Oxidation Of Α-methylstyrene Research Articles

Synthesis and characterization of N4-donor Schiff base copper(II) immobilized on superparamagnetic Fe3O4@SiO2 and its use as a recyclable catalyst for oxidation of alkenes, alcohols, and determination of antibacterial activity

N4-donor Schiff base copper(II) nanoparticles were easily prepared through surface modification of silica-coated magnetite nanoparticles (Fe3O4@SiO2) with pyrrole 2-carbaldehyde Schiff base and a subsequent reaction with Cu(CH3COO)2.H2O in ethanolic solution. This nanocatalyst was characterized using thermogravimetric analysis (TGA), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), and magnetization. Efficient oxidation of alkenes and alcohols was carried out over the Schiff base copper(II) nanoparticles. Catalytic tests showed that the catalyst was particularly effective for the oxidation of α-methyl styrene, norbornene, benzyl alcohol, and benzohydrol. The results showed that acetophenone, 2-norbornanone, benzoic acid, and benzophenone with selectivity values of 88, 100, 100, and 100, respectively, were obtained. The heterogeneous catalyst of N4-donor Schiff base copper(II) offers advantages such as ease of product separation, catalyst recycling, and ease of preparation. Antibacterial tests against two gram-positive and two gram-negative bacterial species found that the bacteria stopped growing in the catalyst medium.

The Cerium–Zirconium Binary Oxide as an Efficient Catalyst for Oxidation of α-Methylstyrene Oxide into Atrolactic Acid

The atrolactic acid is an important intermediate for synthesis of non-steroidal anti-inflammatory pharmaceuticals, and meanwhile the traditional synthesis of atrolactic acid demands harsh conditions, lengthy steps, or big power consumption. In order to overcome these drawbacks, a series of Ce–Zr binary oxides are first developed as catalysts for oxidation of α-methylstyrene oxide into atrolactic acid. Catalytic results reveal these catalysts have high activity and recycling potential. This work shows a new method for preparation of atrolactic acid, which could be carried out under benign conditions, providing satisfactory outputs.

Ionic Liquid Dispersed Ti/SBA-15 for Double-Bond Cleavage Oxidation of α-Methylstyrene into Acetophenone

A composite material Ti/SIL was prepared by Ti(OC4H9)4 coordinating to imidazolium ionic liquid grafted on SBA-15 and characterized by FT-IR, XRD, TEM, XPS, NH3-TPD and N2 adsorption–desorption technique. The catalytic performance of the prepared Ti/SIL for solvent-free oxidation of α-methylstyrene (AMS) to acetophenone using H2O2 oxidant was evaluated, achieving high TOF (23.2 h−1). The adsorption behavior of AMS via interaction with Ti4+ and Si–O active sites on the catalyst surface was measured by in situ DRIFTS, 29Si CP MAS NMR spectroscopy and analyzed by DFT theoretical calculation. Based on these analysis results, the reaction mechanism, involving the activation, consecutive conversion of AMS and homolytic decomposition of H2O2 on the catalyst surface to generate the product was proposed.

Improving the catalytic activity of magnetic Fe3O4/ZnO-CdO/reduced graphene oxide for ultrasonic degradation of the organic pollutants and the green oxidation of olefins

Magnetic Fe3O4/ZnO-CdO/reduced graphene oxide (MFZC/RGO) has been synthesized by simple hydrothermal method. The structure and morphology were investigated by X-ray diffraction (XRD), Transmission electron microscopy (TEM), Scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDS), Diffuse reflectance spectroscopy (DRS), Vibrating sample magnetometer (VSM), Raman and Fourier-transform infrared spectroscopy (FTIR). MFZC/RGO was applied as catalyst in degradation of methylene blue (MB), rhodamin B (RhB) and methylorange (MO) under ultrasonic irradiation. Based on the results, excellent degradation efficiencies of MB, RhB and MO (>99%) were achieved within 10, 20 and 20 min, respectively under oxygen flow. Moreover the catalytic property of MFZC/RGO was investigated in oxidation of styrene, α-methyl styrene, cyclohexene and cyclooctene under oxygen flow. In addition, MFZC/RGO can be easily collected and separated by an external magnet. The catalyst displayed negligible loss in activity and selectivity within several successive runs due to super paramagnetism.

