Presence Of Tert-butyl Hydroperoxide Research Articles

Cu6Se4.5 Nanoparticles from a single source precursor: Recyclable and efficient catalyst for cross-dehydrogenative coupling of tertiary amines with terminal alkynes

The use of copper selenide nanocatalyst for an efficient and regioselective cross-dehydrogenative coupling (CDC) of tertiary amines with terminal alkynes in the presence of tert-butyl hydroperoxide as the oxidant is demonstrated for the first time. The catalyst comprising of unique Cu6Se4.5 nanoparticles synthesized from a single source precursor CuSePh, is required in much lower amount (1mol%), and is recyclable up to four reaction cycles with slight loss in activity. The reaction can be executed in the absence of solvent, is applicable to aromatic, benzylic, and aliphatic tertiary amines, and furnishes propargylamines in moderate to good yields.

ChemInform Abstract: Direct Difunctionalization of Activated Alkynes via Domino Oxidative Benzylation/1,4‐Aryl Migration/Decarboxylation Reactions under Metal‐Free Conditions.

The oxidative difunctionalization of aryl alkynoates via benzyl radical initiated intramolecular 1,4-aryl migration and decarboxylation tandem process was developed in the presence of tert-butyl hydroperoxide as an oxidant, which provides a direct and selective route to a variety of trisubstituted alkenes from simple toluene derivatives and aryl alkynoates.

Highly efficient and recyclable magnetic nanoparticles-supported gold(III)-bipy catalyst for oxidative α-cyanation of tertiary amines

Oxidative α-cyanation of tertiary amines with trimethylsilyl cyanide was achieved by using a magnetic nanoparticles-supported gold(III)-bipy complex as catalyst to afford the corresponding α-aminonitriles in good to excellent yields in the presence of tert-butyl hydroperoxide under acid-free conditions. The new heterogeneous gold catalyst can easily be separated from the reaction mixture by using an external magnet and can be recycled for at least 10 times without any loss of activity.

Solvent-free aerobic oxidation of 1-octene using graphite-supported gold–palladium nanoparticle catalysts

The catalytic activity of gold nanoparticles on 1-octene oxidation was investigated under various reaction conditions using air as the oxygen source. We demonstrated that 1-octene can be oxidized by gold catalyst under solvent-free conditions. We also investigated the effect of support, the preparation method, and the choice of metal. We showed that graphite provided the best support for these gold catalysts, and the preparation methods that afforded the smallest particles were the most active. The effect of the gold:palladium ratio on the oxidation of 1-octene was investigated, and monometallic gold catalysts showed better activity when compared with bimetallic catalysts. Thus, the oxidation of 1-octene can be achieved using graphite-supported gold nanoparticles under solvent-free conditions in the presence of tert-butyl hydroperoxide as a radical initiator using oxygen from the air.

Triphenylbismuth bis(3,4-dimethylbenzenesulfonate): Synthesis and structure

Triphenylbismuth bis(3,4-dimethylbenzenesulfonate) Ph3Bi(OSO2C6H3Me2-3,4)2 (I) has been synthesized by the reaction between triphenylbismuth and 3,4-dimethylbenzenesulfonic acid in the presence of tert-butylhydroperoxide (1: 2: 1 mol) in ether. The bismuth atom in complex I has a trigonal bipyramidal coordination to arenesulfonates substituents in axial positions (axial OBiO angle, 173.99(8)°; equatorial CBiC angles, 106.94(11)°, 112.24(11)°, 140.77(11)°). The Bi‒C distances are 2.189(3), 2.192(3), and 2.197(3) A; the Bi‒O distances are 2.284(2) and 2.301(2) A. Some intramolecular contacts are observed between the central atom and the oxygen atoms of sulfonate groups at the maximum equatorial angle (Bi···O 3.122(3), 3.189(4) A).

