- Redox Cascades and Making of a C-C Bond: 1,2-Benzodiazinyl Radicals and a Copper Complex of a Benzodiazine
-
Two 1,2-benzodiazinyl radicals, cinnolinyl radicals by name, were successfully isolated by cascade routes using 1,4-naphthoquinone as a precursor. Reaction of 1,4-naphthoquinone with hydrazine hydrate promotes a (5e + 5H+) redox cascade affording benzo[g]naphtho[1,2-c]cinnolinyl-7,12,14-trione (Cn·) in 69% yields, while the similar reaction with 2-hydrazinopyridine is a (7e + 7H+) oxidative cascade and furnishes N-pyridinecinnolinyl radical (PyCn·). The cascades are composed of C-N and C-C bond making reactions. The neutral even alternate arenes are always diamagnetic; thus, the isolation of Cn· and PyCn· is a breakthrough. The Cn·/Cn- and PyCn·/PyCn- redox couples are reversible, and the reaction of Cn· with [CuI(PPh3)3Cl] in the presence of hydrazine hydrate and Et3N affords a Cn- complex of copper(I), [(Cn-)CuI(PPh3)2] (1). Similar to phenalenyl radical, PyCn· exists in three redox states, PyCn+PyCn·, and PyCn-, in a smaller potential range (-0.30 V to -0.60 V vs Fc+/Fc couple) and can be used as an oxidant as well as a reductant. PyCn· acts as a catalyst for the oxidative cleavages of benzil to benzoic and 2,2′-pyridil to picolinic acids in methanol in the presence of air. The molecular and electronic structures of Cn·PyCn·, and 1·1/2MeOH were confirmed by single crystal X-ray crystallography, EPR spectroscopy, and DFT calculations.
- Mondal, Sandip,Bera, Sachinath,Ghosh, Prasanta
-
-
Read Online
- Kinetics and Mechanism of the Oxidation of Aromatic Aldehydes by Pyridinium Fluorochromate
-
Kinetics of oxidation of a number of ortho-, meta-, and para-substituted benzaldehydes by pyridinium fluorochromate (PFC), in dimethyl sulfoxide, were studied.The main product of oxidation is the corresponding benzoic acid.The reaction is first order with
- Agarwal, Sarswati,Chowdhury, Kakuli,Banerji, Kalyan K.
-
-
Read Online
- Study of a benzoylperoxy radical in the gas phase: Ultraviolet spectrum and C6H5C(O)O2 + HO2 reaction between 295 and 357 K
-
This work reports the ultraviolet absorption spectrum and the kinetic determinations of the reactions 2C6H5C(O)O2 → products (I) and C6H5C(O)O2 + HO 2 → C6H5C(O)O2H + O2 (IIa), → C6H5C(O)OH + O3 (IIb), → C6H5C(O)O + OH + O2 (IIc). Experiments were performed using a laser photolysis technique coupled with UV-visible absorption detection over the pressure range of 80-120 Torr and the temperature range of 293-357 K. The UV spectrum was determined relative to the known cross section of the ethylperoxy radical C2H5O2 at 250 nm. Kinetic data were obtained by simulating the temporal behavior of the UV absorption at 245-260 nm. At room temperature, the rate constant value of reaction I (cm3 . molecule-1 . s-1) was found to be kI ) (1.5 ± 0.6) × 10-11. The Arrhenius expression for reaction II is (cm3 . molecule-1 . s -1) kII(T) ± (1.10 ± 0.20) × 10 -11 exp(364 ± 200/T). The branching ratios βO3 and βOH, respectively, of reactions IIb and IIc are evaluated at different temperatures; βO3 increases from 0.15 ± 0.05 at room temperature to 0.40 ± 0.05 at 357 K, whereas βOH remains constant at 0.20 ± 0.05. To confirm the mechanism of reaction II, a theoretical study was performed at the B3LYP/6-311++G(2d,pd) level of theory followed by CBS-QB3 energy calculations.
- Roth,Chakir,Ferhati
-
-
Read Online
- Highly efficient activated carbon loaded TiO2 for photo defluoridation of pentafluorobenzoic acid
-
The activated carbon loaded TiO2-P25 catalysts were prepared and characterized by diffuse reflectance spectra (DRS), FT-IR, scanning electron micrograph (SEM), X-ray diffraction (XRD) and BET surface area analysis. The photocatalytic efficiency
- Ravichandran,Selvam,Swaminathan
-
-
Read Online
- Effect of pyridine and tribenzylamine on the hydrolysis kinetics of benzoyl chloride in water-dioxane system
-
The aim of this paper was to study the effect of tribenzylamine and pyridine on the kinetics of the hydrolysis reaction of benzoyl chloride in water-dioxane solution. The benzoyl chloride and water initial concentrations were 0.005 and 1 mol/L, respectively. While, the initial concentrations of pyridine and tribenzylamine varied in the range of 0.005-0.02 mol/L and 0.007-0.014 mol/L, respectively. It was found that the addition of tribenzylamine to benzoyl chloride hydrolysis reaction has no catalytic effect and hence the rate constant can be calculated using a first-order rate equation. In the presence of pyridine, reaction obeyed second-order rate. The relationship between the reaction rate constant and pyridine initial concentration was found to be linear with a rate constant of 0.752 × 10–3 min–1.
- Batiha, Mohammad A.,Chizhova, Elena A.,Batiha, Marwan M.,Al-Makhadmeh, Leema A.,Rawadieh, Saleh,Alqasaimeh, Muawia,Marashli, Abdullah
-
-
Read Online
- COMPONENTS OF THE GALLS ON THE LEAVES OF PONGAMIA GLABRA: STRUCTURES OF PONGAGALLONE-A AND PONGAGALLONE-B
-
The chemical examination of the galls present on the infected leaves of the plant Pongamia glabra has yielded, in addition to a number of known compounds, two new prenylated β-diketones, pongagallone-A and pongagallone-B.Evidence for their structures is presented. Key Word Index--Pongamia glabra; Leguminosae; pongagallone-A; pongagallone-B; β-diketones.
- Gandhidasan, Rathinasamy,Neelakantan, Sthanusubramania,Raman, Pathai Venkateswara,Devaraj, Savithri
-
-
Read Online
- Preparation and Characterization of Destructible Surfactants
-
Surfactants have been designed and prepared specifically for the application of surfactant-based media to organic synthesis.Condensation of 5-chloro-2-pentanone with 1,2-dodecanediol (3) yielded 2-methyl-2-(3-chloropropyl)-4-decyl-1,3-dioxolane (6), which on reaction with quinuclidine and pyridine gave 1--1-azoniabicyclooctane chloride (1) and 1-pyridinium chloride (2a), respectively.Ketal-based surfactants 1 and 2a are stable under neutral and basic conditions but readily hydrolyze under acidic conditions to 1-(4-oxopentyl)-1-azoniabicyclooctane chloride (4) and 1-(4-oxopentyl)pyridinium chloride (5), respectively, and diol 3.In catalysis of the potassium permanganate oxidation of piperonal to piperonylic acid and the aqueous sodium hydroxide hydrolysis of α,α,α-trichlorotoluene to benzoic acid, surfactants 1 and 2a are about as effective as cetyltrimethylammonium bromide.
- Jaeger, David A.,Frey, Moira R.
-
-
Read Online
- Boron triiodide-N-N-diethylaniline complex: A new reagent for cleaving esters
-
Boron triiodide N,N-diethylaniline complex was used for the hydrolysis, transesterification, and aminolysis of esters.
- Kabalka,Narayana,Reddy
-
-
Read Online
- Biocompatible Ionic Liquid Based on Curcumin as Fluorescence Probe for Detecting Benzoyl Peroxide without the Interference of H2O2
-
Accurate estimation of the level of benzoyl peroxide (BPO) is of considerable significance because of its threat to humanity and environment. Several research efforts have been devoted to the detection of BPO by fluorescent method with high sensitivity and selectivity. However, it remains challenging to eliminate the interference of H2O2 due to its similar properties to BPO. In this work, the first demonstration of fluorescent and colorimetric probe for specific detection of BPO without the disturbance of H2O2 was achieved by curcumin-based ionic liquid (CIL) that possesses simple fabrication, good biocompatibility, and low cost. The fluorescence quenches and emission peak blue-shifts once the probe selectively interacts with BPO, whereas the other possible interfering agents, including H2O2, do not have this phenomenon. The probe CIL exhibits prominent sensitivity for BPO sensing and enables the detection limit at levels as ultralow as 10 nM. The local detection of BPO in practical samples is realized by visualization using a portable device derived from CIL-based liquid atomizer.
