Synthesis and catalytic activity of polymer‐anchored metal complex for oxidation of cyclohexane

Catalytic oxidation of cyclohexane was investigated over polymer‐anchored Co(II) catalyst prepared by modification of polymer surface by NO_x and subsequent functinalization by amination. The catalyst characterized by various techniques, such as elemental analysis, atomic absorption spectroscopy, Fourier transform infrared spectroscopy (FT‐IR), thermo‐gravimetric analysis, and scanning electron microscopy confirmed the modification of polymer surface and bond formation between functionalized resin and metal ion. The oxidation of cyclohexane using molecular oxygen (O₂) as an oxidant was studied in the temperature and pressure range of 373–413 K and 1.0–1.4 MPa, respectively. The maximum cyclohexane conversion of 18.4% was obtained at 413 K and 1.2 MPa pressure. Cyclohexanone and cyclohexanol were found as the main reaction products with 93.0% selectivity. No appreciable change in catalytic activity and on product selectivity was observed after the catalyst recycled three times. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2127–2135, 2013     

Efficient liquid phase oxidation of olefins and aromatic alcohol catalyzed by reusable polymer anchored Schiff base complexes

BACKGROUND: Heterogenization of homogeneous catalyst has become an interesting process for the catalytic oxidation of olefins and aromatic alcohol. This may provide a new kind of catalyst that is not only friendly to the environment but also exhibits higher thermal and chemical stabilities. RESULTS: Polymer anchored Schiff‐base complexes of iron(III), copper(II) and cobalt(II) have been synthesized and characterized. The catalytic potential of these complexes has been tested for the oxidation of cyclohexene. The effect of varying solvent, oxidant, substrate oxidant molar ratio, temperature and catalyst amount has been studied. Under optimized reaction conditions 91, 88 and 81% conversion of cyclohexene was obtained with Fe(III), Cu(II) and Co(II) catalysts, respectively. Moreover, the oxidation of other substrates, such as styrene, benzylalcohol, toluene and 1‐hexene were also efficiently carried out by these catalysts. CONCLUSION: The immobilized complexes showed excellent catalytic activity along with high selectivity for the oxidation of olefins and alcohols. The catalysts can be recycled more than five times without any noticeable loss of catalytic activity. Copyright © 2009 Society of Chemical Industry     

Oxidation of styrene over polymer‐ and nonpolymer‐anchored Cu(II) and Mn(II) complex catalysts

Catalytic oxidation of styrene was investigated over polymer‐ and nonpolymer‐anchored Cu(II) and Mn(II) complex catalysts prepared by schiff base tridentate ligands. The effect of temperature, styrene to H₂O₂ mole ratio and catalyst amount on the catalytic activity and product selectivity was investigated. Further, the catalysts were characterized by various techniques, such as elemental analysis, atomic absorption spectroscopy (AAS), FTIR, FE‐SEM, EDAX, TGA, and UV–vis spectrophotometer. The elemental analysis, EDAX and AAS results confirmed the formation of Cu(II) and Mn(II) complexes, and it was found that the metal loading in the polymer‐anchored complex catalysts were in the range of 0.53–3.74 %. FTIR results showed the co‐ordination bond formation between the polymer ligands and metal ion. The catalytic data showed that, over all the catalysts, the main reaction products were benzaldehyde, styrene oxide, and benzoic acid. The polymer‐anchored complex catalysts were found to be much more active when compared with nonpolymer‐anchored catalysts. The maximum conversion of styrene (92.3%) was obtained over PS‐[Cu(Hfsal‐aepy)Cl] catalyst with benzaldehyde selectivity to 69% at the styrene to H₂O₂ mole ratio of 1 : 4 at 75°C. Although the PS‐[Mn(Hfsal‐aepy)Cl] catalyst was less active, it was highly selective to benzaldehyde. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Effect of the nature and degree of crosslinking on the catalase‐like activity of polystyrene‐supported schiff base‐metal complexes

