi, Jiro
-
-
Read Online
- Cooperative structure direction of organosilanes and tetrapropylammonium hydroxide to generate hierarchical ZSM-5 zeolite with controlled porous structure
-
Hierarchical ZSM-5 zeolite with short-range ordered mesoporosity and hierarchical ZSM-5 zeolite nanorods were obtained via a direct hydrothermal synthesis by the cooperative structure direction of dimethyloctadecyl[3-(trimethoxysilyl)propyl]- ammonium chloride (TPOAC) and tetrapropylammonium hydroxide (TPAOH). Dimethyloctadecyl[3-(dimethoxymethylsilyl)propyl]ammonium chloride (DPOAC) and octadecyltrimethylammonium chloride (OTAC) were also employed as structure directing agents (SDA) to further explore the role of methoxysilyl groups in organosilanes during the formation of hierarchical structure. The prepared materials were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), N2 adsorption-desorption, FT-IR, UV-vis and inductively coupled plasma-optical emission spectroscopy (ICP-OES). The characterization results showed that the use of TPOAC and DPOAC would generate short-range ordered mesopores and irregular mesopores, respectively. Hierarchical ZSM-5 zeolite nanorods with worm-like intracrystalline mesopores could be obtained by adjusting the amount of silicon source. The lack of methoxysilyl groups in OTAC however could lead to phase separation problems. Furthermore, the hierarchical Fe-ZSM-5 zeolite with short-range ordered mesoporosity showed enhanced catalytic activity and stability for the hydroxylation of phenol at room temperature.
- Shen, Yu,Han, Zongzhuang,Li, Hang,Li, Haichao,Wang, Gang,Wang, Fumin,Zhang, Xubin
-
-
Read Online
- Reactions of phenol-OH-adduct radicals. Phenoxyl radical formation by water elimination vs. oxidation by dioxygen
-
The reactions of OH radicals generated radiolytically in N2O-saturated aqueous solutions with phenol have been examined, focusing special attention on the addition of dioxygen and the competing dehydration reactions of the OH-adduct radicals. Using the pulse radiolysis technique, the overall rate constant of dioxygen addition of the dihydroxycyclohexadienyl radicals was determined to be k = 1.2 * 109 dm3 mol-1 s-1. This dioxygen addition reaction was found to be practically irreversible, in contrast to other hydroxycyclohexadienyl radicals. The so-formed dihydroxycyclohexadienylperoxyl radicals subsequently eliminate HO2./O2.-. By using tetranitromethane (TNM) as a probe for O2.- (formation of the nitroform anion), the overall rate constant of HO2.-elimination (mainly of the para- and ortho-isomers, formation of hydroquinone and catechol, respectively) was determined to be 1.3 * 105 s-1. The rate constant of the dehydration of the p-OH-adduct in neutral to acidic solution was determined by monitoring the absorbance build-up of the phenoxyl radical to be k7 = 1.8 * 103 + 1.7 * 109 * [H+] s-1, and that of the o-OH-adduct to be k6 = 1.1 * 108 * [H+] s-1 (the uncatalysed reaction is too slow to be measurable by this technique). The HPO42--catalysed dehydration rate constant of the p-OH-adduct was similarly determined to be 5.8 * 107 dm3 mol-1 s-1. Based on the above rate constant of dioxygen addition, the rate constant of the proton-catalysed dehydration of the p-OH-adduct was determined by the competition of these two reactions on the yield of hydroquinone to be 1.0 * 109 dm3 mol-1 s-1, and similarly that of the ortho-OH-adduct (on the yield of catechol) to be 2.1 * 108 dm3 mol-1 s-1.
- Mvula, Eino,Schuchmann, Man Nien,Sonntag, Clemens von
-
-
Read Online
- Radical Spectra and Product Distribution following Electrophilic Attack by the OH. Radical on 4-Hydroxybenzoic Acid and Subsequent Oxidation
-
The distribution of electrophilic OH. radical addition to 4-hydroxybenzoic acid (HBA) has been determined by oxidizing the radical intermediates (substituted hydroxycyclohexadienyl radicals) with quinones and viologens, to yield products.It is deduced from product analysis using high-performance liquid chromatography that the fractions of OH. attack at the 1:2:3:4 positions of HBA are 0.16:0.04:0.65:0.15 respectively.Pulse radiolysis studies show that the rate of electron transfer from the radical intermediate formed by OH. addition to position 3 of HBA is dependent on the one-electron reduction potential of the oxidant.This electron-transfer process is in competition with the elimination of water by general acid-base catalysis to yield the phenoxyl radical.Catalysis by OH- proceeds through the formation of the deprotonated species, pKa=8.4+/-0.2, followed by the elimination of water, ke=3.0+/-0.3*105 s-1.The addition of an OH. radical ipso to the hydroxy group of HBA also gives rise to the phenoxyl radical through rapid water elimination, k=2*107 s-1.The addition of an OH. radical to position 3 of HBA gives rise to an absorption band centred at 365 nm.
- Anderson, Robert F.,Patel, Kantilal B.,Stratford, Michael R. L.
-
-
Read Online
- New Zn(II) coordination polymers constructed from amino-alcohols and aromatic dicarboxylic acids: Synthesis, structure, photocatalytic properties, and solid-state conversion to ZnO
-
Four new coordination polymers have been obtained solvothermally from the reactions of Zn(NO3)2·6H2O with 1,2-, 1,3-, or 1,4-benzedicarboxylic acids in the presence of various amino-alcohols: 1 [Zn2(Htea)2(1,2-bdc)] (1), 1 [Zn(H3tris)(1,3-bdc)(CH3OH)] (2), 3 [Zn5(Htea)2(1,3-bdc)3(H2O)]·2.6H2O (3), and 3 [Zn3(H2dea)2(1,4-bdc)3] (4) (H3tea = triethanolamine, H3tris = tris(hydroxymethyl)aminomethane, H2dea = diethanolamine, 1,2-H2bdc =1,2-benzenedicarboxylic acid, 1,3-H2bdc =1,3-benzenedicarboxylic acid, and 1,4-H2bdc =1,4-benzenedicarboxylic acid). Their crystal structures, thermogravimetric analyses, solid-state transformation to ZnO and characterization of the resultant zinc oxide particles are reported. Compounds 1 and 2 show three-dimensional (3D) supramolecular architectures, generated from the interconnection of the zigzag (in 1) and respectively the linear (in 2) chains through hydrogen bonding interactions. The crystal structure of 3 revealed the presence of five different types of zinc atoms that are successively linked through carboxilato or alkoxo bridges in a helicoidal chain running along the crystallographic a axis. Both right-handed (P) and left-handed (M) helices are present in the crystal, and they are alternately interconnected by pairs of isophthalato bridges, resulting in channels of hexagonal shape, filled with water molecules. Compound 4 has a 3D structure in which linear centrosymmetric {Zn3(H2dea)2}6+ nodes are joined by terephthalate bridges. Owing to its porous network, compound 3 was tested in two selective reactions: photooxidation of phenol to hydroquinone and aerobic photooxidative condensation of benzylamine to N-benzylidenebenzylamine.
- Paraschiv, Carmen,Cucos, Andrei,Shova, Sergiu,Madalan, Augustin M.,Maxim, Catalin,Visinescu, Diana,Cojocaru, Bogdan,Parvulescu, Vasile I.,Andruh, Marius
-
-
Read Online
- Synthesis and characterization of bio-inspired diiron complexes and their catalytic activity for direct hydroxylation of aromatic compounds
-
Three [FeFe]-hydrogenase model complexes [(μ-dmedt){Fe(CO)3}2] [1; dmedt = SCH(CH3)CH(CH3)S], [(μ-dmedt){Fe(CO)3}{Fe (CO)2PPh3}] (1-PPh3), and [(μ-dmest){Fe(CO)3}2] [1-O; dmest = SCH(CH3)CH(CH3)S(O)], 1-O were synthesized and characterized. These model complexes, which are generally used as the functional biomimics of the hydrogen-producing dinuclear active site in [FeFe]-hydrogenase, were used as efficient catalysts for the selective hydroxylation of aromatic compounds to phenols under mild conditions. Because both the dithiolato-sulfur site and the Fe-Fe bond in the model complexes were possible active oxidation sites, DFT calculations were used to investigate the oxygenated products, that is, the S-oxygenated products or the Fe-oxygenated forms of the model complexes, which may be involved in the catalytic cycle. The experimental and computational results indicate that the thermodynamically favored Fe-oxygenated intermediates dominate the hydroxylation of the aromatic compounds. A possible mechanism for the hydroxylation is also proposed. Three FeI-FeI organometallic complexes were synthesized and used as highly selective catalysts for the direct hydroxylation of aromatic compounds to phenols, forming FeII-μ-O-FeII intermediates as the active oxygen-transfer species.
- Wang, Xiao,Zhang, Tianyong,Yang, Qiusheng,Jiang, Shuang,Li, Bin
-
-
Read Online
- Synthesis, characterization and catalytic reactivity of pentacoordinate iron dicarbonyl as a model of the [Fe]-hydrogenase active site
-
Two mono iron complexes Fe(CO)2PR3(NN) (R = Cy (3), Ph (4), NN = o-phenylenediamine dianion ligand, N2H2Ph2-) derived from the ligand substitution of Fe(CO)3I2PR3 by t
- Zhang, Tianyong,Sheng, Liao,Yang, Qiusheng,Jiang, Shuang,Wang, Yanhong,Jin, Chaohui,Li, Bin
-
-
Read Online
- Beyond esterase-like activity of serum albumin. Histidine-(nitro)phenol radical formation in conversion cascade of p-nitrophenyl acetate and the role of infrared light
-
Serum albumin, recognized mainly for its capacity to act as a carrier protein for many compounds, can also actively transform some organic molecules. As a starting point in this study, we consider esterase-like activity of bovine serum albumin (BSA) toward p-nitrophenyl acetate (p-NPA). Our results reveal that the reaction goes beyond ester hydrolysis step. In fact, the transformation product, p-nitrophenol (p-NP), becomes a substrate for further reaction with BSA in which its nitro group in subtracted and released in the form of HNO2. Spectral data indicate that this cascade of events proceeds through formation of phenoxyl radical via proton-coupled electron transport (PCET) between OH group of p-NP and imidazole ring of histidine from the protein. Furthermore, the effect of application of electromagnetic radiation in the infrared range suggests that this remote physical trigger can support interactions based on PCET mechanism by acting on polarization and mutual alignment of water dipoles serving as effective water wires.