- Zhu, Qiu-Hong,Yuan, Wen-Li,Zhang, Lei,Zhang, Guo-Hao,He, Ling,Tao, Guo-Hong
-
-
Read Online
- Prenylated benzoylphloroglucinols and xanthones from the leaves of garcinia oblongifolia with antienteroviral activity
-
An acetone extract of the leaves of Garcinia oblongifolia showed antiviral activity against enterovirus 71 (EV71) using a cytopathic effect inhibition assay. Bioassay-guided fractionation yielded 12 new prenylated benzoylphloroglucinols, oblongifolins J-U (1-12), and five known compounds. The structures of 1-12 were elucidated by spectroscopic analysis including 1D- and 2D-NMR and mass spectrometry methods. The absolute configurations were determined by a combination of a Mosher ester procedure carried out in NMR tubes and ECD calculations. Compared to ribavirin (IC50 253.1 μM), compounds 1, 4, and 13 exhibited significant anti-EV71 activity in vitro, with IC50 values of 31.1, 16.1, and 12.2 μM, respectively. In addition, the selectivity indices of these compounds were 1.5, 2.4, and 3.0 in African green monkey kidney (Vero) cells, respectively.
- Zhang, Hong,Tao, Ling,Fu, Wen-Wei,Liang, Shuang,Yang, Yi-Fu,Yuan, Qing-Hong,Yang, Da-Jian,Lu, Ai-Ping,Xu, Hong-Xi
-
-
Read Online
- Kinetics and mechanism of oxidation of benzohydrazide by bromate catalyzed by vanadium(IV) in aqueous acidic medium
-
The reaction between benzohydrazide and potassium bromate catalyzed by vanadium(IV) was studied under pseudo-first-order condition keeping large excess of hydrazide concentration over that of the oxidant. The initiation of the reaction occurs through oxidation of the catalyst vanadium(IV), VO2+, to vanadium(V), VO2+, which then reacts with hydrazide to give N,N′-diacylhydrazine and benzoic acid as the products. The order in [H+] is found to be two, and its effect is due to protonation and hydrolysis of oxidized form of the catalyst to form HVO3. The oxidized form of the catalyst, VO2+, forms a complex with the protonated hydrazide as evidenced by the occurrence of absorption maxima at 390 nm. The rate of the reaction remains unaffected by the increase in the ionic strength. The activation parameters were determined, and data support the mechanism. The detailed mechanism and the rate equation are proposed for the reaction.
- Shewale,Phadkule,Gokavi
-
-
Read Online
- ELECTRON-TRANSFER MEDIATED PHOTOOXYGENATION OF BIPHENYL AND ITS DERIVATIVES IN THE PRESENCE OF Mg(ClO4)2
-
The 9,10-dicyanoanthracene-sensitized photooxygenation of biphenyl and its derivatives in the presence of Mg(ClO4)2 in acetonitrile brought about the oxidative cleavage of benzene nucleus to give benzoic acid and its derivatives.
- Mizuno, Kazuhiko,Ichinose, Nobuyuki,Tamai, Toshiyuki,Otsuji, Yoshio
-
-
Read Online
- Facile synthesis of polystyrene/gold composite particles as a highly active and reusable catalyst for aerobic oxidation of benzyl alcohol in water
-
PS/Au composite particles have been synthesized facilely based on a thermodynamic effect. More significantly, the PS/Au composite particles can catalyze the aerobic oxidation of benzyl alcohol remarkably under mild conditions (1 atm, air as oxidant, Ksub
- Li, Yunxing,Gao, Yan,Yang, Cheng,Sha, Shengsheng,Hao, Jiefu,Wu, Yan
-
-
Read Online
- Catalytic and inhibitory effects of β-cyclodextrin on the hydrolysis of benzoic anhydride
-
The hydrolysis of benzoic anhydride (Bz2O) in the presence of β-cyclodextrin (β-CD) was studied in aqueous solution as a function of pH, temperature and ionic strength, at 25°C. The experimental rate constant versus pH profiles show that, in the region of spontaneous water reaction (pH 3.0-6.5), β-CD inhibits the reaction and the isotope effect (k H2O/kD2O = 4.7) indicates that the rate determining step of the reaction corresponds to the water-catalyzed nucleophilic attack of water on the carbonyl group of Bz2O. Conversely, whereas inhibition is observed at pH 6.0, catalysis of the hydroxide ion reaction is observed at pH 8.0 and it is found that the activation entropy is responsible for the catalytic phenomena in the basic hydrolysis of benzoic anhydride. Copyright 2004 John Wiley & Sons, Ltd.
- Brandao, Tiago A.S.,Dal Magro, Jacir,Chiaradia, Louise D.,Da Graca Nascimento, Maria,Nome, Faruk,Tato, Jose V.,Yunes, Rosendo A.
-
-
Read Online
- Hydrolysis of several substituted methyl benzoates in the aqueous solution
-
The hydrolysis of several ring substituted methyl benzoates was investigated in aqueous solution over a pH range of 3-10. Both the pH dependence (at pH5) and the variation of hydrolysis rates with ring substitution are consistent with a mechanism involving the addition of hydroxide ion to the ester carbonyl group. Extrapolation of the rate data to a pH and temperature that would be consistent with soil and groundwater (pH 8, 10 degrees C) indicate that these esters could have hydrolysis half lives from several months to several years in the environment. (Authors)
- Steinberg,Lena
-
-
Read Online
- Novel oxo-peroxo molybdenum(VI) complexes incorporating 8-quinolinol: Synthesis, structure and catalytic uses in the environmentally benign and cost-effective oxidation method of methyl benzenes: Ar(CH3), (n = 1, 2)
-
A hitherto unknown distorted pentagonal bipyramidal complex, [MoO(O2)(QO)2], very efficiently catalyses homogeneous liquid phase oxidation of methylbenzenes, viz. toluene and o- and p-xylenes to benzoic acid, phthalic acid and p-toluic acid respectively, using H2O2 and O2 as oxidants.
- Bandyopadhyay, Ratna,Biswas, Sudeb,Guha, Subhadra,Mukherjee, Alok K.,Bhattacharyya, Ramgopal
-
-
Read Online
- Facile synthesis of 2,3-diacetoxyflavanones from 3-aminoflavones
-
3-Aminoflavone reacts with isopentyl nitrite in acetic acid to give 2,3-diacetoxyflavanone in good yield. 3-Aminoflavone, the starting material, is readily available, and this method is a powerful tool for the synthesis of 2,3-dihydroxyflavanone derivativ
- Miyake, Hideyoshi,Nishino, Shouko,Sasaki, Mitsuru
-
-
Read Online
- A DITERPENE FROM EUPHORBIA MADDENI
-
Key Word Index - Euphorbia maddeni; Euphorbiaceae; euphornin; jatrophone diterpene. From the anticancer-active CHCl3 extract of the plant Euphorbia maddeni, a polyacylated diterpene of jatrophone type, euphornin, has been isolated and its structure elucidated by physico-chemical methods.
- Sahai, R.,Rastogi, R. P.,Jakupovic, J.,Bohlmann, F.
-
-
Read Online
- Zn(II)-to-Cu(II) transmetalation in an amide functionalized complex and catalytic applications in styrene oxidation and nitroaldol coupling
-
The mononuclear zinc(II) complex cis-[ZnL2(H2O)2] (1; L = 4-(pyridin-3- ylcarbamoyl)benzoate) was synthesized and characterized. By soaking crystals of 1 in a mixture of DMF-H2O solution containing a slight excess of Cu(NO3)2 × 3H2Oa transmetalation reaction occurred affording the related copper(II) complex trans-[CuL2(H2O)2] (2). The structures of the compounds were authenticated by single crystal X-ray diffraction revealing, apart from a change in the isomerism, an alteration in the relative orientation of the chelating carboxylate groups and of the pyridine moieties. H-bond interactions stabilize both geometries and expand them into two-dimensional (2D) networks. The transmetalation was confirmed by SEM-EDS analysis. Moreover, the thermodynamic feasibility of the transmetalation is demonstrated by density-functional theory (DFT) studies. The catalytic activities of 1 and 2 for the oxidation of styrene and for the nitroaldol (Henry) C-C coupling reaction were investigated. The copper(II) compound 2 acts as heterogeneous catalyst for the microwave-assisted oxidation of styrene with aqueous hydrogen peroxide, yielding selectively (>99percent) benzaldehyde up to 66percent of conversion and with a turnover frequency (TOF) of 132 h-1. The zinc(II) complex 1 is the most active catalyst (up to 87percent yield) towards the nitroaldol (Henry) coupling reaction between benzaldehyde and nitro-methane or -ethane to afford the corresponding β-nitro alcohols. The reaction of benzaldehyde with nitroethane in the presence of 1 produced 2-nitro-1-phenylpropanol in the syn and the anti diastereoisomeric forms, with a considerable higher selectivity towards the former (66:34).
- Da Silva, M. Fátima C. Guedes,Karmakar, Anirban,Kuznetsov, Maxim L.,Martins, Luísa M. D. R. S.,Paul, Anup,Pombeiro, Armando J. L.
