Reaction Of Toluene Research Articles

ChemInform Abstract: Catalytic Activity of Co‐Aakermanite and Co‐Pyroxene in Oxidation Reactions.

AbstractThe catalytic activity of Ca2CoSi2O7 (I) and CaCoSi2O6 (II) in oxidation reactions of CO and toluene is examined.

The Efficient Copper(I) (Hexabenzyl)tren Catalyst and Dendritic Analogues for Green “Click” Reactions between Azides and Alkynes in Organic Solvent and in Water: Positive Dendritic Effects and Monometallic Mechanism

AbstractAn easily synthesized, copper(I) (hexabenzyl)tren complex 1 is an efficient catalyst for the copper(I)‐catalyzed Huisgen‐type 1,3‐cycloaddition between azides and alkynes (CuAAC) reaction in toluene. Alternatively, a convenient procedure involves mixing copper(I) bromide (CuBr) with hexabenzyltren and the substrates in toluene which gives, for instance, 100% yield of triazole in 10 min using 0.1 equiv. catalyst with phenylacetylene and benzyl azide at room temperature. The toluene‐soluble catalyst 1 is recyclable and is applied, for example, to the CuAAC synthesis of an 81‐branched dendrimer that previously required the use of a stoichiometric amount of copper(II) sulfate (CuSO4)+sodium ascorbate “catalyst”. Dendritic copper(I)‐centered analogues 2 and 3 of the first and second generations (G1 and G2, respectively) containing respectively 18 and 54 branch termini, including a 54‐branched water‐soluble metallodendrimer 5, are also very efficient catalysts for the CuAAC reaction. With the metallodendritic Cu(I) derivatives 2 and 3, the dendritic frame brings about steric protection against the well‐known inner‐sphere aerobic oxidation of Cu(I) to bis(μ‐oxo)‐bis‐Cu(II). The metallodendrimers 2 and 3 are also sometimes more efficient than the parent catalyst, as shown by kinetic studies. Catalysis in water without co‐solvent of the CuAAC reactions of water‐insoluble substrates was achieved under ambient conditions in good yields with the recyclable catalyst 5. Efficient catalysis of the CuAAC reaction by these bulky Cu(I) metallodendrimers emphasizes the monometallic mechanism. The difference of kinetic behavior between 1 and CuBr+hexabenzyltren suggests, however, that whereas a monometallic mechanism is working for 1, the mixture of CuBr+hexabenzyltren might involve the bimetallic mechanism proposed by Fokin and Finn.

Methanogenic toluene metabolism: community structure and intermediates

Toluene is a model compound used to study the anaerobic biotransformation of aromatic hydrocarbons. Reports indicate that toluene is transformed via fumarate addition to form benzylsuccinate or by unknown mechanisms to form hydroxylated intermediates under methanogenic conditions. We investigated the mechanism(s) of syntrophic toluene metabolism by a newly described methanogenic enrichment from a gas condensate-contaminated aquifer. Pyrosequencing of 16S rDNA revealed that the culture was comprised mainly of Clostridiales. The predominant methanogens affiliated with the Methanomicrobiales. Methane production from toluene ranged from 72% to 79% of that stoichiometrically predicted. Isotope studies using (13)C(7) toluene showed that benzylsuccinate and benzoate transiently accumulated revealing that members of this consortium can catalyse fumarate addition and subsequent reactions. Detection of a BssA gene fragment in this culture further supported fumarate addition as a mechanism of toluene activation. Transient formation of cresols, benzylalcohol, hydroquinone and methylhydroquinone suggested alternative mechanism(s) for toluene metabolism. However, incubations of the consortium with (18)O-H(2)O showed that the hydroxyl group in these metabolites did not originate from water and abiotic control experiments revealed abiotic formation of hydroxylated species due to reactions of toluene with sulfide and oxygen. Our results suggest that toluene is activated by fumarate addition, presumably by the dominant Clostridiales.

The Role of Surface Carbon in Oxidation of Ethylene and Toluene on Platinum-Ceria Anodes for Solid Oxide Fuel Cells

Surface reactions of ethylene and toluene on a Pt-modified, samarium-doped ceria (Pt/CSO) anode were examined as a function of hydrocarbon to oxygen ratio and cycling of oxy- gen ion current through the electrolyte. Reaction conditions were temperatures of 540 °C (C2H4) and 730 °C (C7H8), hydro- carbon partial pressures of 0.001-0.04 Torr, and oxygen partial pressures of 0.1 Torr (anode) and 5 Torr (cathode). A gen- eral result is that reactions of both ethylene and toluene are strongly sensitive to surface carbon. A step change in oxygen ion current results in electrochemical enhancements of up to 80 and catalytic enhancements as high as 3. Cycling of oxygen ion currents leads to enhanced catalytic activity that remained for 1 hour or more after cycling was terminated. Enhance- ment was sensitive to the ratio of hydrocarbon to oxygen and attributed to a combination of carbon removal and redox ki- netics in the ceria anode.

