Abstract  The dispersion of functionalized multiwalled carbon nanotubes (MWNTs) in various solvents is characterized. The nanotubes were functionalized using a Birch alkylation method that afforded a 50-100% increase in o-dichlorobenzene solubility while rendering measurable solubility in otherwise insoluble chloroform and decreasing solubility in N,N-dimethylformamide and N-methyl-2-pyrrolidinone. Dispersibility was contingent on fostering polar interactions between the functionalized nanotubes and solvent despite the purely dispersive nature of the aliphatic chains. Interpretation of these results was performed using the Hansen solubility parameters and the three component surface energy analysis pioneered by van Oss and co-workers. It was found that the simplest interpretation of the Hansen solubility parameter scheme was unable to explain the data. In contrast, the surface energy analysis provides a robust interpretation of the solubility and yields values of 45.6 +/- 1.2, 0.78 +/- 0,04, and 2.4 +/- 0.9 mJ/m(2) for the Lifshitz-van der Waals (gamma(LW)), electron acceptor (gamma(+)), and electron donor (gamma(-)) surface energy components respectively.

Abstract  A model structure of Zao Zhuang bituminous coal (Shan Tong province in China, 86.9 wt % C) based on the structural analyses and the computer simulation was constructed. The coal was extracted with pyridine or carbon disulfide-N-methyl-2-pyrrolidinone (CS2-NMP) mixed solvent, and the extracts obtained were further fractionated. The extract fractions were hydrogenated using Adkins catalyst under mild condition at 430 degrees C for 1 h. The structure of the oil (n-hexane solubles) obtained from each extract fraction was analyzed by mass spectrometry after column separation and the molecular models of the fractions including the extraction residue were constructed assuming associated structure of coal molecules. Finally, a model structure of Zao Zhuang coal which consists of a huge associate of coal molecules was constructed three-dimensionally using computer-aided molecular design (CAMD) by assuming an anisotropic model structure formed from a periodic boundary cell. Good agreement of the physical density (1.22 g/cm(3)) of the constructed model with that (1.29 g/cm(3)) observed experimentally suggests that Zao Zhuang coal has a possibility to have associated structure of coal molecules having a continuous distribution of molecular weight from the lighter fraction to the solvent-insoluble residue.

Abstract  The saturated vapor pressures were measured for samples, of mole fraction purity of 99.98%, of 1-methyl-2-pyrrolidone (NMP), 1-methyl-azepan-2-one (N-methylcaprolactam), and 1,2-epoxy-3-chloropropane (epichlorohydrin) over wide temperature ranges by comparative ebulliometry. Measurements were made over the temperature range of (380.73 to 475.72) K for 1-methyl-2-pyrrolidone, (402.95 to 510.60) K for N-methylcaprolactam, and (315.67 to 388.29) K for epichlorohydrin, respectively. The experimental data were correlated, and overall measures of data reproducibility are given. The results are compared with literature data.

Abstract  Kinetics of swelling of Chinakuri coal in NMP, EDA, and NMP+EDA (1:1) (vol/vol) mixed solvent system were studied at temperatures ranging from 15 degreesC to 60 degreesC. The results obtained indicated that the diffusion of NMP, EDA, and NMP+EDA (1:1) in coal was described by Fickian diffusion. The values of diffusion exponent "n" were closer to Fickian diffusion in most cases though in some cases the value of "n" was even as low as 0.3. The activation energies for the combined diffusion and swelling process were in the range 20-30 kJ/mol. suggesting that the activation energy barrier may be associated with the disruption of hydrogen-bonding interactions in coal. The present paper reports the details of the studies.

Abstract  We have developed 6FDA-durene polyimide and poly(4-vinylpyridine) (PVP)/6FDA-durene composite hollow fibers. The 6FDA-durene fiber was defect-free and had a selectivity of 4.3-5.1 for O2/N2. It had an average permeance for O2 of approximately 240 x 10(-6) cm3 (STP)/cm2 s cmHg and its dense layer thickness was approximately 2000-3000 mum. The dense layer location was at the outer surface. This fiber was wet-spun directly from an in-situ imidization dope consisting of 14.94 wt% 6FDA-durene in a (70.24/21.5/7.51/0.75) N-methyl-2-pyrrolidone (NMP)/propionic acid (PA)/beta-picoline/propionic anhydride solvent mixture. The fiber diameter was approximately 500 mum with a wall thickness approximately 50-75 mum. The PVP/6FDA-durene composite fiber had a selectivity of 6.9 for O2/N2 and a permeance for O2 of 14.5 x 10(-6) cm3 (STP)/cm2 s cmHg. The newly developed technology suggests, for the first time, that a defect-free hollow fiber can be produced from a modified Lewis acid: base complex dope. Compared to most other conventional hollow fiber fabrication processes, our approach has many advantages because that (1) it is simpler and more economical, (2) spins fibers at low temperatures, (3) employs a dope directly from polymerization, and (4) requires no secondary operations, such as silicone coating and curing.