Highly efficient asymmetric epoxidation of olefins with a chiral manganese-porphyrin covalently bound to mesoporous SBA-15: Support effect

A chiral MnIII-porphyrin complex covalently bonded with mesoporous SBA-15 (SBA15-[Mn(TCPP-R∗)Cl]) was synthesized and fully characterized. The heterogeneous SBA15-[Mn(TCPP-R∗)Cl] exhibited remarkable catalytic activity toward enantioselective olefin epoxidation using O2 as terminal oxidant in the presence of isobutyraldehyde. The catalyst showed higher enantioselectivity than its homogeneous counterpart in the oxidation of α-methylstyrene. SBA15-[Mn(TCPP-R∗)Cl] catalyzed epoxidation of styrene was achieved within 8h and optically active styrene oxide was obtained in 89% ee and 90% yield. Likewise, styrene derivatives (trans-β-methylstyrene, indene), conjugated cis- and trans-disubstituted olefins (e.g. cis- and tans-stilbene) and terminal olefins were converted effectively to their corresponding epoxides in 63–99%ee under the Mn(III)-catalyzed conditions. The catalyst could be recycled five times without any significant loss in activity.

N-Hydroxyphthalimide Immobilized on Poly(HEA-co-DVB) as Catalyst for Aerobic Oxidation Processes

In the present study, poly(HEA-co-DVB) was synthesized (loading of OH groups: 8.07 mmol OH/g, crosslinking degree: 6 % DVB) and used for N-hydroxyphthalimide (NHPI) immobilization via ester bond (NHPI loading: 2.06 mmol NHPI/g). The obtained polymeric support and poly(HEA-co-DVB)/NHPI catalyst were characterized by FT-IR and XPS spectroscopy, elemental analysis, thermogravimetry and particle size measurement. The novel polymer-supported NHPI catalyst was tested in aerobic oxidation of p-methoxytoluene and α-methylstyrene. The studied reactions were carried out in the presence of AIBN and/or Co(II) salt without solvent or in acetic acid as solvent. It was found that the obtained polymer-supported NHPI catalyst showed the best catalytic performance, which was attributed to a high content of accessible NHPI moieties. The recovery and recycling of the obtained HEA/DVB-NHPI was only possible in reactions proceeded in solvent-free conditions.

Pathways of α-methylstyrene Oxidation by P. aeruginosa DS-26

Today in world practice the biotechnological methods of cleaning of environment from oil and oil products are widely used. They based on the use of microorganisms-destructors that are able to utilize<br />hydrocarbons. The microbial object of the research was bacterial strain <em>P. aeruginosa</em> DS-26. This bacterial culture was isolated from sewage water of rubber industry. This strain was able to grow in a medium, which contained <em>α</em>-methylstyrene. This compound, which is widely used as an active component in many industries, has a<br />strong toxic effect on living organisms including humans. Different types of microbial metabolism play an important role in the hydrocarbon degradation process in the environment Metabolism of <em>α</em>-methylstyrene by <em>P. aeruginosa</em> DS-26 characterized by variety and in depth of carried out transformations. The analysis of the obtained data allowed offering two ways of oxidation of α-methylstyrene. The first way, primary, was accompanied by formation of products of the direct hydroxylation of aromatic ring - cis-2.3-dihydroxy-1-isopropenyl-6-cyclohexene and 3-isopropyl-catehol which are later metabolized by meta-pathway with formation of keto-acids. The next, secondary pathway came true through oxidation of α-phenylpropionic acid and 4-methylbenzene alcohol with formation of acetophenone as a final product.<br />There are many researches that are devoted to study biochemical conversion of oil hydrocarbons. In order to utilize specific compounds as the only one source of carbon, microorganisms have to actively maintain a specific system of enzymes. Investigation of <em>α</em>-methylstyrene degradation by <em>P. aeruginosa</em> DS-<br />26 enzymes has revealed specific enzymes that oxidize aromatic hydrocarbons. Investigation results of the studying strain enzymes can be confirmation of the proposed above scheme of primary α-methylstyrene metabolic pathway oxidized by <em>P. aeruginosa</em> DS-26.

