Toluene System Research Articles

Molecular complexation between PCBM and porphyrazine in solution: A case study of non-covalent interaction

The present investigations report the non-covalent interaction of a fullerene derivative, namely, [6,6]-phenyl C71 butyric acid methyl ester (PC70BM) with 2,7,12,17-tetra-tert-butyl-5,10,15,20-tetraaza-21H,23H-porphine (1) and zinc-2,7,12,17-tetra-tert-butyl-5,10,15,20-tetraaza-21H,23H-porphine (2) in toluene and also in mixed solvent comprising toluene and 1,2-dichlorobenzene (volume:volume=3:2). Complex formation by steady state fluorescence studies reveal high value of binding constant (K) for both PC70BM-1 and PC70BM-2 systems in toluene, i.e., KPCBM-1=10,820dm3·mol−1 and KPCBM-2=9655dm3·mol−1, and very good selectivity of binding for 1 as a result of change in solvent polarity, viz., KPC70BM-1 (Toluene)/KPC70BM-1 (Mixed Solvent) ~3.0. Due to solvophobic effect, the selectivity in binding for 2 in two different solvents, i.e., KPC70BM-2 (Toluene)/KPC70BM-2 (Mixed Solvent) estimated to be ~1.0. Lifetime measurements establish that static quenching mechanism is operative behind the photoexcited decay of 1⁎ (and/2⁎) in presence of PC70BM both in toluene and in mixed solvent. However, in mixed solvent, PC70BM-1 system is found to exhibit much higher value of magnitude of rate constant of charge-separation (i.e., kCSs(PC70BM-1)=2.97×107s−1) and kCSs(PC70BM-2)=5.60×106s−1) and quantum yield of charge-separation (ϕCS(PC70BM-1)=0.070) compared to PC70BM-2 system (ϕCS(PC70BM-1)=0.015). Ab initio calculations in vacuo predict the geometric structures of PC70BM-1 and PC70BM-2 systems and provide very good support in favour of charge-separation in former system in terms of multipole moment calculations.

Liquid–Liquid Equilibrium Data, Density, Viscosity, and Interfacial Tension of Ternary System (Toluene–Acetic Acid–Water) at 298.15 K: Experiment and Correlation

Liquid–liquid equilibrium (LLE) data, density, viscosity, and interfacial tension for the ternary system of toluene–acetic acid–water were measured at 298.15 K and 101.7 kPa. The Othmer–Tobias and the Hand correlations were used to check the reliability of the experimental tie-lines. Moreover, the distribution coefficient and the separation factor were explored. It was found from the experimental results that a maximum separation factor value happens at an acetic acid mass fraction of 0.02 in the organic phase. Density, viscosity, and interfacial tension were correlated using the appropriate correlations such that the predicted results have excellent agreement with the experimental data. The experimental data in this work and the literature were correlated using both the nonrandom two-liquid (NRTL) and the universal quasi chemical (UNIQUAC) activity coefficient models at various temperatures (288.2, 298.15, 303.15, and 313.15 K). The experimental results were used to obtain binary interaction parameters in these models. The root-mean-square deviation (RMSD) values for both models were less than 3.58%, and the model predictions show acceptable agreement with the measured data particularly at the plait point.

Analysis of a Polystyrene-Toluene System through "Dynamic" Sorption Tests: Glass Transitions and Retrograde Vitrification.

Exposing a glassy polymer to a fluid phase (in gaseous or liquid state) containing a low molecular weight compound results in the sorption of the latter within the polymer, inducing, among other effects, the plasticization of the material which also promotes a change in the glass transition temperature. The amount of sorbed penetrant is often related in a complex fashion to the temperature and pressure of the fluid, thus determining that the locus of glass transition, when represented in pressure-temperature coordinates, may display as well rather complex patterns. This is an issue of particular importance in several applications of glassy polymers. In particular, we investigated the behavior of polystyrene in contact with toluene vapor by performing several modes of dynamic sorption experiments, in which the rate of change of the temperature of the system and/or of the pressure of the vapor phase are controlled with high accuracy, with the aim of creating a map of rubbery and glassy states of the polymer as a function of temperature and pressure of the toluene vapor. Isothermal tests were performed by changing the pressure at a controlled rate, isobaric tests were performed by changing the temperature at a controlled rate, and isoactivity tests were performed by concurrently changing, in a proper way, both temperature and pressure. A relevant feature resulting from these experiments is the presence of a discontinuity in the slope of the mass of toluene sorbed within polystyrene reported as a function of temperature and/or pressure. This discontinuity has been interpreted as the indication of the occurrence of a glass transition. The elaboration of the experimental results allowed identification of the pressure/temperature conditions at which rubbery or glassy states of the polymer mixture are established. Quite interestingly, the system displays the so- called "retrograde vitrification" phenomenon, which consists of the occurrence of a rubbery-to-glassy state transition as the temperature increases at a fixed pressure. The whole set of results has been successfully interpreted on the basis of thermodynamics of II order transitions accounting for the fact that experimental evidence of such transitions is significantly affected by the kinetics of polymer relaxation.

