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Aromatic Solvents (aromatic + solvent)
Selected AbstractsThermodynamic micellization model for asphaltene precipitation inhibitionAICHE JOURNAL, Issue 2 2000Huanquan Pan Aromatic solvents and oil-soluble amphiphiles are recognized as asphaltene precipitation inhibitors in oil production and transportation. In the absence of the model describing the effect of these inhibitors on asphaltene precipitation from crudes, proposed is a thermodynamic micellization model explaining the inhibition mechanism for both aromatic solvents and oil-soluble amphiphiles. The model shows that aromatic solvents are concentrated in the micellar shell, and the interfacial tension between the asphaltene micellar core and shell is reduced as the micelles becomes stabler. A crude, mixed with a small amount of an oil-soluble amphiphile, achieves a high micellar stability. The amphiphiles behave like resin species of the crude and coadsorb onto the micellar core with resins. The adsorption enthalpy of an amphiphile onto the micellar core is much higher than that of the resin and, therefore, amphiphiles can be very effective inhibitors. The results suggest that the adsorption enthalpy data can be used to screen the amphiphiles for asphaltene precipitation inhibition. For a given oil-soluble amphiphile, this model can predict the amount of the amphiphile required to inhibit the precipitation. [source] High-performance liquid chromatography with electrospray ionisation mass spectrometry and diode array detection in the identification and quantification of the degradation products of calix[4]arene crown-6 under radiolysisRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 13 2004C. Lamouroux The extraction of 135Cs from high-activity liquid waste, arising from reprocessing of spent nuclear fuel, can be achieved by using calix[4]arene crown-6 compounds. The radiolytic degradation of di(n-octyloxy)calix[4]arene crown-6 (octMC6), in aliphatic or aromatic solvent in contact with 3 M nitric acid, was studied by high-performance liquid chromatography directly coupled to electrospray ionisation mass spectrometry (LC/ESI-MS). More than 50 distinct degradation products were observed, and about 30 of these were identified. These compounds can be assigned to three categories, namely, products of reactions involving radical cleavage or addition, of oxidation reactions, or of aromatic substitution reactions. The major product, corresponding to substitution by an NO2 group, was quantified by external standard calibration using a purified synthetic sample. Despite the observation of all these degradation compounds, octMC6 appears to be remarkably stable under these drastic conditions, combining hydrolysis (HNO3 3,M) and an extreme exposure to radiolysis (106,Gy). Less than 35% degradation of octMC6 was observed in aromatic solvent under these conditions. Copyright © 2004 John Wiley & Sons, Ltd. [source] A Stacking Interaction between a Bridging Hydrogen Atom and Aromatic , Density in the n -B18H22,Benzene SystemCHEMISTRY - A EUROPEAN JOURNAL, Issue 9 2006Ewan J. M. Hamilton Prof. Abstract The structures of n -B18H22 and of n -B18H22,C6H6 were determined by single-crystal X-ray analysis at ,60,°C. The geometry of the boron cluster itself does not seem to be appreciably affected by solvation. There does, however, appear to be an unusual interaction of a polyborane bridging hydrogen atom with the benzene , system, giving rise to an extended stacked structure. The 1H{11B} spectrum of n -B18H22 in [D6]benzene differs from that in [D12]cyclohexane most noticeably in the bridging proton region. Upon moving from the aliphatic to the aromatic solvent, the greatest increase in shielding was for the signal corresponding to the bridge hydrogen atom that interacts with the , system of benzene; the signal was shifted upfield by 0.49 ppm. Density functional theory calculations were performed on 1:1 and 2:1 complexes of the n -B18H22 unit with benzene. [source] Dynamics of Benzene and Toluene Degradation in Pseudomonas putida F1 in the Presence of the Alternative Substrate SuccinateENGINEERING IN LIFE SCIENCES (ELECTRONIC), Issue 4 2007I. Rüegg Abstract In batch and continuous culture, the regulation of benzene and toluene degradation by Pseudomonas putida,F1 was investigated in the presence of the alternative carbon and energy source succinate. In batch culture, benzene and toluene were used simultaneously, whereas succinate suppressed benzene consumption under carbon excess conditions resulting in diauxic growth. In carbon-limited continuous culture mixed substrate growth was observed. Since in nature low substrate concentrations and ever changing conditions prevail, this paper focuses on the dynamics of benzene/toluene degradation, biomass synthesis, and the regulation of benzene/toluene-degrading enzymes in cultures growing continuously at a dilution rate of 0.1,h,1, when shifting the supply of the carbon and energy source from succinate to various mixtures of succinate and benzene/toluene, or to benzene only. When the succinate concentration was kept constant (1.25,mM) and the medium was supplemented with benzene (2,mM), growth with benzene began already two hours after the shift. In contrast, replacing succinate with benzene only led to a wash out of biomass for more then ten hours, before biomass production from benzene started. A striking and reproducible transition pattern was observed for all shifts where the succinate concentration was reduced or succinate was