-
-
Read Online
- Carbonylation of bromobenzene in a biphasic medium catalysed by water-soluble palladium complexes derived from tris(3-sulphophenyl)phosphine
-
The hydroxycarbonylation of bromobenzene has been explored in a biphasic medium.Water-soluble (TPPTS = sodium salt of tris(3-sulphophenyl) phosphine) catalyses selectively this carbonylation reaction into benzoic acid.This complex is maintained intact in the presence of an excess of tris(3-sulphophenyl)phosphine salt.Even when a hydrogen donor is added, the reaction is limited to hydroxycarbonylation.The two complexes and have been synthesized.A catalytic cycle is proposed.Key words: Palladium; Carbonylation; Biphatic medium Phosphines; Mechanism
- Monteil, Fanny,Kalck, Philippe
-
-
Read Online
- Carboxylic acids from methyl aryl ketones by means of a new composite aerobic oxidation process
-
A new aerobic oxidation method for conversion of methyl aryl ketones to the corresponding benzoic acids is presented. The method is cheap and environmentally friendly, which also makes it suitable for large scale industrial use. The method affords a yield of >75% with an almost 100% selectivity. Experiments have shown that the process operates following two mechanistic pathways, namely by base-catalysed autoxidation and by single electron transfer processes.
- Bj?rsvik, Hans-René,Liguori, Lucia,Rodríguez González, Raquel,Vedia Merinero, José Angel
-
-
Read Online
- Co/rGO synthesized: Via the alcohol-thermal method as a heterogeneous catalyst for the highly efficient oxidation of ethylbenzene with oxygen
-
Co3O4 nanoparticles uniformly dispersed on reduced graphene oxide (Co/rGO) were synthesized by the alcohol-thermal method as a highly efficient catalyst with initiator NHPI for the selective oxidation of ethylbenzene to acetophenone using O2 as a green oxidant. X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) were carried out for chemical, morphological, and size analyses of the nanocomposite. The ensuing catalyst was evaluated for the oxidation of ethylbenzene with a high conversion of 84.1% and an acetophenone selectivity of 96.2% within only 2 h. Moreover, the Co/rGO catalyst showed good recyclability and activity towards the selective oxidation of ethylbenzene. It was revealed that the enhanced catalytic activity of Co/rGO was derived from the interaction of the active Co3O4 center and the graphene support material.
- Gao, Lingfeng,Zhuge, Wenyun,Feng, Xue,Sun, Wei,Sun, Xu,Zheng, Gengxiu
-
-
Read Online
- HCl-Catalyzed Aerobic Oxidation of Alkylarenes to Carbonyls
-
The construction of C?O bonds through C?H bond functionalization remains fundamentally challenging. Here, a practical chlorine radical-mediated aerobic oxidation of alkylarenes to carbonyls was developed. This protocol employed commercially available HCl as a hydrogen atom transfer (HAT) reagent and air as a sustainable oxidant. In addition, this process exhibited excellent functional group tolerance and a broad substrate scope without the requirement for external metal and oxidants. The mechanistic hypothesis was supported by radical trapping, 18O labeling, and control experiments.
- Niu, Kaikai,Shi, Xiaodi,Ding, Ling,Liu, Yuxiu,Song, Hongjian,Wang, Qingmin
-
-
- Stepwise benzylic oxygenation via uranyl-photocatalysis
-
Stepwise oxygenation at the benzylic position (1°, 2°, 3°) of aromatic molecules was comprehensively established under ambient conditions via uranyl photocatalysis to produce carboxylic acids, ketones, and alcohols, respectively. The accuracy of the stepwise oxygenation was ensured by the tunability of catalytic activity in uranyl photocatalysis, which was adjusted by solvents and additives demonstrated through Stern–Volmer analysis. Hydrogen atom transfer between the benzylic position and the uranyl catalyst facilitated oxygenation, further confirmed by kinetic studies. Considerably improved efficiency of flow operation demonstrated the potential for industrial synthetic application.
- Hu, Deqing,Jiang, Xuefeng
-
supporting information
p. 124 - 129
(2022/01/19)
-
- Functionalized-1,3,4-oxadiazole ligands for the ruthenium-catalyzed Lemieux-Johnson type oxidation of olefins and alkynes in water
-
Three arene-ruthenium(II) complexes bearing alkyloxy(5-phenyl-1,3,4-oxadiazol-2-ylamino)(4-trifluoromethylphenyl)methyl ligands were quantitatively obtained through the reaction of (E)-1-(4-trifluoromethylphenyl)-N-(5-phenyl-1,3,4-oxadiazol-2-yl)-methanimine with the ruthenium precursor [RuCl2(η6-p-cymene)]2 in a mixture of the corresponding alcohol and CH2Cl2 at 50 °C. The obtained complexes were fully characterized by elemental analysis, infrared, NMR and mass spectrometry. Solid-state structures confirmed the coordination of the 1,3,4-oxadiazole moiety to the ruthenium center via their electronically enriched nitrogen atom at position 3 in the aromatic ring. These complexes were evaluated as precatalysts in the Lemieux-Johnson type oxidative cleavage of olefins and alkynes in water at room temperature with NaIO4 as oxidizing agent. Good to full conversions of olefins into the corresponding aldehydes were measured, but low catalytic activity was observed in the case of alkynes. In order to get more insight into the mechanism, three analogue arene-ruthenium complexes were synthesized and tested in the oxidative cleavage of styrene. The latter tests clearly demonstrated the importance of the hemilabile alkyloxy groups, which may form more stable (N,O)-chelate intermediates and increase the efficiency of the cis-dioxo-ruthenium(VI) catalyst.
- Hkiri, Shaima,Touil, Soufiane,Samarat, Ali,Sémeril, David
-
-
- Selective catalytic synthesis of bio-based high value chemical of benzoic acid from xylan with Co2MnO4@MCM-41 catalyst
-
The efficient synthesis of bio-based chemicals using renewable carbon resources is of great significance to promote sustainable chemistry and develop green economy. This work aims to demonstrate that benzoic acid, an important high added value chemical in petrochemical industry, can be selectively synthesized using xylan (a typical model compound of hemicellulose). This novel controllable transformation process was achieved by selective catalytic pyrolysis of xylan and subsequent catalytic oxidation. The highest benzoic acid selectivity of 88.3 % with 90.5 % conversion was obtained using the 10wt%Co2MnO4@MCM-41 catalyst under the optimized reaction conditions (80 °C, 4 h). Based on the study of the model compounds and catalyst's characterizations, the reaction pathways for the catalytic transformation of xylan to bio-based benzoic acid were proposed.
- Fan, Minghui,He, Yuting,Li, Quanxin,Luo, Yuehui,Yang, Mingyu,Zhang, Yanhua,Zhu, Lijuan
-
-
- Gram-scale synthesis of carboxylic acids via catalytic acceptorless dehydrogenative coupling of alcohols and hydroxides at an ultralow Ru loading
-
Acceptorless dehydrogenative coupling (ADC) of alcohols and water/hydroxides is an emergent and graceful approach to produce carboxylic acids. Therefore, it is of high demand to develop active and practical catalysts/catalytic systems for this attractive transformation. Herein, we designed and fabricated a series of cyclometallated N-heterocyclic carbene-Ru (NHC-Ru) complexes via ligand tuning of [Ru-1], the superior complex in our previous work. Gratifyingly, gram-scale synthesis of carboxylic acids was efficiently enabled at an ultralow Ru loading (62.5 ppm) in open air. Moreover, effects of distinct ancillary NHC ligands and other parameters on this catalytic process were thoroughly studied, while further systematic studies were carried out to provide rationales for the activity trend of [Ru-1]-[Ru-7]. Finally, determination of quantitative green metrics illustrated that the present work exhibited superiority over representative literature reports. Hopefully, this study could provide valuable input for researchers who are engaging in metal-catalyzed ADC reactions.
- Chen, Cheng,Cheng, Hua,Verpoort, Francis,Wang, Zhi-Qin,Wu, Zhe,Yuan, Ye,Zheng, Zhong-Hui
-
-
- A functional model for quercetin 2,4-dioxygenase: Geometric and electronic structures and reactivity of a nickel(II) flavonolate complex
-
Quercetin 2,4-dioyxgenase (QueD) has been known to catalyze the oxygenative degradation of flavonoids and quercetin. Recent crystallographic study revealed a nickel ion occupies the active site as a co-factor to support O2 activation and catalysis. Herein, we report a nickel(II) flavonolate complex bearing a tridentate macrocyclic ligand, [NiII(Me3-TACN)(Fl)(NO3)](H2O) (1, Me3-TACN = 1,4,7-trimethyl-1,4,7-triazacyclononane, Fl = 3-hydroxyflavone) as a functional model for QueD. The flavonolatonickel(II) complex was characterized by using spectrometric analysis including UV–vis spectroscopy, electrospray ionization mass spectrometer (ESI-MS), infrared spectroscopy (FT-IR) and 1H nuclear magnetic resonance spectroscopy (NMR). The single crystal X-ray structure of 1 shows two isomers with respect to the direction of a flavonolate ligand. Two isomers commonly are in the octahedral geometry with a bidentate of flavonolate and a monodentate of nitrate as well as a tridentate binding of Me3-TACN ligand. The spin state of 1 is determined to be a triplet state based on the Evans' method. Interestingly, electronic configuration of 1 from density functional theory (DFT) calculations revealed that the two singly occupied molecular orbitals (SOMOs) lie energetically lower than the highest (doubly) occupied molecular orbital (HOMO), that is so-called the SOMO-HOMO level inversion (SHI). The HOMO shows an electron density localized in the flavonolate ligand, indicating that flavonolate ligand is oxidized first rather than the nickel center. Thermal degradation of 1 resulted in the formation of benzoic acid and salicylic acid, which is attributed to the oxygenation of flavonolate of 1.