Usage of a deep eutectic solvent based on three compounds for toluene separation

The separation of toluene from a mixture composed of toluene and heptane was carried out in the presence of a deep eutectic solvent (DES). The DES used in this study was synthesized using choline chloride, urea and glycerol with mole ratio of 1 : 2 : 1. The liquid-liquid equilibria (LLE) of the ternary system of toluene, heptane, and DES were determined at atmospheric pressure and three temperatures of 298.2-313.2 K with an interval of 10 K. The distribution coefficients and selectivities of toluene were reported. Only a small amount of heptane was detected in the extract phase, resulting in high value of selectivity. The experimental LLE data were reasonably well correlated using non-random two-liquid (NRTL) model. The ab initio results revealed that the interactions between the DES and toluene are stronger than those between DES and heptane, which may be a reasonable explanation for the high value of selectivity in this ternary system.

MIXTURES OF NON-IONIC SURFACTANTS FOR CLEANING COMPOSITIONS

The surface behavior and micelle formation of binary and ternary compositions of nonionic surfactants are studied in relation to their cleaning ability with respect to cotton fabric. In mixtures of an alkyl glucoside and oxyethylated alcohol, antagonistic interaction of the components is observed. When a tertiary amine oxide (Oksipav) having a semipolar N→O bond in the molecule is introduced, the formation of mixed micelles occurs. In solutions of mixtures of nonionic surfactants, the critical concentration of micelle formation is reduced, surface activity is increased, the values of maximum adsorption in the surface layers become higher, and the area occupied by the surfactant molecules in a saturated adsorption layer (smol) is reduced as compared to the individual surfactants. Low values of interfacial tension (from 1.2 to 0.88 mJ/m 2 ) in the surfactant solution - toluene system increase the degree of surface cleaning from oil pollution. When cleaning solutions contain mixtures of three nonionic surfactants with different functional groups, synergysm of the wetting, stabilizing, foaming and emulsifying abilities of liquid detergents is provided. Compositions developed on the basis of colloid-chemical criteria are characterized by high removal efficiency with respect to pigment-oil stains from the fabric at pH in the range from 8.8 to 10.5.

Experimental studies on the effect of ultrasonic waves on single drop liquid–liquid extraction

The influence of ultrasonic waves on hydrodynamics and mass transfer of circulating drops in liquid–liquid extraction process was studied. The recommended chemical systems of toluene–acetic acid–water with mass transfer resistance mainly in the organic phase, and cumene–isobutyric acid–water in the aqueous phase were used. An extraction column, equipped with an ultrasonic emitter of 35.40kHz real frequency and 0.37mW/cm2 intensity, was employed. The ultrasound properties were measured using the hydrophone standard method. Drops terminal velocity was comparable with the Grace model. In mass transfer study, significant enhancement was revealed in overall mass transfer coefficient for different drop sizes and for the both mass transfer directions by using ultrasonic waves. The average and maximum enhancements were, respectively, 20.8 and 31.7% for toluene–acetic acid–water, and 40.3 and 55.1% for cumene–isobutyric acid–water. Small drops exhibited a higher enhancement percentage. Regarding the mass transfer direction, the system of cumene–isobutyric acid–water with continuous to dispersed phase direction, was benefited more as the consequence of creating effective agitation in continuous phase than in dispersed phase.

