Oxidation Of Various Olefins Research Articles

Catalytic Activity of Fe/Mn Porphyrins Grafted on Graphitic Carbon Nitride in the Heterogeneous Oxidation of Olefins

ABSTRACTBiomimetic heterogeneous catalysts were prepared by immobilization of meso‐tetrakis(4‐carboxyphenyl)porphyrinatomanganese(III) acetate (MnTCPP) and meso‐tetrakis(4‐carboxyphenyl)porphyrinatoiron(III) chloride (FeTCPP) on graphitic carbon nitride (g‐C3N4) nanosheets. The anchored catalysts were characterized by various techniques such as scanning electron microscopy, thermogravimetric analysis, powder X‐ray diffraction, ultraviolet visible, photoluminescence, flame atomic absorption, and Fourier transform infrared spectroscopy. The thermogravimetric analysis demonstrated that the prepared catalysts were thermally stable up to almost 350°C, exhibiting high thermal stability. In the following, the catalytic efficiency of the prepared nanocatalyst was also investigated for the oxidation of various olefins with hydrogen peroxide (as a green oxidant) and the effect of various parameters which may affect the catalytic efficiency was optimized. The maximum conversion (100% for α‐methylstyrene and 97% for cyclooctene) was obtained in the presence of MnTCPP@C3N4. The Mn porphyrin nanocatalyst shows higher catalytic efficiency compared to the Fe porphyrin.

A novel POM/LDH/GO nanocomposite as highly efficient heterogeneous catalyst in green epoxidation of alkenes with hydrogen peroxide

In the present work, various transition metal substituted Keggin-type polyoxometalates/Ni-Al layered double hydroxide/graphene oxide (PWM/Ni-Al LDH/GO; M = Fe, Ni, Cu, Mn, Co, Cr, Zn) nanocomposites have been synthesized and utilized as catalysts in the epoxidation of alkenes. Results confirmed that in the epoxidation of alkenes, PWFe/Ni-Al LDH/GO nanocomposite could perform its role as the best catalyst. The selected nanocomposite evaluated as a heterogeneous catalyst in the green oxidation of various alkenes into the corresponding epoxides while aqueous hydrogen peroxide was used as an environmentally benign oxidant. The results of recovery and reusability experiments on PWFe/Ni-Al LDH/GO nanocomposite revealed that even after five times it could be easily reused without any considerable decrease in catalytic efficiency.

Cobalt ferrite magnetic nanoceramics as an efficient nanocatalyst for the oxidation of olefins in the presence of molecular O2 as an environmentally safe oxidant

Selective oxidation of olefins using catalysts with unique structural and compositional characteristics, high cost‐efficiency, and optimal catalytic performance is still one of the ongoing tasks. In the present study, we synthesized cobalt ferrite (CoFe2O4) magnetic nanoceramics by the sol–gel process as a feasible and effective technique for synthesizing high purity, homogeneous, and crystalline nanoceramics. The nanoceramics were characterized by different analyses such as FT‐IR, XRD, DLS, SEM, XPS, and VSM to investigate their size, morphology, crystallinity, and magnetic properties. Then, the obtained nanoceramics were applied as an environmentally clean catalyst for the oxidation of various olefins to the corresponding epoxides in the presence of molecular O2 and at ambient conditions. The results showed that the CoFe2O4 nanoceramic could act as an efficient catalyst for converting olefins to the corresponding products with excellent yields. To further study the catalytic activity, the effects of some parameters, including catalyst concentration, temperature, time, and solvent, on the oxidation reactions were also studied. In addition, the heterogeneous CoFe2O4 catalyst has advantages such as high selectivity, facile recovery, and reusability of catalyst without a significant decrease in catalytic activity. Finally, our results showed that the catalytic performance of these nanoceramics is among the best reported catalysts for olefin oxidation.