- Kowacz, Magdalena,Warszyński, Piotr
-
-
Read Online
- Reductions by aquatitanium(II)
-
Solutions of titanium(II), prepared by dissolving titanium wire in mixtures of hydrofluoric and triflic acids, reduce quinones, nitrosodisulfonate anion, and complexes of cobalt(III). When the oxidant is taken in excess, these reactions yield Ti(IV), whereas with excess reductant, the principal product is Ti(III). These reactions are compared with those by Ti(III). Despite differences in rate laws, it is clear that rate ratios for the two reductants (k TiII/kTiIII) fall well below 10 4, the minimum selectivity corresponding to estimated differences in formal potentials, and in some instances, Ti(II), the stronger reductant, reacts more slowly. For both Ti(III) and Ti(II), reductions within the series [Co(NH3)5X]2+ (where X = F, Cl, Br, and I), the fluoro complex reacts much more rapidly than its congeners, and the bromo and iodo complexes are slowest, an order similar to that for Eu2+ reductions, but opposite to that for Cr(II) and Cu(I). The [Co(NH 3)5Br]2+ reaction with excess Ti(II) proceeds at rates very nearly independent of [oxidant] during the first 80-90% reaction, implying that initiation occurs via unimolecular conversion of Ti(II) to an activated cationic reducing species, in the same manner as the earlier described reduction of I3- by Ge(II) in aqueous HCl. The Royal Society of Chemistry 2005.
- Yang, Zhiyong,Gould, Edwin S.
-
-
Read Online
- Evidence for single electron transfer (SET) pathway in the reaction of primary alkylcadmium reagents with p-benzoquinone
-
The reaction of primary alkylcadmium reagents with p-benzoquinone at various conditions was studied. On the basis of our results, reaction proceeds through a SET mechanism that forms loose and tight intermediates, which produce quinole (1) and substituted hydroquinone (2). In both cases, hydroquinone (3) is obtained in different yields.
- Shahidzadeh, Mansour,Ghandi, Mehdi
-
-
Read Online
- Briggs-Rauscher reaction with 1,4-cyclohexanedione substrate
-
A new organic substrate has been used to promote oscillations under batch conditions in the Briggs-Rauscher oscillating system. The new substrate, 1,4-cyclohexanedione (CHD), reacts with aqueous iodine via an enol mechanism. We discuss the effect of the initial concentrations, the temperature and chemical perturbations. In a definite range of concentrations long-lived oscillations with two significantly different frequency periods were observed. The low frequency parts are temperature-dependent while the high frequency oscillations do not show temperature dependence. The inhibitory effects of 1,4-hydroquinone and 1,4-benzoquinone on the oscillations and the kinetics of some important component reactions were studied to develop a model for the simulation of the observed oscillations. by Oldenbourg Wissenschaftsverlag.
- Kereszturi, Klara,Szalai, Istvan
-
-
Read Online
- Highly selective hydrogenation of Α, Β-unsaturated carbonyl compounds over supported Co nanoparticles
-
A nitrogen-doped porous carbon materials (CPNs) with supported Co nanoparticles (Co@CPNs) with lamellar structure, high surface area and excellent magnetic properties was synthesized successfully by one-pot method. The Co@CPNs exhibited an excellent catalytic activity with 99% conversion and selectivity for hydrogenation of furfural (FAL) to furfuryl alcohol (FOL) under the pressure of H2. In addition, the Co@CPNs were further investigated in the kinetic study and selective hydrogenation of the other α, β unsaturated carbonyl compounds. The study of the Co@CPNs indicated that it was suitable for selective hydrogenation of the α, β unsaturated carbonyl compounds in the industry.
- Jiang, Pengbo,Li, Xinlin,Gao, Wenbin,Wang, Xiang,Tang, Yu,Lan, Kai,Wang, Bin,Li, Rong
-
-
Read Online
- Activation of Water with Anionic Platinum Carbonyl Clusters
-
Rate parameters have been determined for the oxidation of water to oxygen by (2-).The cluster anion is found to catalyse the conversion of p-benzoquinone to benzene-1,4-diol with water or hydrogen.U.v.-visible and i.r.spectroscopy suggest the
- Basu, Amitabha,Bhaduri, Sumit,Sharma, Krishna R.
-
-
Read Online
- N,N-bis(quinonyl)amines; synthesis and X-ray structure
-
The preparation of several symmetrical and nonsymmetrical N,N-bis(quinonyl)amines is reported. These compounds, which have two quinones separated by one amino group, were obtained by an unexpected reaction of primary or secondary substituted aminoquinones
- Bittner, Shmuel,Meenakshi, Chandran,Temtsin, Galina
-
-
Read Online
- Molybdenum and copper catalysis of reductions by titanium(II) and titanium(III)
-
Reductions of vanadium(iv), benzoquinone, and tri-iodide, both by titanium(iii) and by titanium(ii), are catalyzed by molybdenum(vi). The VO 2+-Ti(ii) reaction is catalyzed by copper(ii) as well. Reactions of Ti(ii) with the oxidant in excess y
- Yang, Zhiyong,Gould, Edwin S.
-
-
Read Online
- Effects of Pressure on the Photoreduction of p-Benzoquinone in Normal and Reversed Micellar Sysytems
-
The photoreduction of p-benzoquinone (p-BQ) in normal and reversed micellar systems has been studied kinetically under high pressures up to 150 MPa.Anionic sodium dodecyl sulphate (SDS) micelles accelerated the reaction, while cationic hexadecyltrimethyla
- Tamura, Katsuhiro,Abe, Masatoshi,Terai, Masayoshi
-
-
Read Online
- Synthesis and characterization of mesoporous-TiO2 with enhanced photocatalytic activity for the degradation of chloro-phenol
-
Mesoporous-titania (TiO2) photocatalysts have been synthesized using polyethylene glycol (PEG) as a template in dilute acetic acid aqueous solution by hydrothermal process. The effect of PEG molecular weights and thermal treatment on the resultant structure and photocatalytic activity are investigated. Structural and phase compositional properties of the resultant photocatalysts are characterized by transmission electron microscopy, X-ray diffraction and nitrogen sorption analysis. When the molecular weights of PEG vary from 600 to 20,000, the particle sizes of mesoporous structure decrease from 15.1 to 13.3 nm and mean pore sizes increase from 6.9 to 10.6 nm. The chemical reactions of the formation of mesoporous-TiO2 during its synthesis have been proposed and discussed. The activities of mesoporous-TiO2 photocatalysts are evaluated and compared with Degussa P-25 using chloro-phenol as a testing compound. The reaction mechanism of photodegradation is also described on the basis of high performance liquid chromatography.
- Shamaila, Sajjad,Sajjad, Ahmed Khan Leghari,Chen, Feng,Zhang, Jinlong
-
-
Read Online
- Ultrasound-promoted rapid and efficient iodination of aromatic and heteroaromatic compounds in the presence of iodine and hydrogen peroxide in water
-
A rapid and efficient ultrasound-promoted protocol for iodination of aromatic and heteroaromatic compounds, using molecular iodine in the presence of aqueous hydrogen peroxide in water without any cosolvent, has produced versatile iodinated organic molecules with potential application in organic synthesis and medicine in short reaction times and good to excellent yields. Copyright
- Ferreira, Irlon M.,Casagrande, Gleison A.,Pizzuti, Lucas,Raminelli, Cristiano
-
-
Read Online
- Benzene-free synthesis of hydroquinone
-
All current routes for the synthesis of hydroquinone utilize benzene as the starting material. An alternate route to hydroquinone has now been elaborated from glucose. While benzene is a volatile carcinogen derived from nonrenewable fossil fuel feedstocks, glucose is nonvolatile, nontoxic, and derived from renewable plant polysacharrides. Glucose is first converted into quinic acid using microbial catalysis. Quinic acid is then chemically converted into hydroquinone. Under fermentor-controlled conditions, Escherichia coli QP1.1/pKD12.138 synthesizes 49 g/L of quinic acid from glucose in 20% (mol/mol) yield. Oxidative decarboxylation of quinic acid in clarified, decolorized, ammonium ion-free fermentation broth with NaOCl and subsequent dehydration of the intermediate 3(R),5(R)-trihydroxycyclohexanone afforded purified hydroquinone in 87% yield. Halide-free, oxidative decarboxylation of quinic acid in fermentation broth with stoichiometric quantities of (NH4)2Ce(SO4)3 and V2O5 afforded hydroquinone in 91% and 85% yield, respectively. Conditions suitable for oxidative decarboxylation of quinic acid with catalytic amounts of metal oxidant were also identified. Ag3PO4 at 2 mol % relative to quinic acid in fermentation broth catalyzed the formation of hydroquinone in 74% yield with K2S2O8 serving as the cooxidant. Beyond establishing a fundamentally new route to an important chemical building block, oxidation of microbe-synthesized quinic acid provides an example of how the toxicity of aromatics toward microbes can be circumvented by interfacing chemical catalysis with biocatalysis.
- Ran,Knop,Draths,Frost
-
-
Read Online
- Biomass-Based and Oxidant-Free Preparation of Hydroquinone from Quinic Acid
-
A biomass-based route to the preparation of hydroquinone starting from the renewable starting material quinic acid is described. Amberlyst-15 in the dry form promoted the one-step formation of hydroquinone from quinic acid in toluene without any oxidants or metal catalysts in 72 % yield. Several acidic polymer-based resins and organic acids as promoters as well as a variety of reaction conditions were screened including temperature, concentration and low- and high-boiling-point solvents. A 1:4 (w/w) ratio of quinic acid/Amberlyst-15 was determined to be optimal to promote hydroquinone formation with only traces of a dimeric side-product. A mechanism has been proposed based on the decarbonylation of protonated quino-1,5-lactone that is supported by experimental and computational calculation data.
- Assoah, Benedicta,Veiros, Luis F.,Afonso, Carlos A. M.,Candeias, Nuno R.
-
-
Read Online
- Preparation of magnetic composite photocatalyst Bi2WO 6/CoFe2O4by two-step hydrothermal method and itsphotocatalytic degradation of bisphenol A
-
Easily separable magnetic photocatalyst Bi2WO 6/CoFe2O4 was synthesized by a two-step hydrothermal method. Pure spinel CoFe2O4 in nano-scale was prepared by a hydrothermal method, which was followed by a second hydrothermal process to coat CoFe2O4 with Bi2WO6. The prepared Bi2WO6/CoFe2O4 kept the magnetic property of CoFe2O4 and high efficient photocatalytic activity of Bi2WO6 as well. The photoactivity of Bi2WO6/CoFe2O4 (mass ratio 10:1) to degrade bisphenol A (BPA) was close to that of pure Bi 2WO6 after 120 min of simulated solar light irradiation. After reaction, the catalyst particles could be easily harvested from the suspension by applying an external magnetic field.
