Toluene Medium Research Articles

Rationalization of the effects of hydrogen bond donor solvent and nucleofugicity of fluoride ion on nucleophilic aromatic substitution reactions in non-polar aprotic solvent: reaction of 2,4-dinitrofluorobenzene with cyclohexylamine in toluene and toluene

The kinetics of the reaction of 2,4-dinitrofluorobenzene with cyclohexylamine were studied at different concentrations in toluene and toluene-alkanol mixtures. The reaction was not base-catalysed in toluene. Addition of small amounts of hydrogen-bond donor solvent, alkanol (ranging from methanol to hexanol) to the toluene medium of the reactions produced a different effect in comparison to uncatalysed reactions — slight increase in rate of reaction. The results are rationalized in terms of the effect of amine-solvent interaction on the nucleophilicity of the amine in addition to some other factors operating through cyclic transition states leading to products. It is also attributed to the peculiar nature of fluoride ion as a leaving group.

Investigations on the Ethylene Polymerization with Bisarylimine Pyridine Iron (BIP) Catalysts

The kinetics and terminations of ethylene polymerization, mediated by five bisarylimine pyridine (BIP) iron dichloride precatalysts, and activated by large amounts of methyl aluminoxane (MAO) was studied. Narrow distributed paraffins from initially formed aluminum polymeryls and broader distributed 1-polyolefins and (bimodal) mixtures, thereof, were obtained after acidic workup. The main pathway of olefin formation is beta-hydrogen transfer to ethylene. The rate of polymerization in the initial phase is inversely proportional to the co-catalyst concentration for all pre-catalysts; a first-order dependence was found on ethylene and catalyst concentrations. The inhibition by aluminum alkyls is released to some extent in a second phase, which arises after the original methyl groups are transformed into n-alkyl entities and the aluminum polymeryls partly precipitate in the toluene medium. The catalysis is interpretable in a mechanism, wherein, the relative rate of chain shuttling, beta-hydrogen transfer and insertion of ethylene are determining the outcome. Beta-hydrogen transfer enables catalyst mobility, which leads to a (degenerate) chain growth of already precipitated aluminum alkyls. Stronger Lewis acidic centers of the single site catalysts, and those with smaller ligands, are more prone to yield 1-olefins and to undergo a faster reversible alkyl exchange between aluminum and iron.

The effect of treatment with sodium carbonate and hydrogen on the activity and selectivity of polymeric Pd-containing catalysts for hydrogenation of acetylene compounds

Catalytic hydrogenation of the triple carbon-carbon bond of acetylene compounds is an important industrial process. High selectivity to the olefin compound should be provided in the process. This study considers the effect exerted by sodium carbonate treatment of the palladium catalysts containing super-cross-linked polystyrene (SPS) on their activity and selectivity in the hydrogenation of 2-methyl- 3-butin-2-ol and phenylacetylene. The effect of such treatment was shown to depend on the chosen palladium precursor and the type of polymeric support (non-functionalized SPS or that containing ternary amino groups). At atmospheric pressure of hydrogen and a temperature of 90 °C in a toluene medium, the 1%-Pd/SPS catalysts treated with Na2CO3 provided a 98 % selectivity in the hydrogenation of 2-methyl-3-butin-2-ol (at a 95 % conversion of the substrate), while selectivity in the hydrogenation of phenylacetylene reached 99.5 %.

Preparation of Petrochemical Feedstock from Rubber Wastes by Thermal Solvolysis

The thermal decomposition of crumb rubber based on isoprene pure rubber in an autoclave in various media such as toluene, isopropyl alcohol, and water has been studied. The highest degree of conversion of pure rubber is achieved in a toluene medium, while the lowest is in water. The formation of a gas is minimum in the aqueous medium and maximum in a medium of isopropyl alcohol; however, the yield of the gaseous products is much lower than in the processes of high-temperature pyrolysis of rubber. The fractional composition of the liquid products varies within a wide range, namely, more gasoline fractions are formed in the medium of toluene; oil fractions, in water; and middle distillates predominate in the products obtained in the isopropyl alcohol medium. The concentration of dipentene and p-cymene, which may be of interest as the feedstock for industrial organic synthesis, in the distillate fractions reaches 10–16 wt %. Unsaturated aliphatic structures predominate in the oil fractions obtained in the medium of water or isopropyl alcohol, while alkylbenzenes predominate in the “toluene” oils. The oil fractions can be of interest as a feedstock for the production of both lubricating and process oils. The solid carbonaceous residue from the thermal solvolysis of rubber contains not only untransformed carbon black, but also zinc oxide and sulfide, so that it can be sent to the production of zinc or be reused as a rubber filler.

