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141.
Preparation,characterization and heterogeneous catalytic applications of GO/Fe3O4/HPW nanocomposite in chemoselective and green oxidation of alcohols with aqueous H2O2 下载免费PDF全文
Graphene oxide ‐ Fe3O4 ‐ NH3+H2PW12O40 ‐ magnetic nanocomposite (GO/Fe3O4/HPW) was prepared by linking amino ‐ functionalized Fe3O4 nanoparticles (Fe3O4 ‐ NH2) on the graphene oxide (GO), and then grafting 12 ‐ tungstophosphoric acid (H3PW12O40) on the graphene oxide ‐ magnetite hybrid (GO ‐ Fe3O4 ‐ NH2). The obtained GO/Fe3O4/HPW nanocomposite was well characterized with different techniques such as FT ‐ IR, TEM, SEM, XRD, EDX, TGA ‐ DTA, AGFM, ICP and BET measurements. The used techniques showed that the graphene oxide layers were well prepared and the various stages of preparation of the GO/Fe3O4/HPW nanocomposites successfully completed. This new nanocomposite displayed excellent performance as a heterogeneous catalyst in the oxidation of alcohols with H2O2. The as ‐ prepared GO/Fe3O4/HPW catalyst was more stable and recyclable at least five times without significantly reducing its catalytic activity. 相似文献
142.
《应用有机金属化学》2017,31(5)
Tungstate salt with imidazolium framework is found to be a recoverable and heterogeneous system favouring the highly selective oxidation of primary benzylic alcohols to corresponding aldehydes with 30% H2O2 as a green oxidant under neutral aqueous reaction conditions. Furthermore, in order to demonstrate the recyclability of the catalyst, it was recovered and efficiently reused in seven succeeding reaction cycles without any significant loss. The use of green solvent, very short reaction time with excellent yields and recyclability of the catalyst make this protocol highly advantageous. 相似文献
143.
Oxygen bridged Homobinuclear Mn(II) compounds with Anthranilic acid: Theoretical calculations,oxidation and catalase activity 下载免费PDF全文
Two new homobinuclear manganese compounds with mixed ligands, [Mn2(μ1,1–2‐NH2C6H4COO)2(phen)4](ClO4)2(CH3OH) ( 1 ), and [Mn2(μ1,3–2‐NH2C6H4COO)2(bipy)4](ClO4)2 ( 2 ) (NH2C6H4COOH = anthranilic acid, bipy = 2,2′‐bipyridine, phen = 1,10‐ phenanthroline) were synthesized and thoroughly characterized by elemental analysis, IR, UV and single crystal X‐ray crystallography. X‐ray structure analysis shows that in the mono‐ and bidentate carboxylate bridged compounds, Mn–Mn distances of 1 and 2 are 3,461 Å, and 4,639 Å, respectively. The energy of the compounds was determined with a DFT (Density Functional Theory) calculation on B3LYP/6‐31G(d,p) optimized geometry by using the B3LYP/6‐31G(d,p) basis set. These compounds acts as biomimetic catalyst and show catalase‐like activity for the hydrogen peroxide dismutation at room temperature in different solvents with remarkable activity (TOF, Turnover frequency = mol of subst./(mol of cat. × time)) up to 12640 h?1 with 1 , and 17910 h?1 with 2 in Tris–HCl buffer). Moreover, the catalytic activity of 1 and 2 has been studied for oxidation of alcohols (cinnamyl alcohol, benzyl alcohol, cyclohexanol, 1‐octanol and 1‐heptanol) and alkenes (cyclohexene, styrene, ethyl benzene, 1‐octene and 1‐hexene) in a homogeneous catalytic system consisting t‐butylhydroperoxide (TBHP) as an oxidant in acetonitrile. Both compounds exhibited very high activity in the oxidation of cyclohexene to cyclohexanone (~80% selectivity, ~99% conversion in 1 h, TOF = 243 h?1 and 226 h?1) and cinnamyl alcohol to cinnamaldehyde (~64% selectivity) as the main product with very high TOF value (9180 h?1 and 13040 h?1 in the first minute of reaction) (~100% conversion in 0.5 h) with TBHP at 70 °C in acetonitrile, for 1 and 2 , respectively. 相似文献
144.
In this study, we present a versatile and easy procedure for modifying a cobalt ferrite nanoparticle step by step. A new nanocatalyst was prepared via CuII immobilized onto CoFe2O4@HT@Imine. The catalyst was fully characterized by Fourier‐transform infrared (FT‐IR), energy‐dispersive X‐ray spectroscopy (EDX), field emission scanning electron microscopy (FE‐SEM), X‐ray diffraction (XRD), and vibrating sample magnetometer (VSM) analyses. The current procedure as a green protocol offers benefits including a simple operational method, an excellent yield of products, mild reaction conditions, minimum chemical wastes, and short reaction times. Without any significant reduction in the catalytic performance, up to five recyclability cycles of the catalyst were obtained. The optimization results suggest that the best condition in the oxidation of benzyl alcohol derivatives is 0.003 g of the CoFe2O4@HT@Imine‐CuII catalyst, TEMPO, at 70°C under solvent‐free condition and air. 相似文献
145.