Catalase‐like activity of the metal complexes of various crosslinked polystyrene‐supported Schiff bases were carried out and correlated with the nature and degree of crosslinking in the polymer support. Polystyrenes with 2–20 mol % ethyleneglycol dimethacrylate (EGDMA), 1,4‐butanediol dimethacrylate (BDDMA) and 1,6‐hexanediol diacrylate (HDODA) were used as polymer supports. functions of diethylenetriamine and salicylaldehyde were incorporated to the chloromethylpolystyrene by polymer analogous reactions and complexed with Fe(II), Fe(III), Co(II), Ni(II), and Cu(II) ions. The metal uptake decreased in the order: Cu(II) > Co(II) > Ni(II) > Fe(III) > Fe(II), and extent of metal uptake by the various crosslinked system varied with the nature and degree of the crosslinking agent. The polymeric ligands and the metal complexes were characterized by various analytical techniques. The catalytic activities of these metal complexes were investigated towards the decomposition reaction of hydrogen peroxide. Generally among the various metal complexes, the catalytic activities decreased in the order: Co(II) > Cu(II) > Ni(II) > Fe(III) ? Fe(II). With increasing rigidity of the crosslinking agent their catalytic activity also decreased. Of the various crosslinked systems, the catalytic activity decreased in the order: HDODA‐ > BDDMA‐ > EGDMA‐crosslinked system. Also, the catalytic activity is higher for low crosslinked systems and decreased further with increasing degree of crosslinking. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1271–1278, 2004     

钼铋复合金属氧化物催化低碳烯烃选择氧化制备醛类研究进展

低碳烯烃选择氧化制备醛类等含氧化合物是生产有机化工中间体及产品的关键步骤,钼铋复合金属氧化物因其优异的催化性能在相关工业界和学术界受到广泛关注,然而目前关于该催化剂上选择氧化反应机制和催化反应本质等科学问题的认识尚未形成统一理论。本文系统综述了钼铋复合金属氧化物在催化低碳烯烃选择氧化制备醛类反应中的研究进展,包括催化剂微观结构的三种调控手段,即主组分钼酸铋物相结构、助剂及载体等对反应性能的影响,并对反应机理进行了深入讨论与总结。最后展望了钼铋复合金属氧化物在该选择氧化反应中的发展前景,为钼铋复合金属氧化物修饰改性及开发高效低碳烯烃选择氧化制含氧化合物催化剂提供思路。     

Catalytic activity of a reusable polymer‐anchored nickel(II)–phenanthroline complex on the oxidation of various organic substrates

A polymer‐anchored nickel(II)–phenanthroline complex [polyNi(II)–phen] was synthesized and used effectively as a reusable catalyst in various oxidation reactions in the presence of tert‐butylhydroperoxide as an oxidant in acetonitrile medium. The catalyst was characterized with elemental analysis, atomic absorption spectrometry (AAS), thermogravimetric analysis, scanning electron microscopy, and spectrometric methods such as diffuse reflectance spectroscopy, ultraviolet–visible spectroscopy, and Fourier transform infrared spectroscopy. The study of the effects of the time, temperature, oxidant, catalyst concentration, molar ratio of substrate to oxidant, and solvent in the oxidation of styrene individually gave the optimized reaction conditions. Under optimized conditions, the catalyst exhibited good conversions for the oxidation reactions of various olefins, alkanes, aromatic alcohols, and thioethers. The catalyst was easily recovered by simple filtration and reused for more than five times with consistent catalytic activity. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Controlled‐release polyurethane created by absorbing transition‐metal acetate and benzyl carbinol

Three kinds of the transition‐metal acetates were absorbed into polyurethane to investigate its effect on the desorption velocity of benzyl carbinol and ethyl alcohol from polyurethane. The results show that a small amount of transition‐metal acetate can enhance the absorption amount of benzyl carbinol and ethyl alcohol in polyurethane. With the existence of transition‐metal acetate, benzyl carbinol and ethyl alcohol desorb from polyurethane more slowly. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1170–1173, 2002     