- Jeong, Donghyun,Sun, Seungwon,Moon, Dohyun,Cho, Jaeheung
-
-
- 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)
-
- 3D structured TiO2-based aerogel photocatalyst for the high-efficiency degradation of toluene gas
-
Photocatalytic technology is a green , environmentally friendly, energy-saving technology, which is considered to be an ideal method for removing volatile organic compounds (VOCs). At present, photocatalytic technology mostly uses powdered catalysts, which is not conducive to recycling and restricts the contact between the gas and catalyst. In this work, a three-dimensional (3D)-structured TiO2-based aerogel with TiO2 as the main body and all the components beneficial to photocatalysis was prepared for the first time. Under simulated sunlight irradiation, the toluene-removal rate of the Pt-loaded TiO2 and reduced graphene oxide (RGO) composite aerogel (denoted as Pt-TiO2/RGO aerogel, or PTA thereafter) was 60.47% higher than that of the pure RGO aerogel, and 56.03% higher than that of the bare TiO2 nanofibers. The block-shaped composite aerogel could be easily recycled, and the C/C0 of toluene using the recycled sample decreased by only 5.31% in the 5th run. The Pt-TiO2/RGO composite aerogel had the highest photocatalytic degradation rate of toluene with a relative humidity (RH) of 60-80%, which is conducive to the purification of VOCs in high-humidity areas. The 3D aerogel enriches the contact between the solid photocatalyst and the toluene molecules, and also solves the problem of low adhesion between the catalyst and the carrier. This work provides a new perspective for the efficient removal of toluene gas by constructing a highly active 3D TiO2 aerogel with an increased gas-solid reaction rate.
- Dai, Li,Guan, Jie,Li, Shijie,Li, Xueying,Yu, Wei,Zhang, Li
-
p. 2272 - 2281
(2022/02/16)
-
- 2-(4-Nitrophenyl)-1H-indolyl-3-methyl Chromophore: A Versatile Photocage that Responds to Visible-light One-photon and Near-infrared-light Two-photon Excitations
-
Due to cell damage caused by UV light, photoremovable protecting groups (PPGs) that are removed using visible or near-infrared light are attracting attention. A 2-(4-nitrophenyl)- 1H-indolyl-3-methyl chromophore (NPIM) was synthesized as a novel PPG. Various compounds were caged using this PPG and uncaged using visible or near-infrared light. Low cytotoxicity of NPIM indicates that it may be applied in physiological studies.
- Abe, Manabu,Guo, Runzhao,Hamao, Kozue,Lin, Qianghua,Takagi, Ryukichi
-
supporting information
p. 153 - 156
(2022/02/14)
-
- One-step solvent-free aerobic oxidation of aliphatic alcohols to esters using a tandem Sc-Ru?MOF catalyst
-
Esters are an important class of chemicals in industry. Traditionally, ester production is a multi-step process involving the use of corrosive acids or acid derivatives (e.g. acid chloride, anhydride, etc.). Therefore, the development of a green synthetic protocol is highly desirable. This work reports the development of a metal-organic framework (MOF) supported tandem catalyst that can achieve direct alcohol to ester conversion (DAEC) using oxygen as the sole oxidizing agent under strictly solvent-free conditions. By incorporating Ru nanoparticles (NPs) along with a homogeneous Lewis acid catalyst, scandium triflate, into the nanocavities of a Zr MOF, MOF-808, the compound catalyst, Sc-Ru?MOF-808, can achieve aliphatic alcohol conversion up to 92% with ester selectivity up to 91%. A mechanistic study reveals a unique “via acetal” pathway in which the alcohol is first oxidized on Ru NPs and rapidly converted to an acetal on Sc(iii) sites. Then, the acetal slowly decomposes to release an aldehyde in a controlled manner for subsequent oxidation and esterification to the ester product. To the best of our knowledge, this is the first example of DAEC of aliphatic alcohols under solvent-free conditions with high conversion and ester selectivity.
- Feng, Tingkai,Li, Conger,Li, Tao,Zhang, Songwei
-
supporting information
p. 1474 - 1480
(2022/03/08)
-
- Synthesis and pyrolysis of two novel pyrrole ester flavor precursors
-
In order to develop the high-temperature-released pyrrole aroma, two novel flavors precursors of methyl 2-methyl-5-(((2-methylbutanoyl)oxy)methyl)-1-propyl-1H-pyrrole-3-carboxylate and methyl 2-methyl-5-(((2-methylbutanoyl)oxy)methyl)-1-propyl-1H-pyrrole-3-carboxylate were synthesized using glucosamine hydrochloride and methyl acetoacetate as raw materials through cyclization, oxidation, alkylation, reduction, and esterification. The target compounds were characterized by nuclear magnetic resonance (1H NMR, 13C NMR), infrared spectroscopy (IR) and high-resolution mass spectrometry (HRMS). Thermogravimetry (TG), differential scanning calorimeter (DSC) and the pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) methods were used to analyze the heating-stability of the target compounds, and the pyrolysis mechanism was inferred. Py-GC/MS results indicated that some fragrance compounds were formed during?thermal degradation such as 2-methylbutyric acid, 2-methylbutyrate, alkylpyrroles, and benzoic acid, which were important aroma components or flavor additives. This provided a theoretical reference for the application of pyrrole ester in cigarette and heat-processed food flavoring.
- Cheng, Biao,Chu, Wenjuan,Fan, Wenpeng,Feng, Yingjie,Gao, Ziting,Ji, Xiaoming,Lai, Miao,Tian, Haiying,Zhang, Zhan
-
-
- Transformation of Thioacids into Carboxylic Acids via a Visible-Light-Promoted Atomic Substitution Process
-
A visible-light-promoted atomic substitution reaction for transforming thiocacids into carboxylic acids with dimethyl sulfoxide (DMSO) as the oxygen source has been developed, affording various alkyl and aryl carboxylic acids in over 90% yields. The atomic substitution process proceeds smoothly through the photochemical reactivity of the formed hydrogen-bonding adduct between thioacids and DMSO. A DMSO-involved proton-coupled electron transfer (PCET) and the simultaneous generation of thiyl and hydroxyl radicals are proposed to be key steps for realizing the transformation.
- Fu, Qiang,Liang, Fu-Shun,Lou, Da-Wei,Pan, Gao-Feng,Wang, Rui,Wu, Min,Xie, Kai-Jun
-
supporting information
p. 2020 - 2024
(2022/03/31)
-
- Urchin-like Nb2O5 hollow microspheres enabling efficient and selective photocatalytic C–C bond cleavage in lignin models under ambient conditions
-
Selective cleavage of robust C?C bonds to harvest value-added aromatic oxygenates is an intriguing but challenging task in lignin depolymerization. Photocatalysis is a promising technology with the advantages of mild reaction conditions and strong sustainability. Herein, we show a novel urchin-like Nb2O5 hollow microsphere (U-Nb2O5 HM), prepared by one-pot hydrothermal method, are highly active and selective for Cα?Cβ bond cleavage of lignin β-O-4 model compounds under mild conditions, achieving 94% substrate conversion and 96% C?C bond cleavage selectivity. Systematic experimental studies and density functional theory (DFT) calculations revealed that the superior performance of U-Nb2O5 HMs arises from more exposed active sites, more efficient free charge separation and the active (001) facet, which facilitates the activation of Cβ?H bond of lignin models and generate key Cβ radical intermediates by photogenerated holes, further inducing the Cα?Cβ bond cleavage to produce aromatic oxygenates. This work could provide some suggestions for the fabrication of hierarchical photocatalysts in the lignin depolymerization system.
- Chen, Huan,Hong, Donghui,Long, Donghui,Niu, Bo,Wan, Kun,Wang, Junjie,Zhang, Yayun
-
-
- Synthesis of α-Hydroxy Acids via Dehydrogenative Cross-Coupling of a Sustainable C2 Chemical (Ethylene Glycol) with Alcohols
-
Ir(NHC) (NHC, N-heterocyclic carbene)-catalyzed dehydrogenative coupling of sustainable ethylene glycol and various bioalcohols can produce industrially valuable α-hydroxy acids (AHAs). This study is the first to report the sustainable synthesis of higher Cn AHAs, in addition to glycolic acid (C2 AHA) and lactic acid (C3 AHA). This catalytic system can be recycled to the seventh cycle while maintaining good yields. A reaction mechanism, including facile dehydrogenation of each alcohol and fast cross-coupling of dehydrogenated aldehydes forming products, was proposed based on 18O- and 2H-labeling experiments and electron spray ionization-mass spectrometry (ESI-MS) and NMR spectral analyses.