- Wang, Chunying,Zhu, Lingyan,Chang, Chun,Fu, Yu,Chu, Xiaolong
-
-
Read Online
- Kinetics of phenol oxidation with iron-manganese concretions
-
Kinetics of oxidation of phenols on the iron-manganese concretions in the temperature range 293-353 K at pH 5.5±0.5 was studied. Reaction of oxidation on the iron-manganese concretions has the second order by phenol. It is characterized by low activation energy, 17.5 kJ mol-1, due to the catalytic action of iron(III) oxide. Lower rate of oxidation of phenols on the iron-manganese concretions is observed as compared to oxidation on the pyrolusite surface. It occurs because of the decrease in MnO2 concentration in the iron-manganese concretions.
- Cheremisina,Chirkst,Sulimova
-
-
Read Online
- Photocatalytic degradation of acetaminophen over Ag, Au and Pt loaded TiO2 using solar light
-
The sustainability and feasibility of using solar irradiation instead of UV light in photocatalysis is a promising approach for water remediation. In this study, photocatalytic degradation (PCD) of a widely used analgesic and antipyretic drug, acetaminophen (AP), with noble metal loaded TiO2 photocatalysts (Ag/TiO2, Au/TiO2 and Pt/TiO2) was investigated in aqueous suspension using solar light. The deposition of noble metals (Ag, Au and Pt) onto the TiO2 surface enhanced the PCD of AP under different operating conditions including pH, surfactants and drug excipients. However, lower degradation rate constants of AP were obtained under simulated and direct solar light as compared to UV light. The degradation mechanism of AP under UV as well as simulated solar light was found to follow similar, though not identical, reaction pathways leading to hydroxylated intermediates (e.g. 4-acetamidoresorcinol (4-AR), 4-acetamidocatechol (4-AC) and hydroquinone (HQ)) through competitive routes. The PCD of AP followed a pseudo first order kinetics according to Langmiur-Hinshelwood model. Noble metal (Ag, Au and Pt) loaded TiO2 photocatalysts can be used effectively to degrade AP in water under both solar and UV light.
- Nasr, Osama,Mohamed, Omima,Al-Shirbini, Al-Sayed,Abdel-Wahab, Aboel-Magd
-
-
Read Online
- The 1,4-cyclohexanedione-bromate-acid oscillatory system. 3. Detailed mechanism
-
1,4-Cyclohexanedione (CHD) in its reaction with acidic bromate undergoes aromatization and one of the main resulting products 1,4-dihydroxybenzene (H2Q) is further oxidized and brominated to 1,4-benzoquinone and bromoorganics. The kinetics of H2Q formation, of the reaction of CHD and Br2. as well as of the reaction between H2Q and bromate ion, were followed spectrophotometrically. The latter reaction exhibited Landolt (clock)-type dynamics. On the basis of our earlier analytical and present kinetic investigations, a detailed mechanistic model has been suggested that could well simulate the temporal oscillations of the title system. H2Q plays an essential role in the mechanism and is responsible for the unusual behavior (200-300 oscillations) of this chemical oscillator. We pointed to the relation that may exist between the CHD-bromate-acid system and those reported as oscillatory Landolt-type reactions [e.g., IO3- - SO32- - Fe(CN)64-].
- Szalai, Istvan,Koeroes, Endre
-
-
Read Online
- Photo-catalyzed p-nitrophenol degradation in aqueous dispersions of ferrihydrite and H2O2
-
Nitrophenols are hazardous and toxic to living organisms. For this study, ferrihydrite was prepared to test its capabilities for p-nitrophenol degradation. A ferrihydrite particle prepared in neutral environmental conditions is sphere-like with a diameter of 2-4 nm and its total surface area is approximately 229 m2g-1. The combination of ferrihydrite and trace H2O2is effective for the degradation of p-nitrophenol under simulated sunlight irradiation. Hydroquinone, the initial intermediate of p-nitrophenol decomposition, autocatalyses the subsequent degradation of p-nitrophenol because it accelerates the photo-reductive dissolution of ferrihydrite. The effect of key operating parameters such as ferrihydrite dosage, initial solution pH and H2O2dosage were also studied on the photocatalytic degradation of p-nitrophenol. The results indicate that the combination of 0.2 g-L-1ferrihydrite, 0.45 mmol ? L-1H2O2is highly efficient for the degradation of p-nitrophenol (0.15 mmol ? L-1) at pH 2.5～3.0. A ferrihydrite was reused several times, still keeping its original photocatalysis. Copyright
- Wu, Yongjuan,Chen, Rufen,Liu, Hui,Wei, Yu,Wu, Dong
-
-
Read Online
- Analysis of Products from Reactions of Chemisorbed Monolayers at Smooth Platinum Electrodes: Electrochemical Hydrodesulfurization of Thiophenol Derivatives
-
The product mixtures from electrochemical hydrodesulfurization of selected thiophenolic compounds chemisorbed through the -SH moiety at smooth Pt electrodes in molar acid have been analyzed quantitatively by using thin-layer electrochemical methods in conjunction with capillary gas chromatography and liquid chromatography.The following compounds were studied: pentafluorothiophenol (PFT), mercaptohydroquinone (MHQ), and 2-mercaptobenzoic acid (MBA).A comparatively high area, large-volume preparative thin-layer electrode (TLE) was constructed to facilitate sample analysis.The results obtained from TLE, GC, and HPLC analysis were in good agreement.The extent of hydrodesulfurization (defined here as simple cleavage of the C-S bond without impairment of the aromatic functionality) depended on the nature of the pendant aromatic ring, decreasing in the order PFT (100percent) >> MHQ (50percent) >>MBA (15percent).Only one desulfurization product was observed for MHQ and MBA; the absence of other products was probably because ring hydrogenation (to form alkyl-type groups) competed with simple desulfurization, and detachment of the alkyl moieties from the -SH anchor occured with greater difficulty than that of the aromatic group.
- Vieira, Kenneth L.,Zapien, Donald C.,Soriaga, Manuel P.,Hubbard, Arthur T.,Low, Karen P.,Anderson, Stanley E.
-
-
Read Online
- Role of proton-coupled electron transfer in the redox interconversion between benzoquinone and hydroquinone
-
Benzoquinone/hydroquinone redox interconversion by the reversible Os(dmb)33+/2+ couple over an extended pH range with added acids and bases has revealed the existence of seven discrete pathways. Application of spectrophotometric moni
- Song, Na,Gagliardi, Christopher J.,Binstead, Robert A.,Zhang, Ming-Tian,Thorp, Holden,Meyer, Thomas J.
-
-
Read Online
- One-Electron and Two-Electron Redox Switch in the Reactions of 1,5-Dihydroflavin and Quinones Controlled by Acid and Base in Acetonitrile
-
The acid-catalyzed reactions of 1,5-dihydroriboflavin-2',3',4',5'-tetraacetate (FlH2) with quinones (Q) result in the one-electron oxidation of FlH2 to FlH2+* and the two-electron reduction of Q to hydroquinones (QH2) in the presence of HClO4 in acetonitrile.In the presence of Me4NOH, the base catalyzed reactions result in the two-electron oxidation of FlH2 to Fl and the one-electron reduction of Q to Q-*.
- Ishikawa, Masashi,Matsuda, Yoshiharu,Yamamoto, Kazuhiko,Fukuzumi, Shunichi
-
-
Read Online
- A PHENOL ALLOSIDE FROM VIBURNUM WRIGHTII
-
A new phenol alloside, p-hydroxyphenyl β-D-alloside, has been isolated from the leaves of Viburnum wrightii in addition to several known compounds.The structures were elucidated by spectroscopic and chemical methods. - Keywords: Viburnum wrightii; Caprifoliaceae; phenol alloside.
- Iwagawa, Tetsuo,Takahashi, Hideo,Munesada, Kiyotaka,Hase, Tsunao
-
-
Read Online
- A highly photosensitive covalent organic framework with pyrene skeleton as metal-free catalyst for arylboronic acid hydroxylation
-
Covalent organic frameworks (COFs) have been widely utilized in metal-free photocatalytic synthesis base on their excellent properties such as super conjugation, porosity and stability. In this work, we synthesized a new COF material using 1,3,6,8-Tetrakis (p-formylphenyl)pyrene (TFPPy) and 2,2′-Dimethylbenzidine (DMBZ) as basic units through Schiff base condensation reaction. The new COF (TF-DM COF) was applied as metal-free catalyst for hydroxylation of arylboronic acids. The results indicated that the extended π conjugation of COFs enhanced the absorption of visible light, and the large porosity (BET surface area: 113.782 m2g?1) accelerated the reaction rate. Good recyclability enables it with multiple applications, which result in a great reducing of the cost. This study reports that TF-DM COF has a broad application prospect as a new generation of metal-free photocatalysts for organic conversions.
- Chen, Ying,Huo, Jianqiang,Zhang, Yubao
-
-
- Photocatalytic removal of benzene over Ti3C2T: XMXene and TiO2-MXene composite materials under solar and NIR irradiation
-
MXenes, a family of two-dimensional (2D) transition metal carbides, nitrides and carbonitrides based on earth-abundant constituents, are prospective candidates for energy conversion applications, including photocatalysis. While the activity of individual MXenes towards various photocatalytic processes is still debatable, these materials were proved to be excellent co-catalysts, accelerating the charge separation and suppressing the exciton recombination. Titanium-containing MXenes are well compatible with the classical TiO2 photocatalyst. The TiO2 component can be directly grown on MXene sheets by in situ oxidation, representing a mainstream processing approach for such composites. In this study, an essentially different approach has been implemented: a series of TiO2-MXene composite materials with controlled composition and both reference end members were prepared, involving two different strategies for mixing sol-gel-derived TiO2 nanopowder with the Ti3C2Tx component, which was obtained by HF etching of self-propagating high-temperature synthesis products containing modified MAX phase Ti3C2Alz (z > 1) with nominal aluminium excess. The prospects of such composites for the degradation of organic pollutants under simulated solar light, using benzene as a model system, were demonstrated and analysed in combination with their structural, microstructural and optical properties. A notable photocatalytic activity of bare MXene under near infrared light was discovered, suggesting further prospects for light-to-energy harvesting spanning from UV-A to NIR and applications in biomedical imaging and sensors.
- Calvino, José J.,Constantinescu, Gabriel,Frade, Jorge R.,Kovalevsky, Andrei V.,Labrincha, Jo?o A.,Lajaunie, Luc,Lopes, Daniela V.,Sergiienko, Sergii A.,Shaula, Aliaksandr L.,Shcherban, Nataliya D.,Shkepu, Viacheslav I.,Tobaldi, David M.