Synthesis and catalytic oxidation properties of polymer‐bound cobalt complexes

Polymer‐bound 2,2′‐bipyridine cobalt complexes PSBPY‐Co, PSBPY‐Co‐bipy, PSBPY‐Co‐oxine, and PSBPY‐Co‐phen (where PSBPY: polystyrene bound‐2,2′‐bipyridine; bipy: 2,2′‐bipyridine; phen: 1,10‐phenanthroline) were synthesized and investigated by IR, X‐ray photoelectric spectroscopy, thermogravimetry–differential thermal analysis, inductively coupled plasma atomic emission spectrometry, and elemental analysis. The complexes were found to be catalysts for the oxidation of alkylbenzenes and cyclohexene in the presence of molecular oxygen in the absence of solvent. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 1068–1074, 2000     

Thermal and catalytic aspects of Ln(III) polymer–metal complexes

BACKGROUND: In this era, polymer‐supported catalysts are gaining more attention, as they are effective in reduction of pollution, production cost and give good yield. Due to the versatility of lanthanide catalysts in organic synthesis, we envisioned that lanthanides(III) supported polymers would afford a novel type of solid phase Lewis acids. RESULTS: The polymer–metal complexes are found to be efficient and effective catalysts in the Biginelli three‐component, one‐pot synthesis of 3,4‐dihydropyrimidin‐2(1H)‐ones. The synthesized polymer is thermally more stable and porous in nature than polychelates. CONCLUSION: The polymer–metal complexes can be used as economical and eco‐friendly catalysts for synthesis of substituted 3,4‐dihydropyrimidin‐2(1H)‐ones with different aromatic aldehydes and β‐ketoesters. Thermal stability of the polymer is higher than that of polychelates due to the presence of intramolecular hydrogen bonding. Copyright © 2009 Society of Chemical Industry     

Polyaniline‐supported acid catalyst: Esterification of cinnamic acid with alcohols

Polyaniline‐supported acid salts such as polyaniline‐hydrochloride, polyaniline‐sulfate, and polyaniline‐nitrate were prepared by oxidation of aniline using benzoyl peroxide and ammonium persulfate as oxidizing agents. Polyaniline salts were used as catalysts in the esterification of cinnamic acid with alcohols. Polyaniline‐sulfate salt was found to be the best catalyst for the esterification of cinnamic acid. The reusability, handling, and recovery of the catalyst were found to be good. The yield of the ester depended on the type of the polyaniline salt, amount of the catalyst, amount of alcohol, and both the time and the temperature of the reaction. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1584–1590, 2005     

硼杂碳包镍负载钯催化芳香醇需氧氧化

以硼杂碳包镍(Ni@BC)为载体,采用乙醇还原前驱体H_2PdCl_4法制备了一种新型磁可分离Pd/Ni@BC催化剂,并对其进行AAS、TEM、XRD和XPS表征,选取苯甲醇需氧氧化为探针反应,考察催化剂用量、反应温度和反应时间对催化性能的影响,研究催化剂对其他芳香醇的催化性能和循环使用性能。AAS结果表明,Pd负载质量分数为9.1%,与理论负载量一致。TEM结果显示,Pd纳米颗粒均匀分散在载体表面,平均粒径为4 nm。XRD和XPS结果均表明,催化剂的活性物种为Pd0。在反应温度80℃、O2_压力101.325 k Pa(流速20 m L·min~(-1))、CH_3CN为溶剂和K_2CO_3为碱性助剂条件下,Pd/Ni@BC对多种芳香醇的氧化反应表现出很高的催化活性和选择性,能将苯甲醇、对甲基苯甲醇、对乙基苯甲醇、对异丙基苯甲醇、肉桂醇、安息香、二苯甲醇以及邻甲基苯甲醇等定量转化为相应的醛或酮。催化剂重复使用5次,苯甲醇转化率由97.3%降至78.9%,Pd的少量脱落和部分氧化是催化剂活性降低的主要原因。     

Stability constants of polymer‐bound iminodiacetate‐type chelating agents with some transition‐metal ions