- Byeon, Heemin,Jang, Hye-Young,Lee, Mi-Hyun
-
supporting information
p. 4631 - 4639
(2022/04/07)
-
- Oxygenolysis of a series of copper(ii)-flavonolate adducts varying the electronic factors on supporting ligands as a mimic of quercetin 2,4-dioxygenase-like activity
-
Four copper(ii)-flavonolate compounds of type [Cu(LR)(fla)] {where LR = 2-(p-R-benzyl(dipyridin-2-ylmethyl)amino)acetate; R = -OMe (1), -H (2), -Cl (3) and -NO2 (4)} have been developed as a structural and functional enzyme-substrate (ES) model of the Cu2+-containing quercetin 2,4-dioxygenase enzyme. The ES model complexes 1-4 are synthesized by reacting 3-hydroxyflavone in the presence of a base with the respective acetate-bound copper(ii) complexes, [Cu(LR)(OAc)]. In the presence of dioxygen the ES model complexes undergo enzyme-type oxygenolysis of flavonolate (dioxygenase type bond cleavage reaction) at 80 °C in DMF. The reactivity shows a substituent group dependent order as -OMe (1) > -H (2) > -Cl (3) > ?NO2 (4). Experimental and theoretical studies suggest a single-electron transfer (SET) from flavonolate to dioxygen, rather than valence tautomerism {[CuII(fla?)] ? [CuI(fla˙)]}, to generate the reactive flavonoxy radical (fla˙) that reacts further with the superoxide radical to bring about the oxygenative ring opening reaction. The SET pathway has been further verified by studying the dioxygenation reaction with a redox-inactive Zn2+ complex, [Zn(LOMe)(fla)] (5).
- Anoop, Anakuthil,Dey, Subhasis,Mandal, Sukanta,Podder, Nirmalya
-
supporting information
p. 4338 - 4353
(2022/04/07)
-
- Heterogeneous vanadium-catalyzed oxidative cleavage of olefins for sustainable synthesis of carboxylic acids
-
The development of green and sustainable processes to synthesize active pharmaceutical ingredients and key starting materials is a priority for the pharmaceutical industry. A green and sustainable protocol for the oxidative cleavage of olefins to produce pharmaceutically and biologically valuable carboxylic acids is achieved. The developed protocol involves 70% aq. TBHP as an oxidant over a heterogeneous vanadium catalyst system. Notably, the synthesis of industrially important azelaic acid from various renewable vegetable oils is accomplished. The catalyst could be recycled for up to 5 cycles without significant loss in yield and the protocol was successfully demonstrated at the gram-scale.
- Upadhyay, Rahul,Rana, Rohit,Sood, Aakriti,Singh, Vikash,Kumar, Rahul,Srivastava, Vimal Chandra,Maurya, Sushil K.
-
supporting information
p. 5430 - 5433
(2021/06/09)
-
- Selective oxidation of alkenes to carbonyls under mild conditions
-
Herein, a practical and sustainable method for the synthesis of aldehydes, ketones, and carboxylic acids from an inexpensive olefinic feedstock is described. This transformation features very sustainable and mild conditions and utilizes commercially available and inexpensive tetrahydrofuran as the additive, molecular oxygen as the sole oxidant and water as the solvent. A wide range of substituted alkenes were found to be compatible, providing the corresponding carbonyl compounds in moderate-to-good yields. The control experiments demonstrated that a radical mechanism is responsible for the oxidation reaction.
- Huo, Jie,Xiong, Daokai,Xu, Jun,Yue, Xiaoguang,Zhang, Pengfei,Zhang, Yilan
-
supporting information
p. 5549 - 5555
(2021/08/16)
-
- Photoinduced FeCl3-Catalyzed Alkyl Aromatics Oxidation toward Degradation of Polystyrene at Room Temperature?
-
While polystyrene is widely used in daily life as a synthetic plastic, the subsequently selective degradation is still very challenging and highly required. Herein, we disclose a highly practical and selective reaction for the catalytically efficient oxidation of alkyl aromatics (including 1°, 2°, and 3° alkyl aromatics) to carboxylic acids. While dioxygen was used as the sole terminal oxidant, this protocol was catalyzed by the inexpensive and readily available ferric compound (FeCl3) with irradiation of visible light (blue LEDs) under only 1 atmosphere of O2 at room temperature. This system could further facilitate the selective degradation of polystyrene to benzoic acid, providing an important and practical tool to generate high-value chemical from abundant polystyrene wastes.
- Zhang, Guoxiang,Zhang, Zongnan,Zeng, Rong
-
supporting information
p. 3225 - 3230
(2021/09/28)
-
- New Cu(II), Co(II) and Ni(II) azo-Schiff base complexes: Synthesis, characterization, catalytic oxidation of alkenes and DFT study
-
Three new complexes with general formula of ML (M = Cu (1), Co (2), Ni (3)) containing an azo-Schiff base ligand (H2L) derived from 2,3-butanediamine and 4-(benzeneazo) salicylaldehyde were synthesized by template method. Characterization of the ligand and complexes were accomplished with FT-IR, UV–Vis, and 1H NMR. The catalytic activity of the complexes (1–3) were tested for the oxidation of various alkenes (cyclooctene, cyclohexene, styrene, α-methyl styrene, and norbornene) applying tert-butyl hydroperoxide (TBHP) as an oxidizing agent, and it was found that they were acceptable catalysts. Under the optimized reaction conditions, CuL complex displayed 94% conversion for the oxidation of cyclooctene, and CoL and NiL complexes exhibited 90 and 85% conversions for oxidizing α-methyl styrene, respectively. Based on our density functional computations, diffuse functions are compulsory in the basis set for geometry optimization of these systems. Therefore, the most stable structures and the vibrational frequencies were calculated at the M06-2X/6–311++G(d,p) level. By establishing the correlation between observed and calculated frequencies, the assignment of the vibrational modes was performed. Based on natural charge analysis (NAO), the back electron transfer from ML to the TBHP breaks the O–O bond and facilitates the formation of tert-butoxyl radicals.
- Lashanizadegan, Maryam,Asna Ashari, Hadiseh,Sarkheil, Marzieh,Anafcheh, Maryam,Jahangiry, Samira
-
-
- Tuneable oxidation of styrene to benzaldehyde and benzoic acid over Co/ZSM-5
-
Co/ZSM-5 preparedviathe simple impregnation method was used as a catalyst for the solvent-free oxidation of styrene with molecular oxygen as the oxidant. Co/ZSM-5-500 catalyst prepared at a calcination temperature of 500 °C demonstrated high catalytic activity (TON 566.6 mol molCo?1) and selectivity toward benzaldehyde (96%) at 80 °C. Meanwhile, the Co/ZSM-5-450 catalyst showedca.100% conversion and 94.7% selectivity to benzoic acid for styrene oxidation at 90 °C. The tuneable synthesis of benzaldehyde and benzoic acid by styrene oxidation over Co/ZSM-5-500 and Co/ZSM-5-450 catalysts, respectively, was realized. This reason that the two catalytic systems exhibited two different target products was explored by analyzing the surface properties of the catalysts by XRD,29Si and27Al MAS NMR, NH3-TPD, pyridine-adsorption IR, and H2-TPR techniques, and the related reaction mechanism was authenticated byin situDRIFTS. Besides, the recovery and reuse of the catalyst was tested and the activity was effectively maintained even in the fourth run.
- Cai, Qinghai,Duan, Chongda,Guan, Xin,Lu, Bin,Wang, Hongxia,Zhao, Jingxiang
-
p. 18192 - 18201
(2021/10/12)
-
- 1,2-Dibutoxyethane-Promoted Oxidative Cleavage of Olefins into Carboxylic Acids Using O2 under Clean Conditions
-
Herein, we report the first example of an effective and green approach for the oxidative cleavage of olefins to carboxylic acids using a 1,2-dibutoxyethane/O2 system under clean conditions. This novel oxidation system also has excellent functional-group tolerance and is applicable for large-scale synthesis. The target products were prepared in good to excellent yields by a one-pot sequential transformation without an external initiator, catalyst, and additive.
- Ou, Jinhua,Tan, Hong,He, Saiyu,Wang, Wei,Hu, Bonian,Yu, Gang,Liu, Kaijian
-
p. 14974 - 14982
(2021/10/25)
-
- Catalytic epoxidation of β-ionone with molecular oxygen using selenium-doped silica materials
-
A novel Se-doped silica material was fabricated, and this easily prepared material could be used as an efficient recyclable catalyst for β-ionone oxidation. Interestingly, by doping with fluorine in the catalyst, the reaction selectivity was significantly enhanced to produce the important pharmaceutical intermediate β-ionone epoxide selectively. Characterization of the materials indicated that by doping with F, the electropositivity of the catalytic Se species was obviously enhanced due to the strong electron-withdrawing features of F, and this was a key factor for controlling the reaction selectivity in the β-ionone epoxidation reaction. The electropositivity of a silica support might also increase and the reinforced electropositivity of Si sites might be beneficial for the adsorption of a β-ionone substrate and for the contact of the electron-enriched endocyclic C-C with the catalyst.