Abstract  In recent publications (D'Agostino et al., 2011; Moggridge, 2012a), we have proposed an equation to relate the mutual diffusion coefficient in a binary liquid mixture to the tracer diffusivities in the same mixture. The equation proved satisfactory for mixtures close to their consolute point as well as the general case of non-ideal mixtures; most of the available data relates to positive deviations from Raoult's law. In only one case, mixtures of acetone and chloroform, was the proposed equation not found to be consistent with the available experimental data. However, the tracer diffusivity data on which this assessment was based is old (1959 and 1967), of low accuracy and with few measurements to cover the range of compositions. For this reason we have re-measured the tracer diffusivities in acetone-chloroform mixtures at 25 degrees C with greater accuracy, by PFG-NMR, and used these measurements to re-examine the applicability of our equation to this system. We conclude that the proposed equation does in fact provide a good description of acetone-chloroform mixtures at 25 degrees C. This is of particular interest because acetone-chloroform shows a negative deviation from Raoult's law. The equation also gives a satisfactory fit for diethyl ether-chloroform and water-N-methylpyrrolidone (Moggridge, 2012a), both systems showing negative deviations from Raoult's law. (c) 2013 Elsevier Ltd. All rights reserved.

Abstract  In ultrafiltration membranes, selective layer composed of nodular microstructure usually formed by nucleation and growth during phase separation. The nodule size and extent of nodule packing can be varied by the use of inorganic nanoparticles of zeolite to render hydrophilic and hydrophobic microdomain structure to the membrane which minimizes fouling. The zeolite nanoparticles are dispersed from 0.01 to 1 wt% in N-methyl-2-pyrrolidone (NMP) solvent with the compatibilizer (D-alpha-tocopheryl polyethylene glycol succinate, TPGS) to form nanocomposites of Psf/zeolite in the form of hollow fiber membranes (HFMs). High Resolution Scanning Electron Microscopy (HRSEM) and EDAX studies show that zeolite nanoparticles participate in the nucleation process during phase separation. An almost linear increase in the tensile modulus with nanoparticle concentration shows that the mechanical properties of the HFMs also get influenced. We observed that water permeability of HFMs increases from 15.92 to 21.31 mL/m(2) h mm Hg, when zeolite loading increased from 0.01 to 0.1 wt% loading. Further, permeability decreases to 11.79 mL/m(2) h mm Hg at 1 wt%. The molecular weight cut off of composite HFM shows a steady increase with loading concentration from 9500 Da to 54,000 Da. We proposed a microstructural model explaining the influence of zeolite addition on HFM properties which forms the basis for selection and optimization of such additives. Crown Copyright (C) 2012 Published by Elsevier B.V. All rights reserved.

Abstract  An electron spin and proton magnetic relaxation study is presented on the effects of the solvent extraction of coal on the macromolecular network of the coal and on the mobile molecular species that are initially within the coal. The eight Argonne Premium coals were extracted at room temperature with a 1:1 (v/v) N-methylpyrrolidinone (NMP)-CS2 solvent mixture under an inert atmosphere. As much solvent as possible was removed from extract and residue by treatment under vacuum oven conditions (approximately 10(-2) Torr at 145-150-degrees-C) until constant weight was achieved. The extraction, without further washing with other solvents, results in substantial uptake of NMP, apparently by H-bonding or acid-base interactions. The NMP uptake tends to be higher, and the NMP tends to be more tightly bound in coal matter with higher heteroatom (N, 0, S) content. The molecular material in the medium rank bituminous coals is more aromatic and heteroatom-poor than the macromolecular material and is mobilized by the extracting solvent. Likewise, the more aromatic and heteroatom-poor molecular free radicals are also extracted. However, mobilization of the molecular free radicals by solvent and the exposure of free radicals in the macromolecular matrix to solvent or species dissolved in the solvent result in preferential reactions of the more aromatic and heteroatom-poor free radicals. Greater losses of extract free radicals, being the more aromatic, occur than residue free radicals. As a consequence, the surviving extract radicals exhibit a greater heteroatom content than the original whole coals, as determined from EPR g value changes. The electron paramagnetic resonance (EPR) spin-lattice relaxation (SLR) of these coal free radicals has previously been inferred (Doetschman and Dwyer, Energy Fuels 1992, 6, 783) to be from the modulation of the intramolecular electron-nuclear dipole interactions of the CH groups in a magnetic field by motions of the radical in the coal matrix. Such a modulation depends on the flexing amplitude and frequency and to a lesser extent upon the electron spin density at the CH groups in the radical. The observed EPR SLR rates decrease with coal rank in agreement with the smaller spin densities and the lower rocking amplitudes that are expected for increasing aromaticity with rank and increasing polycondensation at the highest ranks. The EPR SLR rates are found to be generally faster in the extracts (than residues) where the molecular species would be expected to be smaller and more flexible than in the cross-linked, polymeric, macromolecular matrix of the residue.