-
p. 626 - 639
(2022/01/22)
-
- Highly efficient titanosilicate catalyst Ti-MCM-68 prepared using a liquid-phase titanium source for the phenol oxidation
-
A highly efficient Ti-MCM-68 catalyst for phenol oxidation with H2O2 was prepared by a mild liquid-phase treatment for the first time. The key preparation procedures to excellent catalytic activity and high para-selectivity were the use of aqueous solutions of the Ti source and calcination at 650 °C prior to catalytic use.
- Inagaki, Satoshi,Ishizuka, Ryo,Ikehara, Yuya,Odagawa, Shota,Asanuma, Kai,Morimoto, Shunsuke,Kubota, Yoshihiro
-
p. 3681 - 3684
(2021/02/03)
-
- Preparation and photocatalytic performance of silver-modified and nitrogen-doped TiO2nanomaterials with oxygen vacancies
-
The photocatalysis of titanium dioxide (TiO2) exerts excellent degradation performance against contaminants in the environment. However, it prefers to absorb ultraviolet light rather than visible light, which significantly constrains its widespread use under visible light. Here, we prepared oxygen vacancy-containing TiO2viaAg-modification and N-doping. The utilization of visible light for phenol degradation was significantly enhanced by Ag/N co-doping. The characterization results showed a shuttle-like material coupled with multiple oxygen vacancies, and a well-designed experiment demonstrated that the Ti?:?N?:?Ag ratio of 1?:?0.45?:?0.32 presented optimal performance for phenol degradation. The batch experiment results also proved the modified TiO2as a potent photocatalyst against phenol degradation with an 80.8% degradation efficiency within 5 hours under visible light and with a 99.3% degradation efficiency within 2 hours under ultraviolet light. What is more, we also demonstrated that hydroxyl radical was the mainly effective radical in the mineralization of phenol and put forward a possible degradation pathway based on the observed intermediates. Lastly, the cycling tests indicated that the proposed photocatalyst is durable with a fair phenol degradation ability after recycling 5 times.
- Zhang, Hong,Jiang, Yingyu,Zhou, Baiqin,Wei, Zhuo,Zhu, Zhenya,Han, Lijuan,Zhang, Ping,Hu, Yingying
-
p. 4694 - 4704
(2021/03/22)
-
- A high-nuclearity CuI/CuIInanocluster catalyst for phenol degradation
-
Herein, we report a 54-nuclei copper nanocluster, [Cu54S13O6(tBuS)20(tBuSO3)12] (Cu54), which is the largest atom-precise CuI/CuIImix-valent cluster reported. The Cu54nanoclusters supported by TiO2exhibit decent photocatalytic activity for phenol degradation under visible light. This work provides a platform to explore the catalytic behaviors of CuI/CuIInanosystems.
- Liu, Li-Juan,Zhang, Jiang-Wei,Asad, Muhammad,Wang, Zhao-Yang,Zang, Shuang-Quan,Mak, Thomas C. W.
-
supporting information
p. 5586 - 5589
(2021/06/12)
-
- Hydroxylation of benzene to phenol over heteropoly acid H5PMo10V2O40supported on amine-functionalized MCM-41
-
Supported catalysts with Keggin type heteropoly acids (H5PMo10V2O40) loaded onto amine-functionalized MCM-41 for the catalytic hydroxylation of benzene to phenol with H2O2were prepared by a wet impregnation method. The effects of the preparation conditions on the properties and activity of the supported catalysts were fully investigated. The results showed that the catalyst retained the mesoporous structure of MCM-41 and H5PMo10V2O40was dispersed uniformly on the surface of the amine-functionalized MCM-41. Meanwhile, the reusability and catalytic performance of the catalyst were affected by two key factors,i.e., the interaction between the heteropoly acid and the surface of MCM-41, and the hydrophobicity of the catalyst since they decide the leaching of H5PMo10V2O40and the adsorption of benzene. The catalyst with H5PMo10V2O40loaded onto amine-functionalized MCM-41, which was prepared using ethanol as the solvent, exhibited the highest phenol yield (20.4%), a turnover frequency value of 20.3 h?1and good reusability. We believe this work offers an effective and facile strategy for the preparation of a new catalyst for hydroxylation of benzene to phenol.
- Kong, Yan,Li, Shichao,Li, Yanjun
-
p. 26571 - 26580
(2021/08/17)
-
- Rapid biosynthesis of phenolic glycosides and their derivatives from biomass-derived hydroxycinnamates
-
Biomass-derived hydroxycinnamates (mainly includingp-coumaric acid and ferulic acid), which are natural sources of aromatic compounds, are highly underutilized resources. There is a need to upgrade them to make them economically feasible. Value-added phenolic glycosides and their derivatives, both belonging to a class of plant aromatic natural products, are widely used in the nutraceutical, pharmaceutical, and cosmetic industries. However, their complex aromatic structures make their efficient biosynthesis a challenging process. To overcome this issue, we created three novel synthetic cascades for the biosynthesis of phenolic glycosides (gastrodin, arbutin, and salidroside) and their derivatives (hydroquinone, tyrosol, hydroxytyrosol, and homovanillyl alcohol) fromp-coumaric acid and ferulic acid. Moreover, because the biomass-derived hydroxycinnamates directly provided aromatic units, the cascades enabled efficient biosynthesis. We achieved substantially high production rates (up to or above 100-fold enhancement) relative to the glucose-based biosynthesis. Given the ubiquity of the aromatic structure in natural products, the use of biomass-derived aromatics should facilitate the rapid biosynthesis of numerous aromatic natural products.
- Zhao, Mingtao,Hong, Xulin,Abdullah,Yao, Ruilian,Xiao, Yi
-
supporting information
p. 838 - 847
(2021/02/09)
-
- Catalyst for synthesizing benzenediol, and preparation method and application thereof
-
The invention relates to a catalyst for synthesizing benzenediol, and a preparation method and application thereof. The complex is composed of EDTA -salicylaldehyde bis-amine Schiff base which is complexed with metal ions. The preparation method comprises the following steps: firstly dropping the second amine into an ethanol solution of salicylaldehyde, and heating and refluxing. Washing, drying to give bis salicylaldehyde bis-amine Schiff base and mixing with any ratio EDTA to form a bidentate ligand. Then, the double-ligand preparation solution is added dropwise into the central ion solution, and the EDTA -salicylaldehyde condensed diamine Schiff base metal complex composite catalyst is prepared by heating, refluxing, washing and drying. The composite catalyst is used for phenol hydrogen peroxide hydroxylation reaction and phenol conversion rate _AOMARKENCODEGTX0AOA 30%, Benzenediol selectivity-AOMARKENCODEGTX0AOA 90 -93%.
- -
-
Paragraph 0031; 0034; 0037; 0040; 0043-0047
(2021/10/27)
-
- Efficient demethylation of aromatic methyl ethers with HCl in water
-
A green, efficient and cheap demethylation reaction of aromatic methyl ethers with mineral acid (HCl or H2SO4) as a catalyst in high temperature pressurized water provided the corresponding aromatic alcohols (phenols, catechols, pyrogallols) in high yield. 4-Propylguaiacol was chosen as a model, given the various applications of the 4-propylcatechol reaction product. This demethylation reaction could be easily scaled and biorenewable 4-propylguaiacol from wood and clove oil could also be applied as a feedstock. Greenness of the developed methodversusstate-of-the-art demethylation reactions was assessed by performing a quantitative and qualitative Green Metrics analysis. Versatility of the method was shown on a variety of aromatic methyl ethers containing (biorenewable) substrates, yielding up to 99% of the corresponding aromatic alcohols, in most cases just requiring simple extraction as work-up.
- Bomon, Jeroen,Bal, Mathias,Achar, Tapas Kumar,Sergeyev, Sergey,Wu, Xian,Wambacq, Ben,Lemière, Filip,Sels, Bert F.,Maes, Bert U. W.
-
supporting information
p. 1995 - 2009
(2021/03/26)
-
- Electrochemical-induced hydroxylation of aryl halides in the presence of Et3N in water
-
A thorough study of mild and environmentally friendly electrochemical-induced hydroxylation of aryl halides without a catalyst is presented. The best protocol consists of hydroxylation of different aryl iodides and aryl bromides by water solution in the presence of Et3N under air, affording the target phenols in good isolated yields. Moreover, aryl chlorides were successfully employed as substrates. This methodology also provides a direct pathway for the formation of deoxyphomalone, which displayed a significant anti-proliferation effect.
- Ke, Fang,Lin, Chen,Lin, Mei,Long, Hua,Wu, Mei,Yang, Li,Zhuang, Qinglong
-
supporting information
p. 6417 - 6421
(2021/08/03)
-
- Photocatalytic synthesis of phenols mediated by visible light using KI as catalyst
-
A transition-metal-free hydroxylation of iodoarenes to afford substituted phenols is described. The reaction is promoted by KI under white LED light irradiation and uses atmospheric oxygen as oxidant. By the use of triethylamine as base and solvent, the corresponding phenols are obtained in moderate to good yields. Mechanistic studies suggest that KI and catalysis synergistically promote the cleavage of C-I bond to form free aryl radicals.
- Huiqin, Wei,Wu, Mei
-
supporting information
(2021/11/30)
-
- Metal-free reduction of unsaturated carbonyls, quinones, and pyridinium salts with tetrahydroxydiboron/water
-
A series of unsaturated carbonyls, quinones, and pyridinium salts have been effectively reduced to the corresponding saturated carbonyls, dihydroxybenzenes, and hydropyridines in moderate to high yields with tetrahydroxydiboron/water as a mild, convenient, and metal-free reduction system. Deuterium-labeling experiments have revealed this protocol to be an exclusive transfer hydrogenation process from water. This journal is
- Li, Tiejun,Peng, Henian,Tang, Wenjun,Tian, Duanshuai,Xu, Guangqing,Yang, He
-
p. 4327 - 4337
(2021/05/31)
-
- Coordination Polymers as a Functional Material for the Selective Molecular Recognition of Nitroaromatics and ipso-Hydroxylation of Arylboronic Acids
-
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
-
-
- Building a Pyrazole–Benzothiadiazole–Pyrazole Photosensitizer into Metal–Organic Frameworks for Photocatalytic Aerobic Oxidation
-
Charge separation plays a crucial role in regulating photochemical properties and therefore warrants consideration in designing photocatalysts. Metal–organic frameworks (MOFs) are emerging as promising candidates for heterogeneous photocatalysis due to their structural designability and tunability of photon absorption. Herein, we report the design of a pyrazole–benzothiadiazole–pyrazole organic molecule bearing a donor–acceptor–donor conjugated π-system for fast charge separation. Further attempts to integrate such a photosensitizer into MOFs afford a more effective heterogeneous photocatalyst (JNU-204). Under visible-light irradiation, three aerobic oxidation reactions involving different oxygenation pathways were achieved on JNU-204. Recycling experiments were conducted to demonstrate the stability and reusability of JNU-204 as a robust heterogeneous photocatalyst. Furthermore, we illustrate its applications in the facile synthesis of pyrrolo[2,1-a]isoquinoline-containing heterocycles, core skeletons of a family of marine natural products. JNU-204 is an exemplary MOF platform with good photon absorption, suitable band gap, fast charge separation, and extraordinary chemical stability for proceeding with aerobic oxidation reactions under visible-light irradiation.