- Cao, Kuanhong,Jing, Xiaobi,Li, Peizi,Liu, Yonghong,Yu, Lei
-
p. 17241 - 17246
(2021/10/04)
-
- Photo-induced deep aerobic oxidation of alkyl aromatics
-
Oxidation is a major chemical process to produce oxygenated chemicals in both nature and the chemical industry. Presently, the industrial manufacture of benzoic acids and benzene polycarboxylic acids (BPCAs) is mainly based on the deep oxidation of polyalkyl benzene, which is somewhat suffering from environmental and economical disadvantage due to the formation of ozone-depleting MeBr and corrosion hazards of production equipment. In this report, photo-induced deep aerobic oxidation of (poly)alkyl benzene to benzene (poly)carboxylic acids was developed. CeCl3 was proved to be an efficient HAT (hydrogen atom transfer) catalyst in the presence of alcohol as both hydrogen and electron shuttle. Dioxygen (O2) was found as a sole terminal oxidant. In most cases, pure products were easily isolated by simple filtration, implying large-scale implementation advantages. The reaction provides an ideal protocol to produce valuable fine chemicals from naturally abundant petroleum feedstocks. [Figure not available: see fulltext.].
- Wang, Chang-Cheng,Zhang, Guo-Xiang,Zuo, Zhi-Wei,Zeng, Rong,Zhai, Dan-Dan,Liu, Feng,Shi, Zhang-Jie
-
p. 1487 - 1492
(2021/07/10)
-
- Selective Degradation of Styrene-Related Plastics Catalyzed by Iron under Visible Light**
-
Efficient degradation of plastics, the vital challenge for a sustainable future, stands in need of better chemical recycling procedures that help produce commercially valuable small molecules and redefine plastic waste as a rich source of chemical feedstock. However, the corresponding chemical recycling methods, while being generally restricted to polar polymers, need improvement. Particularly, degradation of chemically inert nonpolar polymers, the major constitutes of plastics, suffers from low selectivity and very harsh transformation conditions. Herein, an efficient method was developed for selective degradation of styrene-related plastics under gentle conditions through multiple oxidation of sp3 C?H bonds and sp3 C?C bonds. The procedure was catalyzed with inexpensive iron salts under visible light, using oxygen as green oxidant. Furthermore, simple iron salts could be used to degrade plastics in the absence of solvent under natural conditions, highlighting the potential application of iron salts as additives for degradable plastics.
- Wang, Miao,Wen, Jinglan,Huang, Yahao,Hu, Peng
-
p. 5049 - 5056
(2021/10/12)
-
- Heterogeneous Cobalt-Catalyzed C?C Bond Cleavage in Alcohols to Carbonyl Compounds
-
Cobalt oxide hydrate (Co(OH)x) supported on metal oxides were prepared. The oxidative cleavage of C(OH)?C bond in alcohol was catalyzed by Co(OH)x/metal oxides using molecular oxygen as the oxidant, and the corresponding product was obtained with high selectivity. The composition and characteristics of the catalysts were analyzed by X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), high-angle ring dark-field scanning TEM (HAADF-STEM), N2 physico-adsorption characterization, inductively coupled plasma optical emission spectrometry (ICP-OES), Fourier transform infrared spectrum (FTIR), X-ray photoelectron spectroscopy (XPS) and NH3-temperature-programmed desorption (NH3-TPD). Additionally, a reasonable reaction mechanism was proposed based on the characterization results and a series of controlled experiments. Notably, this heterogeneous catalytic system did not require any additives and had good recycling performance.
- Teng, Jia-nan,Zhu, Rui,Li, Xinglong,Fu, Yao
-
p. 4355 - 4363
(2021/09/14)
-
- Isotruxene-based porous polymers as efficient and recyclable photocatalysts for visible-light induced metal-free oxidative organic transformations
-
Two new isotruxene-based porous polymers were prepared and demonstrated to be highly efficient, metal-free heterogeneous photocatalysts for oxidative transformations using air as the mild oxidant under visible-light irradiation. Both catalysts show excellent recyclability. In addition, the reactions can be performed in water, further indicating the greenness of this method. This journal is
- Zhang, Haowen,Zhang, Xiao,Zheng, Ying,Zhou, Cen
-
supporting information
p. 8878 - 8885
(2021/11/27)
-
- Aerobic oxidation of aldehydes to carboxylic acids catalyzed by recyclable ag/c3 n4 catalyst
-
The oxidation of aldehydes is an efficient methodology for the synthesis of carboxylic acids. Herein we hope to report a simple, efficient and recyclable protocol for aerobic oxidation of aldehydes to carboxylic acid by using C3N4 supported silver nanoparticles (Ag/C3N4) as a catalyst in aqueous solution under mild conditions. Under standard conditions, the corresponding carboxylic acids can be obtained in good to excellent yields. In addition, Ag/C3N4 is convenient for recovery and could be reused three times with satisfactory yields.
- Wu, Chaolong,Yao, Xiaoquan,Yu, Min,Zhou, Li,Zhu, Li
-
p. 167 - 175
(2021/03/19)
-
- Practical scale up synthesis of carboxylic acids and their bioisosteres 5-substituted-1H-tetrazoles catalyzed by a graphene oxide-based solid acid carbocatalyst
-
Herein, catalytic application of a metal-free sulfonic acid functionalized reduced graphene oxide (SA-rGO) material is reported for the synthesis of both carboxylic acids and their bioisosteres, 5-substituted-1H-tetrazoles. SA-rGO as a catalytic material incorporates the intriguing properties of graphene oxide material with additional benefits of highly acidic sites due to sulfonic acid groups. The oxidation of aldehydes to carboxylic acids could be efficiently achieved using H2O2as a green oxidant with high TOF values (9.06-9.89 h?1). The 5-substituted-1H-tetrazoles could also be effectively synthesized with high TOF values (12.08-16.96 h?1). The synthesis of 5-substituted-1H-tetrazoles was corroborated by single crystal X-ray analysis and computational calculations of the proposed reaction mechanism which correlated well with experimental findings. Both of the reactions could be performed efficiently at gram scale (10 g) using the SA-rGO catalyst. SA-rGO displays eminent reusability up to eight runs without significant decrease in its productivity. Thus, these features make SA-rGO riveting from an industrial perspective.
- Mittal, Rupali,Kumar, Amit,Awasthi, Satish Kumar
-
p. 11166 - 11176
(2021/03/31)
-
- Scope and limitations of biocatalytic carbonyl reduction with white-rot fungi
-
The reductive activity of various basidiomycetous fungi towards carbonyl compounds was screened on an analytical level. Some strains displayed high reductive activities toward aromatic carbonyls and aliphatic ketones. Utilizing growing whole-cell cultures of Dichomitus albidofuscus, the reactions were up-scaled to a preparative level in an aqueous system. The reactions showed excellent selectivities and gave the respective alcohols in high yields. Carboxylic acids were also reduced to aldehydes and alcohols under the same conditions. In particular, benzoic, vanillic, ferulic, and p-coumaric acid were reduced to benzyl alcohol, vanillin, dihydroconiferyl alcohol and 1-hydroxy-3-(4-hydroxyphenyl)propan, respectively.
- Zhuk, Tatyana S.,Skorobohatko, Oleksandra S.,Albuquerque, Wendell,Zorn, Holger
-
supporting information
(2021/02/02)
-
- Platinum supported on nanosilica and fibrous nanosilica for hydrogenation reactions
-
Platinum nanoparticles supported on nanosilica (NP) and fibrous nanosilica (dendritic fibrous nano-spheres, DFNS) were prepared by direct grafting of the Pt precursor onto the silanol groups or via a polyethylenimine (PEI) linker. From the SEM and TEM images the average diameter of the nanosilica and fibrous nanosilica (DFNS), was determined to be 21.4 and 503 nm, respectively. While surface areas as measured by ASAP is 463.4 m2 g?1 for DFNS and 142.5 m2 g?1 for the nanosilica. For the four Pt containing catalysts (Pt/NP, Pt/DFNS, Pt/PEI/NP and Pt/PEI/DFNS), a Pt loading between 1.35 × 1017 and 8.46 × 1017 Pt atoms per gram support were determined. The PEI-containing catalyst gave higher Pt-loading than the direct anchoring of the Pt onto the silanol groups of the support. The catalysts were further characterised ATR FTIR and XPS. After oxidation of the pre-catalysts 85% of the Pt was in the oxide form. While after reduction, ca. 82% the Pt supported on DFNS was in the metallic form. Reduction of the Pt supported on NP, resulted in 100% of the Pt in the Pt0 oxidation state. These catalysts were tested for the hydrogenation of C[dbnd]C and/or C[dbnd]O bonds in cyclohexene, benzaldehyde and cinnamaldehyde. The % conversion and product distribution will be discussed in term of diameter, surface area and Pt-loading.
- Erasmus, E.,Xantini, Z.
-
-
- RhNPs supported onN-functionalized mesoporous silica: effect on catalyst stabilization and catalytic activity
-
Amine and nicotinamide groups grafted on ordered mesoporous silica (OMS) were investigated as stabilizers for RhNPs used as catalysts in the hydrogenation of several substrates, including carbonyl and aryl groups. Supported RhNPs on functionalized OMS were prepared by controlled decomposition of an organometallic precursor of rhodium under dihydrogen pressure. The resulting materials were characterized thoroughly by spectroscopic and physical techniques (FTIR, TGA, BET, SEM, TEM, EDX, XPS) to confirm the formation of spherical rhodium nanoparticles with a narrow size distribution supported on the silica surface. The use of nicotinamide functionalized OMS as a support afforded small RhNPs (2.3 ± 0.3 nm), and their size and shape were maintained after the catalyzed acetophenone hydrogenation. In contrast, amine-functionalized OMS formed RhNP aggregates after the catalytic reaction. The supported RhNPs could selectively reduce alkenyl, carbonyl, aryl and heteroaryl groups and were active in the reductive amination of phenol and morpholine, using a low concentration of the precious metal (0.07-0.18 mol%).
