Abstract  The preparation and the IR study of some compounds of the type (arene)Co4(CO)9 (where arene denotes toluene, tetrahydronaphthalene, or mesitylene) are reported. The CO stretching bands in the spectra of the compounds have been assigned, and the force and interaction constants calculated. The relative band intensities have been used in a tentative determination of bond angles and relative dipole moment gradients. The “anomalously” high intensity of the v3(E) bands is discussed in detail, and an induced dipole moment mechanism is suggested to account for it.

Abstract  A high-performance liquid chromatographic method was applied to the determination of the adsorption isotherms and heats of benzene, toluene, ethylbenzene, o-xylene, pseudocumene, p-diethylbenzene and anisole from n-heptane on carbon adsorbents. The retention times of these compounds were determined at 20, 40 and 60°C. Comparison of the results of chromatographic and static investigations allowed the character of the dynamic process to be established. The heats of adsorption of aromatic compounds on carbon and silica adsorbents were compared. The mechanism of the adsorption interaction is discussed. © 1990.

Abstract  As a part of our studies on the thermodynamics of binary mixtures containing organic nitrogen compounds, we report here the experimental excess molar enthalpies HEm for [(1 --x){HCON(CH3) 2 or CH3CON(CH3)2} + x{CH3(CH2)4CH 3 (at 313.15 K) or c6n 6 or C6HsCH 3 or 1,4-C6H4(CH3) 2 or 1,3,5-C6H3(CH3) 3 (at 303.15 K)]. The more recent calorimetric studies on these mixtures are those of Bitrich etal31) on (N,N-dimethylformamide + hexane), Geier etal. ~a) and Winkelmann ~3) on (N,N-dimethylformamide + benzene), Decker ~4) and Saskovets et al35) on (N,N-dimethylformamide + toluene), and Ukibe etalJ 6) on (an N,N-dialkylamide + cyclohexane or benzene or toluene).

Abstract  He(I) ultraviolet photoelectron (UV-PES) spectra are reported for several bis(arene)chromium compounds. The arenes concerned are m-trifluoromethylbenzotrifluoride, p-fluorobenzotrifluoride, p-difluorobenzene, m-dichlorobenzene, fluorobenzene, chlorobenzene, methylbenzoate, p-chlorotoluene, diphenyl ether, toluene, o-xylene, trimethylsilylbenzene, isobutylbenzene, 1,2,3-trimethylbenzene, 1,3,5-trimethylbenzene, and 1,2,4,5-tetramethylbenzene. The spectra have been interpreted using a qualitative perturbation molecular orbital model. The two major findings of the work are: (i) the ionizations from the metal-localized a1g and e2g molecular orbitals are governed primarily by ligand electronegativity, but there is some evidence for the operation of conjugative effects, and (ii) the ionization energies of the free and coordinated arenes are quite similar. © 1982.

Abstract  The auto-ignition features of 11 alkylbenzenes in a rapid compression machine have been compared for stoichiometric mixtures in the lower temperature region (600-900 K), and at compressed pressures up to 25 bar, by following pressure traces and light emission. They are classified in two groups. Toluene, m-xylene, p-xylene, and 1,3,5-trimethylbenzene ignite only above 900 K and 16 bar. o-Xylene, ethylbenzene, 1,2,3-trimethylbenzene, 1,2,4-trimethylbenzene, n-propylbenzene, 2-ethyltoluene, and n-butylbenzene ignite at much lower temperature and pressure. The second group shows a complex phenomenology similar to alkanes and alkenes when submitted to adapted conditions of reactant concentrations. Ignition in two steps and negative temperature dependence of ignition delays are observed in favorable cases. Some of them show a low-temperature luminescence. Ignition features of o-xylene and n-butylbenzene are similar, in spite of their dissimilar molecular structure. The higher degree of reactivity of the second group is ascribed to the close proximity and/or length of their alkyl chains. (C) 2000 by The Combustion Institute.