omitted. After an initial period of biomass production from benzene, the culture collapsed and a wash-out of biomass was observed. However, this wash-out was not accompanied by an increase in benzene in the cultivation liquid, indicating a benzene uptake without conversion into biomass. Another possibility is that in phases of low biomass concentrations, cells were only able to use the low amounts of benzene/toluene dissolved in the cultivation liquid yielding low biomass concentrations whereas in phases of high biomass concentrations, they were able to rapidly utilize the aromatic solvents so that additional benzene from the gas phase diffused into the cultivation liquid resulting in more biomass production. In most cases, growth resumed again after 10 to 80,h. Currently, the reasons for the decrease in biomass after the first rise are unknown. However, several indications rule out intoxication of the cells by either the solvents benzene or toluene themselves, or by toxic degradation intermediates, or by-products. [source] Donor,Acceptor C60 -Containing Polyferrocenylsilanes: Synthesis, Characterization, and Applications in Photodiode Devices,ADVANCED FUNCTIONAL MATERIALS, Issue 3 2008Masato Nanjo Abstract A series of polyferrocenylsilane (PFS) random copolymers containing covalently bound pendant [C60]fullerene groups, the first well-characterized metallopolymers with pendant C60 units, have been prepared and characterized. The fullerene content of the prepared copolymers ranges from 7 to 24% relative to monomer unit. The desired copolymers were synthesized in three steps: metal-catalyzed ring opening polymerization of sila[1]ferrocenophanes was performed to synthesize random copolymers of poly(ferrocenylmethylphenylsilane -co- ferrocenylchloromethylsilane); the resulting random PFSs were then functionalized by reaction with 11-azido-1-undecanol to give PFSs with pendant azide groups; the desired donor,acceptor C60 -containing PFSs were then synthesized by the reaction of the azide group in the side chains with C60 in toluene at 110,°C. The resulting C60 -containing PFSs are air-stable and soluble in aromatic solvents, chloroform, or THF. The UV-vis spectra of these materials show broad absorption up to 800 nm. Thin films of these materials were examined as the active layer in rare examples of all solid-state sandwich-type diode devices based on ferrocene-fullerene dyads. The devices exhibit photoconducting and photovoltaic responses, with an open circuit potential of ca. 0.3 V under white light illumination. [source] Oxazoline chemistry part III.JOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 3 2003-anilinyl)-2-oxazolines], Synthesis, characterisation of [2-(, some related compounds The syntheses and characterisation of a series of chiral and achiral 2-(aminophenyl)-2-oxazolines and some related compounds is reported. All of the derivatives have been produced by a one-step procedure involving the treatment of isatoic anhydride (i.e. [2H]-3, 1-benzoxazine-[1H -2,4-dione: 1) or its 5-chloro analogue with a slight excess of appropriate amino-alcohols. In most cases, anhydrous ZnCl2 is shown to be an effective Lewis acid catalyst for this reaction at reflux temperature in high boiling aromatic solvents (PhCl or PhMe). Oxazolines have been readily formed using rac -2-amino-1-butanol, (S)-phenylglycinol, 2-methyl-2-amino-1-propanol and (1S,2R) or (IR,2S)-cis - 1 -amino-2-indanol; yields range from 85% to 22%. The use of aminoalcohols such as 2-ethanolamine, (±)-2-amino-1-phenyl-1-propanol or 3-amino-1-propanol (to give the corresponding 4,5-dihydro-1,3-oxazine) results in poor yields. The use of other Lewis acid catalysts (silicic acid, Cd(acac)2·2H2O, CuCl2·2H2O, InCl3) or higher temperatures did not improve the yields with these latter two substrates. Benzoxazoles and N-substituted benzoxazoles can also be obtained in reasonable yields from 1 using 2-aminophenol (36%) or 2-amino-3-hydroxypyridine (45%). [source] Thermodynamic micellization model for asphaltene precipitation inhibitionAICHE JOURNAL, Issue 2 2000Huanquan Pan Aromatic solvents and oil-soluble amphiphiles are recognized as asphaltene precipitation inhibitors in oil production and transportation. In the absence of the model describing the effect of these inhibitors on asphaltene precipitation from crudes, proposed is a thermodynamic micellization model explaining the inhibition mechanism for both aromatic solvents and oil-soluble amphiphiles. The model shows that aromatic solvents are concentrated in the micellar shell, and the interfacial tension between the asphaltene micellar core and shell is reduced as the micelles becomes stabler. A crude, mixed with a small amount of an oil-soluble amphiphile, achieves a high micellar stability. The amphiphiles behave like resin species of the crude and coadsorb onto the micellar core with resins. The adsorption enthalpy of an amphiphile onto the micellar core is much higher than that of the resin and, therefore, amphiphiles can be very effective inhibitors. The results suggest that the adsorption enthalpy data can be used to screen the amphiphiles for asphaltene precipitation inhibition. For a given oil-soluble amphiphile, this model can predict the amount of the amphiphile required to inhibit the precipitation. [source] Molecular transport of aromatic hydrocarbons through lignin-filled natural rubber compositesPOLYMER COMPOSITES, Issue 1 2007Thomas V. Mathew The diffusion and transport of organic solvents through lignin-filled natural rubber composites