3132-99-8Relevant academic research and scientific papers
Synthesis, characterization and catalytic performance of a Fe polyoxometalate/silica composite in the oxidation of alcohols with hydrogen peroxide
Farsani, Mostafa Riahi,Yadollahi, Bahram
, p. 8 - 15 (2014)
Fe(III) substituted Keggin type polyoxometalate in amorphous silica matrix, (n-C4H9)4N)4[PW 11FeO39]/SiO2 (PWFe/SiO2), has been synthesized by sol-gel method. The synthesized PWFe/SiO2 composite was characterized by various analytical and spectroscopic techniques. Results indicated that the primary Keggin structure remain after incorporation in silica matrix. As a heterogeneous catalyst, PWFe/SiO2 composite showed an elevated catalytic activity and selectivity with high to excellent yields for oxidation of alcohols into aldehydes by H2O2. The stability and reusability of the catalyst was very high, so these composites are suitable for the heterogeneous catalysis by hydrogen peroxide.
The superiority of cuprous chloride to iodide in the selective aerobic oxidation of benzylic alcohols at ambient temperature
Ma, Ruonan,Xiao, Zhiyin,Zhong, Wei,Lu, Chunxin,Shen, Zhongquan,Zhao, Dan,Liu, Xiaoming
, (2021)
Cuprous halides, best described as (CuX)n (X = Cl?, Br?, and I?) in their solid state, catalyse selective aerobic oxidation of alcohols with the assistance of both NMI (N-methylimidazole) and TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl), and the iodide generally demonstrates the highest activity, for example, in the oxidation of 1-octanol at ambient temperature under 24 h' reaction. However, in the aerobic oxidation of benzylic alcohols, the chloride showed superiority to the iodide in that the aerobic oxidation was quantitatively completed within 3 h at ambient temperature whereas the iodide showed only about half the activity of the chloride analogue. By probing the system using electrochemistry, electric conductivity, and 1H NMR titration, it was revealed that the surprising anomaly was due to the difference in the rate of forming active species, [Cu (NMI)2X(MeCN)], from the polymeric solid in a two-stage process. Substrates expansion of 11 benzylic alcohols indicated that CuCl/NMI/TEMPO system demonstrated quantitative conversion of benzylic alcohols into corresponding aldehydes within 3 h and showed great tolerance to the substituents on the phenyl ring of the substrates. Furthermore, electron-withdrawing substituent was beneficial to the oxidation and could offset the steric effect at orthro-substituent. Such a behaviour suggested that in the catalysis, increasing the acidity of the hydroxyl group (OH) of the substrates could ease the oxidation, which implied that the deprotonation via an internal pathway might be one of the rate-determining steps. Our results also showed that the anion halide participated actively in the catalysis by coordinating to Cu(I) in the active species.
Oxidation of Substituted Benzyl Alcohols by Quinoxalinium Dichromate. A Kinetic Study
Oezguen, Beytiye,Degirmenbasi, Nebahat
, p. 483 - 492 (2004)
Quinoxalinium dichromate (QxDC) oxidizes benzyl alcohol and substituted benzyl alcohols smoothly in dimethyl sulfoxide (DMSO) and in the presence of acid to the corresponding aldehydes. The reaction has unit dependence on each of the alcohol, QxDC, and acid concentrations. Electron-releasing substituents accelerate the reaction, whereas electron-withdrawing groups retard the reaction, and the rate data obey Hammett's relationship. The reaction constant ρ was -1.09 +/- 0.01 at 303 K. Oxidation of α,α-dideuteriobenzyl alcohol indicated the presence of a substantial primary kinetic isotope effect (kH/kD = 6.78 at 303 K). The reaction failed to induce the polymerization of acrylonitrile. The rates of oxidation were determined at different temperatures and the activation parameters were evaluated. The analysis of the dependence of the kinetic isotope effect on temperature indicated that the reaction involves a symmetrical cyclic transition state. A suitable mechanism is proposed.
Use of sodium bromate for aromatic bromination: Research and development
Groweiss, Amiram
, p. 30 - 33 (2000)
Sodium bromate is a powerful brominating agent for aromatic compounds that contain deactivating substituents. A bromination process, in which sodium bromate was utilized, was optimized on laboratory scale. Addition of a strong acid into a stirred aqueous solution, or slurry, of the substrate and bromate salt at 40-100°C, leads to the decomposition of the bromate ions and production of the active brominating species. Substrates such as nitrobenzene, benzoic acid, and benzaldehyde were brominated in high yields (85-98%) and specificity. The reaction is especially useful for the bromination of disubstituted benzenes, such as 4-nitrofluorobenzene or 4-fluorobenzoic acid. Several substrates, such as dinitrobenzenes or nitrobenzoic acids, did not undergo bromination at all. The main parameters of the reaction and some of its synthetic potential are discussed.
Solvent free aerobic oxidation of alcohols with 1-methyl-2-azaadamantane N-oxyl as a recyclable catalyst through phase separation
Kuang, Yongbo,Nabae, Yuta,Hayakawa, Teruaki,Kakimoto, Masa-Aki
, p. 1659 - 1663 (2011)
An expedient, non-metallic green protocol for aerobic oxidation of alcohols was established. 1-Methyl-2-azaadamantane N-oxyl was used as the core catalyst due to its superior chemical stability and catalytic performance. The catalyst can be easily reused through phase separation by taking advantage of its solubility feature, which varies with its oxidation state.