Abstract  FeCl(3)/AgOTf-catalyzed hydroarylation of propiolic acid with electron-rich arenes such as mesitylene, tetramethylbenzene, and pentamethylbenzene in trifluoroacetic acid proceeded to give 3-arylpropenoic acids in moderate to high yields. The same reactions with anisole and 1,4-dimethoxybenzene afforded double hydroarylation products, 3,3-diarylpropionic acids. (C) 2009 Elsevier Ltd. All rights reserved.

Abstract  All three methyl groups in mesitylene become nonequivalent in the H-1 NMR spectra of PhCH2Co(dmestgH)(2)Py, PhCH2(SO2)Co(dmestgH)(2)Py, and PhCH2(O-2)CO(dmestgH)(2)Py, due to weak interactions between the axial benzyl and the equatorial dioxime ligands. (c) 2007 Elsevier Ltd. All rights reserved.

Abstract  Treatment of dodec-6-yne with triallylmanganate in the presence of 1,3,5-trimethylbenzene provides (Z)-dodec-6-ene. An addition of D2O before quenching the reaction affords the corresponding dideuterated alkene. The result suggests the existence of the manganese-alkyne complex as an intermediate. Treatment of methyl propargyl ethers as alkynes with tributylmanganate generates propargylmanganese species. The reaction of non-2-ynyl tetrahydropyran-2-yl ether with tributylmanganate provides tetradec-7-yn-1,5-diol and 6-hexylocta-6,7-dien-1,5-diol. (C) 2003 Elsevier Ltd. All rights reserved.

Abstract  Dynamic nuclear polarization (DNP) studies of asphaltene/some hydrocarbons solutions were performed at 1.53 mT. The low field EPR spectrum of Asphaltene/Mesitylene sample was recorded. The DNP parameters such as enhancement factor, nuclear-electron coupling constant, saturation factor, leakage factor, the parameter for the relative importance of scalar and translational dipolar interaction and the total spin-lattice relaxation rate were determined. The effect of irradiation with neutrons from the Ra-Be source to the DNP parameters was investigated. Dissolved molecular oxygen effect on the enhancement factor for each sample was examined experimentally. We also make some interpretations depending on the results obtained for the interactions between nuclei of the solvent and electrons delocalized on the asphaltene. (C) 2010 Elsevier B.V. All rights reserved.

Abstract  The total neutron cross sections of mesitylene, toluene and a solution 3:2 by volume of mesitylene and toluene were measured at the electron LINAC based pulsed neutron source of Centro Atomico Bariloche. Measurements were performed at 180 K, 120 K and 31.6 K for mesitylene and at 120 K and 31.6 K for toluene and a solution 3:2 by volume of mesitylene and toluene. The systems are potential moderator materials to be considered in the design of a cold neutron source due to their high resistance to radiation and the richness in low-energy excitations of their frequency spectra, that lead to produce an enhanced cold neutron flux. (c) 2008 Elsevier B.V. All rights reserved.

Abstract  Four bile acid-arene conjugates, 1,4-bis[dimethyl(3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cliolan-24-amidoethyl)ammoniomethyl]benzene dibromide (1), 1,3,5-tris[dimetliyl(3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cholan-24-amidoethyl)ammoniomethyl]benzene tribromide (2), bis{4-[dimethyl-(3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cholan-24-amidoethyl)ammoniomethyl]phenyl}diazene dibromide (3), and bis{4-[dimethyl(3 alpha-hydroxy-5 beta-cholan-24-amidoethyl)ammoniomethyl]phenyl}diazene dibromide (4), have been synthesized in good yields, and their structures have been characterized by H-1, C-13, C-13 DEPT-135, PFG H-1, C-13 HMQC, PFG H-1, C-13 HMBC, and PFG H-1, N-15 HMBC NMR spectra. Their molecular weights and elemental compositions have been determined by ESI-TOF mass spectrometry and elemental analyses. Trans to cis isomerization of azobenzene derivatives 3 and 4 have also been studied. It was found that by increasing the hydrophobicity of bile acid moiety (from cholyl to lithocholyl) the trans to cis photoinduced isomerization tendency is increased in a protic solvent. (C) 2007 Elsevier B.V. All rights reserved.