Abstract  Solid-liquid equilibria (SLE), have been measured from 270 K to the boiling temperature of the solvent for 10 binary mixtures of N-methyl-2-pyrrolidinone, with ethers (dipropyl ether, dibutyl ether, dipentyl ether, methyl 1,1-dimethylethyl ether, methyl 1,1-dimethylpropyl ether, ethyl 1,1-dimethylpropyl ether, 1,4-dioxane, tetrahydrofuran, tetrahydropyran, 18-crown-6) using a dynamic method. The solubility of N-methyl-2-pyrrolidinone in ethers is lower than in alcohols and generally decreases with an increase of the number of carbon atoms of ether chain. The highest intermolecular solute-solvent interaction is observed for the cyclic ethers and for methyl 1,1-dimethylethyl ether. Experimental solubility results are compared with values calculated by means of the Wilson, UNIQUAC ASM and two NRTL equations utilizing parameters derived from SLE results. The existence of a solid-solid first-order phase transition in 18-crown-6 ether has been taken into consideration in the calculations. The correlation of the solubility data has been obtained with the average root-mean-square deviation of temperature sigma(T) = 0.9 K with UNIQUAC ASM and two NRTL equations and 0.6 K with the Wilson equation. (C) 2004 Elsevier B.V. All rights reserved.

Abstract  Activity coefficients at infinite dilution (gamma(infinity)(13)) for 34 solutes: alkanes, alkenes, alkynes, cycloalkanes, aromatic hydrocarbons, alcohols, thiophene, ethers, acetone, and water in the ionic liquid 1-hexyl-3-methylimidazolium thiocyanate ([hmim][SCN]) were determined by gas liquid chromatography over temperature range from (298.15 to 368.15) K. The partial molar excess enthalpies at infinite dilution values (AM:) were calculated from the experimental gamma(infinity)(13) values, obtained over the temperature range. The selectivities for aliphatic/aromatic hydrocarbon separation problems were calculated from the gamma(infinity)(13) and compared to the literature values for other ionic liquids with a thiocyanate-based anion or a -C N group in an anion or a cation, N-methyl-2-pyrrolidinone (NMP) and sulfolane.

Abstract  We have determined the effects of dope extrusion speed (or sheer rate within a spinneret) during hollow fibre spinning on ultrafiltration membrane's morphology, permeability and separation performance, and thermal and mechanical properties. We purposely chose wet-spinning process to fabricate the hollow fibres without drawing and used water as the external coagulant in the belief that the effects of gravity and elongation stress on fibre formation could be significantly reduced and the orientation induced by shear stress within the spinneret could be frozen into the wet-spun fibres. An 86/14 (weight ratio) NMP/H2O mixture was employed as the bore fluid with a constant ratio of dope fluid to bore fluid dow rate while increasing the spinning speed from 2.0 to 17.2 m/min in order to minimise the complicated coupling effects of elongation stress, uneven external solvent exchange rates, and inner skin resistance on fibre formation and separation performance. Hollow fibre UF membranes were made from a dope solution containing polyethersulphone (PES)/N-methyl-2-pyrrolidone (NMP)/diethylene glycol (DG) with a weight ratio of 18/42/40, This dope formulation was very close to its cloud point (binodal line) in order to speed up the coagulation of nascent fibres as much as possible so that the relaxation effect on molecular orientation was reduced. Experimental results suggested that a higher dope flow rate (shear rate) in the spinneret resulted in a hollow fibre UF membrane with a smaller pore size and a denser skin due to a greater molecular orientation. As a result, when the dope extrusion speed increased, pore size, water permeability, CTE and elongation of the final membranes decreased, but the separation performance, storage modulus, tensile strength and Young's modulus increased. Most surprisingly, for the first time, we found that there was a certain critical value, when the dope extrusion rate was over this value, the final fibre performance could not be influenced significantly. The results suggested that it was possible to dramatically enhance the production efficiency of hollow fibre UF membranes with the same fibre dimension and similar separation performance by the method proposed in this paper. (C) 1999 Elsevier Science B.V. AU rights reserved.