A chelating vinyl monomer, glycidyl methacrylate (GMA)–iminodiacetic acid (IDA), was formed by the reaction between GMA and IDA. Three polymeric chelating agents, PGMA–IDA, PGMA–IDA‐co‐methyl acrylate (MA), and PGMA–IDA‐co‐acrylamide (AAm), were also synthesized. Acid dissociation constants and stability constants of these chelating agents with Ni(II), Zn(II), and Co(II) were determined by means of potentiometric titration and ultraviolet–visible spectrophotometry, respectively. The values of K_a1 and K_a2 of all the polymeric chelating agents were smaller than those of GMA–IDA. The stability constants of all the polymeric chelating agents were larger than those of GMA–IDA. Increasing the MA content within PGMA–IDA‐co‐MA affected the stability constant only slightly. A proper molar ratio of AAm in PGMA–IDA‐co‐AAm, stability constants was 30–60 times greater than that of GMA–IDA. However, as the molar content of AAm increased, the stability constant of PGMA–IDA‐co‐AAm decreased. The results obtained in the polymer system are explained in terms of the polymer's stereo and entanglement structure, the neighboring effect, and the hydrophobic/hydrophilic nature of MA or AAm. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1986–1994, 2002     

Poly(4‐vinylphenol)/tetra‐n‐butylammonium iodide: Efficient organocatalytic system for synthesis of cyclic carbonates from CO2 and epoxides

An efficient polymer‐based catalytic system of poly(4‐vinylphenol) and tetra‐n‐butylammonium iodide was developed for the synthesis of cyclic carbonates from epoxides and CO₂. Owing to the synergistic effects of hydroxyl groups and iodide anions, this commercially available and metal‐free system was highly active for the reaction of various terminal epoxides under environmentally benign conditions, at 25 to 60 °C and atmospheric pressure of CO₂, without the use of any organic solvents. The catalyst system can be easily separated by adding ether, and its ability was recovered by treating it with 40% CH₃CO₂H aq. The recyclability was investigated in detail for three substrates, epichlorohydrin, 1,2‐epoxyhexane, and styrene oxide, using ¹H nuclear magnetic resonance analysis. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45189.     

Bis(imino)pyridyl Co(II) and Fe(II) catalysts immobilized on SBA-15 mesoporous material: new highly active supported catalysts for the polymerization of ethylene

A series of bis(imino)pyridyl Co(II) and Fe(II) complexes containing allyloxy group on the pyridine ring were prepared. These metal complexes were heterogenized covalently immobilizing on modified SBA-15 mesoporous material in the presence of Karstedt catalyst. This immobilization technique was demonstrated to be an ideal one since the resulting supported catalysts resembled closely their homogeneous counterparts, mirroring the feature of active sites.     

Synthesis and application of polycarbosilane supported manganese ions as catalyst in mannich reaction

Polycarbosilane (PCS) with highly crosslinked structure and high surface area was synthesized by the polycondensation reaction between trimethoxyvinylsilane and trichloromethylsilane. The reaction was conducted in the presence of sodium metal. Manganese ion was supported on PCS. The immobilization of transition metal ions to polymer support leads to a number of advantages over homogeneous catalyst, viz easy product recovery, increased selectivity, etc. The catalytic activity of PCS supported manganese ion was studied by considering three‐component Mannich reaction. Reaction with diverse sets of aldehydes, amines, and ketones was examined. PCS‐supported manganese ion catalyst has been prepared for the first time and used successfully in Mannich reaction. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

过渡金属多相催化剂催化的分子氧选择性氧化邻二醇研究进展

邻二醇选择性氧化断键生成醛、酮和羧酸是重要和基本的有机反应,氧化剂通常采用化学计量的高碘酸盐或四乙酸铅,无论从经济还是环保的角度考虑,这些传统方法都有违绿色化工的发展理念。理论上以分子氧为氧化剂选择性氧化邻二醇断键的副产物只有水,而且分子氧廉价易得,因而具有环境友好和经济可行的双重优势。经过多年探索,人们已发展了多个基于不同过渡金属为活性组分的多相催化剂或催化体系用于分子氧选择性氧化邻二醇断键反应,如钌、金、锰、钴,为未来广泛应用奠定了基础。本文将按贵金属和非贵金属分类综述此类催化剂及相关反应工艺的研究进展,并指出该领域的发展方向     

Polystyrene-supported thiosemicarbazone–transition metal complexes: synthesis and application as heterogeneous catalysts