The effect of water presence on the photocatalytic oxidation of benzene, toluene, ethylbenzene and m-xylene in the gas-phase

In the present work, the gas–solid heterogeneous photocatalytic oxidation of benzene, toluene, ethylbenzene and m-xylene (BTEX) over UV-irradiated titanium dioxide was studied in an annular reactor operated in the CSTR (continuous stirred-tank reactor) mode. GC-FID and GC-MS were used for analysing reactor inlet and outlet streams. Initial BTEX concentrations were in the low parts per million (ppmv) range, whereas the water concentration was in the range of 0–35,230 ppmv and the residence time varied from 50 to 210 s. The effect of water addition on the photocatalytic process showed strong dependence on the type of the BTEX and the water vapour concentration. The increase in residence time resulted in a considerable increase in the conversion achieved for all compounds and experimental conditions. There was a clear interaction between residence time and water presence regarding the effect on conversions achieved. It was established that conversions over 95% could be achieved by adjusting appropriately the experimental conditions and especially the water concentration in the reactor. In all cases, no by-products were detected above the detection limit and carbon dioxide was the only compound detected. Finally, various Langmuir-Hinshelwood kinetic models have been tested in the analysis of the experimental data obtained. The kinetic data obtained confirmed that water had an active participation in the photocatalytic reactions of benzene, toluene, ethylbenzene and m-xylene since the model involving reaction of BTEX and water adsorbed on different active sites yielded the most successful fitting to the experimental results for the first three compounds, whereas the kinetic model based on the assumption that reaction between VOC and water dissociatively adsorbed on the photocatalyst takes place was the most appropriate in the case of m-xylene.

Spiro heterocyclization of dimethyl 1-(4-methylphenyl)-4,5-dioxo-4,5-dihydro-1H-pyrrole-2,3-dicarboxylate by the action of 3-arylamino-5,5-dimethylcyclohex-2-en-1-ones

Reactions of dialkyl 4,5-dioxo-4,5-dihydro-1H-pyrrole-2,3-dicarboxylates with enamines were reported previously. By reaction of 1-(4-methylphenyl)-4,5-dioxo-4,5-dihydro-1H-pyrrole-2,3-dicarboxylate (I) with an equimolar amount of 3-arylamino-5,5-dimethylcyclohex-2-en-1-one IIa or IIb in boiling toluene (reaction time 3–4 h) we obtained methyl 1-aryl-1′-(4methylphenyl)-4′-hydroxy-6,6-dimethyl-2,4,5′-trioxo1,1′,2,4,5,5′,6,7-octahydrospiro[indole-3,2′-pyrrole]-3′carboxylates IIIa and IIIb. The spectral parameters of compounds IIIa and IIIb turned out to be quite similar to those of model 3′-benzoyl-1-cyclohexyl-4′-hydroxy6,6-dimethyl-1′-phenyl-1,1′,2,4,5,5′,6,7-octahydrospiro[indole-3,2′-pyrrole]-2,4,5′-trione whose structure was proved by X-ray analysis [1].

Stannylium Ions, a Tin(II) Arene Complex, and a Tin Dication Stabilized by Weakly Coordinating Anions

The reactivity of aryl-substituted stannylenes, Ar(2)Sn (4), towards silylarenium borates, [R(3)SiArH][B(C(6)F(5))(4)] (3), was investigated. The reaction with 2,3,4-trimethyl-6-tert-butylphenyl (mebp)-substituted stannylene gave silyl-substituted stannylium ions 2a,b, which were characterized by NMR spectroscopy supported by the results of quantum-mechanical computations of molecular structures and magnetic properties. The tri-iso-propylphenyl-substituted stannylium ions 2c,d undergo a decomposition reaction in toluene to give the dicationic tin-arene complex [Sn(C(7)H(8))(3)](2+) (5) in the form of the [B(C(6)F(5))(4)] salt in high yields. The 5[B(C(6)F(5))(4)](2) salt was identified by single crystal X-ray diffraction analysis and by Mössbauer spectroscopy. The bonding situation was investigated by using natural bond orbital (NBO) and quantum theory of atoms in molecules (QTAIM) calculations. The substitution of the weakly coordinating borate anion by the carboranate [CB(11)H(6)Br(6)](-) results in replacement of the toluene ligands and formation of tin(II) carboranate with only weak Sn(2+)-anion interactions as suggested by the solid-state structure of the isolated salt.