Polyaniline co-doped with dodecyl benzene sulfonic acid and zwitterionic-based ionic liquids prepared by inverse emulsion polymerization

Sulfonate zwitterionic ionic liquids with methyl-imidazolium (mim.ZIL) or triphenylphosphonium (PPh3.ZIL) as the cations were mixed with dodecylbenzenesulfonic acid (DBSA) and used as co-doping agent for the synthesis of polyaniline (PANI) by inverted emulsion polymerization approach in toluene medium. The ZIL-DBSA combination resulted in PANI with higher DC conductivity (σDC) values and the better response was obtained with mim.ZIL/DBSA in a molar ratio of 1.0, with σDC corresponding to around 8 S cm−1. The presence of cetyl trimethylammonium bromide (CTAB) during the synthesis caused an additional improvement of the conductivity, reaching values as high as 16.3 and 14.0 for PANI prepared in the presence of mim.ZIL and PPh3.ZIL, respectively. Electromagnetic interference shielding effectiveness (EMI SE) of PANI samples prepared with different conditions was also investigated in the X-band frequency range. An improved EMI SE, with electromagnetic attenuation of -55 dB was observed for PANI sample prepared in the presence of CTAB and mim.ZIL/DBSA in a molar ratio of 1.0.

Polyaniline/carbon nanotube hybrids modified with ionic liquids as anticorrosive additive in epoxy coatings

Polyaniline (PAni) doped with dodecylbenzene sulfonic acid was prepared by inverse emulsion polymerization of aniline (Ani) in toluene medium in the presence of unmodified and modified carbon nanotube (CNT). Two different imidazolium based ionic liquids (IL), such as, 1-methyl-3-butyl imidazolium tetrafluorate (bmim.BF4) and (1-(1-methyl-3-imidazole) butane-4-sulfonate) as zwitterion IL (mimbutylSO3) modified with dodecylbenzene sulfonic acid were used to disperse CNT and assist the polymerization of Ani. The presence of IL gave rise to PAni.IL and PAni.IL/CNT hybrid composites with superior electrical conductivity when compared with PAni and PAni/CNT without IL. PAni and the CNT-based hybrids were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). 1 wt% of the synthesized hybrids were formulated with epoxy resin and applied on AISI 1020 carbon steel plates to investigate the corrosion resistance of the coating using electrochemical impedance spectroscopy (EIS) technique. The epoxy coating loaded with PAni/CNT hybrid materials displayed outstanding anti-corrosion properties when compared with those loaded with PAni. The hybrid conducting additive prepared in the presence of bmim.BF4 provided the highest anti-corrosion performance of the corresponding epoxy coating. Moreover, the corrosion resistance increased with immersion time. The complex viscosity of the dispersions and dynamic-mechanical analysis (DMA) as well as differential scanning calorimetry (DSC) of the epoxy-based networks were also evaluated.

Reversible Ultra-Slow Crystal Growth of Mixed Lead Bismuth Perovskite Nanocrystals: The Presence of Dynamic Capping.

An ultra-slow crystal growth over a period of 24 h of a newly synthesized CH3 NH3 Pb1/2 Bi1/3 I3 perovskite (MPBI) nanocrystal in non-polar toluene medium is reported here. From several spectroscopic techniques as well as from TEM analysis we found that the size of nanocrystals changes continuously with time, in spite of being capped by the ligands. Using a single molecular spectroscopic technique, we also found that this size change is not due to the stacking of nanocrystals but due to crystal growth. The notable temperature dependence and reversible nature of the nanocrystals growth is explained by the dynamic nature of the capping. The observed temperature-dependent ultra-slow growth is believed to be a pragmatic step towards controlling the size of perovskite NC in a systematic manner.

