Presence Of Tert-butyl Hydroperoxide Research Articles

Real-Time Raman Monitoring during Photocatalytic Epoxidation of Cyclohexene over V-Ti/MCM-41 Catalysts

A series of V- and/or Ti-loading MCM-41 catalysts are successfully synthesized with a hydrothermal method. The photocatalytic and thermal epoxidations of cyclohexene in the presence of tert-butyl hydroperoxide (t-BuOOH) were investigated with real-time monitored by NIR-Raman spectroscopy. It suggests that both V- and Ti-loading can be responsible for the cyclohexene epoxidation. Moreover, the complementary behavior of V- and Ti-loading may be related to a similar role of activation. Interestingly, the progress of the photo-epoxidation on V0.25Ti2/MCM-41 photocatalyst was monitored by changes in intensity of the characteristic Raman bands without interference from the UV-light irradiation. The result, for the first time, reveals that cyclohexene was directly photo-epoxidized to 1,2-epoxycyclohexane by t-BuOOH during the reaction. A possible mechanism of cyclohexene photo-epoxidation is also proposed for this study.

ChemInform Abstract: Cobalt‐Catalyzed Direct C—C Bond Formation Between Tetrahydrofuran and Alkynes.

Abstract We aimed to describe an efficient CoCl2-catalyzed direct C–C bond formation of tetrahydrofuran (THF) with various alkynes in the presence of tert-butyl hydroperoxide and catalytic amount of acid to obtain vinyl-substituted THFs. Mono- and di-substituted alkynes were suitable for this transformation.

Mononuclear Manganese(II)/4′-Ar-2,2′:6′,2″–Terpyridine Complexes: Synthesis, Characterization, and Olefins Oxidation Study

A series of mononuclear Mn(II)/terpyridine complexes were synthesized and characterized by elemental analysis, IR spectrum, and UV-vis spectrum. Catalytic activities of Mn(II)/4′-Ar-2,2′:6′,2″–terpyridine complexes were tested in the oxidation of cyclohexene or styrene in the presence of tert-butylhydroperoxide as oxidant. Significant catalytic effects of these complexes were observed in the oxidation of olefins, especially in the cyclo-oxidation of styrene.

Use of a molybdenum(VI) dioxide complex as a homogeneous and heterogeneous magnetically recoverable epoxidation catalyst

A Mo(VI) complex, [MoO2HL(HOCH3)], HL = 2-[(2-hydroxy-benzylidene)-amino]-3-(4-hydroxy-phenyl)-propionic acid, was reacted with 3-(chloropropyl)-trimethoxysilane-functionalized silica that had been fused with magnetite to yield a magnetically separable catalyst in which the Mo complex was covalently linked to the silica matrix through a silane linkage. Both the free [MoO2HL(HOCH3)] and the immobilized complex function as efficient catalysts for the oxidation of olefins in the presence of tert-butylhydroperoxide as primary oxidant. The Fe3O4@SiO2/[MoO2L(HOCH3)] showed lower catalytic activity and turnover numbers compared to its homogeneous counterpart. However, the immobilized catalyst could be readily recovered from the reaction mixture by using a magnet and could be reused up to seven times without any loss of activity.

Specifics of reaction between tri-ortho-tolylantimony and cyclohexanone oxime in the presence of peroxides: Structure of tri-ortho-tolylantimony bis(cyclohexanone oximate) and its adduct with tri-ortho-tolylantimony oxide

Tri-ortho-tolylantimony bis(cyclohexanone oximate) (o-Tol)3Sb(ON=C6H10-cyclo)2 (I) has been synthesized by the reaction between tri-o-tolylantimony and cyclohexanone oxime in the presence of tert-butyl hydroperoxide (1: 2: 1 mol/mol/mol). When the molar ratio of reagents was 1: 1: 1, the adduct (o-Tol)3Sb(ON=C6H10-cyclo)2 · [(o-Tol)3SbO]2 (II) has been isolated from the reaction. According to X-ray diffraction data, the axial OSbO and equatorial CSbC angles in complex I are 168.61(7)° and 112.4(1)°–124.2(1)°, respectively. The Sb-C and Sb-O bonds are 2.123(3)–2.126(2) and 2.062(2), 2.068(2) A, respectively. The molecules in adduct II have geometric parameters close to the respective parameters of the individually crystallizing compounds.

Mechanistic insights into the vanadium-catalyzed Achmatowicz rearrangement of furfurol.