Abstract  Densities, rho, have been measured for the binary systems of n-heptane + toluene, + o-xylene and + mesitylene in the whole range of composition between 303.15 and 323.15 K at an interval of 5 K. From measured, rho, excess molar volumes, V(m)(E), partial molar volumes, (V(i)) over bar, thermal expansivities, alpha, and excess thermal expansivities, alpha(E), are also estimated. For all systems, measured rho, (V(i)) over bar and alpha values are fitted to polynomial equations of appropriate forms, whereas, V(m)(E) and alpha(E) are fitted to the Redlich-Kister equations. In the whole range of composition, v(m)(E) are positive for n-heptane + toluene but negative for the other two systems. In n-heptane + toluene, dispersive forces are suggested to dominate, whereas, in the other two 'favorable geometric fitting' seem to overpower due to increasing number of -CH(3) as substituent in the relevant aromatic hydrocarbons. (C) 2011 Elsevier By. All rights reserved.

Abstract  The viscosities eta, densities rho, speeds of sound u and refractive indices no of binary mixtures of 1-decanol with o-xylene, m-xylene, p-xylene, ethylbenzene and mesitylene have been measured over the entire range of composition at 298.15 and 308.15 K and at atmospheric pressure. Excess molar volumes V(E), deviations of isentropic compressibilities Delta kappa, deviations of the speeds of sound Delta u, viscosity deviations Delta eta, excess free energies of activation for viscous flow Delta G*(E) and deviations of refractive indices Delta n(D) have been calculated from the density rho, speed of sound u, viscosity eta and refractive index n(D) data. The calculated excess and deviation functions have been fitted to the Redlich-Kister polynomial equations and the results analyzed in terms of molecular interactions and structural effects. The viscosity data have been correlated using McAllister's three body interaction model at different temperatures. (C) 2010 Elsevier B.V. All rights reserved.

Abstract  Viscosities (eta) of binary mixtures between some polar aliphatic molecules viz. 1-bromopropane, 1-bromobutane and 1-bromopentane and nonpolar hydrocarbons viz. cyclohexane, benzene, 1, 4-dimethylbenzene and 1,3,5-trimethylbenzene have been measured at 308.15 K in the whole concentration range. Deviations from ideal mixture viscosities (Delta eta) for all the systems have been evaluated from the viscosity data. Delta eta values for all the binary systems are negative except for 1-bromopropane+1, 4-dimethylbenzene binary mixture which has a few positive values beyond the equimolar mixture, and for 1-bromopropane +1, 3, 5-trimethylbenzene system, these are positive except a few negative values at lower mole fractions of the hydrocarbon. The mixture viscosities (eta) have been analysed on the basis of several equations such as Grunberg-Nissan, Hind-McLaughlin-Ubbelohde and Katti and Chaudhary. The strengths of molecular interactions in the binary mixtures studied are discussed on the basis of variations in Grunberg-Nissan parameter (d). It is suggested that molecular interactions are dipole-induced dipole type between components of binary mixtures and the strength of interactions increases with increase in polarizability of aromatic hydrocarbons. (C) 2007 Elsevier B.V. All rights reserved.

Abstract  Reactivity of oxygen species generated by N2O decomposition over Fe-ZSM-5 and Fe-Beta zeolites was investigated using oxygen isotopic exchange as test reaction. The generated species are very stable up to 300 degrees C in the absence of the organic traces or residual N2O in the gas phase. The reactivity of the oxygen species towards organics depends on the size of the organic molecules and their ability to penetrate into the zeolite pores. For example, in case of Fe-ZSM-5 zeolite, the oxygen species react readily with toluene, but stay intact with more bulky 1,3,5-trimethylbenzene. (C) 2011 Elsevier B.V. All rights reserved.