- Jin, Ji-Kang,Wu, Kun,Liu, Xin-Yi,Huang, Guo-Quan,Huang, Yong-Liang,Luo, Dong,Xie, Mo,Zhao, Yifang,Lu, Weigang,Zhou, Xiao-Ping,He, Jian,Li, Dan
-
supporting information
p. 21340 - 21349
(2021/12/17)
-
- Eco-friendly preparation of ultrathin biomass-derived Ni3S2-doped carbon nanosheets for selective hydrogenolysis of lignin model compounds in the absence of hydrogen
-
Lignin is an abundant source of aromatics, and the depolymerization of lignin provides significant potential for producing high-value chemicals. Selective hydrogenolysis of the C-O ether bond in lignin is an important strategy for the production of fuels and chemical feedstocks. In our study, catalytic hydrogenolysis of lignin model compounds (β-O-4, α-O-4 and 4-O-5 model compounds) over Ni3S2-CS catalysts was investigated. Hence, an array of 2D carbon nanostructure Ni3S2-CSs-X-Yderived catalysts were produced using different compositions at different temperatures (X= 0 mg, 0.2 mg, 0.4 mg, 0.6 mg, and 0.8 mg; Y = 600 °C, 700 °C, 800 °C, and 900 °C) were prepared and applied for hydrogenolysis of lignin model compounds and depolymerization of alkaline lignin. The highest conversion of lignin model compounds (β-O-4 model compound) was up to 100% and the yield of the obtained corresponding ethylbenzene and phenol could achieve 92% and 86%, respectively, over the optimal Ni3S2-CSs-0.4-700 catalyst in iPrOH at 260 °C without external H2. The 2D carbon nanostructure catalysts performed a good dispersion on the surface of the carbon nanosheets, which facilitated the cleavage of the lignin ether bonds. The physicochemical characterization studies were carried out by means of XRD, SEM, TEM, H2-TPR, NH3-TPD, Raman and XPS analyses. Based on the optimal reaction conditions (260 °C, 4 h, 2.0 MPa N2), various model compounds (β-O-4, α-O-4 and 4-O-5 model compounds) could also be effectively hydrotreated to produce the corresponding aromatic products. Furthermore, the optimal Ni3S2-CSs-0.4-700 catalyst could be carried out in the next five consecutive cycle experiments with a slight decrease in the transformation of lignin model compounds.
- Chen, Changzhou,Jiang, Jianchun,Li, Jing,Liu, Peng,Wu, Dichao,Xia, Haihong,Zhou, Minghao
-
p. 3090 - 3103
(2021/05/07)
-
- Fabrication of a stable Ti/Pb-TiOxNWs/PbO2 anode and its application in benzoquinone degradation
-
To delay passivation of a titanium (Ti) substrate as well as enhance adhesion between an electrodeposited PbO2 coating and the Ti substrate, a titanium-lead composite oxide nanowire (Pb-TiOxNWs) intermediate layer was formed in situ on the surface of porous Ti by alkali etching, ion substitution, and high-temperature calcination. At the same time, Ti/PbO2 and Ti/TiO2NWs/PbO2 electrodes with porous Ti as a matrix were prepared for comparison. The surface structure and morphology of the prepared intermediate layer and the PbO2 coating were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The influences of the composite oxide intermediate layer on the electrochemical performance of the PbO2 electrode were analyzed by cyclic voltammetry (CV), linear sweep voltammetry (LSV), and AC impedance spectroscopy (EIS). Accelerated lifetime tests were performed for electrodes with and without different intermediate layers. The results showed that PbOx was incorporated into the titanium dioxide three-dimensional network structure, resulting in formation of Pb-TiOxNWs. The surface of the Ti/Pb-TiOxNWs/PbO2 electrode was denser due to the smaller particle size of PbO2. The preferred crystal orientation of β(110) was observed for PbO2 deposited on Ti/Pb-TiOxNWs. The oxygen evolution potential reached a maximum of 2.19 V for Ti/Pb-TiOxNWs/PbO2. Accelerated life tests showed that compared with Ti/PbO2 and Ti/TiO2NWs/PbO2, the electrode life of Ti/Pb-TiOxNWs/PbO2 was increased by 91.7% and 35.3%, respectively. Therefore, it can be concluded that significantly improved morphology and electrochemical performance were achieved for titanium-based PbO2 electrodes by the addition of a Pb-TiOxNWs intermediate layer. In particular, the electrochemical stability of the PbO2 coating electrodes was improved markedly by the Pb-TiOxNWs intermediate layer. The electrodes were used for electrochemical oxidation of benzoquinone in wastewater (100 mg/L). It was found that chloride ions played a critical role in improving the current efficiency of electro-oxidative degradation. Under the same conditions, the COD removal rate in the presence of NaCl was 45% higher than in the presence of sulfate. The results of HPLC analysis of the intermediate products indicated that the oxidants electro-generated by chloride ions had stronger ring-opening and mineralization capabilities than those electro-generated by sulfate ions.
- Guo, Yingjuan,Tang, Changbin,Xue, Juanqin,Yu, Lihua,Zhang, Lihua
-
-
- Nickel Hydride Catalyzed Cleavage of Allyl Ethers Induced by Isomerization
-
This report discloses the deallylation of O - and N -allyl functional groups by using a combination of a Ni-H precatalyst and excess Bronsted acid. Key steps are the isomerization of the O - or N -allyl group through Ni-catalyzed double-bond migration followed by Bronsted acid induced O/N-C bond hydrolysis. A variety of functional groups are tolerated in this protocol, highlighting its synthetic value.
- Kathe, Prasad M.,Berkefeld, Andreas,Fleischer, Ivana
-
supporting information
p. 1629 - 1632
(2021/02/09)
-
- Enhanced nonradical catalytic oxidation by encapsulating cobalt into nitrogen doped graphene: highlight on interfacial interactions
-
Supported metal catalysts are widely used for heterogeneous catalytic processes (e.g., Fenton-like reaction), but the mechanisms of interfacial processes are still ambiguous. Herein, unique nanocarbon based catalysts with Co nanoparticles encapsulated in
- Yu, Xiaoyong,Wang, Lijing,Wang, Xin,Liu, Hongzhi,Wang, Ziyuan,Huang, Yixuan,Shan, Guoqiang,Wang, Weichao,Zhu, Lingyan
-
supporting information
p. 7198 - 7207
(2021/03/29)
-
- Aluminum Metal-Organic Framework-Ligated Single-Site Nickel(II)-Hydride for Heterogeneous Chemoselective Catalysis
-
The development of chemoselective and heterogeneous earth-abundant metal catalysts is essential for environmentally friendly chemical synthesis. We report a highly efficient, chemoselective, and reusable single-site nickel(II) hydride catalyst based on robust and porous aluminum metal-organic frameworks (MOFs) (DUT-5) for hydrogenation of nitro and nitrile compounds to the corresponding amines and hydrogenolysis of aryl ethers under mild conditions. The nickel-hydride catalyst was prepared by the metalation of aluminum hydroxide secondary building units (SBUs) of DUT-5 having the formula of Al(μ2-OH)(bpdc) (bpdc = 4,4′-biphenyldicarboxylate) with NiBr2 followed by a reaction with NaEt3BH. DUT-5-NiH has a broad substrate scope with excellent functional group tolerance in the hydrogenation of aromatic and aliphatic nitro and nitrile compounds under 1 bar H2 and could be recycled and reused at least 10 times. By changing the reaction conditions of the hydrogenation of nitriles, symmetric or unsymmetric secondary amines were also afforded selectively. The experimental and computational studies suggested reversible nitrile coordination to nickel followed by 1,2-insertion of coordinated nitrile into the nickel-hydride bond occurring in the turnover-limiting step. In addition, DUT-5-NiH is also an active catalyst for chemoselective hydrogenolysis of carbon-oxygen bonds in aryl ethers to afford hydrocarbons under atmospheric hydrogen in the absence of any base, which is important for the generation of fuels from biomass. This work highlights the potential of MOF-based single-site earth-abundant metal catalysts for practical and eco-friendly production of chemical feedstocks and biofuels.
- Antil, Neha,Kumar, Ajay,Akhtar, Naved,Newar, Rajashree,Begum, Wahida,Dwivedi, Ashutosh,Manna, Kuntal
-
p. 3943 - 3957
(2021/04/12)
-
- One-pot synthesis of benzofurans via heteroannulation of benzoquinones
-
Three different reactions were explored leading to the synthesis of various benzofurans. All reactions took place under AcOH catalysis in a one-pot manner. As a result, benzoquinone derivatives underwent heteroannulation with either itself or cyclohexanones to produce furanylidene-benzofuran or benzofuran structures, respectively.
- Pirouz, Maryam,Saeed Abaee,Harris, Pernille,Mojtahedi, Mohammad M.
-
-
- Three-Step One-Pot Process of 3-Methyl-5-Benzofuranol from Amine, Aldehydes, and p-Benzoquinone
-
3-Methyl-5-benzofuranol was prepared by a one-pot process from morpholine, propionaldehyde, and p-benzoquinone in 85-87% isolated yields. Avoiding the tedious multistep isolation and purification operations, this practical and efficient process dramatically enhanced the production efficiency as well as reduced the amount of chemical wastes of reaction. The scale-up results showed that the performance was maintained, suggesting potential large-scale applications. Furthermore, the synthesis strategy showed high efficiency for a wide range of aliphatic aldehydes and ketone derivatives.
- Liang, Chaoming,Sun, Maolin,Shen, Xinyuan,Shan, Chao,Wang, Weijuan,Cheng, Ruihua,Ye, Jinxing
-
p. 810 - 816
(2021/04/05)
-
- Aryl phenol compound as well as synthesis method and application thereof
-
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.
