589-38-8Relevant articles and documents
A nanohybrid self-assembled from exfoliated layered vanadium oxide nanosheets and Keggin Al13 for selective catalytic oxidation of alcohols
Fu, Guoyuan,Li, Lei,Li, Shuying,Luo, Fang,Shi, Rui,Wang, Shuang,Zhang, Zhijuan,Zou, Xinyu
, p. 2559 - 2569 (2020)
A nanoscale hybrid material (V2O5-Al13) for highly efficient alcohol oxidation is synthesized through electrostatic self-assembly between oppositely charged Keggin Al13 polyoxocations and exfoliated V2O5 nanosheets. The analyses by X-ray diffraction, electron microscopy, X-ray photoelectron spectroscopy and structural consideration based on charge balance indicate that the Keggin Al13 ions could be sparsely distributed in the nanosheet galleries. The as-prepared catalyst successfully achieved high catalytic activity toward alcohols (96.8% sel.) with the oxygen molecule as an ideal oxidant under mild conditions. Also, the nanohybrid showed an outstanding adsorption capability for benzyl alcohol (773 mg g-1). In comparison to individual exfoliated V2O5 nanosheets and bulk V2O5, the V2O5-Al13 nanohybrid catalyst exhibited superior catalytic activity and selectivity under the same experimental conditions. The results highlight the outstanding functionality of the V2O5-Al13 nanohybrid as an efficient oxidation catalyst. A detailed study of its structure-activity relationship showed that the high performance of the V2O5-Al13 nanohybrid is attributed to the adsorption-catalysis synergistic effect between V2O5 and Al13
MnII and CuII complexes with arylhydrazones of active methylene compounds as effective heterogeneous catalysts for solvent- and additive-free microwave-assisted peroxidative oxidation of alcohols
Mahmudov, Kamran T.,Sutradhar, Manas,Martins, Luísa M. D. R. S.,Guedes da Silva, M. Fátima C.,Ribera, Alice,Nunes, Ana V. M.,Gahramanova, Shahnaz I.,Marchetti, Fabio,Pombeiro, Armando J. L.
, p. 25979 - 25987 (2015)
A one-pot template reaction of sodium 2-(2-(dicyanomethylene)hydrazinyl)benzenesulfonate (NaHL1) with water and manganese(ii) acetate tetrahydrate led to the mononuclear complex [Mn(H2O)6](HL1a)2·4H2O (1), where (HL1a)- = 2-(SO3-)C6H4(NH)NC(CN) (CONH2) is the carboxamide species derived from nucleophilic attack of water on a cyano group of (HL1)-. The copper tetramer [Cu4(H2O)10(1κN:κ2O:κO,2κN:κO-L2)2]·2H2O (2) was obtained from reaction of Cu(NO3)2·2.5H2O with sodium 5-(2-(4,4-dimethyl-2,6-dioxocyclohexylidene)hydrazinyl)-4-hydroxybenzene-1,3-disulfonate (Na2H2L2). Both complexes were characterized by elemental analysis, IR spectroscopy, ESI-MS and single crystal X-ray diffraction. They exhibit a high catalytic activity for the solvent- and additive-free microwave (MW) assisted oxidation of primary and secondary alcohols with tert-butylhydroperoxide, leading to yields of the oxidized products up to 85.5% and TOFs up to 1.90 × 103 h-1 after 1 h under low power (5-10 W) MW irradiation. Moreover, the heterogeneous catalysts are easily recovered and reused, at least for three consecutive cycles, maintaining 89% of the initial activity and a high selectivity.
