111-30-8Relevant articles and documents
One-pot synthesis of a hierarchical microporous-mesoporous phosphotungstic acid-HKUST-1 catalyst and its application in the selective oxidation of cyclopentene to glutaraldehyde
Yang, Xinli,Qiao, Liming,Dai, Weilin
, p. 1875 - 1885 (2015)
A hierarchical microporous-mesoporous metal-organic framework of HKUST-1(Cu)-encapsulated phosphotungstic acid (HPW) material, referred to as HPWs@Meso-HKUST-1, is prepared by a one-pot synthesis method using cetyltrimethylammonium bromide as the supramolecular template. The addition of HPWs to the synthesis mixture of hierarchical porous HKUST-1 results in the direct encapsulation of HPWs inside the mesopores of the HKUST-1 structure, with a homogeneous distribution over the HKUST-1 crystals, which is confirmed by XRD, FT-IR, N2 adsorption, UV-Vis DRS, and TEM. FT-IR-CO adsorption experiments indicated that additional Lewis acid sites were present in the HPWs@Meso-HKUST-1 sample. The novel heterogeneous catalyst demonstrates excellent catalytic performance for the selective oxidation of cyclopentene (CPE) to glutaraldehyde (GA) using tert-butyl hydroperoxide and acetonitrile (MeCN) as the oxidant and solvent, respectively. The high activity of the catalyst is attributed to the mesostructure of the catalyst and the nature and appropriate abundance of the HPWs - being highly dispersed with the addition of Lewis sites. After a reaction for 36 h, the 30% wt% HPWs@Meso-HKUST-1 catalyst exhibits a CPE conversion of 92.5% and a high GA yield of 73%. Furthermore, the HPWs@Meso-HKUST-1 material is sufficiently stable to prevent the leaching of HPWs, and behaves as a true heterogeneous catalyst that can be repeatedly recycled without sustaining a loss of activity and selectivity in the selective oxidation of CPE.
Oxidation of Cyclopentene with Hydrogen Peroxide Catalyzed by 12-Heteropoly Acids
Furukawa, Hiroshi,Nakamura, Teiji,Inagaki, Hiroyuki,Nishikawa, Eiichiro,Imai, Chihiro,Misono, Makoto
, p. 877 - 880 (1988)
12-Heteropoly acids exhibited high performance for selective oxidation of cyclopentene to glutaraldehyde with hydrogen peroxide.Especially, heteropoly acids with mixed addenda atoms of Mo and W, H3PMo(12-x)WxO40 (x= 1-9, showed excellent results.
Enantioselective Rauhut-Currier reactions promoted by protected cysteine
Aroyan, Carrie E.,Miller, Scott J.
, p. 256 - 257 (2007)
We report highly enantioselective examples of the Rauhut-Currier cycloisomerization reaction (the "vinylogous Morita-Baylis-Hillman reaction"). The reaction is highly practical and is catalyzed by a commercially available derivative of the proteinogenic amino acid cysteine. Reactions are conducted in the presence of potassium tert-butoxide and a critical concentration of water in bulk acetonitrile. A mechanistic model is advanced that may account for reaction selectivity that is predicated on organizational chelation of K ion in the product-determining step in which the Cys derivative undergoes elimination. Copyright
Pd-Ce nanoparticles supported on functional Fe-MIL-101-NH2: An efficient catalyst for selective glycerol oxidation
Li, Xinhang,Tjiptoputro, Adrian Kaizen,Ding, Jun,Xue, Jun Min,Zhu, Yinghuai
, p. 77 - 83 (2017)
Metal organic framework Fe-MIL-101-NH2 was prepared at different reaction time. The morphology of the Fe-MIL-101-NH2 slightly changed following a longer reaction time; the crystal structure remained. Neocuproine ligand coordinating palladium complex has demonstrated high activity in selective glycerol oxidation towards 1,3-dihydroxyacetone (DHA). Neocuproine ligand was attached to MOF Fe-MIL-101-NH2 by forming an amide (CO[sbnd]NH) bond in this work. The functional Fe-MIL-101-NH2 was used as catalyst supports to hold palladium and cerium nanoparticles. The resulting composite of the Pd-Ce/Fe-MIL-101[sbnd]N[dbnd]CHNeocuproine was found to be a high efficient catalyst in the selective oxidation conversion of glycerol to dihydroxyacetone in comparison with catalysts Pd/Fe-MIL-101[sbnd]N[dbnd]CHNeocuproine and Pt-Bi/C. The catalysts and products were analyzed by FT-IR, XRD, SEM, TEM and 1H, 13C NMR spectroscopy. In addition, the supported catalyst is recyclable with sustainable activity.
Synthesis, x-ray crystallography, and computational analysis of 1-azafenestranes
Denmark, Scott E.,Montgomery, Justin I.,Kramps, Laurenz A.