- -
-
Paragraph 0158-0161
(2021/05/12)
-
- Method for preparing p-benzoquinone through catalytic oxidation of 1, 4-benzenediol
-
The invention discloses a method for preparing p-benzoquinone through catalytic oxidation of 1, 4-benzenediol. The method comprises the following steps: carrying out centrifugal treatment on mother liquor for preparing 2, 3-dicyanohydroquinone; adding the centrifuged mother liquor and sodium hypochlorite into a micro-channel reactor; sequentially mixing and stirring the to-be-reacted liquid added into the microchannel reactor, and then crystallizing and filtering; and adding water into solid phase benzoquinone obtained after crystallization treatment for washing to obtain a p-benzoquinone product. According to the invention, the problem of waste of raw materials caused by conversion of the raw materials into 1, 4-benzenediol in the preparation process of 2, 3-dicyanohydroquinone at present is solved.
- -
-
Paragraph 0022
(2021/07/28)
-
- Heterogeneous Fenton-like oxidative degradation of sulfanilamide catalyzed by RuO2-rectorite composite
-
RuO2-rectorite (RuO2-Rec) was prepared by intercalation, deposition and calcination. Its structure was characterized by XRD, XPS, SEM and EDS. It was used as a catalyst for the sulfanilamide (SA) degradation in the presence of H2O2. Unlike sodium-rectorite and RuO2 which couldn’t catalyze the degradation of SA, RuO2-Rec could effectively catalyze the decomposition of H2O2 into hydroxyl radicals to degrade SA. The degradation rate could reach ~ 100% under the optimal conditions of 58?μmol/L of SA, 1.16?mmol/L of H2O2, 0.133?g/L of RuO2-Rec, pH 3.5 and 25?°C in 5?h. The degradation process conformed to pseudo-first-order kinetic correlation. This degradation was affected by pH, the amount of RuO2-Rec and the concentrations of H2O2 and SA. However, under the optimal pH value of 3.5, a high degradation rate could be achieved with the increase in SA concentration from 58?μmol/L to 290?μmol/L as long as the optimal ratio of RuO2-Rec, H2O2 and SA kept unchanged. In addition, RuO2-Rec was stable and possessed low ruthenium leaching rate and excellent reusability. Therefore, RuO2-Rec is expected to be an active catalyst for the pollutant removal in the heterogeneous Fenton-like system.
- Pan, Feifei,Yang, Jianhong,Cai, Jun,Liu, Lianye
-
p. 4595 - 4611
(2021/07/26)
-
- Nickel-catalyzed deallylation of aryl allyl ethers with hydrosilanes
-
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
-
supporting information
(2021/09/28)
-
- Electroanalysis of Enzyme Activity in Small Biological Samples: Alkaline Phosphatase
-
The discovery of sulfite-stabilized anodic current of hydroquinone (HQ) at high pH was used to develop two new methods for measuring the activity of the key biomarker alkaline phosphatase (ALP). Both approaches relied on the monitoring of ALP-triggered release of HQ from a substrate hydroquinone diphosphate (HQDP) into a pH 10.00 solution. One detected the released HQ via the internally calibrated electrochemical continuous enzyme assay (ICECEA) at a glassy carbon (GC) electrode with no sample incubation. The other used sample incubation with HQDP and quantified the released HQ via a coulometric assay at a commercial glucose test strip (GTS). The assay solution was optimized by investigating the ALP/HQDP/HQ system at a GC electrode. The ICECEA revealed high affinity of ALP for HQDP (Kmapp, 87 μM;Vmax, 0.36 μM min-1) and detected ALP down to 0.022 U L-1. At GTS, ALP was detected down to 0.064 U L-1in a 1 μL sample of human serum after a 20 min incubation at room temperature. The linear range (R2, 0.994) extended at least up to 1.7 U L-1ALP, which covered more than the clinical range for ALP in serum. The interferences from the sample matrix including those from indigenous glucose were eliminated using a charge difference ΔQ(=Qtotal-Qsample?matrix) as a signal for ALP. Both advances proposed here are direct (no auxiliary enzymes or labels required), accurate (98 ± 3% ALP signal recovery), and precise (relative standard deviation (RSD), 7%). The HQDP-GTS-based assay advances the analysis of ALP activity in microsized real-life samples.
- Bekhit, Michael,Blazek, Teresa,Gorski, Waldemar
-
p. 14280 - 14286
(2021/11/04)
-
- AEROBIC ELECTROCATALYTIC OXIDATION OF HYDROCARBONS
-
This invention is directed to a method of oxygenating hydrocarbons with molecular oxygen, O2, as oxidant under electrochemical reducing conditions, using polyoxometalate compounds containing copper such as Q10 [Gu4(H2O)2(B-α-PW9O)2] or Q12{ [Cu(H2O)]3[(A-α- PW9O34)2(NO3)-] } or solvates thereof as catalysts, wherein Q are each independently selected from alkali metal cations, alkaline earth metal cations, transition metal cations, NH4+,H+ or any combination thereof.
- -
-
Paragraph 0074
(2022/01/04)
-
- High-efficiency catalytic wet air oxidation of high salinity phenolic wastewater under atmospheric pressure in molten salt hydrate media
-
An improved catalytic wet air oxidation (CWAO) process for high salinity phenolic wastewater is reported for the first time by using molten salt hydrates (MSHs) as reaction media. One feature of such a process is that it allows the operation to be conducted at atmospheric pressure owing to the temperature-increasing effect of MSHs. Another feature is that the inorganic salts in phenolic wastewater can be separated readily, taking advantage of the common-ion salting-out effect between inorganic salts and MSHs. Continuous catalytic oxidation degradation of the simulated high salinity phenolic wastewater demonstrated that more than 92% of phenol can be removed with chemical oxygen demand (COD) as high as 85% after reacting in CaCl2·3H2O medium at 150 °C with air as an oxidant. Meanwhile, the desalination efficiency of NaCl in continuous operation could reach up to 100%. It was found that CeCl3was an excellent catalyst for CWAO of phenol. XPS and UV-vis spectral characterization as well as radical scavenger experiments proved that [˙OH/Ce4+] was responsible for the synergistic catalytic degradation mechanism of phenol. Current work not only paves the way for developing a high-efficiency CWAO technology for concentrated organic wastewaters with high salinity, but also helps to better understand MSHs as reaction media.
- Tan, Hongzi,Wang, Shuai,Wang, Jinghua,Song, Feng,Sun, Xiuyu,Zhao, Rongrong,Zhang, Yuan,Cui, Hongyou
-
supporting information
p. 2167 - 2174
(2021/02/06)
-
- Different performances of Ni3(PO4)2 in TiO2 photocatalysis under aerobic and anaerobic conditions
-
It has been reported that cobalt phosphate (CoP) deposited on TiO2 is beneficial to the photoelectrochemical (PEC) oxidation of water in a phosphate solution, but detrimental to the photocatalytic (PC) oxidation of phenol even in a phosphate solution. Herein, we report amorphous nickel phosphate (NiP) deposited on TiO2 being more active than TiO2 in a phosphate-free solution. This was observed not only from the PEC oxidation of water, but also from the PC oxidation of phenol under air, and from the PC reduction of water to H2 under N2 in the presence of methanol, respectively. During the PC reactions under air and N2, however, the suspension of NiP/TiO2 changed its colour from white to pale yellow and dark grey, respectively. Such colour changes were also observed from CoP/TiO2 under similar conditions. Through a spectral and thermodynamic analysis, it is proposed that under air, NiP is oxidized to a high valence Ni species, and then regenerated through water and phenol oxidation, while NiP under N2 is reduced to metallic Ni, followed by proton reduction.
- Chen, Chen,Wang, Yaru,Xu, Yiming,Zhao, Jianjun
-
p. 1761 - 1768
(2020/04/09)
-
- Reductive Electrochemical Activation of Molecular Oxygen Catalyzed by an Iron-Tungstate Oxide Capsule: Reactivity Studies Consistent with Compound i Type Oxidants
-
The reductive activation of molecular oxygen catalyzed by iron-based enzymes toward its use as an oxygen donor is paradigmatic for oxygen transfer reactions in nature. Mechanistic studies on these enzymes and related biomimetic coordination compounds designed to form reactive intermediates, almost invariably using various "shunt" pathways, have shown that high-valent Fe(V)=O and the formally isoelectronic Fe(IV) =O porphyrin cation radical intermediates are often thought to be the active species in alkane and arene hydroxylation and alkene epoxidation reactions. Although this four decade long research effort has yielded a massive amount of spectroscopic data, reactivity studies, and a detailed, but still incomplete, mechanistic understanding, the actual reductive activation of molecular oxygen coupled with efficient catalytic transformations has rarely been experimentally studied. Recently, we found that a completely inorganic iron-tungsten oxide capsule with a keplerate structure, noted as {Fe30W72}, is an effective electrocatalyst for the cathodic activation of molecular oxygen in water leading to the oxidation of light alkanes and alkenes. The present report deals with extensive reactivity studies of these {Fe30W72} electrocatalytic reactions showing (1) arene hydroxylation including kinetic isotope effects and migration of the ipso substituent to the adjacent carbon atom ("NIH shift"); (2) a high kinetic isotope effect for alkyl C - H bond activation; (3) dealkylation of alkylamines and alkylsulfides; (4) desaturation reactions; (5) retention of stereochemistry in cis-alkene epoxidation; and (6) unusual regioselectivity in the oxidation of cyclic and acyclic ketones, alcohols, and carboxylic acids where reactivity is not correlated to the bond disassociation energy; the regioselectivity obtained is attributable to polar effects and/or entropic contributions. Collectively these results also support the conclusion that the active intermediate species formed in the catalytic cycle is consistent with a compound I type oxidant. The activity of {Fe30W72} in cathodic aerobic oxidation reactions shows it to be an inorganic functional analogue of iron-based monooxygenases.
- Bugnola, Marco,Shen, Kaiji,Haviv, Eynat,Neumann, Ronny
-
p. 4227 - 4237
(2020/05/05)
-
- Method for synthesizing phenol or derivative thereof in aqueous phase by photocatalytic one-pot method
-
The invention discloses a method for synthesizing phenol or a derivative thereof in an aqueous phase by a photocatalytic one-pot method. The method comprises the following steps: by taking a compoundaryl halide shown in formula (I) as a raw material and water as a solvent, adding a catalyst and an auxiliary agent, and carrying out reacting under the conditions of alkali and visible light to obtain the phenol or the derivative (II) thereof. Compared with the prior art, the method is applicable to a large number of functional groups, high in yield, few in byproducts, simple and safe to operate,low in cost and environmentally friendly, wherein R is selected from substituted or non-substituted phenyl, pyridyl, quinolyl or pyrimidinyl; X is selected from halogen; the substituted phenyl is substituted by C1-C4 alkyl, C1-C4 alkoxy, hydroxyl, halogen, cyano, aldehyde group, nitro, amino, acetyl or carboxyl; and the substituted pyridyl, quinolyl or pyrimidinyl is pyridyl, quinolyl or pyrimidinyl substituted by C1-C4 alkyl.