FEATURES OF MOLECULAR AGGREGATION OF BLOCK COPOLYMER ON BASE OF STYRENE AND POLYETHYLENE GLYCOL IN SOLUTIONS

This article focuses on the study of behavior of macromolecules of block copolymer on the base of styrene and polyethylene glycol in toluene media. Unique property of block copolymers is the ability of chemical heterogeneous blocks to phase separation. This process leads to the formation of micelle similar structures in selective solvents. These aggregates have the core from soluble block and the micelles capsule from insoluble block. Similar structures (reverse micelles) would be used for the purpose of stabilization of metal organosols. In this work aggregative stable reverse micelles in such systems as "toluene - water" and "toluene - methanol" have been prepared. Block copolymer of styrene and polyethylene glycol was applied as stabilizer in solutions with polymer concentration from 2.5 g/ 100 ml to 1 g/ 100 ml. Block copolymer has been synthesized by means of isocyanate cure on the end hydroxyl groups. Its structure has been confirmed by differential calorimetry spectroscopy (DSC) method. Dimension of formed particles has been determined by methods of sedimental turbidimetry and dynamic light scattering (DLS). Existence of both individual macromolecules and molecular aggregates in initial solutions has been established by DLS method. It has been found that dimensional homogeneity of organosol particles enlarges with the increase in dispersed phase content to 10 mass. %. At that, the size of the micelles in presence methanol is less than in water presence. Particles size also depends on polymer concentration in solution. The sizes of micelles in both systems increase with increasing concentration of the block copolymer, and with an increase in the content of the dispersed phase, a gradual decrease in their sizes is observed. It was shown that the sedimentation turbidimetry method does not reflect the behavior of the copolymer molecules in solutions, which results in a large scatter of data on the determination of particle sizes of the organosol in the toluene-water system with a water content of less than 5 masses. % . Based on the data obtained, it is assumed that micelles stabilized by a block copolymer based on styrene and polyethylene glycol can be used to introduce metal particles into them, followed by the formation of a metal layer on a solid surface.

Features of the modification of polylactide by (meth)acrylate groups in organic solvents

Polymerizable (meth)acrylate groups were introduced into polylactide (PLA) in the methylene chloride or toluene medium. Polymer modification was carried out both on the carboxyl and hydroxyl groups of polylactide. The efficiency of this modification was studied depending on the type of reaction. It was found that the highest degree of polylactide modification by (meth)acrylate groups (86%) is achieved through the formation of PLA urethane derivatives in the presence of diisocyanates. Samples of photocured, three-dimensionally crosslinked after such a modification polylactides were obtained, their biocompatibility was determined. It was shown that such materials are promising for use in regenerative medicine and tissue engineering.

A facile and efficient method for synthesis of β-iodocarboxylates from terminal epoxides

A facile and efficient method has been developed for synthesis of β-iodocarboxylates in the presences of Ph3P/I2. Starting from epoxides, a series of β-iodocarboxylate compounds can be directly obtained in toluene media with excellent yields. Moreover, the method was successfully applied for the late-stage modification of natural products, such as isosteviol and vincamine derivatives, achieving the corresponding β-iodocarboxylates in good yields.