Abstract  New bead-shaped insoluble polymer-supported multi-site (six-site) phase transfer catalyst (BSIMPTC) was synthesized from mesitylene as a starting material and its catalytic efficiency was studied with the kinetics of Darzen's condensation of 4-nonanolide with 1,6-dibromohexan-2one. The presence of six active-sites in the newly synthesized BSIMPTC, viz., 2,4,6-tris[(4-(2,2'-bis(N-triethylammoniummethylene chloride) eth-1-ene) phenoxy)benzene was characterized through FT-IR, solid H-1 NMR, C-13 NMR, SEM and [chloride ion] analyses and found that the BSIMPTC contains approximate to 6 active-site centers. The Darzen's condensation reaction of 4-nonanolide was performed at lower temperature (40 degrees C) under pseudo-first order rate conditions by taking lower concentration of aqueous NaOH (15 %, w/v, 3.75 M) and excess of 1,6-dibromohexan-2-one. The disappearance of 4-nonanolide was quantitatively monitored by a gas chromatograph for the calculation of the pseudo-first order rate constant. The presence of more number of active-sites in BSIMPTC was further confirmed from the comparative study of pseudo-first order rate constant with the rate constants of single-site polymer-supported phase transfer catalyst. The comparative rate constant results reveal that the BSIMPTC is highly active-than the corresponding soluble six-active-site and almost approximate to 4 times higher active-than with insoluble/soluble single-site PTCs. The effect of various experimental parameters such as [substrate], [catalyst], [NaOH], stirring speed, and temperature on the rate of the reaction have also been studied and found that each variables are influenced the rate of reaction. Based on the obtained kinetic results, a suitable mechanism is proposed. (C) 2007 Elsevier B.V. All rights reserved.

Abstract  Friedel-Crafts-type reaction of p-xylene with gamma-butyrolactone or vinylacetic acid over H4SiW12O40 supported on SiO2 have been investigated with different loadings of H4SiW12O40. The catalytic performance of H4SiW12O40/SiO2 have been compared with those of typical solid acid catalysts such as zeolites, ion-exchanged resins, and binary oxides. H4SiW12O40 supported on SiO2 was superior in activity and selectivity to 5,8-dimethyl-alpha-tetralone compared to other catalysts for the reaction between p-xylene and gamma-butyrolactone. SiO2-supported H4SiW12O40 also was efficient for the formation of 3,4,7-tetramethyl-alpha-indanone from p-xylene and vinylacetic acid. The formation of 5,8-dimethyl-a-tetralone is extremely sensitive to the load of H4SiW12O40 on SiO2, reaching a maximum at approximately 30 wt%, due to the change in the acid amount of the outermost surface as determined by benzonitrile-temperature programmed desorption. By analogy with reaction between 1,3,5-trimethylbenzene and gamma-butyrolactone, the reaction pathway involves initial alkylation of p-xylene with gamma-butyrolactone, followed by intramolecular acylation to 5,8-dimethyl-alpha-tetralone, which was supported by quantum calculations of gamma-butyrolactone and protonated gamma-butyrolactone. (c) 2006 Elsevier B.V. All rights reserved.

Abstract  Friedel-Crafts acylation of aromatic ethers is challenging, which frequently encounters rapid catalyst deactivation by the ether. Although H-Y and H-beta are known to perform better, there is still deactivation due to both the ether and the acylated ether. In the current work, the synthesis of 2,5-dimethoxyacetophenone, an intermediate used in the production of fine chemicals, was carried out via acylation of 1,4-dimethoxybenzene with acetic anhydride over various solid acid catalysts such as sulfated zirconia, UDCaT-1,UDCaT-5, 20% w/w H3P12W4O/K-10, 20% w/w Cs2.5H0.5P12W40/K-10, Amberlyst-15 and Indion-125. The cation exchange resins, Amberlyst-15 and Indion-125, were superior to other inorganic solid acids. A systematic study was undertaken to understand the reaction mechanism and catalyst functioning with Indion-125. The catalyst gets deactivated slowly over repeated use and this was studied independently. The adsorption of reactants and products was studied from pure component solutions and mixtures. The experimental data so generated were used to develop a model, incorporating deactivation. The model fits the experimental data very well. The current work gives an insight into choice of catalyst, kinetic modeling, studies in catalyst deactivation and methods to avoid deactivation. (c) 2006 Elsevier B.V. All rights reserved.