A Pt-Cluster-Based Heterogeneous Catalyst for Homogeneous Catalytic Reactions: X-ray Absorption Spectroscopy and Reaction Kinetic Studies of Their Activity and Stability against Leaching

The design and development of metal-cluster-based heterogeneous catalysts with high activity, selectivity, and stability under solution-phase reaction conditions will enable their applications as recyclable catalysts in large-scale fine chemicals production. To achieve these required catalytic properties, a heterogeneous catalyst must contain specific catalytically active species in high concentration, and the active species must be stabilized on a solid catalyst support under solution-phase reaction conditions. These requirements pose a great challenge for catalysis research to design metal-cluster-based catalysts for solution-phase catalytic processes. Here, we focus on a silica-supported, polymer-encapsulated Pt catalyst for an electrophilic hydroalkoxylation reaction in toluene, which exhibits superior selectivity and stability against leaching under mild reaction conditions. We unveil the key factors leading to the observed superior catalytic performance by combining X-ray absorption spectroscopy (XAS) and reaction kinetic studies. On the basis of the mechanistic understandings obtained in this work, we also provide useful guidelines for designing metal-cluster-based catalyst for a broader range of reactions in the solution phase.

Fit-for-Purpose Development of the Enabling Route to Crizotinib (PF-02341066)

A robust six-step process for the synthesis of crizotinib, a novel c-Met/ALK inhibitor currently in phase III clinical trials, has been developed and used to deliver over 100 kg of API. The process includes a Mitsunobu reaction, a chemoselective reduction of an arylnitro group, and a Suzuki coupling, all of which required optimization to ensure successful scale-up. Conducting the Mitsunobu reaction in toluene and then crystallizing the product from ethanol efficiently purged the reaction byproduct. A chemoselective arylnitro reduction and subsequent bromination reaction afforded the key intermediate 6. A highly selective Suzuki reaction between 6 and pinacol boronate 8, followed by Boc deprotection, completed the synthesis of crizotinib 1.

Highly Enantioselective and Efficient Synthesis of Flavanones Including Pinostrobin through the Rhodium-Catalyzed Asymmetric 1,4-Addition

An efficient synthesis of bioactive chiral flavanones (1) was achieved through the Rh-catalyzed asymmetric 1,4-addition of arylboronic acid to chromone. The reaction in toluene proceeded smoothly at room temperature in the presence of 0.5% Rh catalyst with electron-poor chiral diphosphine MeO-F(12)-BIPHEP. In this reaction, the 1,2-addition to (S)-1 frequently occurred to yield (2S,4R)-2,4-diaryl-4-chromanol as a byproduct, which could be reduced by changing the reaction solvent to CH(2)Cl(2) to deactivate the Rh catalyst (3% required).

Solvothermal Synthesis of Copper Indium Diselenide in Toluene

Polycrystalline CuInSe2 (CIS) was synthesized through solvothermal reactions in toluene with selected alkyl amines as complexing agents. The alkyl amines were used as reducing agent of selenium and catalytic ligands, enhancing the formation of CIS compounds in the colloidal solution. Toluene does not contribute the syntheses directly but minimizes the amounts of amines required for single phase CIS. We systematically studied the reactivity of amine compounds for the solovothermal syntheses, determined critical concentration of amine and the shortest reaction time. Crystallinity, morphology, chemical composition, and band gap of the prepared CuInSe2 were respectively measured by X-ray diffraction, scanning electron microscopy, inductively coupled plasma atomic emission spectroscopy and UV-vis spectroscopy.