Destruction of toluene and xylene by sulfatе-reducing bacteria

As a result of human activity aromatic hydrocarbons enter the environment in large quantities, contaminating it. Dropping of insufficiently treated wastewater drains considerably decrease the quality of water. Quite effective biological methods of purification of contaminated environment are the usage of microorganisms. Prospective microorganisms for sewage treatment are sulfate-reducing bacteria. The purpose of the work was to investigate the ability of sulfate-reducing bacteria to use xylene and toluene as a source of carbon under different cultivation conditions. The study objects were sulfate-reducing bacteria Desulfotomaculum AR1 and Desulfovibrio desulfuricans Ya-11. The biomass of bacteria was determined turbidimetrically, the content of sulfate ion and hydrogen sulfide – photometrically in the culture fluid. The content of fumarate was determined by the method of high-performance liquid chromatography. The ability of Desulfotomaculum AR1 and D. desulfuricans Ya-11 bacteria to use toluene and xylene as the sole source of carbon and energy has been established. In the toluene environment, a better growth of bacteria was observed. A comparison was made between the efficiency of the reduction of sulfate ions and the growth of bacteria in the control medium and the medium with aromatic compounds. The efficiency of sulfate ions reduction was sufficiently high in the control medium, whereas in the toluene/xylene media the efficiency of sulfate utilization and hydrogen sulfide accumulation was lower compared to the control parameters. The growth of Desulfotomaculum AR1 and D. desulfuricans Ya-11 sulfate-reducing bacteria was investigated in xylene and toluene media in the presence/absence of fumarate. According to the results of the studies, the best growth of the tested bacteria was observed in the medium with aromatic compounds in the presence of fumarate and sulfate ion. Efficiency of use of fumarate in the medium with toluene with bacteria Desulfotomaculum AR1 was more than 90 %. Fumarate can be used by sulfate-reducing bacteria as a source of carbon, donor and acceptor of electrons. Fumarate is most likely to inhibit sulfate reduction in Desulfotomaculum AR1 and D. desulfuricans Ya-11 bacteria, as indicated by studies showing that sulfate reduction efficiency in lactate, fumarate, and sulfate ion media was half that of control. Sulfate-reducing bacteria are capable to anaerobically degrade aromatic hydrocarbons in the presence of sulfate ions as terminal electron acceptors. The ability of sulfate-reducing bacteria Desulfotomaculum AR1 and D. desulfuricans Ya-11 to use the aromatics of the BTEХ – toluene, xylene and sulfate-ions, makes them promising at the biological purification step of contaminated wastewater from these pollutants.

Four‐ and Five‐Coordinate Titanium(IV) Complexes Supported by the dpp‐bian Ligand in ROP of L‐Lactide

A titanium(IV) alkoxido complex, (dpp‐bian)Ti(OBn)2 (2), as well as alkoxido chlorido complexes (dpp‐bian)TiCl(OCH2CH2OMe) (3) and (dpp‐bian)TiCl2OBn (4), were synthesized from the titanium(IV) dichloride precursor [(dpp‐bian)TiCl2]2 (1) by exchange with corresponding sodium salts (comps. 2 and 3) or by the alcoholysis with BnOH (comp. 4). The compounds 2–4 were fully characterized by elemental analysis, NMR or EPR, and IR spectroscopy. Molecular structures of the metal complexes in the solid state have been determined by single‐crystal XRD analysis. Compounds 2–4 were tested as catalysts in the ROP of L‐lactide in a toluene medium. Whereas complexes 2 and 3 produce cyclic PLAs with broad dispersities and unpredictable molecular weights, complex 4 acts as an efficient ROP catalyst which polymerizes the monomer in a highly controllable manner. It produces BnO‐capped PLAs with narrow molecular weight distributions as well as linear dependence of Mns on monomer conversion.

Synthesis of Graphene Oxide-Fe3O4 Based Nanocomposites Using the Mechanochemical Method and in Vitro Magnetic Hyperthermia.

The study presented in this work consists of two parts: The first part is the synthesis of Graphene oxide-Fe3O4 nanocomposites by a mechanochemical method which, is a mechanical process that is likely to yield extremely heterogeneous particles. The second part includes a study on the efficacy of these Graphene oxide-Fe3O4 nanocomposites to kill cancerous cells. Iron powder, ball milled along with graphene oxide in a toluene medium, underwent a controlled oxidation process. Different phases of GO-Fe3O4 nanocomposites were obtained based on the composition used for milling. As synthesized nanocomposites were characterized by x-ray diffraction (XRD), alternating magnetic field (AFM), Raman spectroscopy, and a vibrating sample magnetometer (VSM). Additionally, the magnetic properties required to obtain high SAR values (Specific Absorption Rate-Power absorbed per unit mass of the magnetic nanocomposite in the presence of an applied magnetic field) for the composite were optimized by varying the milling time. Nanocomposites milled for different extents of time have shown differential behavior for magneto thermic heating. The magnetic composites synthesized by the ball milled method were able to retain the functional groups of graphene oxide. The efficacy of the magnetic nanocomposites for killing of cancerous cells is studied in vitro using HeLa cells in the presence of an AC (Alternating Current) magnetic field. The morphology of the HeLa cells subjected to 10 min of AC magnetic field changed considerably, indicating the death of the cells.

