Ordinary Solvents Research Articles

Comparative study of the texture and structure of aerogel and xerogel sulphated zirconia doped with nickel

Aerogels and xerogels based on sulphated zirconia doped with nickel in the same atomic ratios S/Zr = 0.5 and Ni/Zr = 0.1 have been synthesized by sol–gel method using two drying ways of the solvent in solid preparation steps. Aerogels obtained by drying in supercritical conditions of solvent stabilize zirconia tetragonal phase even at high calcination temperatures and present a developed surface area, whereas xerogels obtained by ordinary solvent drying in an oven are amorphous. TPR and XPS studies revealed that Ni seems to exist in different species in the two kinds of solids and it is more reducible in aerogels.

Effect of pressure on the structure and electrical conductivity of cardanol–furfural–polyaniline blends

AbstractPressure‐sensitive polymers that simultaneously present reasonable electrical conducting properties, useful thermosetting behavior, and softness are hard to develop. To combine these properties into a single material, a cardanol‐based phenolic resin was prepared and blended in situ with polyaniline (PAni). The final polymer blend was composed of a soft solid material that could not be dissolved in ordinary solvents. Samples were characterized through X‐ray scattering, Fourier transform infrared (FTIR) spectroscopy, and electrical conductivity and pressure sensitivity measurements. FTIR results indicate that the insertion of PAni into the blends did not change the chemical nature of the resin. According to wide‐angle X‐ray scattering results, PAni was dispersed homogeneously in the final polymer samples; this improved the sensitivity of the electrical conductivity to pressure variations, as confirmed through electromechanical tests. Pressure sensitivity and electromechanical analyses indicated that the produced blends could be used as pressure‐sensing materials. Among the tested materials, the blends containing 5 wt % PAni·H2SO4 presented the largest compression sensitivity values. Finally, it was shown for the first time through XRD analyses under pressure that PAni chains were considerably disturbed by compressive stresses. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

A New Type of Composite Turquoise

Introduction Turquoise, best known for its splendid blue colour, has been used for adornment since antiquity. Chemically a hydrous copper aluminium phosphate, it has a cryptocrystalline structure composed of fine, randomly oriented groups of triclinic crystals (Webster, 1994). This cryptocrystalline structure gives rise to the gem’s porosity, making it susceptible to body oils, ordinary solvents, or even dirt, which can alter its colour. For decades, turquoise has been impregnated with wax, plastics, or polymers—a process known as stabilization, which enhances not only the material’s durability but also its colour and surface lustre (Nassau, 1994). Another established treatment is the dyeing of pale-coloured turquoise to give it a rich blue colour (see, e.g., Kammerling, 1994). In recent years, a few other proprietary treatments have been developed for turquoise. The most prominent is Zachery treatment, which decreases the porosity of the original material, so it takes a better polish; the blue colour may also be enhanced through an additional step in the process (Fritsch et al., 1999). Another form of treatment seen on the market, developed by Eljen Stones, involves polymer impregnation (Owens and Eaton-Magana, 2009).

Ab initio study on SN2 reaction of methyl p-nitrobenzenesulfonate and chloride anion in [mmim][PF6

A S(N)2 reaction of methyl p-nitrobenzenesulfonate (p-NBS) and chloride anion in ionic liquid ([mmim][PF(6)]) was studied using RISM-SCF-SEDD method coupled with a highly sophisticated ab initio electronic structure theory (CCSD). The solvation structure as well as the energy profile along the reaction were discussed through comparison with an ordinary solvent system, dichloromethane.

Dispersed Kinetics without Rate Heterogeneity in an Ionic Liquid Measured with Multiple Population-Period Transient Spectroscopy

The kinetics of the electronic-state relaxation of the diphenylmethane dye auramine O are found to be much more dispersed (nonexponential) in a prototypical ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate, than in ordinary solvents. Recent theoretical and experimental evidence for structural heterogeneity in ionic liquids suggest that the dispersion is due to rate heterogeneity, that is, different relaxation rates for solute molecules in different spatial regions. This hypothesis is tested with a new multidimensional spectroscopy, MUPPETS (multiple population-period transient spectroscopy). Rate heterogeneity is not found to be the primary cause of the dispersed kinetics. Rather, a homogeneous mechanism is responsible for this unusual phenomenon.