Synthesis, crystallization mechanism, and catalytic properties of titanium-rich TS-1 free of extraframework titanium species
Fan, Weibin,Duan, Ren-Guan,Yokoi, Toshiyuki,Wu, Peng,Kubota, Yoshihiro,Tatsumi, Takashi
, p. 10150 - 10164 (2008)
A new route to the synthesis of TS-1 has been developed using (NH 4)2CO3 as a crystallization-mediating agent. In this way, the framework Ti content can be significantly increased without forming extraframework Ti species. The prepared catalyst had a Si/Ti ratio as low as 34 in contrast to the ratio of 58 achieved with the methods A and B established by the Enichem group (Clerici, M. G.; Bellussi, G.; Romano, U. J. Catal. 1991, 129, 159) and Thangaraj and Sivasanker (Thangaraj, A.; Sivasanker, S. J. Chem. Soc., Chem. Commun. 1992, 123), respectively. The material contained less defect sites than the samples synthesized by the other two methods. As a result, it showed much higher activity for the oxidation of various organic substrates, such as linear alkanes/alkenes and alcohols, styrene, and benzene. The crystallization mechanism of TS-1 in the presence of (NH4) 2CO3 was studied by following the whole crystallization process with X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), thermogravimetry/differential thermal analysis (TG/DTA), inductively coupled plasma atomic emission spectrometry (ICP), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), diffuse reflectance UV-vis spectroscopy, and 29Si MAS (magic-angle spinning) NMR spectroscopy techniques. It was shown that the presence of (NH 4)2CO3 not only drastically lowered down pH, slowing down the crystallization process and making the incorporation of Ti into the framework match well with nucleation and crystal growth, but also modified the crystallization mechanism. It seems that the solid-phase transformation mechanism predominated in the crystallization process initiated by dissociation, reorganization, and recoalescence of the solidified gel although a small amount of nongelatinated Ti shifted to the solid during the crystal growth period. In contrast, a typical homogeneous nucleation mechanism occurred in the method A system. Thus, although in the method A system most of Ti cations was inserted into the lattice after the crystallization was nearly completed, the inclusion of Ti started at the earlier nucleation period in the presence of (NH 4)2CO3. This is favorable for the incorporation of Ti into the framework, resulting in a more homogeneous distribution of Ti in the framework. Oxidation of 1-hexene and 2-hexanol over the samples collected during the whole crystallization process indicated that condensation of Ti-OH and Si-OH proceeded even after the crystallization was completed. This resulted in an increase in hydrophobicity and an overall improvement in microscopic character of Ti species and consequently a great increase in the catalytic activity with further progress of crystallization.
Wacker oxidation of 1-hexene in 1-n-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]), supercritical (SC) CO2, and SC CO2/[bmim][PF6] mixed solvent
Hou, Zhenshan,Han, Buxing,Gao, Liang,Jiang, Tao,Liu, Zhimin,Chang, Yanhong,Zhang, Xiaogang,He, Jun
, p. 1246 - 1248 (2002)
Oxidation of 1-hexene by molecular oxygen is conducted in 1-n-butyl-3-methylimidazolium hexafluorophosphate [bmim][PF6], supercritical (SC) CO2, SC CO2/[bmim][PF6] mixed solvent, and in the absence of solvent. T
Halogen-bonded tris(2,4-bis(trichloromethyl)-1,3,5-triazapentadienato)-M(iii) [M = Mn, Fe, Co] complexes and their catalytic activity in the peroxidative oxidation of 1-phenylethanol to acetophenone
Shixaliyev, Namiq Q.,Gurbanov, Atash V.,Maharramov, Abel M.,Mahmudov, Kamran T.,Kopylovich, Maximilian N.,Martins, Luísa M. D. R. S.,Muzalevskiy, Vasily M.,Nenajdenko, Valentine G.,Pombeiro, Armando J. L.