The Achmatowicz rearrangement is a powerful method for the construction of pyranones from simple furan derivatives. Here, we describe the development of improved reaction conditions and an interrogation into the fate of the metal center during this interesting transformation. The reaction to form the synthetically important lactol, 6-hydroxy-2H-pyran-3(6H)-one (3), proceeds cleanly in the presence of tert-butyl hydroperoxide (TBHP, 2) using low loadings of VO(O(i)Pr)3 as catalyst. The nonaqueous conditions developed herein allow for easy isolation of product 3 and synthetically important derivatives, a key advantage of this new protocol. Detailed experimental, spectroscopic, and kinetic studies along with kinetic modeling of the catalytic cycle support a positive-order dependence in both furfurol and TBHP concentrations, first-order dependence in catalyst (VO(O(i)Pr)3), and a negative dependence on the 2-methyl-2-propanol (4) concentration. (51)V-NMR spectroscopic studies revealed that 2-methyl-2-propanol (4) competes with substrates for binding to the metal center, rationalizing its inhibitory effect.

Metal-Free Csp3–N Bond Cleavage of Amides Using tert-Butyl Hydroperoxide as Oxidant

A mild and efficient protocol for the metal-free C–N bond-cleavage of amides has been developed. The methodology employs iodine as a catalyst to cleave the C(Me)–N bond of dimethylformamide or dimethylacetamide, providing novel access to methylene-bridged bis-1,3-dicarbonyl compounds instead of enol carbamates in the presence of tert-butyl hydroperoxide.

Oxidation of substituted benzyl amines using a phenoxo-bridged dimeric nickel(II) complex: synthesis, crystal structure and catalytic activity

A benzimidazole-based Schiff base ligand and its dinuclear complex [Ni2(L)2(NO3)2] where L = 2-[2-(1H-benzo[d]imidazole-2-yl)ethylimino)methyl] phenol have been synthesized. An X-ray crystallographic study showed that both the metal centers in the complex adopt a distorted octahedral geometry. Variable-temperature magnetic studies suggest that the nickel(II) centers are antiferromagnetically coupled. Cyclic voltammetry confirms that the dinickel complex retains its identity in the presence of tert-butyl hydroperoxide in the solution state. The complex has been used as a catalyst for the homogeneous oxidation of substituted benzyl amines in the presence of tert-butyl hydroperoxide. The yields of these reactions depend upon the nature of the substituent in the aromatic ring.

Multifunctional membranes based on natural polymers: preparation, characterization and in vitro performance evaluation

The aim of this study was to synthesize new multifunctional biopolymers via esterification of hemp fibres with two reagents: meso-2,3-dimercaptosuccinic acid and ethylenediaminetetraacetic acid. The obtained biopolymers were characterized using infrared spectroscopy. The antibacterial activity of the derivative containing ethylenediaminetetraacetic acid moiety was evaluated by assessing the growth inhibition of Pseudomonas aeruginosa in Petri dishes. The results suggest that this biomaterial exhibits an excellent in vitro antibacterial activity. The antioxidant activity of the biopolymer from meso-2,3-dimercaptosuccinic acid was tested in rat liver microsomal membranes in the presence of tert-butylhydroperoxide as free radical source. Results suggest that this material inhibits lipid peroxidation induced by the free radical species. Both derivatives were used to prepare multifunctional membranes that were characterized and tested indicating the maintenance of biopolymer functionalized properties. Moreover, these functionalized biopolymers interact with metal ions due to their chelating functional groups. The absorption capacity for a selected metal ion, Cd(II), was investigated in aqueous solutions at pH = 0.65, 4.1 and 7.0 using optical emission spectroscopy. This study demonstrates that these new materials are very effective in chelating cadmium ions showing maximum efficiency at pH = 7.0. © 2014 Society of Chemical Industry

Facile Synthesis of Copper-Based Metal Oxide Nanoparticles with Exceptional Catalytic Activity for the Selective Oxidation of Styrenes into Benzaldehydes.

The development of highly efficient catalysts for the selective oxidation of styrene to benzaldehyde has attracted great attention in recent years because of its significance in synthetic chemistry. In this study, two different kinds of copper-based metal oxide nanoparticles (NPs), namely, CuO and CuO/Co3 O4 NPs, were synthesized by a simple and scalable method, and these nanoparticles demonstrated efficient catalytic abilities for the selective oxidation of styrene and its derivatives to the corresponding aldehydes in the presence of tert-butyl hydroperoxide (TBHP) under mild reaction conditions in excellent yields. Importantly, both of the heterogeneous catalysts can be recycled up to five runs while still maintaining their high catalytic activity.