Hierarchically porous Brønsted acidic ionic liquid functionalized nitrogen-doped carbons for pyrolysis biofuel upgrading via esterification of acetic acid with high boiling point alcohols

Brønsted acidic ionic liquid (BAIL) functionalized hierarchically porous nitrogen-doped carbons (NHPCs) with interesting 3D interconnected macro-meso-microporous structure are successfully prepared by chemical bonding ‒[C3][SO3CF3−] (C3 = PrSO3H) groups throughout the NHPC supports that are obtained via a single step CaCO3 nanoparticle-directed nanocasting approach combined with K2C2O4 chemical activation and urea/melamine self-activation during the process of carbonization of glucose and urea/melamine. By changing initial urea-to-glucose weight ratio in the preparation systems, the macro/meso/micropore proportion of the resulting GU‒[C3N][SO3CF3] catalysts are well-adjusted. The morphological characteristics, porosity properties and chemical structure of the prepared catalysts are well-characterized so that the contribution of the synergistic effect of CaCO3 nanoparticle and K2C2O4 to the formation of hierarchically porous structure is revealed. Owing to super strong Brønsted acidity and unique hierarchically porous structure of the catalysts, they exhibit excellent heterogeneous acid catalytic activity in raw pyrolysis biofuel upgrading via esterification of acetic acid with high boiling point benzyl alcohol or 4-methoxybenzyl alcohol in toluene media, and therefore high acetic acid removal efficiency and efficient production of value-added benzyl acetate or 4-methoxybenzyl acetate are obtained simultaneously. The catalysts also show good reusability in target reactions, attributing to chemical interactions between BAILs and NHPC supports.

First molecular electronic hyperpolarizability of series of π-conjugated oxazole dyes in solution: an experimental and theoretical study.

In this work, we report the experimental and theoretical first molecular electronic hyperpolarizability (βHRS) of eleven π-conjugated oxazoles compounds in toluene medium. The Hyper-Rayleigh Scattering (HRS) technique allowed the determination of the experimental dynamic βHRS values, by exciting the compounds with a picosecond pulse trains from a Q-switched and mode-locked Nd:YAG laser tuned at 1064 nm. Theoretical predictions based on time-dependent density functional theory level using the Gaussian 09 program package were performed with three different functionals (B3LYP, CAM-B3LYP, and M06-2X), to calculate both static and dynamic theoretical βHRS values. Good accordance was found between the experimental and theoretical values, in particular for the CAM-B3LYP and M06-2X functionals.

High-Performance Synthesis of Phosphorus-Doped Graphene Materials and Stabilization of Phosphoric Micro- and Nanodroplets.

A thermally induced cascade process leading to the formation of stable micro- and nanometer-size phosphoric droplets was developed starting from a molecular precursor. Microwave-induced pyrolysis of 1,2,3,4,5-pentaphenylphosphole oxide proceeded through a series of subsequent transformations involving formation of phosphorus-doped graphene oxide layers, seeding of carbon surface with phosphorus centers, and assembling of stable droplets. A complex nanostructured organization of the material was established in a remarkably short time of 3 min, and the process was performed in a thermally induced manner using microwave irradiation. High stability of the liquid phosphoric structures on the surface of doped graphene oxide over a few-month period was demonstrated, as well as under challenging conditions in organic solvents (chloroform, methylene chloride, or toluene media) and even under sonication. Detailed examination of this material by electron microscopy and a number of analytical methods showed its unique organization at the nanoscale, whereas computational modeling revealed unusually strong binding of phosphorus oxide P4O10 to the graphene surface. The study demonstrates a fascinating opportunity to access a complex nanostructured multicomponent material from a single and easily available molecular precursor.

Synthesis and Characterization of Electromagnetic Material Based On Composite of Barium M-Ferrite and Zinc Oxide