Abstract  An elegant one-step synthesis of two novel spiro ring systems viz., spiro[3H-indole-3,4'(1'H)-pyrano[2,3 -d-imidazol]-2-oxo-2'-thiones-5' carbonitrile (VI) and spiro[3H-indole-3,4' (1'H)pyrano[2,3-c] pyrrole]- 5'carbonitrioles (VII) in 44-59% yields is described. The spiro heterocycles were prepared by the Michael reactions of 3-dicyanomethylene-2H-indol-2-ones (III) with 1-phenyl-2-thio-hydanroin (IV) and 2-pyrrolidone/N-methyl-2-pyrrolidone (V), respectively while the intermediate (III) has been synthesized from substituted indole-2,3-diones (I) with malanonitrile (II). The synthesized compounds have been characterized on the basis of elemental analyses, IR, H-1 NMR, F-19 NMR and mass spectral studies. All the compounds have been screened in vitro for antifungal activity against Alternaria alternata.

Abstract  In this paper thermophysical properties of 2-pyrrolidone, N-methyl-2-pyrrolidone, and N-cyclohexyl-2-pyrrolidone, in binary and ternary liquid mixtures with water are reported at 298.15 K and 0.1 MPa over the whole composition range. Derived excess and mixing properties were used to analyze mixtures' structure. To infer a detailed picture of the intermolecular interactions in the studied fluids, attenuated total reflection infrared absorption spectroscopy was used. To study fluid properties from a molecular viewpoint, density functional theory computations were carried out, leading to structural and energetic information. Formation of H-bonding and dipolar interactions between cyclic amides and with water were observed, resulting in complex fluid structures that were stronger in binary mixtures containing water than in ternary ones. Intermolecular forces are weakened upon mixing by the presence of a second cyclic amide in the mixture.

Abstract  Printing or film coupling processes use engraved rollers whose surface is formed by microscopic cells that carry inks or adhesives on the film. During their use, cells are progressively filled up of residual dry ink and/or adhesive that reduce their efficiency. Cells cleaning is very complex, due to their microscopic dimensions. A new technique based on the use of supercritical mixtures (carbon dioxide and organic solvents) to clean engraved rollers was developed. To study the feasibility of this process, various combinations liquid solvent-supercritical CO2 and the effect of some operating parameters was investigated, as operating pressure, temperature and residence time. Due to supercritical fluid mixture characteristics as, near zero surface tension and high diffusivity, a fast and complete removal of the dried residue from the microscopic cells was obtained. An almost complete cleaning was obtained in 40 and 60 min operating with a supercritical solution of carbon dioxide plus 80% w/w of N-methyl pyrrolidone at 150 bar and 40 degrees C for poly-urethane adhesive and polychlorovinyl resin red ink, respectively. (c) 2006 Elsevier B.V. All rights reserved.

Abstract  A case study has been conducted on the reduction of N-methyl-2-pyrrolidone (NMP) solvent waste in the manufacture of polyimide and polybenzoxazole precursors. The evaluation includes the environmental and economic life cycle assessment of solvent recovery and solvent substitution strategies. A two-step distillation process proved effective in recovering 95 % of the NMP at a purity of 99.97 % from an aqueous waste stream comprised 17 % NMP, 0.5 % hydroxyethyl methacrylate, 0.5 % trifluoroacetic acid, and 0.5 % hydrochloric acid. Yearly operating costs were reduced by 83 %, with the greatest impact on the reduction in virgin NMP purchase and hazardous waste disposal cost. Even if a capital acquisition was needed, the recovery option would still result in a net present value at 10 years of 3.12 MM $US. The environmental life cycle assessment (LCA) showed that a 44 % reduction of total emissions is possible with the solvent recovery process, impacting the virgin NMP and hazardous waste disposal life cycle emissions the most. The efficiency in the reduction in life cycle emissions is limited by the thermodynamics of the system, in particular the large composition of water in the waste stream which requires significant energy to distill, thus generating significant life cycle emissions. Solvent substitutes dimethyl sulfoxide and sulfolane reduce life cycle emissions by 44 and 47 %, respectively, when they replace NMP in the process, even without a recovery operation, due to their greener manufacturing profile. Although, when the recovery systems for the solvent substitutes are incorporated into the design, no further reductions in the environmental impact are seen. This demonstrates the need for a complete analysis of all the aspects of a greener design (including the recovery step), since the thermodynamic characteristics of the solvents are important when performing an LCA. Water reuse was also considered for the overall process, but not recommended due to the cost of recovering it from the waste stream to ultrapure water standards.