Efficient and selective oxidation of alcohols in water employing palladium supported nanomagnetic Fe3O4@hyperbranched polyethylenimine (Fe3O4@HPEI.Pd) as a new organic–inorganic hybrid nanocatalyst
Ramazani, Ali,Khoobi, Mehdi,Sadri, Fariba,Tarasi, Roghayeh,Shafiee, Abbas,Aghahosseini, Hamideh,Joo, Sang Woo
, (2018)
Palladium immobilized magnetic nanoFe3O4@hyperbranched polyethylenimine (Fe3O4@HPEI.Pd) was prepared according to a simple and cost effective pathway and it was employed as a new efficient and selective organic–inorganic hybrid nanocatalyst for the aqueous oxidation of primary and secondary alcohols to their corresponding products in good yields applying oxone (potassium hydrogen monopersulfate) and H2O2 as an oxidant at room temperature. Moreover, the catalytic system was reused at least 13 times without significant loss of activity. The complete characterization of this efficient nanocatalyst was investigated by FTIR, UV–Vis, TEM, SEM, XRD, TGA, VSM, ICP and EDX techniques.
SBA-15-functionalized TEMPO confined ionic liquid: An efficient catalyst system for transition-metal-free aerobic oxidation of alcohols with improved selectivity
Karimi, Babak,Badreh, Ebrahim
, p. 4194 - 4198 (2011)
A novel SBA-15-functionalized TEMPO confined ionic liquid [BMIm]Br was found to be a highly efficient and recyclable catalyst system for the transition-metal-free aerobic oxidation of a wide range of structurally diverse alcohols. Thanks to the strong physical confinement of the ionic liquid inside the mesochannels of SBA-15-supported TEMPO, the resulting solid catalyst showed improved selectivity in the aerobic oxidation of allylic alcohols. The catalyst can be recovered and re-used for at least 11 reaction runs without significant loss of either activity or confined IL.
Magnetic copper ferrite nanoparticles/TEMPO catalyzed selective oxidation of activated alcohols to aldehydes under ligand- and base-free conditions in water
Zhu, Xiao,Yang, Daoshan,Wei, Wei,Jiang, Min,Li, Lulu,Zhu, Xiangbing,You, Jinmao,Wang, Hua
, p. 64930 - 64935 (2014)
A novel, effective and sustainable strategy for the synthesis of aldehydes has been developed using inexpensive, readily available, oxygen-stable and recyclable CuFe2O4 nanoparticles as the catalyst. The corresponding substituted aldehydes were obtained in moderate to good yields by aerobic oxidation of aromatic alcohols in water under dioxygen atmosphere. Importantly, a ligand or a base was not necessary. The catalyst was completely recoverable with an external magnet and could be reused six times without significant loss of catalytic activity.
A green approach for aerobic oxidation of benzylic alcohols catalysed by CuI-Y zeolite/TEMPO in ethanol without additional additives
Senthilkumar, Samuthirarajan,Zhong, Wei,Natarajan, Mookan,Lu, Chunxin,Xu, Binyu,Liu, Xiaoming
, p. 705 - 713 (2021)
An efficient and green protocol for aerobic oxidation of benzylic alcohols in ethanol using CuI-Y zeolite catalysts assisted by TEMPO (TEMPO = 2,2,6,6-tetramethyl-1-piperidine-N-oxyl) as the radical co-catalyst in the presence of atmospheric air under mild conditions is reported. The CuI-Y zeolite prepared via ion exchange between CuCl and HY zeolite was fully characterized by a variety of spectroscopic techniques including XRD, XPS, SEM, EDX and HRTEM. The incorporation of Cu(i) into the 3D-framework of the zeolite rendered the catalyst with good durability. The results of repetitive runs revealed that in the first three runs, there was hardly a decline in activity and a more substantial decrease in yield was observed afterwards, while the selectivity remained almost unchanged. The loss in activity was attributed to both the formation of CuO and the bleaching of copper into the liquid phase during the catalysis, of which the formation of CuO was believed to be the major contributor since the bleaching loss for each run was negligible (2%). In this catalytic system, except TEMPO, no other additives were needed, either a base or a ligand, which was essential in some reported catalytic systems for the oxidation of alcohols. The aerobic oxidation proceeded under mild conditions (60 °C, and 18 hours) to quantitatively and selectively convert a wide range of benzylic alcohols to corresponding aldehydes, which shows great potential in developing green and environmentally benign catalysts for aerobic oxidation of alcohols. The system demonstrated excellent tolerance against electron-withdrawing groups on the phenyl ring of the alcohols and showed sensitivity to steric hindrance of the substrates, which is due to the confinement of the pores of the zeolite in which the oxidation occurred. Based on the mechanism reported in the literature for homogenous oxidation, a mechanism was analogously proposed for the aerobic oxidation of benzylic alcohols catalysed by this Cu(i)-containing zeolite catalyst. This journal is
Kinetics of Oxidation of Substituted Benzyl Alcohols by Quinolinium Dichromate
Dey, Doyamoy,Mahanti, Mahendra K.
, p. 5848 - 5850 (1990)
Quinolinium dichromate (QDC) oxidizes benzyl alcohol and substituted benzyl alcohols smoothly in dimethyl formamide, in the presence of acid.The reaction has unit dependence on each of the alcohol, QDC, and acid concentrations.Electron-releasing substituents accelerate the reaction, whereas electron-withdrawing groups retard the reaction, and the rate data obey Hammett's relationship.The reaction constant ρ was -1.67 +/- 0.08 at 313 K.The kinetic isotope effect, kH/kD, was 5.89 at 313 K.The reaction does not induce polymerization of acrylonitrile.The observed experimental data have been rationalized in terms of a hydride ion transfer in the rate-determining step.