Use of Porphyrin Containing Porous Materials in Heterogeneous Catalyst

Due to their potential applications in catalysis, separation, gas storage, drug delivery, and biosensing, porous materials (PMs) such as porous organic polymers (POPs), polymers with intrinsic microporosity (PIMs), porous coordination polymers (PCPs), and metal–organic frameworks (MOFs), have received much attention. Various building blocks have been prepared and demonstrated various functional materials. Among the various organic building blocks, porphyrin has become one of the most important building blocks for the construction of such materials witnessed by a wide range of molecular architectures using porphyrin derivatives with various applications. Mn(III)- and Fe(III)-containing metalloporphyrins are often used to fabricate various functional molecular architectures and to mimic the extraordinary behavior of enzymes in both homogeneous and heterogeneous catalytic systems. In the case of homogeneous catalysis, Mn(III)- and Fe(III)-containing metalloporphyrins have frequent trouble with fast catalytic degradation because of µ-oxo dimer formation or ligand oxidation. To avoid the catalyst degradation, the immobilization and/or site-isolation of homogeneous catalysts using supporters such as polymers, membranes, and MOFs, are widely used strategy. In addition, they are often used to modify the surface of porous silica materials such as SBA-15, MCM-41 and MCM-48, because these porous silica materials exhibit narrow pore size distributions, high thermal stability and easy accessibility.In this presentation, we like to show the use of metalloporphyrins in various porous materials and their use as heterogeneous catalysts.References D. Y. Shin, J. H. Yoon, S. H. Kim, H. Baik, S. J. Lee,* "Immobilization of Porphyrinic Mn(III) Catalyst on a New Class of Silica Support Comprising Three-Dimensionally Interconnected Network with Two Different Sizes of Pores", Catal. Sci. Technol. 2018, 8, 6306-6310.J. Yi, H. Y. Jeong, D. Y. Shin, C. Kim, S. J. Lee,* "Mn(III)-Porphyrin Containing Heterogeneous Catalyst based on Microporous Polymeric Constituents as a New Class of Catalyst Support", ChemCatChem 2018, 10, 3974-3977.J. Yoon, H. M. Choi, S. J. Lee,* "Cu(II)Cl2 containing bispyridine-based porous organic polymer support prepared via alkyne–azide cycloaddition as a heterogeneous catalyst for oxidation of various olefins", New J. Chem. 2020, 44, 9149-9152.H. M. Choi, Y. J. Kim, E. T. Choi, S. J. Lee,* "Selective Photocatalytic Oxidative Detoxification of a Chemical Warfare Agent Simulant by Porphyrin-Containing Polymers of Intrinsic Microporocity." ACS Appl. Polym. Mater.2021, submitted .

New Cu(II), Co(II) and Ni(II) azo-Schiff base complexes: Synthesis, characterization, catalytic oxidation of alkenes and DFT study

Three new complexes with general formula of ML (M = Cu (1), Co (2), Ni (3)) containing an azo-Schiff base ligand (H2L) derived from 2,3-butanediamine and 4-(benzeneazo) salicylaldehyde were synthesized by template method. Characterization of the ligand and complexes were accomplished with FT-IR, UV–Vis, and 1H NMR. The catalytic activity of the complexes (1–3) were tested for the oxidation of various alkenes (cyclooctene, cyclohexene, styrene, α-methyl styrene, and norbornene) applying tert-butyl hydroperoxide (TBHP) as an oxidizing agent, and it was found that they were acceptable catalysts. Under the optimized reaction conditions, CuL complex displayed 94% conversion for the oxidation of cyclooctene, and CoL and NiL complexes exhibited 90 and 85% conversions for oxidizing α-methyl styrene, respectively. Based on our density functional computations, diffuse functions are compulsory in the basis set for geometry optimization of these systems. Therefore, the most stable structures and the vibrational frequencies were calculated at the M06-2X/6–311++G(d,p) level. By establishing the correlation between observed and calculated frequencies, the assignment of the vibrational modes was performed. Based on natural charge analysis (NAO), the back electron transfer from ML to the TBHP breaks the OO bond and facilitates the formation of tert-butoxyl radicals.