Phase behavior and densities of propylene + toluene and ethylene + toluene systems to 580 K and 70 MPa

In this study, we report phase behavior data for propylene + toluene and ethylene + toluene mixtures at temperatures to 580 K and pressures to 8.5 MPa. We also report high-pressure, mixture density data for the two mixtures at temperatures to 555 K and pressures to 70 MPa. Both the phase behavior and density data are simultaneously determined using a windowed variable-volume, high-pressure view cell coupled with a linear variable differential transformer. The phase behavior and mixture density data are modeled with the Soave–Redlich–Kwong (SRK), Peng–Robinson (PR), Modified Sanchez–Lacombe (MSL), and Perturbed–Chain Statistical Associating Fluid Theory (PC-SAFT) equations of state (EoS). The PC-SAFT and MSL EoS provide very good fits of the phase behavior for both the propylene + toluene and ethylene + toluene systems with each binary interaction parameter, kij, set to zero. The PC-SAFT equation also provides the best fit of the high-pressure, mixture density data for the ethylene + toluene system. However, the SRK EoS provides the best fit of the high-pressure, mixture density data for the propylene + toluene system. Although both equations slightly over predict the solution density for the two studied systems, the fit of the densities are insensitive to small variations in kij.

Effect of Solvents on Controlling the Photophysical Properties of Poly[2-Methoxy-5-(2’-Ethylhexyloxy)-1,4-Phenylenevinylene] (MEH-PPV) Nanoparticle

Abstract. This study focuses on detailed investigation of solvent effects on controlling photophysical properties of poly [2-methoxy,5-(2’-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) nanoparticles prepared by using reprecipitation techniques. In this work, the MEH-PPV polymer is dissolved in various solvents, including chlorobenzene (CRB), toluene (TOL) and pyridine (PYR). The polymers in solutions adopt different conformations (i.e. collapsed or extended coils), depending on local polymer-solvent interactions. The differences of chain conformations cause the variations of chain packing within the nanoparticles. The majority of nanoparticles exhibit diameter of about 65-70 nm. The photophysical properties of MEH-PPV nanoparticles varied with type of solvents. The absorption spectra of nanoparticles exhibit a broad pattern with a long red tail at about 550 nm, indicating the formation of inter-and/or intrachain aggregates within the nanoparticles. However, the nanoparticle from TOL system shows blueshift of λmax, corresponding to the decrease of conjugation length due to the existence of collapsed coil. The photoluminescence (PL) spectra of MEH-PPV nanoparticles show consistent result with the shift of λmax to about 590 nm and vibronic shoulder at about 640 nm. The PL patterns vary with the type of solvents. In addition, the PL patterns depend on the variations of excitation wavelengths. These discrepancies indicated the variation of chain conformation and degree of aggregation within the nanoparticles. Our results demonstrate the simple method to prepare the conjugated polymer nanoparticle with different photophysical properties by changing solvents.

Ternary phase behavior of phenol + toluene + zwitterionic alkaloids for separating phenols from oil mixtures via forming deep eutectic solvents

Phenols are important materials for the organic chemical industry. They mainly come from coal liquefaction oil, coal tar, petroleum and biomass pyrolysis oil, making the separation of phenols from oil mixtures of great commercial value. Two zwitterionic alkaloids, betaine and L-carnitine, biodegradable and environmentally benign ionic compounds, can efficiently separate phenols from oils by forming deep eutectic solvents (DESs). In this work, the phase equilibria of two ternary systems of toluene + phenol + betaine and toluene + phenol + L-carnitine were measured at 25.0 °C, 45.0 °C and 65.0 °C under atmospheric pressure. The phase behaviors of the two ternary systems were studied, which indicated that there were three kinds of phase regions: liquid, liquid-liquid, and liquid-liquid-solid. The separation of phenol from oil mixtures occurs at the latter two phase regions. Effects of temperature, zwitterionic alkaloid type and its dosage on the phase equilibrium were investigated. With decreasing temperature, the distribution and selectivity coefficients increase. L-carnitine shows better performance in separating phenol from oils via forming DES than betaine.

Effects of Electrolyte Composition on AC-Driven Electrochemiluminescence from Anthracene Derivatives Having Blue Emission