, p. 11620 - 11630 (2006)
The tandem [4+2]/[3+2] cycloaddition of nitroalkenes has been employed in the synthesis of 1-azafenestranes, molecules of theoretical interest because of planarizing distortion of their central carbon atoms. The synthesis of c,c,c,c-[5.5.5.5]-1-azafenestrane was completed in good yield from a substituted nitrocyclopentene, and its borane adduct was analyzed through X-ray crystallography, which showed a moderate distortion from ideal tetrahedral geometry. The syntheses of two members of the [4.5.5.5] family of 1-azafenestranes are also reported, including one with a trans fusion at a bicyclic ring junction which brings about considerable planarization of one of the central angles (16.8° deviation from tetrahedral geometry). While investigating the [4.5.5.5]-1-azafenestranes, a novel dyotropic rearrangement that converts nitroso acetals into tetracyclic aminals was discovered. Through conformational analysis, a means to prevent this molecular reorganization was formulated and realized experimentally with the use of a bulky vinyl ether in the key [4+2] cycloaddition reaction. Finally, DFT calculations on relative strain energy for the 1-azafenestranes, as well as their predicted central angles, are disclosed.
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Cope et al.
, (1963)
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A novel green process for the synthesis of glutaraldehyde by WS 2@HMS material with aqueous H2O2
Zhu, Quanjing,Chu, Xiaofeng,Zhang, Zhaoyan,Dai, Wei-Lin,Fan, Kangnian
, p. 1744 - 1747 (2013)
A novel and green route is reported for the selective oxidation of cyclopentene oxide to glutaraldehyde by using aqueous H2O2 as the oxidant and WS2@hexagonal mesoporous silica (WS2@HMS) material as the catalyst, which shows a very large surface area, high efficiency, excellent selectivity and outstanding reusability.
Selective oxidation of cyclopentene to glutaraldehyde by H2O2 over the WO3/SiO2 catalyst
Jin, Ronghua,Li, Hexing,Deng, Jing-Fa
, p. 75 - 81 (2001)
A novel WO3/SiO2 was prepared by incipient wetness impregnation of the SiO2 support synthesized by the xerogel method with the W-containing salt solution. The as-prepared WO3/SiO2 catalyst exhibited a very high yield of glutaraldehyde in the liquid phase cyclopentene oxidation by aqueous H2O2 and the leach of WO3 species during the reaction could be neglected. As a heterogeneous catalyst, it seems more suitable for the industrial process than those homogeneous catalysts owing to its easy separation from reaction products, which makes it possible to use the catalyst repetitively. According to the XRD patterns, the WO3 was present in amorphous state due to its high dispersion on the SiO2 support. These amorphous WO3 species were proved to be the active sites since the crystallization at high temperature caused a considerable deactivation. The lifetime of the catalyst was measured and its regeneration method was proposed. Effects of various factors on the catalytic behaviors, such as the WO3 loading, the calcination temperature, and the reaction media, were also investigated and discussed based on the characterizations of BET, XRD, DSC, TEM, EXAFS, and Raman spectra.
Understanding the mechanism of N coordination on framework Ti of Ti-BEA zeolite and its promoting effect on alkene epoxidation reaction
Liang, Xiaohang,Liu, Dan,Luo, Yibin,Peng, Xinxin,Shu, Xingtian,Xia, Changjiu
, (2021/07/31)
The function of ammonium salts on the epoxidation performance over Ti-BEA zeolite was investigated in detail. Experiments of alkene epoxidation, side reactions of epoxide and decomposition of H2O2 with or without ammonium salts were designed, and the UV-Vis spectroscopy was employed to analyze the structure of Ti-hydroperoxo species. It is revealed that the ammonia (or amines) dissociated from the ammonium salt would chelate with the linear Ti-η1(OOH) species and form a bridged Ti-η2(OOH)-R species, which is more stable, more weaker in epoxide adsorption and acidity as well. Therefore, side reactions and H2O2 decomposition would be suppressed, and both alkene conversion and epoxide selectivity would be promoted simultaneously. On the other hand, the excessive NH3?H2O (NH3/Ti>1) or NaOH bond with the Ti-η2(OOH)-R species and generate salt-like Ti-η2(OO)-M+ species, resulting in the deactivation of Ti active center. While for ammonium salts, e.g. NH4Cl, the limited dissociation degree along with the acidic environment help the Ti active center to maintain in highly active. In short, this work provides a practical Ti active center tuning method for Ti-BEA zeolite, as well as a thorough understanding of its Ti-hydroperoxo species.
Reductive Electrochemical Activation of Molecular Oxygen Catalyzed by an Iron-Tungstate Oxide Capsule: Reactivity Studies Consistent with Compound i Type Oxidants
Bugnola, Marco,Shen, Kaiji,Haviv, Eynat,Neumann, Ronny
, p. 4227 - 4237 (2020/05/05)
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.