Abstract  The relative abundance of coke particles, injectant coal-char, and soot found in blast furnace dust provides clues about the operation and efficiency of the blast furnace. The aim of the work has been to determine whether the source of the soots could be related to the injectant coal, in particular, to the nature of the extractable material within it. This paper describes the separation of soot from blast furnace dust and its characterization. Dust samples collected during coal injection tests in a blast furnace and in a pilot scale, "single-tuyere" test rig have been extracted with NMP (1-methyl-2-pyrrolidinone). The parent coals used in these tests were also extracted with NMP; the solvent is highly polar and useful in dissolving various types of soot as well as coal extracts and tars. Fresh coke gave no extract. The coal and dust extracts were characterized by size exclusion chromatography (SEC). Differences were observed between chromatograms of the extracts from the two coals used-the first in the "single-tuyere" test rig, and the second in the blast furnace. SEC was useful in identifying similar features in the chromatograms of extracts from the parent coal and the soot extracted from the blast furnace dust; similar observations were made on the "single-tuyere" test rig dust and the coal injected into it. These findings support the view that tar evolution from the injectant coal contributes directly to soot formation and is a major contributor to levels of dust emission observed at high coal injection rates.

Abstract  The possibility of use of Astrakhan gas condensate residue above 350 degrees C as feedstock for catalytic cracking has been explored. The feedstock was submitted to extraction cleaning with a mixture of N-methylpyrrolidone and heptane to improve the ecological properties of the cracking products.

Abstract  The development of new isotopic laser-based analyzers currently represents a clear alternative to conventional isotope ratio mass spectrometers. However, this analytical technique also suffers some disadvantages such as the memory effect, problems related to the overall stability of the equipment and other issues associated with the injection system, essentially regarding the syringe's longevity. This paper aims to minimize these disadvantages in order to increase the overall performance, in terms of precision and accuracy, of these kinds of analyzers. The main results of the experiments carried out in this paper have shown that: (i) the minimum number of discarded injections needed to eliminate the memory effect can be determined just considering the expected isotopic signature difference between two consecutive samples; (ii) both accuracy and precision of the isotopic measurements increase with increasing injection volume up to 2.1-2.2 mu L; (iii) it is possible to extend the syringe lifetime by almost a factor of 6 by using n-methyl 2-pyrrolidone as a lubricant. Besides, it has been concluded that, by using the appropriate procedure, the main disadvantages associated with CRDS laser spectroscopy analyzers can be minimized, achieving measurement accuracy and precision of the order of +/- 0.05 parts per thousand for delta O-18 and +/- 0.3 parts per thousand for delta H-2.

Abstract  Hollow fiber membranes are of great commercial interest with several applications at the forefront of research to carryout bioseparations, drinking water purification, wastewater treatment besides liquid phase separations and gaseous separations. An experimental study was carried out to synthesize hollow fiber membranes from polyethersulfone (PES) and polyacrylonitrile (PAN) polymers to fabricate modules for surface water treatment and clarification of fungal enzyme broth. Design drawings of a manual hollow fiber spinning machine and spinneret were prepared to fabricate the necessary equipment for extrusion of hollow fibers. Effect of various spinning conditions on specific macroscopic fiber properties, such as outer diameter and wall thickness and membrane pore structure was studied. Concentrations of 15-20 wt% PES in n-methylpyrrolidone (NMP) and PAN in dimethyl formamide (DMF) solvents with important additives and pore formers were prepared. These polymer solutions were extruded through the spinneret and subjected to phase inversion in a water bath. The membranes were characterized by scanning electron microscopy (SEM) and pure water flux studies. PAN and PES exhibited 99.8 and 95.4% turbidity rejection. PAN exhibited a 5 log reduction of Escherichia coli bacteria for surface water treatment at a low hydraulic pressure of 1 bar with a flux of 54.2 L/m(2) h at a water recovery of 80% whereas PES gave a flux of 36.6 L/m(2) h with 4 log reduction of E. coli. PAN and PES membranes exhibited 54.9 and 69.3% xylanase enzyme recoveries from fungal broth at reasonable flux with turbidity rejection of 94.8 and 95.7% respectively.