Extra virgin olive oil phenolic extracts counteract the pro-oxidant effect of dietary oxidized lipids in human intestinal cells

The phenolic fraction of extra virgin olive oil (EVOO) concentrates before absorption in the intestinal lumen, where it may contribute to the modulation of enterocytes response to oxidative and inflammatory stimuli. We evaluated the ability of two monovarietal EVOOs phenolic extracts, Bosana and Nera di Gonnos/Tonda di Cagliari, typical and widespread varieties in Sardinia (Italy), to counteract in enterocytes like Caco-2 cells the pro-oxidant action of oxidized lipids, tert-butyl hydroperoxide (TBH) or a mixture of oxysterols of dietary origin. We confirmed that TBH treatment causes a significant increase of ROS production, GSH depletion, increase of MDA, fatty acids hydroperoxides and 7-ketocholesterol, and showed first evidence of oxidative imbalance and cell damage due to oxysterols exposure. Preincubation of cells with the phenolic extracts significantly attenuated oxidative modifications. Bosana extract showed the highest concentration of total phenols, mainly hydroxytyrosol and tyrosol, and was the most active in presence of TBH, where the free radical scavenging activity of these simple phenols seems to be a determining factor. The two extracts were equally effective, in spite of the different composition, in presence of oxysterols, where ROS production probably occurs according to different and more complex mechanisms.

New molybdenum(VI) complexes with thiazole-hydrazone ligand: Preparation, structural characterization, and catalytic applications in olefin epoxidation

The reaction of [MoO2(acac)2] with (E)-2-((2-(benzo[d]thiazol-2-yl)hydrazono)methyl)-6-methoxyphenol (H2L), in acetonitrile and ethanol resulted in the formation of {[MoO2(HL)(H2O)]2[Mo6O19]·2MeCN} (1) (mononuclear cationic complex with hexamolybdate anion) and [MoO2L(EtOH)] (2) (neutral mononuclear complex), depending on the reaction conditions. In these compounds, the ligand is coordinated to the cis-MO22+ core via phenolic-oxygen, thiazole and azomethine nitrogen atoms, while the remaining sixth coordination site is occupied by the oxygen atom from the solvent molecule. Crystal and molecular structures of the compounds 1 and 2 were determined by the single crystal X-ray diffraction method. All of the investigated compounds were further characterized by elemental analysis, FT-IR and NMR spectroscopy. The molybdenum(VI) species were used as catalyst for olefin oxidation in the presence of tert-butylhydroperoxide (TBHP) as an oxidant. Under similar experimental conditions with equal Mo loading, the presence of the {[MoO2(HL)(H2O)]2[Mo6O19]·2MeCN} (1) resulted in higher oxidation conversion than [MoO2L(EtOH)] (2). It seems 1 contains two potentially active parts, the [MoO2(HL)H2O]+ cation and the Mo6O19−2 anion.

Tris(4-fluorophenyl)antimony dicarboxylates (4-FC6H4)3Sb[OC(O)R]2 (R = C10H15 or cyclo-C3H5): Synthesis and structure

Tris(4-fluorophenyl)antimony dicarboxylates (4-FC6H4)3Sb[OC(O)R]2, where R = C10H15 (I) or cyclo-C3H5 (II), have been synthesized by the reaction between tris(4-fluorophenyl)antimony and adamantanecarboxylic or cyclopropanecarboxylic acids in ether in the presence of tert-butyl hydroperoxide with a high yield. The antimony atoms in complexes I and II have a distorted trigonal bipyramidal coordination to the carboxylate ligands in axial positions (OSbO angles are 174.02(10)° (I) and 176.53(5)° (II)). The Sb-O and Sb-Ceqv bond lengths are 2.120(3), 2.121(2), and 2.110(3)-2.117(3) A (I), 2.147(1), 2.122(1), and 2.120(3)-2.123(2) A (II). Molecules contain intramolecular contacts between the antimony atom and the carbonyl oxygen atom (2.740(3), 2.867(4) A (I); 2.694(3), 2.773(4) A (II)). The structural organization in a crystal of complex I is due to weak intermolecular hydrogen bonds H···F (2.42-2.66 A). Complex II involves the intermolecular contacts H···F (2.63 A) and H···O=C (2.50 A).