Cu(II) Schiff base complex on magnetic support: An efficient nano-catalyst for oxidation of olefins using H2O2 as an eco-friendly oxidant

A heterogeneous magnetic supported copper(II) nanocatalyst has been obtained through the reaction of 2-hydroxy-1-naphthaldehyde with the functionalized silica coated iron oxide nanoparticle (Fe3O4@SiO2@NH2) to synthesize immobilized Schiff base ligand (Fe3O4@SiO2/Schiff base). This procedure was followed by the addition of Cu(CH3COO)2·H2O to the prepared particles in order to form the copper(II) Schiff base complex on the surface of iron oxide nanoparticles. Versatile techniques such as FT-IR, SEM, XRD, ICP-OES, EDS and VSM were employed to characterize the synthesized Cu nanocatalyst. Furthermore, its catalytic functionality has been investigated for the oxidation of various olefins with the help of hydrogen peroxide (H2O2) as an eco-friendly oxidant. In the next step, the final samples of reactions were isolated quite simply by using magnets and analyzed by GC and GC–MS instruments. The obtained copper(II) nanocatalyst grants some superiorities such as simple magnetic separation from the mixture, short reaction time (2 h) and high conversion through green processes exclusively for styrene (conversion: 100%) and norbornene (conversion: 79%).

Solvent-Free Environmentally Benign Approach for the Selective Olefin Epoxidation Catalyzed by Mn(III)-Immobilized Mesoporous Nanoarchitectonics.

Immobilization of transition metal complexes at the surface of 2D-hexagonal functionalized SBA-15 material is one of the promising strategies in designing an efficient catalytic system for the olefin epoxidation reaction. Here we have immobilized Mn(III) on the Schiff-base anchore 2D-hexagonally ordered functionalised mesoporous SBA-15 material. Powder X-ray diffraction (PXRD), N₂-sorption and high resolution transmission electron microscopic (HRTEM) studies of the resulting SBA-15-SB-Mn material suggested 2D-hexagonally ordered porous nanostructure and X-ray photoelectron spectroscopy (XPS) analysis suggested the presence of surface bound Mn(III) species in this nanomaterial. This mesoporous material showed excellent performance in the selective catalytic oxidation of various alkenes to the corresponding epoxides in the presence of tert-butyl hydroperoxide (TBHP, 70% aqueous solution) as oxidant under solvent-free mild reaction conditions together with high recycling efficiency.

Intercalated cobalt porphyrin between layered double hydroxide nanosheets as an efficient and recyclable catalyst for aerobic epoxidation of alkenes

Anionic cobalt tetrasulfonatophenyl porphyrin (CoTPPS) intercalated NiAl LDH has been prepared through the exfoliation/restacking route. The obtained hybrids were characterized by XRD, SEM, TEM, IR, UV–Vis and TG-DSC. The volume ratio between the metalloporphyrin solution and LDH nanosheets suspension on the structure of restacking products was investigated and CoTPPS/Ni-Al LDH3.0 was found to exhibit the highest crystallinity. The interlayer spacing determined by XRD shows that CoTPPS was intercalated into the hyroxylated layers of LDH by a perpendicular orientation. The catalytic performance of the obtained hybrid material was investigated in the green epoxidation of various alkenes with oxygen as oxidant and isobutyaldehyde as co-reagent. The immobilized Co porphyrin demonstrated great application potential in oxidative catalysis, exhibiting exceptional stability and catalytic activity in oxidation of various alkenes.

Cu(ii)Cl2 containing bispyridine-based porous organic polymer support prepared via alkyne–azide cycloaddition as a heterogeneous catalyst for oxidation of various olefins

A new type of porous organic polymer (POP) based heterogeneous catalyst Cu-POP was prepared by immobilizing Cu(ii)Cl2 into bpy containing POP prepared via alkyne–azide cycloaddition. It showed good catalytic oxidations towards various olefins.