Tri-m-tolylantimony dibenzoate: Synthesis and structure

Tri-m-tolylantimony dibenzoate (II) has been synthesized by the reaction between tri-m-tolylantimony (I) and benzoic acid in diethyl ether in the presence of tert-butylhydroperoxide with a yield of 95%. According to X-ray diffraction data, a molecule of compound I is shaped as a trigonal pyramid with a lone pair on the antimony atom (Sb-C, 2.146(3), 2.148(3), and 2.152(3) A; CSbC, 96.49(11)°, 96.91(11)°, and 97.28(11)°). An antimony atom in compound II has a distorted trigonal bipyramidal coordination to the oxygen atoms in axial positions. The Sb-C and Sb-O distances are 2.107(3)–2.121(3) A and 2.134(2), 2.140(2) A, respectively. The OSbO and CSbC angles are 175.68(9)° and 108.02(14)°–140.36(15)°, respectively. The Sb…O intramolecular contacts are 2.869(4) and 2.925(4) A.

Cobalt-catalyzed direct C–C bond formation between tetrahydrofuran and alkynes

We aimed to describe an efficient CoCl2-catalyzed direct C–C bond formation of tetrahydrofuran (THF) with various alkynes in the presence of tert-butyl hydroperoxide and catalytic amount of acid to obtain vinyl-substituted THFs. Mono- and di-substituted alkynes were suitable for this transformation.

Copper-free direct C-H trifluoromethylation of acetanilides with sodium trifluoromethanesulfinate.

A copper-free direct C-H ortho trifluoromethylation of electron-deficient 4-substituted acetanilides using Langlois reagent (NaSO2CF3) as the CF3 source in the presence of tert-butyl hydroperoxide (tBuOOH, TBHP) was developed.

Molybdenum (0) and tungsten (0) carbonyl N-heterocyclic carbene complexes as catalyst for olefin epoxidation

A series of Mo(0) and W(0) carbonyl N-heterocyclic carbene (NHC) complexes containing monodentate NHC ligands with the formulae of M(CO)4(NHC)2 (NHC = IBz = 1,3-dibenzylimidazol-2-ylidene, M = Mo (1a), W (2a); NHC = InPr = 1,3-dipropylimidazol-2-ylidene, M = Mo (3), W (4a)) and M(CO)5(NHC) (NHC = IBz, M = Mo (1b), W (2b); NHC = InPr, M = W (4b); NHC = IMes = 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene, M = Mo (5), W (6)) and the complexes containing chelating NHC ligands Mo(CO)4(PyNHC) (PyNHC = 3-methyl-1-picolylimidazol-2-ylidene (7)) and Mo(CO)3(Py2NHC) (Py2NHC = 1,3-dipicolylimidazol-2-ylidene (8)) have been synthesized and fully characterized. They show moderate catalytic activities towards cyclooctene epoxidation in the presence of tert-butyl hydroperoxide (TBHP). The stability of Mo–CNHC bond under oxidative condition has been investigated.

Stability and catalytic properties of μ-oxo and μ-nitrido dimeric iron tetrasulfophthalocyanines in the oxidation of Orange II by tert-butylhydroperoxide

A study of catalytic activity of μ-nitrido- and μ-oxo-dimeric iron tetrasulfophthalocyanines in the oxidation of Orange II by tert-butylhydroperoxide in aqueous solutions has been performed. It is shown that though in one catalytic cycle activity of μ-oxo-dimer is higher, stability of this complex in oxidative conditions is poor. μ-nitrido-dimer combines relatively good catalytic activity with very high stability in the presence of tert-butylhydroperoxide. The mechanisms of oxidative decomposition of dimers and catalytic oxidation of Orange II have been proposed on the base of kinetic results. The products of catalytic processes are shown to be bio-degradable non-toxic small organic compounds.

Chemical modification of chloroperoxidase for enhanced stability and activity

Chloroperoxidase from Caldariomyces fumago (CPO, EC 1.11.1.10) is one of the most interesting enzymes from the group of heme peroxidases and has been extensively applied in synthetic processes. Nevertheless, the practical application of CPO is limited due to its very low operational stability, especially in the presence of peroxidative compounds. For this reason, effect of chemical modifications of CPO in the stability of the enzyme was studied. Side-chain selective modifications of amino groups of Lys residues, and carboxyl groups of Asp and Glu residues, as well as crosslinking and periodate oxidation of sugar moiety were carried out. The stability of modified CPOs was evaluated at elevated pH and temperature, and in the presence of tert-butyl hydroperoxide. Effect of modification of CPO on the performance of the reaction of Cbz-ethanolamine oxidation was studied as well. Those modifications that involved carboxyl groups via carbodiimide coupled method and the periodate oxidation of the sugar moiety produced better catalysts than native CPO in terms of stability and activity at elevated pH values and temperatures.