- -
-
Paragraph 0032-0033; 0038-0039; 0085-0106
(2020/12/08)
-
- Light driven photodegradation of 4-nitrophenol with novel Co and Cu phthalocyanine in aqueous media
-
In this work, we have used two different metal centered water soluble phthalocyanines for the degradation of 4-nitrophenol in water media. In the photodegradation reactions that took place in the photoreactor for 1 h without using any oxidant, 4-nitrophenol compound was completed with 95% (for CoPc) and 97% (for CuPc) conversion to toxic and non-harmful species. The hydroquinone compound was identified as the main product and the benzoquinone compound as the by-product. The turnover number for Cu phthalocyanine was 1896 and for Co phthalocyanine was 2101. Finally, recovery studies were carried out for water soluble Cu phthalocyanine used as photocatalyst and the number of cycles was determined as 7.
- Tekintas, Kader,Tugba Saka, Ece
-
-
- Design, syntheses, spectroscopic, aggregation properties of novel peripheral octa-substituted zinc(II), magnesium(II) and lead(II) phthalocyanines and investigation of their photocatalytic properties on the photooxidation of 4-nitrophenol
-
In the present paper, the syntheses, spectroscopic characterization, aggregation behaviours and photocatalytic properties of phthalocyanine compounds were searched. Octa-substituted phthalocyanines (ZnII (Pc-Zn), MgII (Pc-Mg) and PbII (Pc-Pb)) with eight peripheral (E)-3-(3-hydroxyphenyl)-1-(2,4,5-trimethoxyphenyl)prop-2-en-1-one groups were synthesized by cyclotetramerization. The spectral properties of these compounds were carried out that used widespread spectroscopic techniques. Later on, aggregation properties of synthesized phthalocyanines were examined in polar and apolar solvents. In addition to this, the photocatalytic activities of new synthesized metallophthalocyanines containing various central metal ions (zinc (II), magnesium (II) and lead (II)) were investigated. Three different metal centered phthalocyanines have been prepared for the photodegradation of 4-nitrophenol. In the photodegradation reactions that carried out in the photoreactor for 1 h without using any oxidant, 4-nitrophenol compound was completed with 90% (for PbII (Pc-Pb)), 56% (for ZnII (Pc-Zn)) and 12% (for MgII (Pc-Mg)) conversion from toxic species to non-harmful species and unknown intermediates. The turnover numbers were determined as 1500 for PbII (Pc-Pb), 933 for ZnII (Pc-Zn).
- Kahriman, Nuran,Kantekin, Halit,Serdaro?lu, Vildan,Tekintas, Kader,Tugba Saka, Ece,Yalazan, Halise
-
-
- Synthesis, aggregation, photocatalytical and electrochemical properties of axially 1-benzylpiperidin-4-oxy units substituted silicon phthalocyanine
-
Photosensitized catalysis is the initiation of degradation or transformation reactions of molecules using a combination of light and photoactive materials as catalysts. In this work, 1-benzylpiperidin-4-oxy substituted silicone phthalocyanine (SiPc) 3 has been synthesized and characterized with different spectral data and determined catalytic behavior in p-nitrophenol degradation with 1758 turnover number (TON) and 586 turnover frequency (TOF) values. Metallophthalocyanine 3 is soluble in different organic solvents and investigated aggregation behavior in common organic solvents. Electrochemical properties of metallophthalocyanine 3 was defined by using cyclic voltammetry (CV) technique. Silicone phthalocyanine (SiPc) 3 shows one irreversible reduction couple R1 at ?0.85 V (ΔEp = 288 mV), one reversible reduction couple R2 at ?1.54 V (ΔEp = 95 mV) and one quasi-reversible oxidation couple O1 at 1.07 V (ΔEp = 135 mV).
- Saka, Ece Tugba,Yalazan, Halise,B?y?kl?oglu, Zekeriya,Kantekin, Halit,Tekintas, Kader
-
-
- Periodic mesoporous titania with anatase and bronze phases-the new generation photocatalyst: Synthesis, characterisation, and application in environmental remediation
-
High-quality 2D-hexagonal ordered mesoporous titania with a well-crystallized framework structure and a high surface area was successfully synthesized, in a reproducible way, using Pluronic F127, Pluronic P123, Synperonic F108 and CTAB as structure-directing agents, and the resulting nanostructured matrix is designed as TMF-127, TMP-123, TMF-108 and TMC-016/TMC-036, respectively. The periodic array of the pore structure of these mesoporous materials is described by combining small-angle X-ray diffraction, high-resolution transmission electron microscopy and nitrogen sorption techniques. All these materials show significant amounts of intrinsic defects, viz., electrons trapped in oxygen vacancy and/or Ti3+ centres, by tuning the pore structure. These defects in-turn promote the charge separation of photogenerated excitons, and therefore exhibit excellent photocatalytic activity for the degradation of famotidine (TMP-123: DE100 = 75 min; P-25: DE100 = 120 min), and 4-chlorophenol (TMP-123: DE95 = 180 min; P-25: DE60 = 180 min). The superior activity of the mesoporous titania over the fumed titania (P-25) is ascribed to: (i) light absorption extending into the visible region, (ii) low charge-transfer resistance and high carrier density, and (iii) intrinsic Ti3+ defects, as deduced from DRUV-Visible, photo-electrochemical (Nyquist and Mott-Schottky) and EPR studies, respectively.
- Vatti, Surya Kumar,Gupta, Sanjeev,Raj, Rayappan Pavul,Selvam, Parasuraman
-
p. 16269 - 16284
(2020/10/14)
-
- Nickel-catalyzed oxidative hydroxylation of arylboronic acid: Ni(HBTC)BPY MOF as an efficient and ligand-free catalyst to access phenolic motifs
-
A straightforward and mild oxidative ipso-hydroxylation of arylboronic acids has been achieved using a simple and non-noble metal, nickel-based reusable heterogeneous catalyst Ni(HBTC)BPY MOF (HBTC = benzene-1,3,5-tricarboxylate, BPY = 4,4′-bipyridine) in the presence of benign hydrogen peroxide as an oxidant under ambient reaction condition. The Ni(HBTC)BPY MOF exhibits excellent catalytic activity towards the formation of phenols from diverse arylboronic acids within short time and can be reused up to five times without any notable loss in its activity as well as shown high functional group tolerance even in the presence of sensitive functionalities and useful to achieve hydroxyl group in heterocycles.
- Latha, Ganesapandian,Devarajan, Nainamalai,Karthik, Murugan,Suresh, Palaniswamy
-
-
- Vinylene-Bridged Two-Dimensional Covalent Organic Frameworks via Knoevenagel Condensation of Tricyanomesitylene
-
Vinylene-bridged covalent organic frameworks (COFs) have shown great potential for advanced applications because of their high chemical stability and intriguing semiconducting properties. Exploring new functional monomers available for the reticulation of vinylene-bridged COFs and establishing effective reaction conditions are extremely desired for enlarging the realm of this kind of material. In this work, a series of vinylene-bridged two-dimensional (2D) COFs are synthesized by Knoevenagel condensation of tricyanomesitylene with ditopic or tritopic aromatic aldehydes. With use of appropriate secondary amines as catalysts, high-crystalline vinylene-bridged COFs were achieved, exhibiting long-range ordered structures, well-defined nanochannels, high surface areas (up to 1231 m2 g-1), and excellent photophysical properties. Under a low loading amount and short reaction time, they enable aerobic photocatalytic transformation of arylboronic acids to phenols with high efficiency and excellent recyclability. This work demonstrates a new functional monomer, tricyanomesitylene, feasible for the general synthesis of vinylene-bridged COFs with potential application in photocatalytic organic transformation, which instigates further research on such kind of material.
- Bi, Shuai,Thiruvengadam, Palani,Wei, Shice,Zhang, Wenbei,Zhang, Fan,Gao, Lusha,Xu, Junsong,Wu, Dongqing,Chen, Jie-Sheng,Zhang, Fan
-
supporting information
p. 11893 - 11900
(2020/08/06)
-
- Rongalite-promoted metal-free aerobic ipso-hydroxylation of arylboronic acids under sunlight: DFT mechanistic studies
-
A novel rongalite-promoted metal-free aerobic ipso-hydroxylation of arylboronic acids has been developed. This method employs low-cost rongalite as a radical initiator and O2 as a green oxidizing agent for ipso-hydroxylation. This protocol is compatible with a wide variety of functional groups with good to excellent yields at room temperature. Furthermore, mechanistic insight into the role of superoxide radical anions in C-B cleavage has also been provided based on DFT studies.
- Golla, Sivaparwathi,Poshala, Soumya,Pawar, Ravinder,Kokatla, Hari Prasad
-
supporting information
(2019/12/27)
-
- Iridium complex-linked porous organic polymers for recyclable, broad-scope photocatalysis of organic transformations
-
Two rigid porous organic polymers (Ir-POP-1 and Ir-POP-2) were prepared from the coupling reactions of tetraphenylmethane tetraborate and two [Ir(ppy)2(dtbbpy)]+-based bitopic linkers and applied as heterogeneous visible-light photocatalysts for organic transformations. Ir-POP-2 was found to exhibit high catalytic activity for a wide range of organic reactions, which include Smiles-Truce rearrangement of alkyliodides, desulfurative conjugate addition to Michael acceptors, and aerobic oxidations of sulfides and arylboronic acids. For all the transformations, Ir-POP-2 could achieve heterogeneous photocatalytic efficiency that rivals that of the homogeneous prototype iridium complexes. This remarkably high photocatalytic performance has been attributed to the large pore size of the conjugated backbone. The new heterogeneous photocatalyst was also highly stable to achieve good recyclability for all the studied reactions and could be reused eight to nineteen times.
- Xu, Zi-Yue,Luo, Yi,Zhang, Dan-Wei,Wang, Hui,Sun, Xing-Wen,Li, Zhan-Ting
-
supporting information
p. 136 - 143
(2020/01/21)
-
- Method for preparing alcohol and phenol through aerobic hydroxylation reaction of boric acid derivative in absence of photocatalyst
-
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.