New magnetic supported hydrazone Schiff base dioxomolybdenum (VI) complex: An efficient nanocatalyst for epoxidation of cyclooctene and norbornene

A new dioxomolybdenum (VI) complex with tridentate hydrazone Schiff base ligand (H2L) derived from 2‐hydroxy‐5‐nitrobenzaldehyde and benzhydrazide was synthesized and designated as [MoO2L (DMF)]·2H2O. The Fe3O4@SiO2‐CPS‐L‐MoO2 (EtOH) nanocatalyst was successfully prepared by grafting H2L ligand on modified Fe3O4 nanoparticles followed by reacting with MoO2 (acac)2. The complex and nanocatalyst were characterized by various techniques such as elemental analysis, mass, FT‐IR, UV–Vis, 1H NMR, 13C{1H}‐NMR, TGA, XRD, XPS, TEM, SEM and VSM. The catalytic activity of [MoO2L (DMF)]2H2O and Fe3O4@SiO2‐CPS‐L‐MoO2 (EtOH) were evaluated for the oxidation of various alkenes (cyclooctene, norbornene, cyclohexene, styrene and α‐methyl styrene) in the presence of tert‐butylhydroperoxide as oxidant. The results revealed that the catalysts were especially efficient for oxidation of cyclooctene and norbornene with 100% selectivity towards corresponding epoxide product. Fe3O4@SiO2‐CPS‐L‐MoO2 (EtOH) showed higher catalytic activity, shorter reaction time and higher turnover number (TON) compared with homogeneous complex [MoO2L (DMF)]·2H2O. Moreover, simple magnetic recovery from the reaction mixture and reuse for several times with no significant loss in activity were other advantages of the nanocatalyst.

Mn(III)-porphyrin/graphene oxide nanocomposite as an efficient catalyst for the aerobic oxidation of hydrocarbons

In this study, manganese porphyrin was grafted on the surface of graphene oxide nanosheets via covalent bonding to produce a heterogeneous catalyst. The prepared nanocomposite was characterized using X-ray diffraction, UV–vis spectroscopy, scanning electron microscopy, Fourier transform infrared, and thermogravimetric analysis. Atomic absorption spectroscopy was also used to determine the amount of the loaded catalyst. The catalytic efficiency of the immobilized Mn-porphyrin was investigated for the aerobic oxidation of alkenes and saturated alkanes in acetone under mild reaction conditions. The prepared heterogenized catalyst displays superior catalytic performance as compared to the homogeneous catalyst. Moreover, the excellent turnover number (more than 31,767) achieved for the oxidation of styrene indicates the high longevity of the supported catalyst. The catalyst structure is preserved well after the oxidation reaction and is simply reused at least five times, without any significant loss of the catalytic efficiency. In this research, Mn(THPP)OAc has been grafted on the GO surface to provide an effective catalytic system for the oxidation of various alkenes and alkanes to the corresponding oxidation products, such as epoxy and alcohols.

Cu- and Ni-Grafted Functionalized Mesoporous Silica as Active Catalyst for Olefin Oxidation

Mesoporous silica has been functionalized with 3-aminopropyl triethoxy silane (3-APTES), followed by Schiff-base condensation with 2-hydroxy-1-naphthaldehyde. Incorporation of copper and nickel by covalent grafting onto the Schiff-base loaded materials gives two heterogenized catalysts namely, Cu–Cat and Ni-Cat, respectively. The materials have been characterized by PXRD analyses, nitrogen sorption studies, TEM, TGA, FT-IR, UV-visible and solid state MAS-NMR spectroscopy. The metal-contents in the samples are estimated using ICP-AES studies. Cu–Cat and Ni-Cat have been used as active catalyst in the oxidation of various olefins e. g. styrene, α-methyl styrene, cyclohexene, trans stilbene and cyclooctene in the presence of tert-butyl hydroperoxide as the oxidant in acetonitrile under mild conditions. Different products have been analyzed by gas chromatography and gas chromatography-mass spectrometry. The results show high conversion of the substrates, moderate to good product selectivity and high TOFs of the reactions. The catalysts are recycled without deteriorating their activities and heterogeneous nature.