, p. 4807 - 4815 (2014)
One-pot template condensation of CCl3CN with ammonia on a metal source [MnCl2·4H2O, FeCl3·6H2O or Co(CH3COO)2·4H2O] in DMSO led to the formation of tris{2,4-bis(trichloromethyl)-1,3,5-triazapentadienato}-M(iii) complexes, [M{NHC(CCl3)NC(CCl3)NH}3]·n(CH3)2SO [M = Mn, n = 1 (1); M = Fe, n = 2 (2); M = Co, n = 2 (3)], which were characterized using elemental analysis, and IR, ESI-MS and single-crystal X-ray analysis. The role of inter- and intramolecular non-covalent halogen and hydrogen bonds in the synthesis of 1-3 is discussed. It is shown that the crystal ionic radii of the metal ions [68.5 (Co) 3.155 (2) > 3.133 (1) ?]. Compounds 1-3 and the related di(triazapentadienato)-Cu(ii) complex [Cu{NHC(CCl3)NC(CCl3)NH}2]·2(CH3)2SO (4) act as catalyst precursors for the additive-free microwave (MW) assisted homogeneous oxidation of 1-phenylethanol with tert-butylhydroperoxide (TBHP), leading to the formation of acetophenone with yields up to 99% and TONs up to 5.0 × 103 after 1 h of low power (10 W) MW irradiation. This journal is
Hydroxylation of Benzene and Hexane by Oxygen and Hydrogen over Palladium-containing Titanium Silicalites
Tatsumi, T.,Yuasa, K.,Tominaga, H.
, p. 1446 - 1447 (1992)
Palladium-containing titanium silicalite zeolites catalyse the hydroxylation of benzene and hexane by O2-H2 under mild conditions to give phenol and hexanols, respectively.
Solvent-Free Microwave-Assisted Peroxidative Oxidation of Alcohols Catalyzed by Iron(III)-TEMPO Catalytic Systems
Karmakar, Anirban,Martins,Guedes Da Silva, M. Fátima C.,Hazra, Susanta,Pombeiro, Armando J. L.
, p. 2066 - 2076 (2015)
The iron(III) complexes [H(EtOH)][FeCl2(L)2] (1), [H2bipy]1/2[FeCl2(L)2].DMF (2) and [FeCl2(L)(2,2′-bipy)] (3) (L = 3-amino-2-pyrazinecarboxylate; H2bipy = doubly protonated 4,4′-bipyridine; 2,2′-bipy = 2,2′-bipyridine, DMF = dimethylformamide) have been synthesized and fully characterized by IR, elemental and single-crystal X-ray diffraction analyses, as well as by electrochemical methods. Complexes 1 and 2 have similar mononuclear structures containing different guest molecules (protonated ethanol for 1 and doubly protonated 4,4′-bipyridine for 2) in their lattices, whereas the complex 3 has one 3-amino-2-pyrazinecarboxylate and a 2,2′-bipyridine ligand. They show a high catalytic activity for the low power (10 W) solvent-free microwave assisted peroxidative oxidation of 1-phenylethanol, leading, in the presence of TEMPO, to quantitative yields of acetophenone [TOFs up to 8.1 × 103 h-1, (3)] after 1 h. Moreover, the catalysts are of easy recovery and reused, at least for four consecutive cycles, maintaining 83 % of the initial activity and concomitant rather high selectivity. Graphical Abstract: 3-Amino-2-pyrazinecarboxylic acid is used to synthesize three new iron(III) complexes which act as heterogeneous catalysts for the solvent-free microwave-assisted peroxidative oxidation of 1-phenylethanol. [InlineMediaObject not available: see fulltext.]