- -
-
Paragraph 0025-0028; 0030-0032
(2020/01/25)
-
- Quaternary ammonium hydroxide-functionalized g-C3N4 catalyst for aerobic hydroxylation of arylboronic acids to phenols
-
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
-
p. 1470 - 1476
(2020/07/13)
-
- Carbon nanotubes as catalysts for wet peroxide oxidation: The effect of surface chemistry
-
Three magnetic carbon nanotube (CNT) samples, named A30 (N-doped), E30 (undoped) and E10A20 (selectively N-doped), synthesized by catalytic chemical vapor deposition, were modified by introducing oxygenated surface groups (oxidation with HNO3, samples CNT-N), and by heat treatment at 800 °C for the removal of surface functionalities (samples CNT-HT). Both treatments lead to higher specific surface areas. The acid treatment results in more acidic surfaces, with higher amounts of oxygenated species being introduced on N-doped surfaces. Heat-treated samples are less hydrophilic than those treated with nitric acid, heat treatment leading to neutral or basic surfaces, only N-quaternary and N-pyridinic species being found by XPS on N-doped surfaces. These materials were tested in the catalytic wet peroxide oxidation (CWPO) of highly concentrated 4-nitrophenol solutions (4-NP, 5 g L?1) at atmospheric pressure, T = 50 °C and pH = 3, using a catalyst load of 2.5 g L?1 and the stoichiometric amount of H2O2 needed for the complete mineralization of 4-NP. The high temperature treatment enhanced significantly the activity of the CNTs towards CWPO, evaluated in terms of 4-NP and total organic carbon conversion, due to the increased hydrophobicity of their surface. In particular, E30HT and E10A20HT were able to remove ca. 100% of 4-NP after 8 h of operation. On the other hand, by treating the CNTs with HNO3, the activity of the less hydrophilic samples decreased upon increasing the concentration of surface oxygen-containing functionalities, whilst the reactivity generated inside the opened nanotubes improved the activity of the highly hydrophilic A30 N.
- Martin-Martinez, Maria,Machado, Bruno F.,Serp, Philippe,Morales-Torres, Sergio,Silva, Adrián M.T.,Figueiredo, José L.,Faria, Joaquim L.,Gomes, Helder T.
-
p. 332 - 340
(2019/03/17)
-
- Cuo and ceo2 assisted fe2o3/attapulgite catalyst for heterogeneous fenton-like oxidation of methylene blue
-
In this paper, CuO and CeO2 were screened as co-catalyst components for Fe2O3/attapulgite (ATP) catalyst, and three new catalysts (CuO-Fe2O3/ATP, CeO2-Fe2O3/ATP and Cu
- Dong, Lingyu,Du, Jianhua,Qian, Chunyuan,Wang, Yi,Zhang, Ting
-
p. 23431 - 23439
(2020/07/03)
-
- In situ formation of fluorescent silicon-containing polymer dots for alkaline phosphatase activity detection and immunoassay
-
The discovery and application of analyte-triggered fluorophore generation or fluorogenic reaction are significant and beneficial to the development of novel fluorescence (FL) analysis method. In this study, for the first time, we have reported a fluorogenic reaction to prepare fluorescent silicon-containing polymer dots (Si-PDs) by simply mixing N-[3-(trimethoxysilyl)propyl]ethylenediamine (DAMO) and hydroquinone (HQ) in aqueous solution at ambient temperature. Inspired by the alkaline phosphatase (ALP)-catalyzed hydrolysis of the substrate sodium 4-hydroxyphenyl phosphate (4-HPP) into HQ and the resultant HQ-controlled intense green Si-PDs generation, we have established a straightforward ALP activity assay by innovatively employing commercially available 4-HPP as the substrate. More significantly, the specific preparation method, clear formation mechanism and excellent performance enable the Si-PDs as well as its generation process to develop facile and attractive FL immunoassay. With the help of the universal ALP-based enzyme-linked immunosorbent assay (ELISA) platform and corresponding antibody, a convenient and conceptual ALP-based fluorescent ELISA has been constructed and applied in sensing cardiac troponin I (cTnI), a well-known biomarker of acute myocardial infarction. Our research via in situ formation of fluorescent nanomaterials has great potential application in ALP activity assay, inhibitor screening, and disease diagnosis.
- Liu, Guoyong,Zhao, Jiahui,Yan, Mengxia,Zhu, Shuyun,Dou, Wenchao,Sun, Jian,Yang, Xiurong
-
p. 554 - 560
(2020/03/23)
-
- Reductive Aromatization of Quinols with B2pin2 as Deoxidizing Agent
-
We have demonstrated B2pin2 as superior deoxidizing agent for the reductive deoxygenation of quinol derivatives under basic conditions. A wide range of highly functionalized phenols were obtained in good yields including a complex drug molecule, which revealed the high functional group tolerance of this protocol.
- Liu, Bin,Xu, Yin,Luo, Zhibin,Xie, Jimin
-
supporting information
p. 1022 - 1024
(2020/03/19)
-
- Br?nsted Acid Catalyzed Tandem Defunctionalization of Biorenewable Ferulic acid and Derivates into Bio-Catechol
-
An efficient conversion of biorenewable ferulic acid into bio-catechol has been developed. The transformation comprises two consecutive defunctionalizations of the substrate, that is, C?O (demethylation) and C?C (de-2-carboxyvinylation) bond cleavage, occurring in one step. The process only requires heating of ferulic acid with HCl (or H2SO4) as catalyst in pressurized hot water (250 °C, 50 bar N2). The versatility is shown on a variety of other (biorenewable) substrates yielding up to 84 % di- (catechol, resorcinol, hydroquinone) and trihydroxybenzenes (pyrogallol, hydroxyquinol), in most cases just requiring simple extraction as work-up.
- Bal, Mathias,Bomon, Jeroen,Liao, Yuhe,Maes, Bert U. W.,Sels, Bert F.,Sergeyev, Sergey,Van Den Broeck, Elias,Van Speybroeck, Veronique
-
supporting information
p. 3063 - 3068
(2020/02/05)
-
- Coupled heterogeneous photocatalysis using a P-TiO2-αFe2O3 catalyst and K2S2O8 for the efficient degradation of a sulfonamide mixture
-
Phosphorous-doped Ti-Fe mixed oxide (P-TiO2-αFe2O3) catalysts were prepared by the microwave-assisted sol-gel route and characterized using XRD, SEM, N2 physisorption, UV–vis diffuse reflectance, FTIR, and XPS. P-TiO2-αFe2O3 was evaluated during the degradation of a sulfonamide mixture (5 mg/L, each) under visible light. The photocatalytic process was optimized with a face-centered central composite design. Under optimal conditions (0.5 wt% of αFe2O3, pH 10, and 0.75 g/L of catalyst loading), the sulfate radical advanced oxidation process was carried out using 5 mM K2S2O8 (PS). P doping shifted the light absorption of P-TiO2-αFe2O3 in the visible light range owing to substitutional doping, while the coupling of P-TiO2 with α-Fe2O3 enhanced the absorption in the visible range, which resulted in an increase in the lifetime of the charge carriers and in a superior photoactivity of the P-TiO2-αFe2O3 catalyst in comparison to that of TiO2. The mineralization yield of the sulfonamides (SNs) mixture was enhanced in the presence of an electron acceptor (SO4 ? [rad]), allowing nearly 69 % within 300 min with the P-TiO2-αFe2O3/PS system, while P-TiO2-αFe2O3 and K2S2O8 oxidation achieved only 27 % and 21 %, respectively. The biodegradability index was 0.48 using the P-TiO2-αFe2O3/PS system, indicating a less toxic effluent than the original compounds. Recycling tests demonstrated that P-TiO2-αFe2O3 exhibits good stability in activating PS for SNs degradation during three cycles. Two main intermediates (pyrimidine and hydroquinone) and their hydroxylated re-arrangements were detected during the degradation of the SNs by the coupled process. Oxalic, oxamic, sulfonic, and acetic acids were also identified as by-products from the degradation of the SNs.
- Guzmán-Mar, Jorge L.,Hernández-Ramírez, Aracely,Hinojosa-Reyes, Laura,Mendiola-Alvarez, Sandra Y.,Palomino-Cabello, Carlos,Turnes-Palomino, Gemma
-
-
- Can Donor Ligands Make Pd(OAc)2a Stronger Oxidant? Access to Elusive Palladium(II) Reduction Potentials and Effects of Ancillary Ligands via Palladium(II)/Hydroquinone Redox Equilibria
-
Palladium(II)-catalyzed oxidation reactions represent an important class of methods for selective modification and functionalization of organic molecules. This field has benefitted greatly from the discovery of ancillary ligands that expand the scope, reactivity, and selectivity in these reactions; however, ancillary ligands also commonly poison these reactions. The different influences of ligands in these reactions remain poorly understood. For example, over the 60-year history of this field, the PdII/0 redox potentials for catalytically relevant Pd complexes have never been determined. Here, we report the unexpected discovery of (L)PdII(OAc)2-mediated oxidation of hydroquinones, the microscopic reverse of quinone-mediated oxidation of Pd0 commonly employed in PdII-catalyzed oxidation reactions. Analysis of redox equilibria arising from the reaction of (L)Pd(OAc)2 and hydroquinones (L = bathocuproine, 4,5-diazafluoren-9-one), generating reduced (L)Pd species and benzoquinones, provides the basis for determination of (L)PdII(OAc)2 reduction potentials. Experimental results are complemented by density functional theory calculations to show how a series of nitrogen-based ligands modulate the (L)PdII(OAc)2 reduction potential, thereby tuning the ability of PdII to serve as an effective oxidant of organic molecules in catalytic reactions.
- Bruns, David L.,Musaev, Djamaladdin G.,Stahl, Shannon S.
-
supporting information
p. 19678 - 19688
(2020/12/18)
-
- Chemo- and Regioselective Dihydroxylation of Benzene to Hydroquinone Enabled by Engineered Cytochrome P450 Monooxygenase
-
Hydroquinone (HQ) is produced commercially from benzene by multi-step Hock-type processes with equivalent amounts of acetone as side-product. We describe an efficient biocatalytic alternative using the cytochrome P450-BM3 monooxygenase. Since the wildtype enzyme does not accept benzene, a semi-rational protein engineering strategy was developed. Highly active mutants were obtained which transform benzene in a one-pot sequence first into phenol and then regioselectively into HQ without any overoxidation. A computational study shows that the chemoselective oxidation of phenol by the P450-BM3 variant A82F/A328F leads to the regioselective formation of an epoxide intermediate at the C3=C4 double bond, which departs from the binding pocket and then undergoes fragmentation in aqueous medium with exclusive formation of HQ. As a practical application, an E. coli designer cell system was constructed, which enables the cascade transformation of benzene into the natural product arbutin, which has anti-inflammatory and anti-bacterial activities.
- Zhou, Hangyu,Wang, Binju,Wang, Fei,Yu, Xiaojuan,Ma, Lixin,Li, Aitao,Reetz, Manfred T.
-
supporting information
p. 764 - 768
(2018/12/13)
-