Synthesis, characterization, and X-ray structure of n'-(2-hydroxy-5-methylbenzylidene)-4-trifluoromethylbenzohydrazide and its dioxidomolybdenum(vi) complex with catalytic property

ABSTRACTA new hydrazone compound N’-(2-hydroxy-5-methylbenzylidene)-4-trifluoromethylbenzohydrazide (H2L) was prepared. Based on H2L, a new dioxidomolybdenum(VI) complex [cis-MoO2L(MeOH)], was obtained. Single crystals of H2L and the complex were obtained by slow evaporation of methanolic solution containing the compounds, and were characterized by elemental analysis, infrared spectroscopy, and single-crystal X-ray diffraction techniques. The geometry around the molybdenum center is distorted octahedral in which the tridentate benzohydrazone ligand with two anionic oxygens and one neutral imine nitrogen occupies meridional position. The octahedral geometry of the cis-dioxomolybdenum center is additionally completed by a coordinated methanol solvent molecule. The complex was tested for the homogeneous oxidation of various olefins.

Copper(II) Schiff Base Complex Immobilized on Superparamagnetic Fe3O4@SiO2 as a Magnetically Separable Nanocatalyst for Oxidation of Alkenes and Alcohols

A new heterogeneous catalyst containing a copper(II) Schiff base complex covalently immobilized on the surface of silica‐coated Fe3O4 nanoparticles (Fe3O4@SiO2‐Schiff base‐Cu(II)) was synthesized. Characterization of this catalyst was performed using various techniques. The catalytic potential of the catalyst was investigated for the oxidation of various alkenes (styrene, α‐methylstyrene, cyclooctene, cyclohexene and norbornene) and alcohols (benzyl alcohol, 3‐methoxybenzyl alcohol, 3‐chlorobenzyl alcohol, benzhydrol and n‐butanol) using tert‐butyl hydroperoxide as oxidant. The catalytic investigations revealed that Fe3O4@SiO2‐Schiff base‐Cu(II) was especially efficient for the oxidation of norbornene and benzyl alcohol. The results showed that norbornene epoxide and benzoic acid were obtained with 100 and 87% selectivity, respectively. Moreover, simple magnetic recovery from the reaction mixture and reuse for several times with no significant loss in catalytic activity were other advantages of this catalyst

Two dioxomolybdenum(VI) complexes with hydrazone ligands: synthesis, characterization, crystal structures and catalytic properties

A pair of Mo(VI) complexes, [MoO2L1(MeOH)] (1) and [MoO2L2(MeOH)] (2), where L1 and L2 are the dianions of 2-amino-N’-(3-bromo-5-chloro-2-hydroxybenzylidene)benzohydrazide (H2L1) and 2-amino-N’-(3,5-dibromo-2-hydroxybenzylidene)benzohydrazide (H2L2), respectively, have been prepared and characterized by physico-chemical methods and single-crystal X-ray diffraction. The Mo atom in each complex is coordinated by the phenolate oxygen, imino nitrogen and enolate oxygen of the hydrazone ligand, together with a methanol ligand and two oxo groups, giving a distorted octahedral geometry. The complexes proved to be effective catalysts for the oxidation of various olefins.

A synergistic effect of a cobalt Schiff base complex and TiO2 nanoparticles on aerobic olefin epoxidation

A cobalt Schiff base complex and TiO2 nanoparticles exhibited a synergistic effect on the visible-light photocatalytic activity in the aerobic oxidation of various olefins in the absence of reducing agent.