Синтез и строение бис(4-бромфенокси)трифенилсурьмы

Interaction of triphenylantimony with 4-bromophenol in the presence of tert-butylhydroperoxide in ether has led to the synthesis of bis(4-bromophenoxy)triphenylantimony, whose structure has been established by X-ray diffraction analysis. The antimony atom has distorted trigonal-bipyramidal coordination with aroxy groups in axial positions. The bond lengths equal: 2.094(4), 2.108(5), 2.109(5) A for Sb–C; 2.062(4) and 2.066(3) A for Sb-O. The axial angle OSbO equals 172.41(1)°.

The oxidation of limonene at raised pressure and over the various titanium-silicate catalysts

Abstract This work presents the studies on the oxidation of limonene with hydrogen peroxide and tert-butyl hydroperoxide (TBHP) in the presence of : TS-2, Ti-Beta, Ti-MCM-41 and Ti-MWW catalysts, at the autogenic pressure and atmospheric pressure. The examination were performed at the following conditions: the temperature of 140°C (studies in the autoclave) and 80°C (studies in glass reactor), the molar ratio of limonene/oxidant (H2O2 or WNTB) = 1:1, the methanol concentration 80 wt%, the catalyst content 3 wt%, the reaction time 3 h and the intensity of stirring 500 rpm. The analysis of the results showed that in process not only 1,2-epoxylimonene was formed but also: 1,2-epoxylimonene diol, carveol, carvone and perillyl alcohol but for 1,2-epoxylimonene obtaining the better method was the method at the autogenic pressure and in the presence of TBHP.

Co(II)-MOF: A Highly Efficient Organic Oxidation Catalyst with Open Metal Sites

A porous Co(II)-MOF (1) was synthesized by the combination of a bent imidazole-bridged ligand and p-phthalic acid (PTA) with Co(OAc)2 under solvothermal conditions. This Co(II)-MOF (1) is able to undergo a reversible MeOH substitution reaction on the Co(II) center via a single-crystal-to-single-crystal process. The desolvated Co(II)-MOF (2) with the open Co(II) sites is very stable (up to 350 °C). Furthermore, 2 is a highly active heterogeneous catalyst for various organic substrates oxidation in the presence of tert-butyl hydroperoxide (TBHP) under milder conditions. The importance of open Co(II) sites in 2 for the organic substrates oxidation is directly evidenced by the single-crystal X-ray diffraction.

Immobilization of Cu(II) in KIT-6 supported Co3O4 and catalytic performance for epoxidation of styrene

KIT-6 is a cage type three dimensional cubic mesoporous silicate with Ia3d type structure, which shows scintillating promise in nanocasting, surface functionality, metal incorporation, and pharmaceutics. Nevertheless, little attention was paid to its application as support in heterogeneous catalysts. Cu-containing cobaltosic oxide spinel composite supported by mesoporous silica KIT-6 was synthesized via impregnation method and subsequent calcination under different temperatures. The prepared ordered materials were characterized by X-ray diffraction, N2 adsorption–desorption, transmission electron microscopy, atomic adsorption spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. The results showed that Cu2+ was successfully embedded in spinel structure when calcined at 550°C, in contrast, the samples through thermal treatment at 250°C remained hybrid composition of CuO and Co3O4. Catalytic performance of mesoporous materials was evaluated for epoxidation of styrene in the presence of tert-butylhydroperoxide as oxidant. Among a range of prepared materials, a significant enhancement in styrene conversion and selectivity of styrene oxide was obtained for Cu-spinel catalysts, in comparison with hybrid oxide. A dramatic decrease in catalytic activities was found while KIT-6 support was removed, due to the partial destruction of ordered structure of Cu–Co oxide. Consequently, the catalytic behaviors were chiefly ascribed to copper species and their textural properties.

Manganese-Mediated Coupling Reaction of Vinylarenes and Aliphatic Alcohols.

Alcohols and alkenes are the most abundant and commonly used organic building blocks in the large-scale chemical synthesis. Herein, this is the first time to report a novel and operationally simple coupling reaction of vinylarenes and aliphatic alcohols catalyzed by manganese in the presence of TBHP (tert-butyl hydroperoxide). This coupling reaction provides the oxyalkylated products of vinylarenes with good regioselectivity and accomplishes with the principles of step-economies. A possible reaction mechanism has also been proposed.