The making of composites BaFe12O19/ZnO has been done with Wet Milling method used media toluene. Barium M-Ferrit as a matrix and Zinc Oxide as a filler used as the main raw material for composite manufacturing. The milling process of Barium M-Ferrit was done for 12 hours using the High Energy Milling (HEM). Furthermore, the calcination process used furnace at 900 ° C for 4 hours. While Zinc Oxide is milled for 3 hours and calcined at a temperature of 500 oC for 3 hours. The results of Barium M-Ferrit and zinc Oxide mixed using wet milling touluene media for 15 minutes and dried for 1 hour at 200 oC. X-ray diffraction (XRD) showed that BaFe12O19 as a matrix and ZnO as filler with hexagonal crystal structure was formed and the peak showed a single phase, where each BaFe12O19 lattice parameter a = 5.8930 Å, c = 23.1940 Å and ZnO lattice parameter a = 3.2533 Å, c = 5.2073 Å. Characterization Vibrating Sample Magnetometer (VSM) obtained the value of magnetic properties BaFe12O19 powder (matrix) obtained (Ms) magnetic saturation 54.03 emu/g, (Mr) magnet remanent 33.06 emu/g, (Hcj) coercivity 2943 Oe and (BHmax) product energy 190 kGOe and Zinc Oxide as filler values (Ms) magnet saturation 7.84 emu / g, (Mr) magnet remanent 1.27 emu/g, (Hcj) coercivity 152.4 Oe and (BHmax) energy products 10 kGOe. The results of XRD on 50% mass of composites ZnO additions using match software have two phases, namely the presence of ZnO and BaFe12O19 phases which indicate that heterogeneous structures with hexagonal crystal structures. Composite magnetic properties obtained by adding 50% mass of ZnO were (Mr) magnet 39.40 emu/ g, coercivity 2728 Oe, (BHmax) product energy 110 kGOe and for composites 75% mass addition ZnO remanent 39.36 emu/g with coefficient of 1365 Oe and ( BHmax) product energy was 60 kGOe.

Synthesis of quaternary succinimides promoted by Ferric Nitrate

An efficient protocol has been accomplished for the synthesis of quaternary α-aminosuccinimides in toluene medium involving 2-phenylimidazo[1, 2-a]pyridine in a one-pot reaction promoted by Ferric Nitrate at 120 °C. The protocol presented herein, is for the first time, via a novel transformation where Ferric Nitrate promotes imidazo[1,2-a]pyridine structural metamorphosis to the title compound quaternary succinimides. High compatibility, easy work-up, and excellent yields are the advantages of this protocol. The quaternary α-aminosuccinimides are expected to have great potential in synthesizing quaternary α-amino acids and applications in medicinal chemistry.

Impact of Asphaltene Surface Energy on Stability of Asphaltene–Toluene System: A Parametric Study

Asphaltene is a complex macromolecule whose abundance strongly affects the physical and interfacial properties of crude oil. Asphaltene molecules may precipitate during crude oil production/transportation, which may lead to plugging/clogging of wellbores, pipelines, and equipment. In this study, the solubility of asphaltene in toluene has been investigated by calculation of noncovalent interaction energies between asphaltenes in toluene medium. The results of this study revealed that the main interactions in the asphaltene-toluene system are Lifshitz-van der Waals and Lewis acid-base interactions, whereas the electrostatic double layer is of lower comparative order of significance specifically at lower separation distances and lower ζ potentials. However, the repulsive electrostatic double-layer interactions may assist in stabilizing the asphaltene-toluene system based on the comparative values of Lifshitz-van der Waals, Lewis acid-base, and electrostatic double-layer interactions. This is the case especially at higher separation distances and/or higher temperatures where asphaltene particles have greater values of ζ-potential. Furthermore, it is illustrated that when asphaltene has a lower electron-donor parameter, i.e., a lower basicity than toluene, then Lewis acid-base interactions between asphaltenes in toluene are repulsive. This repulsive Lewis acid-base interaction may compensate for the attractive van der Waals interactions between asphaltene particles at low asphaltene basicity. Finally, the electron donor/acceptor component of the surface energy strongly determines the fate of asphaltene in crude oil colloidal system.

CuI-Catalyzed [3+2] Cycloaddition of Hindered Vinylidenebisphosphonates (VBP) with Azomethine Imines for Highly Regioselective Access to Dinitrogen-Heterobicycle-Containing Bisphosphonates

A concise, atom-economic, and highly regioselective synthetic strategy for the construction of several dinitrogen-fused heterocycles bearing bisphosphonates by 1,3-dipolar cycloaddition reaction of azomethine imines with tetraethyl vinylidene-1,1-bisphosphonate in the presence of CuI in toluene media has been developed. The targeted compounds were obtained in good yields and with excellent regioselectivity. This method for the synthesis of gem-bisphosphonates (BPs) is particularly attractive due to features such as low cost, mild conditions, atom economy, high stereoselectivity, and potential biological activity of the product.