Electrochemiluminescence (ECL) is a light emitting phenomenon of excited species which is generated from electrochemical reaction at electrodes. ECL reaction has attracted great interest to utilize as the novel kinds of light emitting devices. We have reported that the ECL device can be integrated with reflective displaying devices based on liquid crystal[1] or organic electrochromic[2] technologies. Moreover, the ECL emission colors from the ECL electrolyte solution dissolving 9, 10-diphenylanthracene (DPA) and rubrene in N-methyl-2-pirroridone (NMP) can be controlled by changing the frequency of alternating current (AC) voltage.[3] Here, we focused on the blue emission of AC-driven ECL (AC-ECL) systems because the ECL intensity and long-term stability were unsatisfactory in present stage. One of the reasons for the issue is that the balance of redox species in the device did not exactly match. In this study, we introduced mixed solvent of propylene carbonate (PC)-toluene system (volume ratio = 1:1) for achieving the stable blue ECL from DPA molecule. PC is well known as the electrochemically stable solvent; toluene can also dissolve the large amount of aromatic compound such as DPA. We measured the electrochemical and optical properties of the DPA in NMP or PC/toluene electrolyte solution in order to discuss the effect of stabilities of redox species on the AC-ECL properties. As a result, it was found that the composition of electrolyte affected the stability of oxidized and reduced species. Moreover, the emission properties of the AC-ECL device were strongly depended on the stability of redox species. From these results, to achieve the good performance of the blue ECL device, it is required that the exactly matched balance of redox species in the device. Reference [1] S. Tsuneyasu, K. Nakamura, N. Kobayashi, Chem. Lett., 45, 949 (2016). [2] S. Tsuneyasu, L. Jin, K. Nakamura, N. Kobayashi, Jpn. J. Appl. Phys., 55, 041601 (2016). [3] T. Nobeshima, M. Nakakomi, K. Nakamura, N. Kobayashi, Adv. Optical Mater., 1, 144 (2013).

PHARMACOGNOSTICAL SCREENING AND DETERMINATION OF ANTIOXIDANT ACTIVITY OF NELUMBO NUCIFERA GAERTN ETHANOL SEED EXTRACT BY DIFFERENT IN VITRO MODELS

Objective: To perform the pharmacognostical screening and determination of antioxidant activity of Nelumbo nucifera Gaertn ethanol seed extract by different in vitro models.Methods: The different pharmacognostical parameters were evaluated as per standard protocols with some modifications. The various concentrations of ethanol seed extract of Nelumbo nucifera were evaluated for antioxidant activity using the standard in vitro methods like hydrogen peroxide (H2O2) scavenging assay, nitric oxide (NO) radical scavenging assay, reducing power capacity assessment, β-Carotene bleaching assay, ferric thiocyanate method (FTC) and thiobarbituric acid (TBA) assay.Results: Extractive values, ash values and moisture content values of Nelumbo nucifera were found to be as per the IP 2007 and Ayurvedic pharmacopoeia standard. Among the four extracts viz. Petroleum ether, chloroform, ethanol and aqueous, the ethanol extract showed significant antioxidant activity. The ethanol seed extract of Nelumbo nucifera (NNSE) exhibited high antioxidant activity (IC50 = 12.65 µg/ml) in 1, 1-diphenyl-2-picryldydrazyl (DPPH) radical scavenging assay. In FTC method the absorbance of NNSE increased slowly, which shows strong antioxidant ability. The thin layer chromatography (TLC) of the extract revealed 6 spots with the Rf values 0.41, 0.47, 0.59, 0.65, 0.67, 0.74 with the solvent system of toluene: ethyl acetate: formic acid (5:4:0.5, v/v/v). The high-performance thin layer chromatography (HPTLC) revealed the spots at Rf values 0.65 and 0.68. These fractions obtained by preparative TLC also confirmed the same. Conclusion: The present investigation suggested that the NNSE has significant antioxidant activity. These results clearly indicate that Nelumbo nucifera is effective against free radical mediated diseases, thus replacing the synthetic ones.

Role of Aerosol Liquid Water in Secondary Organic Aerosol Formation from Volatile Organic Compounds.

A key mechanism for atmospheric secondary organic aerosol (SOA) formation occurs when oxidation products of volatile organic compounds condense onto pre-existing particles. Here, we examine effects of aerosol liquid water (ALW) on relative SOA yield and composition from α-pinene ozonolysis and the photooxidation of toluene and acetylene by OH. Reactions were conducted in a room-temperature flow tube under low-NOx conditions in the presence of equivalent loadings of deliquesced (∼20 μg m-3 ALW) or effloresced (∼0.2 μg m-3 ALW) ammonium sulfate seeds at exactly the same relative humidity (RH = 70%) and state of wall conditioning. We found 13% and 19% enhancements in relative SOA yield for the α-pinene and toluene systems, respectively, when seeds were deliquesced rather than effloresced. The relative yield doubled in the acetylene system, and this enhancement was partially reversible upon drying the prepared SOA, which reduced the yield by 40% within a time scale of seconds. We attribute the high relative yield of acetylene SOA on deliquesced seeds to aqueous partitioning and particle-phase reactions of the photooxidation product glyoxal. The observed range of relative yields for α-pinene, toluene, and acetylene SOA on deliquesced and effloresced seeds suggests that ALW plays a complicated, system-dependent role in SOA formation.