Bis(4-Nitrophenoxy)triphenylantimony toluene solvate and chloro(4-nitrophenoxy)triphenylantimony: Synthesis and structure

Chloro(4-nitrophenoxy)triphenylantimony Ph3Sb(Cl)[OC6H4(NO2-4)] (I) has been synthesized via the reaction between bis(4-nitrophenoxy)triphenylantimony and triphenylantimony dichloride. Bis(4-nitrophenoxy)triphenylantimony has been synthesized from triphenylantimony and 4-nitrophenol in the presence of tert-butylhydroperoxide in heptane; from toluene, it crystallizes in the solvate form as Ph3Sb[OC6H4(NO2-4)]2 ⋅ 2TolH (II). According to X-ray diffraction data, the antimony atoms in complexes I and II have a distorted trigonal bipyramidal coordination; axial angles: OSbCl, 179.56(6)° (I); OSbO, 178.21(12)° (II); equatorial angles: 113.33(11)°–126.99(11)° (I), 117.51(15)°–121.54(16)° (II); equatorial bond lengths: Sb–C, 2.118(3)–2.129(3) A (I), 2.104(4)–2.116(4) A (II); and axial bonds: Sb–Cl, 2.4606(9) A; Sb–O, 2.075(2) A (I), Sb–O, 2.060(3), 2.068(3) A (II). The structural organization in crystals is formed by intermolecular hydrogen bonds, such as HPh…Cl of 2.82 A (I) and HPh…OAr of 2.56–2.59 A (II).

Investigation of Room Temperature Synthesis of Titanium Dioxide Nanoclusters Dispersed on Cubic MCM-48 Mesoporous Materials

Titania containing cubic MCM-48 mesoporous materials were synthesized successfully at room temperature by a modified Stöber method. The integrity of the cubic mesoporous phase was retained even at relatively high loadings of titania. The TiO2-MCM-48 materials were extensively characterized by a variety of physico-chemical techniques. The physico-chemical characterization indicate that Ti4+ ions can be substituted in framework tetrahedral positions. The relative amount of Ti4+ ions in tetrahedral position was dependent on the order of addition of the precursor. Even at relatively high loadings of titania, no distinct bulk phase of titania could be observed indicating that the titania nanoclusters are well dispersed on the high surface area mesoporous material and probably exist as amorphous nanoclusters. The TiO2-MCM-48 materials were found to exhibit 100% selectivity in the cyclohexene oxidation at room temperature in the presence of tert-butylhydroperoxide (t-BHP) as the oxidant. The results suggest that room temperature synthesis is an attractive option for the preparation of TiO2-MCM-48 materials with interesting catalytic properties.

Manganese and cobalt-terephthalate metal-organic frameworks as a precursor for synthesis of Mn2O3, Mn3O4 and Co3O4 nanoparticles: Active catalysts for olefin heterogeneous oxidation

The thermal decomposition of manganese and cobalt-terephthalate Metal-Organic Framework precursors was utilized as a synthetic route for fabrication of Co3O4, Mn3O4 and Mn2O3 nanoparticles. The prepared metal oxide nanoparticles of Co3O4, Mn3O4 and Mn2O3 possess average size diameter of 40, 60 and 80nm respectively. The findings demonstrate that spinel structure nanoparticles of Co3O4 and Mn3O4 exhibit efficient catalytic activity toward heterogeneous olefin epoxidation in the presence of tert-butyl hydroperoxide. In addition, Co3O4 and Mn3O4 nanoparticles illustrated excellent catalytic stability and reusability for nine and four cycles, respectively, toward olefin oxidation.