A cis-dioxomolybdenum Schiff base complex: synthesis, crystal structure and catalytic activity in oxidation of olefins using hydrogen peroxide

A cis-dioxomolybdenum(VI) Schiff base complex [MoO2L] has been synthesized and structurally characterized. Homogeneous oxidation of olefins using the complex as a catalyst with hydrogen peroxide as oxidant in ethanol solution showed high catalytic activity for this complex. Under reflux conditions, the oxidation of cyclooctene, styrene, α-methyl styrene, 4-methyl styrene and 1-methyl cyclohexene with hydrogen peroxide gave the corresponding epoxides as the sole products.

Synthesis, characterization, optical properties and catalytic activity of CuO/Al2O3 nanoparticles for the green epoxidation of olefins

CuO/Al2O3 nanoparticles were synthesized in the presence of PEG400 by deposition in alkaline environment. CuO/Al2O3 nanoparticles were characterized by SEM, X-ray diffraction, FT-IR, UV–Vis and PL emission spectra. CuO/Al2O3 nanoparticles catalyze the epoxidation of α-methylstyrene, styrene, cyclooctene, cyclohexene, trans-stilbene and norbornene using H2O2 as an oxidant in ethanol. Under optimized reaction conditions, 100 % conversion of α-methylstyrene has been achieved where selectivity of α-methylstyrene oxide was 92 %.

N2O2-Cu(II) Schiff Base Complex and Its Encapsulation Into Nanocavity of Y-Zeolite: An Efficient Heterogeneous and Homogeneous Catalyst for Oxidation of Olefins

Copper(II) complex (CuL) of a Schiff base ligand derived from 2-hydroxy-naphthaldehyde and 3,4-diaminotoluene has been synthesized and encapsulated in the nanocavity of Y-zeolite (CuL-NaY). The synthesis compounds have been characterized by IR, 1H NMR, and UV-Vis spectroscopic studies. CuL and CuL-NaY catalyzed the oxidation of olefins using tert-butylhydroperoxide as oxidant in good yield. Under the optimized reaction condition, the oxidation of cyclooctene, cyclohexene, styrene, and α-methyl styrene catalyzed by CuL gave 83%, 56%, 81%, and 84% conversion, respectively. The oxidation of cyclooctene, cyclohexene, styrene and α-methyl styrene catalyzed by CuL-NaY gave 100%, 45%, 84%, and 79% conversion, respectively.

Trigger factor assisted folding of the recombinant epoxide hydrolases identified from C. pelagibacter and S. nassauensis

Epoxide hydrolases (EHs), are enantioselective enzymes as they catalyze the kinetic resolution of racemic epoxides into the corresponding enantiopure vicinal diols, which are useful precursors in the synthesis of chiral pharmaceutical compounds. Here, we have identified and cloned two putative epoxide hydrolase genes (cpeh and sneh) from marine bacteria, Candidatus pelagibacter ubique and terrestrial bacteria, Stackebrandtia nassauensis, respectively and overexpressed them in pET28a vector in Escherichia coli BL21(DE3). The CPEH protein (42kDa) was found to be overexpressed as inactive inclusion bodies while SNEH protein (40kDa) was found to form soluble aggregates. In this study, the recombinant CPEH was successfully transformed from insoluble aggregates to the soluble and functionally active form, using pCold TF vector, though with low EH activity. To prevent the soluble aggregate formation of SNEH, it was co-expressed with GroEL/ES chaperone and was also fused with trigger factor (TF) chaperone at its N-terminus. The TF chaperone-assisted correct folding of SNEH led to a purified active EH with a specific activity of 3.85μmol/min/mg. The pure enzyme was further used to biocatalyze the hydrolysis of 10mM benzyl glycidyl ether (BGE) and α-methyl styrene oxide (MSO) with an enantiomeric excess of the product (eep) of 86% and 73% in 30 and 15min, respectively. In conclusion, this is the first report about the heterologous expression of epoxide hydrolases using TF as a molecular chaperone in pCold TF expression vector, resulting in remarkable increase in the solubility and activity of the otherwise improperly folded recombinant epoxide hydrolases.