- Pulido-Díaz, Israel T.,Serrano-Maldonado, Alejandro,López-Suárez, Carlos César,Méndez-Ocampo, Pedro A.,Portales-Martínez, Benjamín,Gutiérrez-Alejandre, Aída,Salas-Martin, Karla P.,Guerrero-Ríos, Itzel
-
p. 3289 - 3298
(2021/03/16)
-
- (Hexamethylbenzene)Ru catalysts for the Aldehyde-Water Shift reaction
-
The Aldehyde-Water Shift (AWS) reaction uses H2O as a benign oxidant to convert aldehydes to carboxylic acids, producing H2, a valuable reagent and fuel, as its sole byproduct. (Hexamethylbenzene)RuIIcomplexes are demonstrated to have higher activity and selectivity (up to 95%) for AWS over disproportionation than previously reported catalysts.
- Phearman, Alexander S.,Moore, Jewelianna M.,Bhagwandin, Dayanni D.,Goldberg, Jonathan M.,Heinekey, D. Michael,Goldberg, Karen I.
-
supporting information
p. 1609 - 1615
(2021/03/09)
-
- PHOTOLYTIC COMPOUNDS AND TRIPLET-TRIPLET ANNIHILATION MEDIATED PHOTOLYSIS
-
The invention provides novel photolytic compounds and prodrugs, nanoparticles and compositions thereof, and methods of conducting photolysis mediated by triplet-triplet annihilation.
- -
-
-
- Continuous production method of benzoic acid derivative
-
The invention relates to the technical field of preparation of benzoic acid derivatives. The invention particularly relates to a continuous production method of a benzoic acid derivative. The continuous reaction device is characterized by comprising a small-diameter sleeve, wherein the small-diameter sleeve is sleeved with a large-diameter sleeve, and a small pipeline is arranged between the small-diameter sleeve and the large-diameter sleeve, and a plurality of small holes are arranged on the small pipeline. The small-diameter casing is rotated, the large-diameter casing is fixed, and the reaction liquid composed of the nitric acid and the toluene derivative is between a small-diameter casing pipe and a large-diameter casing pipe.
- -
-
Paragraph 0032-0033; 0035
(2021/11/14)
-
- Method for synthesizing acetophenone or benzoic acid compound by oxidizing toluene compound
-
The invention provides a method for synthesizing an acetophenone or benzoic acid compound through oxidation of a toluene compound, and belongs to the field of organic synthesis. The method for synthesizing the acetophenone or benzoic acid compound through oxidation of the toluene compound comprises the following step of: under the action of a reaction catalyst and an initiator, illuminating the toluene compound in an oxygen-containing atmosphere in a solvent to obtain the acetophenone compound or the benzoic acid compound, wherein the reaction catalyst is lanthanide series rare earth metal salt, and the initiator is a C1-C6 alcohol compound. The method has the advantages of abundant and easily available substrate sources, mild reaction conditions, good compatibility of substrate functional groups, simple operation, high reaction safety, low cost and the like.
- -
-
Paragraph 0019-0034
(2021/05/12)
-
- Method for synthesizing benzoic acid through photocatalysis on basis of microchannel reactor
-
The invention relates to the technical field of chemical engineering, and discloses a method for synthesizing benzoic acid through photocatalysis on the basis of a microchannel reactor. The mixed liquid is pumped into the microchannel reactor through the
- -
-
Paragraph 0022-0033
(2021/09/21)
-
- Ferric ion concentration-controlled aerobic photo-oxidation of benzylic C–H bond with high selectivity and conversion
-
A Fe(III)-promoted highly selective photo-oxidation of benzylic C–H bond delivering relative carbonyl products is reported. By altering the concentration of ferric salt, methylarenes can be selectively oxidized under UV irradiation to furnish aromatic aldehydes or acids, respectively. By this protocol, the oxidation of ethylarenes provides the corresponding acetophenones. The reaction is inferred to involve divergent pathways in different concentrations of catalyst for the alternative selectivity between aldehydes and aicds. The reusable catalyst, high conversion and selectivity make this oxidation a green and economic protocol for the synthesis of aromatic carbonyl compounds.
- Bu, Hongzhong,Gu, Jiefan,Li, Yufeng,Ma, Hongfei,Wan, Yuting,Wu, Zheng-Guang,Zhang, Weijian,Zhou, Ying'ao,Zhu, Hongjun
-
-
- An efficient chromium(iii)-catalyzed aerobic oxidation of methylarenes in water for the green preparation of corresponding acids
-
A highly efficient method to oxidize methylarenes to their corresponding acids with a reusable Cr catalyst was developed. The reaction can be carried out in water with 1 atm oxygen and K2S2O8as cooxidants, proceeds under green and mild conditions, and is suitable for the oxidation of both electron-deficient and electron-rich methylarenes, including heteroaryl methylarenes, even at the gram level. The excellent result, together with its simplicity of operation and the ability to continuously reuse the catalyst, makes this new methodology environmentally benign and cost-effective. The generality of this methodology gives it the potential for use on an industrial scale. Differing from the accepted oxidation mechanism of toluene, GC-MS studies and DFT calculations have revealed that the key benzyl alcohol intermediate is formed under the synergetic effect of the chromium and molybdenum in the Cr catalyst, which can be further oxidized to afford benzaldehyde and finally benzoic acid.
- Jiang, Feng,Liu, Shanshan,Wei, Yongge,Yan, Likai,Yu, Han,Zhao, Wenshu
-
supporting information
p. 12413 - 12418
(2021/09/28)
-
- METHOD FOR PREPARING BENZALDEHYDE
-
Are a method for producing benzaldehyde and a carbon electrode for producing benzaldehyde. The process produces benzaldehyde by oxidizing toluene through direct electron exchange between the carbon electrode and toluene. The process is performed at room t
- -
-
Paragraph 0058; 0059; 0077-0079
(2021/04/06)
-
- Synthesis, structure, magnetic and catalytic competency of a tetradentate (nnoo) schiff base mediated dimeric copper(ii) complex
-
One dinuclear copper(II) complex {μ-[2,2 -{ethane-1,2-diylbis[(azanylylidene)methanylylidene]}bis(phenolato)]}-{μ-[2,2 -{ethane-1,2- diylbis[(azanylylidene)methanylylidene]}bis(phenolato)]}dicopper(II), [Cu2(salen)2] (1) [salen2- = [2,2 -{ethane-1,2-diylbis- [(azanylylidene)methanylylidene]}bis(phenolato)] has been isolated and characterized by X-ray diffraction analysis and spectroscopic studies. X-ray single crystal structure examination revealed that each Cu(II) center in the asymmetric unit of 1 adopts a distorted square planar geometry with a CuN2O2 chromophore, where two asymmetric units are attached through congregation of Salen involving Cu-O bond to form dinuclear molecular unit [Cu2(salen)2]. In crystalline state, these dinuclear entities in 1 are extended through C-H π interactions and π π interactions displaying a 3D network structure. The variable-temperature magnetic susceptibility measurement asserted a dominant antiferromagnetic interaction between the copper(II) centers through Cu-O-Cu linkage in 1 with J = -1.46 cm-1. The catalytic efficacy of complex 1 was studied in a series of solvents for the oxidation of styrene and cyclooctene using tert-butyl-hydroperoxide (TBHP) as an active oxidant under mild conditions. The catalytic reaction mixture has been analyzed by gas chromatography and it displayed that the yield of the epoxidation and its selectivity is optimum in acetonitrile medium.
- CHOWDHURY, HABIBAR,BERA, RAJESH,ADHIKARY, CHANDAN
-
p. 1280 - 1286
(2021/06/09)
-
- Substituent effects in dioxovanadium(V) schiff-base complexes: Tuning the outcomes of oxidation reactions
-
Dioxovanadium(V) salicylaldehyde semicarbazone complexes with substituents on the ligand that span the range of electron donating (methoxy) to electron withdrawing (nitro) have been synthesized and characterized by NMR, IR, CV and EPR. The reactivity of these complexes toward the oxidation of styrene (as compared to the proteo complex and vanadyl acetylacetonate) has been studied in the presence of two different oxidants (hydrogen peroxide and tert-butyl hydrogen peroxide, TBHP). The complexes have been shown to exhibit different selectivity towards epoxidation versus oxidative cleavage based on the substitution of the ligand and the oxidant chosen. Epoxidation is favored with the methoxy substituted complex in the presence of hydrogen peroxide, while oxidative cleavage is the preferred reaction pathway for the nitro substituted complex with hydrogen peroxide. Conversions for these reaction are comparable to similar catalysts but with improved selectivity.
- McCaffrey, Vanessa P.,Conover, Olivia Q.,Bernard, Michael A.,Yarranton, Jonathan T.,Lessnau, Nicholas R.,Hempfling, Jordan P.