Identification of mercury methylation product by tert-butyl compounds in aqueous solution under light irradiation

The methylation of mercury (Hg) is of great concern as methylmercury (MeHg), the most toxic species, is produced. This study examined the possibilities of tert-butyl compounds (tert-butyl alcohol (TBA) and tert-butyl hydroperoxide (TBH)) and other alcohols serving as methyl donors for Hg photo-methylation under light irradiation. The yield of MeHg varied among the methyl donors, and it was also significantly influenced by salinity and pH. MeHg could be generated in the presence of TBH under visible light irradiation. The hydroxyl radical (OH) was found to promote MeHg production at low levels, but degrade MeHg in excess. The photo-production of MeHg was tentatively proposed via the complexation of Hg and methyl donors, the formation of an intermediate (O(Hg)C(CH3)3), and the intramolecular methyl transfer from methyl donors to Hg. This study implicates photoreactions between Hg and organic pollutants in understanding the fate and transformation of Hg in the aquatic environment.

Adsorption of Cd2+ and Cu2+ ions from aqueous solutions by a cross-linked polysulfonate–carboxylate resin

A new cross-linked polyzwitterion (CPZ) was synthesized through cyclocopolymerization of 3-[diallyl(carboxymethyl)ammonio]propane-1-sulfonate (92.5mol%), and a cross-linker 1,1,4,4-tetraallylpiperazine-1,4-diium chloride (7.5mol%) in the presence of tert-butylhydroperoxide. The cross-linked polyzwitterion/anion (CPZA) was obtained by the basification of CPZ with NaOH. The adsorption data fit both Temkin and Freundlich isotherm models. The adsorption trend on CPZA is as Cu2+>Cd2+ and both followed pseudo-second-order kinetic model. The negative ΔG and positive ΔH values ascertained the spontaneous and endothermic nature of the adsorption process. The effectiveness of a zwitterionic–anionic motif consisting of quaternary nitrogen, sulfonate and carboxylate groups has been tested for the first time for capturing Cd2+ and Cu2+ ions at low concentrations.

Immobilization of Cu Complex into Zr-Based MOF with Bipyridine Units for Heterogeneous Selective Oxidation

A catalytically competent Cu species has been immobilized within the framework of a Zr-based metal–organic framework with bipyridine units, Zr-MOF-bpy, by a simple postsynthetic modification method from CuBr2 (Zr-MOF-bpy-CuBr2) and used for the selective oxidation of cyclooctene to cyclooctene oxide. Zr-MOF-bpy was synthesized by a simple solvothermal method and was shown to have a UiO-type structure. Diffuse reflectance UV–vis and XAFS measurements have revealed that the immobilized Cu species has a square-planar geometry of two N atoms and two Br atoms. Zr-MOF-bpy-CuBr2 catalyzed the selective oxidation of cyclooctene to cyclooctene oxide with high activity and selectivity in the presence of tert-butyl hydroperoxide as an oxidant. In addition, the catalytic ability of Zr-MOF-bpy-CuBr2 was demonstrated to be superior to that of the corresponding homogeneous catalyst ((bpy)CuBr2). It was also confirmed that Zr-MOF-bpy-CuBr2 can be reused as a heterogeneous catalyst without significant loss of its activity...

Synthesis and structure of tetra- and triphenylantimony phenylpropiolates

Tetraphenylantimony phenylpropiolate (I) has been synthesized by the reaction between pentaphenylantimony and phenylpropiolic acid or triphenylantimony bis(phenylpropiolate) in toluene. Triphenylantimony bis(phenylpropiolate) (II) has been synthesized from triphenylantimony and phenylpropiolic acid in ether in the presence of tert-butylhydroperoxide. According to X-ray diffraction data, the antimony atoms in complexes I and II are in a trigonal bipyramidal coordination, and the axial CSbO and OSbO angles are 178.63(7)° and 177.68(7)°. The Sb-C and Sb-O bond lengths and the equatorial CSbC angles are 2.120(3)–2.166(3) and 2.267(2) A, and 113.44°, 114.80°, and 128.12° (I) and 2.104(2)–2.109(3) and 2.136(2) A and 108.38°, 108.38°, and 143.23° (II), respectively. Sb⋯O=(C) intramolecular contacts are 3.357(3) A (I) and 2.919(5) A (II).