Catalytic activity of carbon nanotube supported iron(III) and manganese(III) porphyrins in oxidation of olefins with tert-butyl hydroperoxide: Higher activity of the iron(III) porphyrin

Abstract Oxidation of olefins with tert-butyl hydroperoxide (TBHP) catalyzed by carbon nanotube supported iron(III) and manganese(III) complexes of meso-tetrakis(4-hydroxyphenyl)porphyrin is reported. The results show higher catalytic activity of the Fe(III) complex compared to the Mn(III) one. With the exception of cyclooctene which gives cyclooctene oxide as the sole product, oxidation of styrene, α-methyl styrene and cyclohexene leads to the formation of benzaldehyde, acetophenone and cyclohexene-1-one as the major product, respectively. In this study, acetonitrile has been found to be the best solvent for reaction performed in the presence of the manganese and iron porphyrin. In comparison of the two metalloporphyrins, catalytic activity of the manganese porphyrin is more sensitive to the type of solvent than the iron one. In spite of the crucial role of imidazole (ImH) on catalytic performance of the manganese porphyrin, the presence of ImH has a negative effect on the activity of the iron porphyrin. The nano-tube supported iron porphyrin may be recovered and reused at least four times without significant loss of the catalytic activity.

Regioselectivity Control of the Ring Opening of Epoxides With Sodium Azide in a Microreactor

The reaction of different types of aromatic and aliphatic epoxides with sodium azide to give vicinal azido alcohols was studied in a microreactor with and without pillars in the channels. Dependent on the substrate, the regioselectivity of the ring opening is affected by the used solvent system, viz. acetonitrile–water (sometimes with 10% acetic acid to promote the reactivity of substrates) or t-butyl acetate–water containing Tween80 as a surfactant. For styrene oxide and α-methylstyrene oxide, the α/s regioselectivity changes from 4 to 10 and 1.7 to 6.2, respectively, going from acetonitrile–water to Tween80-containing t-butyl acetate–water. The addition of a surfactant (Tween80) stabilizes the interface in the biphasic t-butyl acetate–water. Pillar-containing microreactors gave better conversions than microreactors without pillars and lab scale reactions, probably due to better mixing.

Nonthermal Synthesis of Three-Dimensional Metal Oxide Structures under Continuous-Flow Conditions and Their Catalytic Applications

Continuous-flow synthesis of one-dimensional (1D) metal oxide nanostructures and/or their integration into hierarchical structures under nonthermal conditions is still a challenge. In this work, a nonthermal, continuous-flow approach for the preparation of γ-manganese oxide (γ-MnO2) and cerium oxide (CeO2) microspheres has been developed. By this technique, γ-MnO2 materials with surface areas of 240, 98, and 87 m2/g and CeO2 microspheres with a surface area of 1 m2/g have been fabricated successfully. Characterization of the materials was carried out using powder X-ray diffraction, infrared and inductively coupled plasma optical emission spectrometer (ICP/OES), nitrogen sorption, scanning electron microscopy, transmission electron microscopy, and thermogravimetric analysis. The synthesized materials showed good catalytic activity in the oxidation of α-methyl styrene.

Photocatalytic activities for partial oxidation of α-methylstyrene over zeolite-supported titanium dioxide and the influence of water addition to reaction solvent

The photocatalytic reaction in the partial oxidation of α-methylstyrene (α-MS) to acetophenone (AP) was investigated for TiO 2 supported on H-ZSM-5 (H-MFI), H-mordenite (H-MOR), and H-Y-type (H-FAU) zeolites. XRD results demonstrated that the anatase was the stable phase of TiO 2 supported on zeolites. Photocatalytic activities of supported catalysts decreased in the following order: TiO 2/H-MFI >> TiO 2/H-MOR > (TiO 2) > TiO 2/H-FAU >> (blank). TiO 2/H-MFI catalyst exhibited the best performance for photocatalytic oxidation of α-MS to AP. The maximal activity was obtained by 25 wt% TiO 2/H-ZSM-5. The addition of water to the reaction solvent resulted in significantly lowering the photocatalytic activity for TiO 2/H-ZSM-5 catalyst, although its activity for TiO 2 and TiO 2 + H-ZSM-5 mechanical mixture was little influenced by the amount of water added to reaction solvent.