-
-
- Efficient, Solvent Free and Selective Oxidation of Styrene to Benzaldehyde Over Niobium Modified Phosphomolybdic Acid Catalyst
-
Niobium substituted phosphomolybdic acid with various Nb/P mole ratio of catalysts were successfully synthesised by hydrothermal method. These materials were characterized by X-ray diffraction, FT-IR spectroscopy, Raman spectroscopy, temperature programme
- Chary, Komandur V. R.,Viswanadham, Balaga
-
-
- Preparation of zeolitic bismuth vanadomolybdate using a ball-shaped giant polyoxometalate for olefin epoxidation
-
Zeolitic octahedral metal oxides are interesting materials that have received increasing attention. A bismuth vanadomolybdate-based zeolitic octahedral metal oxide was synthesized using a ball-shaped polyoxovanadomolybdate with different Bi sources. The material was used as a heterogeneous catalyst for olefin epoxidation. Different olefins were converted to their corresponding epoxides by the catalyst under mild conditions. This robust catalyst was reused several times without loss of activity.
- Hara, Michikazu,Li, Denan,Li, Yanshuo,Ueda, Wataru,Zhang, Zhenxin,Zhu, Qianqian
-
p. 21624 - 21630
(2021/12/09)
-
- Oxidative carbon-carbon bond cleavage of 1,2-diols to carboxylic acids/ketones by an inorganic-ligand supported iron catalyst
-
The carbon-carbon bond cleavage of 1,2-diols is an important chemical transformation. Although traditional stoichiometric and catalytic oxidation methods have been widely used for this transformation, an efficient and valuable method should be further explored from the views of reusable catalysts, less waste, and convenient procedures. Herein an inorganic-ligand supported iron catalyst (NH4)3[FeMo6O18(OH)6]·7H2O was described as a heterogeneous molecular catalyst in acetic acid for this transformation in which hydrogen peroxide was used as the terminal oxidant. Under the optimized reaction conditions, carbon-carbon bond cleavage of 1,2-diols could be achieved in almost all cases and carboxylic acids or ketones could be afforded with a high conversion rate and high selectivity. Furthermore, the catalytic system was used efficiently to degrade renewable biomass oleic acid. Mechanistic insights based on the observation of the possible intermediates and control experiments are presented.
- Chen, Weiming,Xie, Xin,Zhang, Jian,Qu, Jian,Luo, Can,Lai, Yaozhu,Jiang, Feng,Yu, Han,Wei, Yongge
-
supporting information
p. 9140 - 9146
(2021/11/23)
-
- Mild selective oxidative cleavage of lignin C-C bonds over a copper catalyst in water
-
The conversion of lignin into aromatics as commodity chemicals and high-quality fuels is a highly desirable goal for biorefineries. However, the presence of robust inter-unit carbon-carbon (C-C) bonds in natural lignin seriously impedes this process. Herein, for the first time, we report the selective cleavage of C-C bonds in β-O-4 and β-1 linkages catalyzed by cheap copper and a base to yield aromatic acids and phenols in excellent yields in water at 30 °C under air without the need for additional complex ligands. Isotope-labeling experiments show that a base-mediated Cβ-H bond cleavage is the rate-determining step for Cα-Cβ bond cleavage. Density functional theory (DFT) calculations suggest that the oxidation of β-O-4 ketone to a key intermediate, i.e., a peroxide, by copper and O2 lowers the Cα-Cβ bond dissociation energy and facilitates its subsequent cleavage. In addition, the catalytic system could be successfully applied to the depolymerization of various authentic lignin feedstocks, affording excellent yields of aromatic compounds and high selectivity of a single monomer. This study offers the potential to economically produce aromatic chemicals from biomass.
- Hu, Yuzhen,Li, Song,Ma, Longlong,Wang, Chenguang,Yan, Long,Zhang, Qi,Zhang, Xinghua,Zhao, Xuelai
-
p. 7030 - 7040
(2021/09/28)
-
- Mixed Micelles of Surface Active Ionic Liquid (SAIL)–Octylphenol Ethoxylate: A Novel Reaction Medium for Selective Oxidation of Toluene to Benzaldehyde
-
Ionic liquids have been found to be suitable alternatives to volatile organic solvents in chemical transformation. Through a proper choice of cations and anions, the properties of an ionic liquid can be tuned so that it resembles an amphiphile. Such specially designed molecules are known as surface-active ionic liquids (SAIL). Like conventional surfactants, SAIL also form aggregates in an aqueous medium. Studies show that the mixing of SAIL with conventional surfactants leads to synergistic micellization. However, very few reports are available on the application of such systems as reaction media. Present study focuses on the application of mixed micelles of 1-tetradecyl-3-methylimidazol-1-ium bromide, ([C14mim]Br) with nonionic surfactant, Octylphenol ethoxylate with 10 moles of ethylene oxide (OPE-10). Enhanced solubilization and selective catalytic oxidation of toluene using hydrogen peroxide as an oxidant and tungstic acid as a catalyst have been studied in detail using this system.
- Deore, Tushar S.,Sadgar, Amid L.,Jayaram, Radha V.
-
p. 185 - 190
(2020/07/30)
-
- High dimensionally structured W-V oxides as highly effective catalysts for selective oxidation of toluene
-
High dimensionally structured W-V-O catalysts (HDS-WVO) were synthesized by hydrothermal method and catalyst structures were investigated by HAADF-STEM analysis. HDS-WVO were rod-shaped crystals and the cross-sections were constituted by W6O21 pentagonal units and MO6 octahedra (M = V, W), forming heptagonal and hexagonal channels. HDS-WVO catalysts showed excellent catalytic performance for selective oxidation of toluene to benzoic acid, and the activity and the selectivity to benzoic acid were superior to those of state-of-the-art catalysts. After the ion exchange using Cs+, the catalytic activity over HDS-WVO was significantly decreased. Since HAADF-STEM analysis and N2 adsorption revealed that Cs+ was located mainly at the heptagonal channel of HDS-WVO, it can be concluded that toluene oxidation takes place at the heptagonal channel site of HDS-WVO.
- Murayama, Toru,Ishikawa, Satoshi,Hiyoshi, Norihito,Goto, Yoshinori,Zhang, Zhenxin,Toyao, Takashi,Shimizu, Ken-ichi,Lee, Shutoku,Ueda, Wataru
-
-
- Highly efficient and selectivity-controllable aerobic oxidative cleavage of C-C bond over heterogeneous Fe-based catalysts
-
A base-free selectivity-controllable aerobic oxidative cleavage of C-C bond with heterogeneous Fe-based catalysts (FexOy-N@C3N4) is developed. In the presence of oxygen, 1,2-diols are selectively transformed to the corresponding aldehyde, while the methyl esters are orientedly produced from 1,2-diones in methanol medium.
- Guo, Pengfei,Liao, Shengyun,Wang, Shun,Shi, Jing,Tong, Xinli
-
p. 399 - 403
(2021/02/27)
-
- A novel two-dimensional metal-organic framework as a recyclable heterogeneous catalyst for the dehydrogenative oxidation of alcohol and theN-arylation of azole compounds
-
A novel metal-organic framework (MOF) with two-dimensional (2D) crystal structure was developed using Cu(NO3)2·3H2O and 2,2′,5,5′-tetramethoxy-[1,1′-biphenyl]-4,4′-dicarboxylic acid. Further, its structure was characterized using infrared spectroscopy, thermogravimetry, X-ray diffraction, and X-ray crystallography. The activated Cu-MOF was used to catalyze the dehydrogenative oxidation of alcohol andN-arylation of azole compounds. Furthermore, it could be easily recovered and reused.
- Liu, Chengxin,Cui, Jin,Wang, Yufang,Zhang, Mingjie
-
p. 11739 - 11744
(2021/03/31)
-
- Trans(Cl)-2,2′-bipyridinedicarbonyldichlororuthenium(II) complex catalyzed oxidation of olefins, aryl hydrocarbons and alcohols in homogeneous phase
-
Catalytic oxidation of organic substrates has wide applications in chemical industries due to which huge extensive research work is continuously going on throughout the world. Present study reports efficacious use of Trans (Cl)-2,2′-bipyridinedicarbonyldichlororuthenium(II) complex catalyzed oxidation of internal and terminal olefins, aryl hydrocarbons and alcohols. CH2Cl2–C2H5OH (6:4) was suitable solvent system for these oxidation reactions. The normal pressure oxidation reaction has been carried out at 1 ?atm. Pressure of oxygen and at 300C. The high pressure oxidation reaction was done at 4.48 ?× ?103 KNm3 pressure of oxygen and at 600C. No diminished catalytic activity was observed while checking the recyclability of catalyst up to 6–8 catalytic runs. Catalytic activity was also investigated using tert-butyl hydroperoxide as oxidant inspite of di-oxygen. Effect of different parameters on the rate of oxidation was also studied i.e. extra ligand, temperature, solvents, acids and bases. Kinetic studies have been done and on the basis of kinetics, the mechanism is proposed.
- Sharma, Varsha,Pant, Bhawana,Prakash, Deep,Sagar, Priyanka
-
-