A water-soluble phosphite derived from sulfonated calix[4]arene. The remarkable stability of its rhodium complexes and two phase hydroformylation studies

The reaction of tetrasulfonated calix[4]arene (trioctylammonium salt) with P(NMe2)3 followed by treatment with gaseous NMe2H gave a zwitterionic six-coordinate phosphorus(V) species 1 containing a P(H)(NHMe2) group which can be stored for months without decomposition. In water, 1 loses NHMe2 and rearranges to form the water soluble phosphite Lcc. Phosphite Lcc has a half-life in water of ca. 5 h decomposing to H3PO3 and free tetrasulfonated calix[4]arene. Compound 1 serves as a convenient precursor to Lcc and complexes of Lcc are formed by dissolving 1 in water in the presence of labile metal complexes. The products have been identified by comparison of their 31P NMR data with well established analogues of calix[4]arene derived phosphites. In this way the water soluble complexes [Rh(acac)(CO)(Lcc)2] (2c) [Rh2Cl2(CO)2(Lcc)2] (3c), [Pt2Cl4(Lcc)2] (4c) and [PtCl2(Lcc)2] have been tentatively identified. The rhodium complex 3c has a half-life in water of 4 months. Two-phase (water/toluene) hydroformylation of 2-methylpentenoate with 2c as a catalyst has been investigated and the results compared with the same reaction in toluene with lipophilic analogues of 2c. Under mild conditions, with 2ccatalyst, branched aldehydes are the only products of hydroformylation and one of the branched aldehydes is selectively hydrogenated to give the lactone derivative.

Silica and hybrid silica hollow spheres from imidazolium-based templating agents

Hollow or dense silica spheres were synthesized by the hydrolysis-condensation of tetraethoxysilane templated by an ionic liquid crystal. A hydrolysable silylated analog of these ionic liquid crystals was also submitted to a sol–gel reaction in a binary toluene–water mixture, yielding hybrid vesicles. All the materials were fully characterized by solid state NMR, FTIR, electron microscopies, N2 adsorption–desorption measurements, and their mechanism of formation was assessed thanks to in situoptical microscopy studies.

Toluene nitration in irradiated nitric acid and nitrite solutions

The kinetics, mechanisms, and stable products produced for the nitration of aryl alkyl mild ortho-para director toluene in irradiated nitric acid and neutral nitrite solutions were investigated using γ and pulse radiolysis. Electron pulse radiolysis was used to determine the bimolecular rate constants for the reaction of toluene with different transient species produced by irradiation. HPLC with UV detection, GC-MS and LC-MS, were used to assess the stable reaction products. Free-radical based nitration reaction products were found in irradiated acidic and neutral media. In 6.0M HNO3, ring substitution, side chain substitution, and oxidation, produced different nitrated toluene products. For ring substitution, nitrogen oxide radicals were added mainly to cyclohexadienyl radicals, whereas for side chain substitution, these radicals were added to the carbon-centered benzyl radical produced by H-atom abstraction. In neutral nitrite solutions, radiolytically-induced ring nitration products approached a statistically random distribution, suggesting a direct free-radical reaction involving addition of the NO2 radical.

Catalysts based on clay and iron oxide for oxidation of toluene

Two samples of heterogeneous catalysts were prepared by impregnating a raw-clay, a montmorillonite-rich material, with iron oxides, in order to be used in oxidative reactions of toluene. The starting clay-sample was collected from a pedon in the region of San Juan, Argentina. All catalysts were characterized with X-ray powder diffraction (XRD), infrared spectroscopy, temperature programmed reduction (TPR), scanning electron microscopy with energy dispersive X-ray analysis (SEM/EDS), and specific surface area measurements. After impregnating the raw clay material with iron oxides, there was a collapse of basal plane spacing and an increase in surface area, from 17 to 62m2g−1 of montmorillonite. The TPR, EDS, and XRD results evidenced that the dispersion of iron-containing species depended on how the impregnation was made. The catalyst with higher exposure to iron oxides on sample preparation presented a higher catalytic activity on toluene oxidation.

Microwave-assisted organic functionalization of silica surfaces: Effect of selectively heating silylating agents

Microwave (MW)-assisted (2.45 GHz) organic functionalization of silica surfaces was investigated using (3-chloropropyl)dimethylsilanes with alkoxy, allyl, or aryl leaving groups in heptane or toluene at 80 °C. 29Si and 13C CP/MAS spectroscopy confirmed the 3-chloropropyldimethylsilyl moiety was covalently grafted onto silica for all the samples. The effect of MW irradiation on the loading amount strongly depended on the leaving group as well as the solvent; using methoxysilane and p-anisylsilane in heptane caused a distinct acceleration. The correlation with the dielectric loss factors of the silylating agents suggested that the MW acceleration effect resulted from selectively heating the strongly MW-absorbing silylating agent. For the grafting reaction in toluene, the MW effect was not observed possibly because toluene masked the selective heating effect of the silylating agent.