Dielectric Relaxation of Polymer/Carbon Dioxide Systems

In general, pressurized CO2 is soluble in polymers (to a concentration determined by the pressure) and affects the polymer relaxation behavior. Focusing on segmental relaxation, this study conducted dielectric measurements for racemic dl-poly(lactic acid) (PLA) as well as polystyrene (PS) under carbon dioxide (CO2) pressurized up to PCO2 = 3.5 MPa. The dielectrically detected segmental dynamics of PLA and PS was found to be accelerated on the increases of the CO2 pressure PCO2 that resulted in an increase of the CO2 concentration (detected through a decrease of the dielectric intensity). In this sense, the pressurized CO2 behaved as an ordinary solvent. However, the dielectrically detected segmental relaxation mode distribution was quite insensitive to PCO2, which was in strong contrast to the mode broadening induced by ordinary solvents such as di-n-butyl phthalate (DBP) (the broadening was confirmed also in this study for PLA plasticized with DBP). The mode broadening due to ordinary solvents is attribu...

Ultrafast bimolecular radical reaction between S1p‐terphenyl and carbon tetrachloride: mode‐specific acceleration of vibrational dephasing in reactant molecule

AbstractUltrafast bimolecular radical reaction proceeds between photoexcited p‐terphenyl and carbon tetrachloride. The lifetime of the first excited singlet (S1) state of p‐terphenyl in carbon tetrachloride measured with picosecond time‐resolved fluorescence spectroscopy is 5.6 ps, shorter than the typical lifetime in ordinary solvents, 0.95–2.8 ns, by a factor of 170 or more. Time‐resolved infrared spectroscopy reveals the generation of the trichloromethyl (CCl3) radical as a reaction intermediate. The decay kinetics of the CCl3 radical indicates that the CCl3 radical and the p‐terphenyl–Cl radical adduct, both of which are produced simultaneously by a radical reaction between S1p‐terphenyl and carbon tetrachloride, recombine to form the product. The picosecond time‐resolved Raman spectrum of the reactant S1p‐terphenyl shows that the dephasing process for the four vibrational modes at 1640, 1497, 1180, and 1017 cm−1 is selectively accelerated in carbon tetrachloride. The four vibrational modes probably have a large contribution from the motion of a specific atom or atoms where the intermolecular interaction that induces the bimolecular reaction is present. Copyright © 2008 John Wiley & Sons, Ltd.

New in situ Blends of Polyaniline and Cardanol Bio‐Resins

AbstractCardanol, a well known natural resource, was used to produce a polymer resin in the presence of formaldehyde, catalyzed by H2SO4. Before reticulation, PAni · H2SO4 was blended with the resin. The blended material was cast into poly(propylene) cups and kept inside a desiccator under vacuum until complete water evaporation. The final in situ polymer blend was solid and could not be dissolved in ordinary solvents, indicating that a reticulated material had been obtained. Samples prepared similarly were then characterized, showing that the produced blends can be used as pressure sensing materials.magnified image

The partial solubility parameters: An equation-of-state approach

The division of the well-known solubility parameter into its dispersion, polar, and hydrogen-bonding components has significantly upgraded its capacity and usefulness in the screening and selection of the appropriate solvents in Industry and in Laboratory. This work presents a new statistical thermodynamic approach for the estimation of these partial components over a broad range of temperature and pressure. Key to this approach is the development of explicit expressions for the contribution of dispersion, dipolar, and hydrogen-bonding interactions to the potential energy of the fluid. The approach is applicable to ordinary solvents, to supercritical fluids, as well as to high polymers. Information on various thermodynamic properties of fluids is used in order to estimate the three solubility parameter components. Extensive tables with the key parameters are presented. On the other hand, available information on these separate components is exploited in order to extract information for the thermodynamic behaviour of the fluids over an extended range of external conditions.