Functionalized polymers are found to be highly efficient in immobilizing transition metal ions. Crosslinked polystyrene supported Schiff's base complexes of metal ions such as Fe(III), Co(II), Ni(II) and Cu(II) are very effective as heterogeneous catalysts. The catalytic activity of these metal complexes has been studied in the decomposition of H₂O₂ and in the epoxidation of cyclohexene and styrene. The reactions show a first order dependence on the concentration of both the substrates and the catalyst. The influence of the degree of crosslinking of the polymer support on the rate of reactions has been studied. The metal complexes show low catalytic activity at low crosslink density (2% and 5%) but 10% crosslinked resins show higher activity. A possible mechanism for the reactions is suggested. © 1999 Society of Chemical Industry     

Selective oxidation of alcohols with hydrogen peroxide catalyzed by hexadentate binding 8-quinolinolato manganese(III) complexes

A series of hexadentate 8-quinolinolato manganese(III) complexes were synthesized and proven to own a distorted octahedral geometry via elemental analysis, solid UV–vis spectroscopy and Hartree–Fock/3-21G+ calculation. These Mn(III) complexes were found to be more efficient than their corresponding tetradentate 8-quinolinolato manganese(II) and salen-Mn^IIIOAc for the oxidation of alcohols in acetone medium, being due to their special hexadentate binding structures that could open an axial MnO bond to form the more active pentadentate structures in the presence of aqueous hydrogen peroxide, as supported by UV–vis spectra. The halogen substituents in ligand's aryl ring could significantly enhance the catalytic activities and 5-chloro-7-iodo-8-quinolinolato manganese(III) gave the highest turnover number (TON). A reasonable mechanism for the present catalytic system was proposed.     

Electron spin resonance spectroscopy study on reduction of constrained‐geometry catalyst systems

The reduction of a constrained‐geometry catalyst (CGCTiMe₂) activated with a series of cocatalysts, including modified methylaluminoxane (MMAO), tris(pentafluorophenyl) borane [B(C₆F₅)₃], and combined B(C₆F₅)₃/MMAO, was experimentally investigated using an on‐line electron spin resonance spectroscopy (ESR) technique. The effects of the solvent type, cocatalyst/catalyst ratio, and temperature on the reduction were examined. In the CGCTiMe₂/MMAO system, increasing the Al/Ti molar ratio from 20 to 250 significantly increased the Ti(III) content. Adding trimethylaluminum to the system lowered the Ti(III) content. Three trivalent Ti species, Ti(a) (g = 1.972), Ti(b) [g = 1.992, α(H) = 7.4 G], and Ti(c) (g = 1.995), were observed. In the CGCMe₂/B(C₆F₅)₃ system, only one trivalent Ti species (g = 1.988) was observed. The CGCTiMe₂/B(C₆F₅)₃ system was more stable to reduction than the CGCTiMe₂/MMAO system. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2474–2482, 2003     

Effect of N‐methylimidazole and 3,5‐dimethylpyrazole ligands on the polymerization of di(2,6‐dichlorophenolato) Cu(II)/Co(II) complexes in the solid state

The polymerization of 2,6‐dichlorophenol (DCPH) was achieved through the thermal decomposition of copper complexes of DCPH with N‐methylimidazole (NMIz) and 3,5‐dimethylpyrazole (DMPz) ligands. Fourier transform infrared (FTIR), differential scanning calorimetry (DSC), mass spectrometry, ultraviolet–visible spectroscopy, diffuse reflectance spectroscopy, magnetic susceptibility balance, electron spin resonance, X‐ray analysis, and elemental analysis were used to characterize the complexes. The polymerization was achieved either in the solid state or in the melt. The structural analyses were performed with FTIR and NMR spectroscopy analyses. The glass‐transition temperatures were determined by DSC, and the intrinsic viscosities were determined by viscosimetry. The effects of the temperature and time on the conversion percentage and viscosity of the polymers were examined. Varying the decomposition temperature during a 3‐h scan showed that the DMPz complex of Cu decomposed at lower temperatures than the NMIz complex, whereas the NMIz complex yielded a higher conversion to the polymer. Complexes of DCPH with NMIz and DMPz ligands produced 1,2‐ and 1,4‐addition products, respectively. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3797–3805, 2004