Toward optimizing the performance of homogeneous L-Au-X catalysts through appropriate matching of the ligand (L) and counterion (X-)
Biasiolo, Luca,Del Zotto, Alessandro,Zuccaccia, Daniele
, p. 1759 - 1765 (2015)
The effects of the ligand (L) and counterion (X-) are considered the two most important factors in homogeneous gold catalysis, but a rational understanding of their synergy/antagonism is still lacking. In this work, we synthesized a set of 16 gold complexes of the type L-Au-X that differ as follows: (i) L = PPh3 (L1), P(tBu)3 (L2), tris(3,5-bis(trifluoromethyl)phenyl)phosphine (PArF, L3), and 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene (NHC, L4), with the deliberate purpose of varying the electron withdrawing ability of the ligand, and (ii) X- = BF4-, OTf-, OTs-, and TFA-, which have various coordinating abilities, basicities, and hydrogen bond acceptor powers. All these catalysts were tested in two different model reactions: the cycloisomerization of N-(prop-2-ynyl)benzamide to 2-phenyl-5-vinylidene-2-oxazoline and the methoxylation of 3-hexyne. The main results are that the choice of the most efficient L-Au-X catalyst for a given process should not be made by evaluating the properties of L and X- alone, but rather based on their best combination. For NHC-Au-X, the noncoordinating and weakly basic anions (such as BF4- and OTf-) have been recognized as the best choice for the cycloisomerization of N-(prop-2-ynyl)benzamide. On the other side, the intermediate coordinating ability and basicity of OTs- provide the best compromise for achieving an efficient methoxylation of 3-hexyne. A completely different trend is found in the case of complexes bearing phosphanes: OTs- and TFA- have been found to accelerate the cycloisomerization of N-(prop-2-ynyl)benzamide, and BF4- and OTf- are suitable for the methoxylation of 3-hexyne. A possible explanation of the observed differences between phosphane and NHC ancillary ligands might be found in the higher affinity of the counterion (especially OTs-) for the gold fragment for phosphane instead of NHC.
Hydration of alkynes catalyzed by [Au(X)(L)(ppy)]X in the green solvent γ-valerolactone under acid-free conditions: The importance of the pre-equilibrium step
Belanzoni, Paola,Belpassi, Leonardo,Del Zotto, Alessandro,Segato, Jacopo,Zuccaccia, Daniele
, p. 7757 - 7767 (2020)
[AuCl(NHC)(ppy)]Cl (1) and [AuCl(PPh3)(ppy)]OTf (2) complexes [ppy = 2-phenylpyridine, NHC = 1,3-bis(2,6-di-isopropylphenyl)-imidazol-2-ylidene] successfully catalyze the hydration of alkynes in γ-valerolactone (GVL), under acid-free conditions. The solution structure, reactivity, and catalytic properties of (1) and (2) were established by means of multinuclear NMR and computational (DFT) studies. Structural features of 1 during the catalysis, inferred by NMR spectroscopy, clearly indicate that complex 1 retains its square planar structure and no reduction to Au(i) and/or Au(0) nanoparticles was observed. The overall catalytic and kinetic investigations [kinetic isotopic effect (KIE), effect of acid additives, the order of reaction with respect to the catalyst, alkyne and nucleophile and the effect of the temperature] supported by computational results confirm that the pre-equilibrium step of the reaction mechanism is the RDS: water or counterion substitution by 3-hexyne in the first co-ordination sphere of Au(iii) is the key step of the whole process. The description of the mechanism of the hydration of 3-hexyne catalyzed by 1 here reported appears therefore to be of high significance because comprehensive mechanistic studies of the Au(iii)-catalyzed hydration reaction of the CC bond are scarce in the literature and generally lack experimental basis.
Synthesis of 3,5-Di-tert-butyl-1,2-dihydroxybenzene Derivatives and Their Effect on Free-Radical Oxidation of Hexane and Oxygen Activation Ability of Neutrophils
Ksendzova,Ostrovskaya,Semenkova,Sorokin,Shishkanova,Shadyro
, p. 391 - 398 (2019)
C6-Substituted derivatives of 3,5-di-tert-butyl-1,2-dihydroxybenzene have been synthesized, and their effect on radiation-induced free-radical oxidation of n-hexane and production of reactive oxygen and chlorine forms in neutrophils have been studied. It has been shown the introduction of the phenylhydrazone and phenylazomethine groups significantly increases the antioxidant activity of pyrocatechol derivatives. For six compounds, the ability to prevent the development of oxidative stress due to hyperproduction of active oxygen intermediates and HOCl/OCl? in neutrophils has been revealed.