《Analytical letters》2012,45(11):2055-2069
Abstract A reagentless fiber optic biosensor specific for NADH, associated with flow injection analysis and based on bacterial bioluminescence is described. Only a buffer solution as flowing stream is required for the probe which works without supply of its coreactants (FMN and N-decyl-aldehyde). These are coentrapped in a poly(vinyl)alcohol (PVA) matrix which allows their internal release in the vicinity of the immobilized enzymes. Two PVA matrices differing by the reticulation process have been tested : first, by polymerization with glutaraldehyde and secondly, by a cyclic freezing-thawing process. The self-containment working time was estimated at 1 and 1.5 h of continuous measurements, respectively. NADH was determined using flow injection analysis. The sensor gave excellent reproducibility (RSD ≤ 3%) in the linear dynamic range 5 — 500 pmol with an average cycle-time of 2.5 min. 相似文献
146.
Novel photochromic composite films have been successfully fabricated by dispersing pyrazolone derivative:1,3-Diphenyl-4-(3-chlorobenzal)-5-hydroxypyrazole 4-phenylsemicarbazone (1a) into hydrosol of polyvinyl alcohol (PVA). The microstructure, photochromic behaviors and thermal bleaching properties were investigated by Raman spectroscopy, X-ray powder diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and ultraviolet-visible absorption spectroscopy (UV-vis). The results showed that 1a was not only blended but also well dispersed in the PVA polymer films with a suitable content of chromophore. Upon UV light irradiation, the composite films gradually changed from colorless to yellow and recovered fully to the initial state upon thermal bleaching. The time constants of photochromic reactions were almost the same as those of 1a observed in their crystalline state, indicating that the photochromic phenomenon is barely disturbed by the polymer matrix. 相似文献
147.
148.
Xiao-Guang Yang Feng-Huan Du Jun-Jie Li Prof. Dr. Chi Zhang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(27):e202200272
The development of convenient new methods for the synthesis of organic azides is highly desirable. Herein, we report a practical method for dehydroxyazidation of alcohols via an SN2 pathway involving PPh3 and trifunctional benziodazolone-based hypervalent azido-iodine(III) reagents, which function as an electrophilic center, an azido source, and a base. This mild, chemoselective method was used for late-stage azidation of structurally complex alcohols, as well as for a new synthetic route to the antiepileptic drug rufinamide. The reaction mechanism was also investigated both experimentally and computationally. 相似文献
149.
Brian Dillman Julie L. P. Jessop 《Journal of polymer science. Part A, Polymer chemistry》2013,51(9):2058-2067
The effects of chain transfer agents (CTA) on cationic ring‐opening polymerization of 3,4‐epoxycyclohexylmethyl‐3′,4′‐epoxycyclohexane carboxylate (EEC) were explored. EEC was polymerized in the presence of various CTAs, and epoxide conversions monitored via Raman spectroscopy. Polymer films were prepared and analyzed by dynamic mechanical analysis. Many of the organic alcohols studied greatly enhanced epoxide polymerization rates and conversion levels. The gel fraction of polymer specimens decreased rapidly with increasing amounts of octanol (gel fraction >90% up to 0.3 equiv OH) but remained high with increasing amounts of 1,2‐propanediol (gel fraction >90% up to 0.6 equiv OH). Increasing the size of primary alcohols had little effect on the polymerization rates and conversions. The polymerization rate decreased with increasing alcohol substitution (1°>2°>3°). Acidic alcohols had very low impact on conversion and polymerization rates relative to the neat epoxy resin. The glass transition temperature was inversely related to the size and amount of CTA. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013 相似文献
150.
Synthesis and characterization of a Ni nanoparticle stabilized on Ionic liquid‐functionalized magnetic Silica nanoparticles for tandem oxidative reaction of primary alcohols 下载免费PDF全文
Rahim Hosseinzadeh‐Khanmiri Yaser Kamel Zahra Keshvari Ahmad Mobaraki Gholam Hossein Shahverdizadeh Esmail Vessally Mirzaagha Babazadeh 《应用有机金属化学》2018,32(9)
In this research, preparation of the magnetic nanoparticle, coating by a silica shell using (3‐aminopropyl) triethoxysilane and synthesis of a novel sulfonic acid‐substituted imidazolium‐based ionic liquid onto the surface of these particles via a multi‐component reaction, is described. The functionalized nanoparticles was loaded by Ni nanoparticles and characterized by means of techniques such as XRD, FTIR, SEM, EDX, TEM, TGA and ICP‐OES. The nanostructures have spherical shapes that ranged in size from 80 to 100 nm. The catalytic activity of these nanoparticles was tested in aerobic oxidation of primary alcohols that showed good performance in the wide range of primary alcohols in water at mild reaction conditions. As a second step of this work, the tandem oxidative synthesis of alkylacrylonitriles and bisindolylmethanes were investigated using primary alcohols under oxidation conditions. This catalyst system can be recovered using external magnet and reused for five consecutive cycles without significantly less of its activity. 相似文献