Abstract  Supported iron(III) ions on neutral gamma-alumina are an efficient catalyst for the oxidation of aromatic hydrocarbons with hydrogen peroxide in acetonitrile at 60 degreesC. The catalyst is active in the low temperatue liquid phase oxidation of benzene, toluene, chlorobenzene, p-xylene, mesitylene, benzaldehyde, with hydrogen peroxide. Conversions of 31-88% with respect to starting substrate were obtained within 6 h. Oxidation on both the side chain and the aromatic ring of hydrocarbons occurred. (C) 2004 Elsevier B.V. All rights reserved.

Abstract  Large-pore periodic mesoporous organosilica (PMO) hollow spheres with controllable pore size and high pore volume (2.5 cm(3) g(-1)) were successfully synthesized at low-temperature (similar to 15 degrees C) by using the triblock copolymer Pluronic F127 as a template and 1,3,5-trimethylbenzene (TMB) as a swelling agent in the presence of inorganic salt (KCl). Transmission electron microscopy (TEM) measurements show that the PMO hollow spheres are uniform and well dispersed, and the composites have a large wall thickness. The influence of TMB, KCl, CTAB contents and media acidity on the mesostructure was systematically studied. The pore size (9.8-15.1 nm) of the hollow spheres can be gradually expanded by increasing TMB content together with a relatively high acidity. By controlling the content of CFAB, successive structural transformation from hollow sphere to wormlike mesostructure and eventually to ordered body-centered cubic (space group of 1m-3m) mesostructure is observed. Our results reveal that the hydrophobicity of bis(triethoxysilyl)ethane (BTSE) and low-temperature approach contribute to the slow hydrolysis rate of silica precursors, which leads to weak interaction between individual TMB/F127 micelles and silicate oligomers. Furthermore, the salting-out effect of KCl may influence the swelling capacity of individual micelles as well as decrease the critical micelle concentration and critical micelle temperature, resulting in the formation of PMO hollow spheres from the assembly of individual TMB/F127 micelles with silicate oligomers. The composites exhibit efficient adsorption capacity (703 mg g(-1)) for toluene, suggesting they are a potentially useful adsorbent for removal of volatile organic compounds. The PMO hollow spheres allow biomolecules with large molecular weight to diffuse in, and show superior encapsulation capacity of bovine serum albumin (BSA) molecules (similar to 585 mg g(-1)) over other porous materials. (C) 2010 Elsevier Inc. All rights reserved.

Abstract  SBA-15, mesoporous material, is a very excellent candidate for drug delivery system because its pore size is easy to control according to synthesis conditions and the presence of swelling agent. In this study, a known swelling agent, 1,3,5-trimethylbenzene (TMB), was used to increase the pore size with increased aging temperature and prolonged aging time. Furthermore, 3-aminopropyltriethoxysilane (APTES) was incorporated on SBA-15 surface via post synthesis method to separate protein effectively. The samples were characterized by X-ray diffraction (XRD), nitrogen adsorption and desorption analyses, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Fourier Transform Infrared (FT-IR). Adsorption capacity increased with temperature at the isoelectric point (pI) of bovine serum albumin (BSA) regardless of the pore size of SBA-15 samples. Release studies were carried out in the range of pH from neutral to basic solution on unmodified and amine-modified samples. In addition, the adsorption mechanism was investigated by employing the pseudo-first order, pseudo-second order, and intraparticle diffusion models. (C) 2007 Elsevier Inc. All rights reserved.

Abstract  A series of binary titania-silica mixed oxides was prepared by sol-gel synthesis at room temperature. The hydrolysis of titanium isopropoxide (Ti((OPr)-O-i)(4)) and tetraethylorthosilicate (TEOS) was facilitated by co-solvent induced gelation in acidic media. The resulting gels were dried, calcined, and then characterized by powder X-ray diffraction analysis, nitrogen sorption studies (at 77 K), diffuse reflectance spectroscopy, Raman microscopy, and transmission electron microscopy. The nitrogen sorption studies indicate that the porosities could be tuned when simple aromatic solvents such as toluene, p-xylene, or mesitylene were added as a co-solvent to the synthesis gel. The binary mixed metal oxide materials obtained in this study showed high activity towards the degradation of phenol, and possessed high surface areas, and large pore volumes with narrow pore size distribution without the need for additional hydrothermal synthesis or supercritical drying. (C) 2011 Elsevier B.V. All rights reserved.