Highly selective and direct oxidation of cyclohexane to cyclohexanone over vanadium exchanged NaY at room temperature under solvent-free conditions

Vanadium exchanged zeolite Y has been synthesized by simple ion-exchange on NaY and resulting V–Y material has been employed as a heterogeneous catalyst for highly selective and direct one-pot liquid phase oxidation of cyclohexane to cyclohexanone under solvent-free conditions at room temperature. The catalyst (V–Y) has been thoroughly characterized by powder X-ray diffraction (PXRD), N2 sorption, transmission electron microscopic (TEM), Fourier transform infrared (FT IR), UV–visible, X-ray photoelectron spectroscopic (XPS) and atomic absorption spectroscopic (AAS) analyses. The selective oxidation reaction proceeds smoothly over this V-containing heterogeneous catalyst in the presence of tert-butylhydroperoxide (TBHP) as oxidant and the progress of the reaction has been monitored thoroughly by gas chromatographic (GC) and gas chromatography coupled with mass spectrometric (GC–MS) analyses. The recycling efficiency of the V–Y catalyst has been tested by conducting the catalytic reaction repeatedly with the recovered catalyst, where almost retention of the original catalytic activity and selectivity after five reaction cycles has been observed. The effect of oxidant amounts on the catalytic reaction has been studied. Mechanistic pathway for the catalytic reaction over this inexpensive, non-air sensitive, eco-friendly and reusable vanadium exchanged zeolite has been proposed, suggesting future potential of V–Y in solvent-free liquid phase selective oxidation reactions under very mild conditions.

Synthesis, characterization and catalytic properties of multinuclear copper(II) complexes

Four tetranuclear [Cu4(O)(Ln)2(CH3COO)4] (1, 2, 4 and 5) and one pentanuclear [Cu5(OH)2(L3)2(CH3COO)6] (3) with N2O-donor Schiff-base ligands have been synthesized, where HL1=4-methyl-2,6-bis(2-hydroxyethyliminomethyl)phenol for complex 1, HL2=4-methyl-2,6-bis(3-hydroxypropyliminomethyl)phenol for complex 2, HL3=4-methyl-2,6-bis(4-hydroxybutyliminomethyl)phenol for complex 3, HL4=4-methyl-2,6-bis(5-hydroxypentyliminomethyl)phenol for complex 4 and HL5=4-methyl-2,6-bis(6-hydroxyhexyliminomethyl)phenol for complex 5. These complexes have been characterized by elemental analysis, FT-IR, UV–Vis spectroscopy. The structures of 1, 3, 4 and 5 have been determined by single crystal X-ray diffraction studies. X-ray analysis reveals that complexes 1, 4 and 5 are μ4-oxido-bridged tetrameric copper(II) complexes, where four copper atoms arrange themselves around an oxidooxygen atom at the vertices of a distorted tetrahedron. The pentanuclear complex, 3, has been found to have two μ3-hydroxido bridging ligands each connecting three copper atoms. These complexes have been employed as catalyst for the epoxidation of olefins in the presence of tert-butyl hydroperoxide (TBHP) as the oxidant under mild conditions.

Template-free method to prepare porous Cu-containing nanotubes with a good catalytic performance for styrene epoxidation

Cu-containing nanotubes with a large surface area and pore volume were prepared by using nanoscrolls derived from K4Nb6O17 as a support and a subsequent thermal transformation of Cu-containing nanoscrolls into Nb2O5 nanotubes. The method is facile and template-free. The catalytic performance of the resulted Cu-containing nanotubes was evaluated for styrene epoxidation in the presence of tert-butyl hydroperoxide (TBHP) and H2O2, respectively. It was found that Cu-containing nanotubes displayed a relative good catalytic performance with a styrene oxide (SO) selectivity of 46.9% by TBHP and a much higher SO selectivity of 94.6% by H2O2. Two possible mechanisms were put forward to explain the different catalytic behaviors in the two types of oxidation systems. Because of the thermal transformation of nanoscrolls into nanotubes, nanoscrolls may be a new kind of promising support for the design and assembly of novel heterogeneous catalysts.

Catalytic activity and selectivity of reusable α-MoO3nanobelts toward oxidation of olefins and sulfides using economical peroxides

The novel catalytic activity of α-MoO3 nanobelts prepared by a new and safe sol–gel method for the epoxidation of olefins and oxidation of sulfides to sulfoxides using H2O2 in ethanol as a safe solvent has been exploited. The reactions also proceeded efficiently in the presence of tert-butyl hydroperoxide (TBHP). Good/high yields and excellent selectivity resulted. The ammonia TPD profile demonstrated strong acidic sites in synthesized α-MoO3 nanobelts, which generated different catalytic activity than the bulk material. The separation and reuse of this heterogeneous nanocatalyst was simple, effective and economical in the presented oxidation methods.