Abstract  Polybenzoxazinoneimide membrane was prepared in three steps: a dichlorodianhydride (obtained by the reaction of trimellitic anhydride with 4,4'-oxydianiline) was treated with methylene-bis(anthranilic acid). The resulting polyamic acid was dissolved in N-methylpyrrolidone, the solution was cast as a thin film, the solvent was evaporated and the membrane was heated under controlled conditions to convert polyamic acid into polybenzoxazinoneimide. Density, free volume parameters, sorption parameters for methanol and ethanol of the membrane were determined. The membrane was used for the pervaporation of methanol/ethanol mixtures containing 5-20 wt.% methanol which are mixtures modeling bioalcohol. The membrane was preferentially permeated by methanol with high separation factors. (C) 2015 Elsevier B.V. All rights reserved.

Abstract  The Taylor dispersion method has been used to determine diffusion coefficients of N-methylpyrrolidone, 2-methyl-2,4-pentanediol, glycerol, 1,3-butanediol, and 1,2,6-hexanetriol at infinite dilution in water and of water, glycerol, and 2-methyl-2,4-pentanediol at infinite dilution in N-methylpyrrolidone. The temperature has been varied between 298 and 348 K.

Abstract  Stable dispersions of pure and nitrogen containing multi-walled carbon nanotubes (MWCNTs and N-MWCNTs respectively) were prepared using a variety of solvents (such as N-methyl-2-pyrrolidone (NMP), benzyl alcohol, acetophenone, N-dimethylacetamide (DMA), etc. with surface energies ranging between 45.8 mJ/m(2) (diethyl ether) and 102.3 mJ/m(2) (water). Sedimentation measurements were employed to confirm the stability of the dispersions over time. Amongst the solvents employed DMA proved to be particularly efficient, i.e., up to 82% of the nanotubes initially dispersed remained in solution. Moreover, we showed that the surface chemistry of carbon nanotubes (CNTs) governs their dispersibility. For instance, the higher the N content is within the N-MWCNTs, the lower the surface energy of the solvent must be to successfully disperse the nanotubes. These findings not only play an important role in overcoming current obstacles commonly encountered in existing CNT processing procedures but also provide a technique for processing CNTs efficiently without altering their properties. Ultimately, it may be possible to manipulate the surface chemistry of CNTs in-situ, e.g., by inserting heteroatoms, to such extend that they may disperse spontaneously in aqueous solutions, hence paving the way for biomedical applications etc.

Abstract  Reaction of starch I dissolved in dimethyl sulfoxide (DMSO) with bulky thexyldimethylehlorosilane (TDSCl) in the presence of pyridine leads to regioselectively functionalized silyl ethers with a degree of substitution (DS) up to 1.8. The control of the DSSi, of the regioselectivity, and of the reaction pathway is described in detail, The reaction proceeds homogeneously up to DSSi of 0.6. With ongoing silylation the polymers form a separate phase incorporating the silylating agent to form TDS-starches with DSSi values higher than 1.0. After peracetylation of the silyl starches, the substitution pattern has been characterized not only in the anhydroglucose repeating units (AGU) but also in the non-reducing terminal end groups (TEG) by means of two-dimensional H-1 NMR techniques. Up to DSSi 1.0, a very high regioselective functionalization of the primary 6-OH groups in the AGU as well as in the TEG is detectable. With increasing silylation (DSSi > 1.0), the subsequent silylation takes place at the 2-OH groups of the AGU and at the 3-OH groups of the TEG. These results are compared with our own investigations on the silylation of starch in the reaction system N-methylpyrrolidone (NMP)/ammonia and on the silylation of cellulose in NN-dimethylacetaniide (DMA)/LiCl/ pyridine solution.

Abstract  Vacuum distillates of an Egyptian crude oil were subjected to solvent extraction process applying N-methyl-2-pyrrolidone (NMP) and furfural as dearomatization solvents. The study shows that the extraction solvent together with the temperature and solvent-to-oil ratio have a significant effect on the yield and quality of produced lubricating oils. The optimum temperature for extracting light waxy distillates with NMP is 55 degrees C at the solvent-to-feed ratio 2:1. These conditions are appropriate to remove the major portion of aromatics from the raffinate. The apparent activation energy (Ea), enthalpy (H*), entropy (S*), and free energy of activation (G*) were calculated for the solvent dearomatization process.