have been studied in the temperature range 25,45°C. The diffusion of aromatic solvents through these samples were studied with special reference to the effect of filler concentration, penetrant size, and temperature. Transport coefficients such as diffusion, permeation, and sorption coefficients were estimated. The van't Hoff relationship was used to determine the thermodynamic parameters. The first order kinetic rate constant has been evaluated. A correlation between theoretical and experimental sorption results was evaluated. POLYM. COMPOS., 28:15,22, 2007. © 2007 Society of Plastics Engineers [source] Transport of aromatic solvents through nitrile rubber/epoxidized natural rubber blend membranesPOLYMER ENGINEERING & SCIENCE, Issue 3 2003Asha Elizabeth Mathai The sorption and diffusion behavior of a series of aromatic solvents through blends of nitrile rubber (NBR) and epoxidized natural rubber (ENR) have been studied in the temperature range of 28,70°C. The effect of blend ratio, penetrant size and temperature on the transport properties was investigated. The relationship between the diffusion behavior and the morphology of the system was examined. Different transport parameters such as diffusion coefficient, permeability coefficient and swelling ratio have been calculated. Experimental permeability coefficients were compared with various theoretical models. The van't Hoff relation was used to compute the thermodynamic parameters. [source] Modeling of polycyclic aromatic hydrocarbon SLE in aromatic solventsASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 3 2010Thenmozhi Muthukumarasamy Abstract Equilibrium solubilities of polycyclic aromatic hydrocarbon (PAH) solutes naphthalene, fluorene, acenaphthalene, fluoranthene, anthracene, phenanthrene, pyrene, chrysene and triphenylene in benzene and substituted benzene solvents are predicted using the Dortmund-AU model. The Dortmund-AU method performs better than the UNIFAC and modified UNIFAC (Dortmund) models when applied to PAH in benzene systems, but the accuracy of predictions deteriorates in the case of PAHs that have melting points greater than 380 K. Accounting for the heat capacity change on melting term makes considerable difference to the ideal solubility calculation in the case of higher-melting PAHs. A new term is added to the residual part of activity coefficient in the UNIFAC model to derive a modified empirical version. Application of this model to PAH solid,liquid equilibria is verified and the results are compared with those of Dortmund-AU model. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Self-Association of Bis-Dendritic Organogelators: The Effect of Dendritic Architecture on Multivalent Cooperative InteractionsCHEMISTRY - A EUROPEAN JOURNAL, Issue 8 2010Myungeun Seo Dr. Abstract A series of bis-dendritic gelators consisting of a benzamide dendron and an alkyl dendron were synthesized to investigate the dendritic effect on self-assembly. The gelators with a first-generation benzamide (benzamide- G1) dendron or a first-generation alkyl (alkyl- G1) dendron formed stable gels in most aromatic solvents, and their self-assembled fibrillar networks were imaged by electron microscopy. The unbranched molecule (G0 - G0) or the molecule possessing a second-generation benzamide (benzamide- G2) dendron did not form gels. Differential scanning calorimetry, powder X-ray diffraction, and Fourier transform IR studies revealed that introduction of a dendritic branch strongly affected the molecular packing as well as the strength of intermolecular interactions. Furthermore, concentration-dependent diffusion coefficient measurements and the evaluation of association constants by 1H NMR spectroscopy indicated that bis-dendritic gelators with a benzamide- G1 dendron possessed high association constants and formed large aggregates, whereas molecules with a single benzamide formed dimers in chloroform. The formation of self-assembled fibrillar networks was driven by the multivalent and cooperative hydrogen bonding observed in the benzamide- G1 dendrons. ,,, stacking of aromatic groups and van der Waals interactions between alkyl chains also played roles in the self-assembly process, thus indicating that a spatial balance between two dendrons is important. [source] Spin-Crossover Physical Gels: A Quick Thermoreversible Response Assisted by Dynamic Self-OrganizationCHEMISTRY - AN ASIAN JOURNAL, Issue 1 2007Tsuyohiko Fujigaya Abstract Iron(II) triazolate coordination polymers with lipophilic sulfonate counterions with alkyl chains of different lengths have been synthesized. In hydrocarbon solvents, these polymers formed a physical gel and showed a thermoreversible spin transition upon the sol,gel phase transition. The formation of a hydrogen-bonding network between the triazolate moieties and sulfonate ions, bridged by water molecules, was found to play an important role in the spin-crossover event. The spin-transition temperature was tuned over a wide range by adding a small amount of 1-octanol, a scavenger for hydrogen-bonding interactions. This additive was essential for the iron(II) species to adopt a low-spin state. Compared with nongelling references in aromatic solvents, the spin-crossover physical gels are characterized by their quick thermal response, which is due to a rapid restoration of the hydrogen-bonding network, possibly because of a dynamic structural ordering through an enhanced lipophilic interaction of the self-assembling components in hydrocarbon solvents. [source] | ||||||||||||||||||||||