Carbonate Formation from CO2 via Oxo versus Oxalate Pathway: Theoretical Investigations into the Mechanism of Uranium-Mediated Carbonate Formation

We report theoretical investigations of the reaction of [((MeArO)3mes)U] with CO2 in order to support previously reported experimental data. Experimentally, the reaction in toluene leads to the imm...

Disproportionation and Methylation of Toluene with Methanol Over Zeolite Catalysts

Zeolites TNU-9, SSZ-33, mordenite (MOR) and ZSM-5 were evaluated for their activities in toluene disproportionation and methylation reaction of toluene with methanol. The medium-pore zeolite TNU-9 was found to possess the highest conversion in toluene disproportionation as compared with SSZ-33, mordenite and ZSM-5 based catalyst. Zeolite mordenite with the highest Si/Al ratio of 135.9 (the lowest concentration of active sites) exhibited the highest toluene conversion and maximum xylene yield in toluene methylation. On mordenite, the presence of channel intersections allows more reaction space for the formation of bulky intermediates and/or products and the 12-ring channels on the other hand, allow diffusion without trapping, since the channel diameter is large enough. In toluene methylation, xylene selectivity at the same conversion level follows the order: ZSM-5 > TNU-9 > MOR > SSZ-33, which implies that xylene selectivity is directly related to the size of channels from medium to large pore zeolites. The medium-pore zeolite ZSM-5, with 10-ring channels, shows the lowest reactivity for further alkylation of xylene, while mordenite with 12-ring channel shows the highest reactivity for further alkylation of xylene.

Formation Yields of Glyoxal and Methylglyoxal from the Gas-Phase OH Radical-Initiated Reactions of Toluene, Xylenes, and Trimethylbenzenes as a Function of NO2Concentration

Aromatic hydrocarbons comprise 20% of non-methane volatile organic compounds in urban areas and are transformed mainly by atmospheric chemical reactions with OH radicals during daytime. In this work we have measured the formation yields of glyoxal and methylglyoxal from the OH radical-initiated reactions of toluene, xylenes, and trimethylbenzenes over the NO2 concentration range (0.2-10.3) × 1013 molecules cm(-3). For toluene, o-, m-, and p-xylene, and 1,3,5-trimethylbenzene, the yields showed a dependence on NO2, decreasing with increasing NO2 concentration and with no evidence for formation of glyoxal or methylglyoxal from the reactions of the OH-aromatic adducts with NO2. In contrast, for 1,2,3- and 1,2,4-trimethylbenzene the glyoxal and methylglyoxal formation yields were independent of the NO2 concentration within the experimental uncertainties. Extrapolations of our results to NO2 concentrations representative of the ambient atmosphere results in the following glyoxal and methylglyoxal yields, respectively: for toluene, 26.0 ± 2.2% and 21.5 ± 2.9%; for o-xylene, 12.7 ± 1.9% and 33.1 ± 6.1%; for m-xylene, 11.4 ± 0.7% and 51.5 ± 8.5%; for p-xylene, 38.9 ± 4.7% and 18.7 ± 2.2%; for 1,2,3-trimethylbenzene, 4.7 ± 2.4% and 15.1 ± 3.3%; for 1,2,4-trimethylbenzene, 8.7 ± 1.6% and 27.2 ± 8.1%; and for 1,3,5-trimethylbenzene, 58.1 ± 5.3% (methylglyoxal).

ChemInform Abstract: Mannich/Friedel-Crafts Preparations of 1-(Arylmethyl)benzotriazoles and Synthetic Transformations of Their Lithio Derivatives.

The synthesis of 1-(arylmethyl)benzotriazoles by Mannich type reactions of benzene, toluene, p-xylene and chlorobenzene with 1-chloromethylbenzotriazole in the presence of aluminium halides is reported. Alkylation, of their lithio derivatives followed by the cleavage of benzotriazole from the resulting 1-(α-arylalkyl)benzotriazoles upon reduction with LiAlH4–AlCl3 or elimination by AcOH are shown to be useful procedures for the preparation of substituted arenes. An oxidative coupling of lithiated 1-(arylmethyl)benzotriazoles gave 1,2-diaryl-1,2-di(benzotriazol-1-yl)ethanes. Novel heterocyclic ring fissions of the lithio derivatives of 1-(arylmethyl)benzotriazoles afforded 1,2,4-benzotriazine and 1,2-bis(N-methylanilino)ethene derivatives.