Influence of the extraction methods to remove organic templates from Al-MCM-41 molecular sieves

The influence of template extraction methods on the structure and physico-chemical properties of Al-MCM-41 molecular sieves has been investigated. Up to 78% of template in Al-MCM-41 could be removed either by extraction with ordinary solvents or methanol-modified supercritical CO 2. Complete template removal was achieved by calcination. Both, solvent and supercritical fluid extraction media influenced the structure, texture and acid properties of the resulting Al-MCM-41 materials and, consequently, their catalytic activity for the Friedel–Crafts acylation of 2-methoxynaphthalene.

Skeletal Reorganization of Enynes into 1‐Vinylcycloalkenes in Ionic Liquids.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Study on effective synthesis and properties of ortho-alkyl-substituted phenyl octasilsesquioxane

ortho-Methyl- and ethyl-substituted phenyl octasilsesquioxanes, (o-MePh, or o-EtPh)8-T8, with cubic structure were synthesized in good yield (>70%) under mild basic conditions. The position of the alkyl substituent on the phenyl group (ortho-, meta-, para-) in the starting phenyltrimethoxysilane had a big effect on the yield of the product. (Meta- and para-methyl and -ethyl)phenyltrimethoxysilane did not give the desired products under basic conditions; instead, the methyl derivatives gave products in low yield under acidic conditions (<10%). (MePh)8-T8 showed different thermal properties and solubility, depending on the position of the methyl substituent on the phenyl group. (o-EtPh)8-T8, the only obtainable isomer from ethyl-substituted starting materials, showed lower melting point and higher solubility in ordinary solvent than (o-MePh)8-T8.

Skeletal Reorganization of Enynes into 1-Vinylcycloalkenes in Ionic Liquids

The skeletal reorganization of enynes catalyzed by transition metal chlorides, such as PtCl(2), [RuCl(2)(CO)(3)](2), [RhCl(CO)(2)](2), and AuCl(3), in ionic liquids proceeds under milder conditions (at lower reaction temperatures and for shorter reaction times) than those needed for ordinary solvents. The products produced by the skeletal reorganization of enynes were easily removed from the catalyst by a simple extraction with Et(2)O or distillation. The PtCl(2) can be reused up to five times.

Comparative Gas-Phase and Solution-Phase Investigations of the Mechanism of C−H Activation by [(N−N)Pt(CH3)(L)]+

Contrary to previous claims in the literature, there is no solvent assistence by 2,2,2-trifluoroethanol (TFE) in C−H activation reactions by cationic Pt(II) complexes. Both electrospray ionization tandem mass spectrometric studies of isolated gas-phase intermediates and solution-phase kinetic spectroscopy indicate that TFE serves only as an inert diluent. TFE was found in the gas-phase experiment to provide no acceleration of the loss of methane or benzene from preselected [(N−N)Pt(CH3)(C6H6)]+ or [(N−N)Pt(CH4)(C6H5)]+ ions. In solution, the overall C−H activation reaction of benzene by [(N−N)Pt(CH3)(H2O)]+BF4- was found to be zero-order in TFE. While it is on one hand disappointing that the claimed facilitation of C−H activation by solvent assistance by TFE at the rate-determining transition state is not supported by the present experimental data, it is on the other hand encouraging that extremely rapid C−H activation (on the time scale of seconds at room temperature) in solution may be achieved in ordinary solvents as long as the solvent is not strongly coordinating.

On the molecular structure and aggregative properties of Sudan dyes in the anisotropic host

Abstract Dichroic ratio R and order parameter S of solutions containing five Sudan dyes in nematic solvents were investigated by the measuring of the intensity of the absorption bands in the visible region of parallel aligned samples. The effective factors such as molecular shape, self-association of the phenolic dye molecules through hydrogen bonding, solvent nature on the visible absorption of the dyes were investigated. Also, from the observed dichroic ratio, the dependence of the order parameter on the shape, size, polarity and steric effect of the substituent was demonstrated and discussed. The role of the anisotropic solvent and ordinary solvent on the self-association of the guest molecules in solution has been investigated without using polarised light.

Spectroscopic properties of two highly substituted PAH heteroanalogs: octakis(pyrazol-1-yl)naphthalene and octakis (3,5-dimethylpyrazol-1-yl)naphthalene

Two heteroanalogs of octaphenylnaphthalene, octakis(pyrazol-1-yl)naphthalene and octakis(3,5- dimethylpyrazol-1-yl)naphthalene have been prepared and fully characterized by NMR ( 1 H and 13 C). Although they are very insoluble in ordinary solvents, such as ethanol and ethyl acetate, absorption and emission spectra were recorded. These experiments show that the new compounds behave photophysically like other highly substituted naphthalenes.