Regioselective Ring Cleavage of Phenyl- or/and Alkyl- Substituted Epoxides with Al-Methanesulfonyldiisobutylalane

C. The regioselectivities shown in these reactions of one alkyl- or phenyl- substituted epoxides such as 1,2-epoxybutane and styrene oxide are extraordinary. The reagent attacked only the more hindered site of epoxy ring to produce the corresponding primary alcohol as a sole product. These results clearly indicate that the reaction proceed s through trapping of β-hydrogen from isobutyl group of the reagent at the site best able to accommodate a carbocation. Such interpretation was further confirmed by the results obtained from the reaction of more substituted epoxides such as 2,3-epoxy-2-methylbutane and α-methylstyrene oxide: the products are 3-methyl-2-butanol and 2-phenyl-1-propanol, respectively. Again, the selectivities are perfects.Particularly interesting example is the reaction of

Enhancement in microporosity and catalytic activity on grafting silica and organosilica moieties in lamellar titanium phosphate framework

New silica-grafted analogs of lamellar semicrystalline titanium phosphate (sc-TiOP), silicotitanium phosphate (STP) and organic–inorganic hybrid silicotitanium phosphate (HSTP) have been synthesized under hydrothermal condition without the assistance of any template or structure-directing agent under acidic pH conditions. These materials were characterized by elemental analysis, powder XRD, field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), N2 sorption and spectroscopic studies. N2 adsorption studies revealed that the surface area increased significantly when the Si atoms were incorporated into the layered titanium phosphate framework. The surface area improves further with the grafting of organosilane moiety in HSTP material. Fourier-transformed infrared (FT IR), UV–vis and X-ray photoelectron spectroscopic (XPS) results suggested the presence of Si–O–P, Ti–O–Si bonds and octahedral coordination of Ti(IV) in these novel microporous materials. Si- and Si–CH2CH2–Si-grafted materials showed considerable enhancement in catalytic activity towards the liquid phase partial oxidation of styrene, α-methyl styrene, cyclohexene and acrylic acid using dilute H2O2 as an oxidant. These materials also showed excellent catalytic activity and selectivity in ammoximation of cyclohexanone to cyclohexanone oxime in the presence of aqueous ammonia and dilute aqueous H2O2 with reference to the silica-free sc-TiOP analogue.

Photocatalytic partial oxidation of α-methylstyrene over TiO 2 supported on zeolites

The photocatalytic reaction in the partial oxidation of α-methylstyrene (α-MS) to acetophenone (AP) was investigated for TiO 2 supported on Y-type, moredenite, and ZSM-5 zeolites. XRD and FT-Raman results demonstrated that the anatase is the stable phase of TiO 2 supported on zeolites and no rutile phase was observed in the supported catalysts calcined at 723–973 K. TiO 2 supported on zeolites was found to catalyze the partial oxidation of α-MS to AP under light irradiation (>290 nm). The photocatalytic activity of TiO 2 supported on zeolites was significantly improved by the addition of the water to the organic solvent. It was found that the optimized amount of water added for TiO 2 supported on zeolite catalysts was smaller than that for TiO 2 catalyst.

Oxidation of α-methylstyrene on an MCM-22 encapsulated (R, R)-(−)-N, N′-bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexanediaminocobalt(II) catalyst

Abstract(R, R)-(−)-N, N′-bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexanediaminocobalt(II) was encapsulated into MCM-22 using the zeolite synthesis method. The encapsulated catalyst proved to be active in the oxidation of α-methylstyrene with NaOCl with higher specific activity than the homogeneous catalyst. At the same time, this encapsulated catalyst was completely inactive in the hydrolytic kinetic resolution of racemic styrene oxide. This observation is in a good correlation with the assumption of the cooperative bimetallic mechanism proposed by Annis and Jacobsen.

Preparation of polymeric sheet porphyrin complexes and their environmentally benignly catalytic activity

The polymeric meso-tetra-(1,5-naphthalene bisulfonyloxo)phenylporphyrin and its complexes (PTNBSOPPM, M=Co, Mn, Fe) have been prepared in the presence of phase-transfer catalyst. Catalyzed by polymeric porphyrin complexes (PTNBSOPPM), styrene can be aerobic oxidized. The main products come from cleavage of double bond is in catalytic oxidation of styrene or α-methyl styrene.