Hydrogen bond controlled formation of trans-dihydroxo porphyrinato platinum(IV) complexes: Synthesis, characterization and catalytic activity in olefin epoxidation

A number of trans-dihydroxo porphyrinato platinum(IV) complexes, [(porp)PtIV(OH)2] have been synthesized and characterized from their platinum(II)-porphyrin precursors by spectroscopic methods. The crystal structure of the platinum complex of trans-dihydroxo-meso-tetramesitylporphyrinato platinum(IV) meta-chlorobenzoic acid ([(TMP)PtIV(OH)2](m-CBA)2) has also been determined. The porphyrin periphery is planar and the platinum atom has a slightly distorted octahedral environment. It must be noted that there is a very strong O–H⋯O hydrogen bond between the hydrogen atoms of m-chlorobenzoic acids and the two hydroxo ligands coordinated to the platinum center. This crystal structure has been previously described by us as trans-dihydroxo-meso-tetramesitylporphyrinato platinum(VI) meta-chlorobenzoate ([(TMP)PtVI(OH)2](m-CB)2), but the spectroscopic data has been reinterpreted due to the contradictory +6 oxidation state for platinum. The UV–Vis and NMR spectroscopic data suggest that the porphyrin skeleton is similar to that of normal porphyrins and are also indicative of the +4 oxidation state for platinum. Cyclic voltammetry studies also indicate that PtIITMP can oxidize up to PtIV(TMP+) species via three successive one-electron oxidation steps. The results of DFT studies and NBO analysis confirm that platinum has +4 oxidation state in both [(TMP)Pt(OH)2](m-CBA)2 and [(TMP)Pt(OH)2](m-CB)2 complexes. The catalytic activity of these porphyrin complexes has been investigated for the oxidation of various alkenes in the presence of iodosylbenzene.

Ultrasound promoted green oxidation of alkenes with hydrogen peroxide in the presence of iron porphyrins supported on multi-walled carbon nanotubes

In the present work, oxidation of alkenes with hydrogen peroxide in the presence of meso-tetrakis(4-hydroxyphenyl)porphyrinatoiron(III) chloride supported onto surface of functionalized multi-wall carbon nanotubes (FMWCNT), [ Fe ( THPP ) Cl@MWCNT ], is reported. The simple heterogeneous catalyst was characterized by FT-IR spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and also thermal analysis. The amount of the catalyst loaded on the nanotubes was determined by atomic absorption spectroscopy. This heterogeneous catalyst proved to be an efficient and green catalyst and was successfully able to activate hydrogen peroxide without any additive toward the oxidation of alkenes in ethanol as a green solvent. Performance of the catalyst in oxidation of various alkenes was inspected under reflux, ultrasonic irradiation and mechanical stirring. Moreover, the catalyst can be reused several times under similar conditions.

Osmium on Chelate Resin: Nonvolatile Catalyst for the Synthesis of Diols from Alkenes

Osmium tetraoxide (OsO₄) was immobilized on a commercially available chelate resin DIAION CR11 (CR11) just by simply immersing it in a methanol solution of OsO₄ at room temperature. The resulting purple solid, 5% Os/CR11, indicated no volatility, and effectively catalyzed the oxidation of various alkenes to the corresponding diols.

Synthesis, Characterization, and X-Ray Structure of [cis-MoO2L(MeOH)] (L = N′-(5-Chloro-2-Hydroxybenzylidene)-3-Chlorobenzohydrazide) and Its Catalytic Property

The synthesis and characterization of [cis-MoO2L(MeOH)] (L = N′-(5-chloro-2-hydroxybenzylidene)-3-chlorobenzohydrazide) are described. The dioxomolybdenum complex was prepared from 1:1 reaction mixture containing the benzohydrazone ligand and MoO2(acac)2. Orange single crystals were obtained by slow evaporation of methanolic solution containing the complex, and were characterized by elemental analysis, infrared spectroscopy, and single-crystal X-ray diffraction techniques. The geometry around the molybdenum center is distorted octahedral in which a tridentate benzohydrazone ligand with two anionic oxygens and one neutral imine nitrogen occupies meridional position. The octahedral geometry of the cis-dioxomolybdenum center is additionally completed by a coordinated methanol solvent molecule. The complex was tested for the homogeneous oxidation of various olefins.