Preparation and characterization of a novel poly(1,4-phenylenevinylene) derivative with an azobenzene side chain

A novel poly(1,4-phenylenevinylene) (PPV) derivative containing an azobenzene side chain was prepared via a dehydrochlorination route. Poly{2-methoxy-5-[(4-(4-methoxyphenylazo)phenyloxy)-hexyloxy]-1,4-phenylenevinylene}, which is soluble in ordinary solvents such as chloroform, tetrahydrofuran (THF), acetone, xylene, etc., was characterized by FTIR, 1H NMR, GPC, and UV-visible spectroscopies, thermogravimetric analysis (TGA), and cyclic voltammetry. The photoluminescence spectrum of the polymer showed an emission maximum at λ = 550 nm.

Accelerated solvent extraction of paclitaxel and related compounds from the bark of taxus cuspidata

Accelerated solvent extraction (ASE) of paclitaxel and related compounds from Taxus cuspidata (Japanese yew) bark has been investigated under various conditions. In ASE, pressure is applied to the sample extraction cell to maintain the heated solvent in a liquid state during the extraction. This method is able to shorten the extraction time and to increase the recovery of target compounds. In this study, ASE of paclitaxel, baccatin III, and 10-deacetylbaccatin III produced amounts of these compounds that were higher than those from ordinary solvent extraction at room temperature. The conditions providing the highest recovery of paclitaxel were as follows: solvent, MeOH-H2O (90:10); temperature, 150 degrees C; and pressure, 10.13 MPa (0.128% w/w recovery based on oven-dried sample powder). ASE does not require chlorinated solvents and can reduce solvent consumption because of its strong dissolving power. Moreover, with water alone, the recovery of paclitaxel and related compounds using ASE is much higher than with other extraction methods.

Vapochromism of a Pyrrolizinato-nickel(II) Complex Incorporated in Polyvinylbutyral. An Optochemical Detecting System for Alcohols in Air

The bis(1,2,6,7-tetracyano-3,5-dihydro-3,5-diiminopyrrolizinido)nickel(II ) complex (NiL2, L = C11H2N7-) has been incorporated as dispersed monomer in polyvinylbutyral (PVB) at a fairly high concentration (0.021 M). NiL2/PVB spin coated thin films (thickness, ∼ 2 μm) on glass and silicon and evaporated free standing thicker films (thickness, ∼ 50 μm) have been studied by means of absorption or reflectivity visible as well as infrared spectroscopy. The light-blue NiL2/PVB film fades slightly on heating (for 7 min at 90 °C) and remains as such after cooling to room temperature. The optical spectrum of the thermally activated NiL2/PVB system, in contact with organic solvent vapors at room temperature, changes with time evolving towards the initial spectrum before the thermal treatment. The system is therefore amenable for sensing organic solvents in air. Several ordinary solvents have been tested. After 12 min exposure to air saturated with vapor a steady-state absorbance signal at the most sensitive wavelength (661 nm) is reached for any tested solvent. The system is most sensitive to alcohols. Response cycles are reported for methanol as solvent.

Synthesis and reactivity of 2-(ethylthio) phenylcopper: A stable organocopper compound carrying an intramolecular sulfane ligand

An unusually stable organocopper compound carrying an intramolecular sulfane ligand, 2-(ethylthio)phenylcopper, was synthesized via the reaction of the corresponding organolithium with a copper(I) halide (CuX). This compound was obtained in two forms: one is a salt-free compound which is insoluble in ordinary solvents, the other is a soluble complex of [2-(ethylthio)phenylcopper] 2 · CuX composition. These compounds were either hydrolyzed or underwent a coupling reaction to produce a biphenyl when heated. While these organocoppers are less reactive towards various electrophiles than other known arylcoppers, the soluble complex gives ketones with acyl halides in low yields. The properties as well as the reactivities of the stable organocopper compounds are reported.