Isobaric phase equilibrium of morpholine + 1-decanol, volumetric properties and molar refractivity from 293.15 to 333.15 K of morpholine + 1-decanol and 1-octanol + toluene system with applications of Prigogine–Flory–Patterson theory

Morpholine, having its applications in process industries is also used as an anticancer agent as well as a building block in the preparation of linezolid antibiotic. 1-decanol can be used as a suitable solvent for recovery of morpholine from its aqueous stream. The present study involves VLE studies and volumetric properties of the morpholine+1-decanol, at 13.32, 39.99, 66.66 and 94.90kPa. Wilson, NRTL, and UNIFAC models were used to correlate and predict the experimental VLE data. Further, thermodynamic properties such as excess molar volume (VmE), and deviation in molar refractivity (ΔR). Partial molar volume (V¯i), apparent molar volume (Vϕi)and excess partial molar volume (V¯iE)were also estimated. Moreover, all the above thermodynamic properties have also been estimated for the 1-octanol+toluene mixture at different temperatures. The applicability of Prigogine–Flory–Patterson theory and different mixing rules were tested for the excess molar volumes and refractive indices, respectively.

Suppression of Homocoupling Side Reactions in Direct Arylation Polycondensation for Producing High Performance OPV Materials

Suppression of side reactions in C–H direct arylation polycondensation is important for developing this method as a reliable synthetic tool for conjugated polymer materials. To find appropriate reaction conditions for avoiding homocoupling side reactions, two types of reaction conditions were investigated: the direct arylation of electron-rich C–H monomers in N,N-dimethylacetamide (DMAc system) and the direct arylation of electron-poor C–H monomers in toluene (toluene system). The investigation reveals that homocoupling side reactions are suppressed under the toluene system. Because the combination of electron-poor C–H monomer (acceptor) and electron-rich C–Br monomer (donor) is applicable to the toluene system, a donor–acceptor polymer without a defect structure can be synthesized under the toluene system. The obtained polymer shows almost same power conversion efficiency (PCE) in bulk-heterojunction OPVs as the same polymer prepared by a conventional method and purified by Soxhlet extraction. These resu...

Investigation the effect of super hydrophobic titania nanoparticles on the mass transfer performance of single drop liquid-liquid extraction process

Hydrophobic titania nanoparticles were synthesized by a novel in situ sol-gel method and applied in a single drop liquid-liquid extraction column to enhance the overall dispersed-phase mass transfer coefficient (Kod). The chemical system of toluene, acetic acid and water was used, and the direction of solute (acetic acid) mass transfer was from dispersed phase, including: toluene and acetic acid to the continuous phase of water. For such system, much of the mass transfer resistance exists in the dispersed phase, which is nonpolar organic liquid. Hence, modified titania nanoparticles (MTNP’s), prepared by sol-gel route, in five different concentrations of 0.001–0.005 wt.% were added in the dispersed phase. Also, the impact of MTNP’s at the different solute concentrations and nozzles was investigated. Results indicated an anomalous enhancement in the overall dispersed-phase mass transfer coefficient at 0.002 wt.% of MTNP’s. A maximum enhancement of 70% in the overall mass transfer coefficient was found in droplets formed from a nozzle of 2.5 mm inner diameter, containing 3 wt.% of solute. Eventually, based on the theoretical model of Newman, a semi-empirical model was presented, that is capable to predict the overall dispersed-phase mass transfer coefficient of nanofluids with an average absolute relative error of 8.6%.

Hydrodynamics and mass transfer characteristics of circulating single drops with effect of different size nanoparticles

The effect of three different size silica nanoparticles, ranged within 11–14, 20–30 and 60–70 nm, on the hydrodynamic and mass transfer of circulating drops in liquid–liquid extraction was investigated. Chemical system of toluene–acetic acid–water was used; toluene in nanofluid drop phase. Six concentrations of each nanoparticle, within 0.0005–0.005 wt%, were examined. Mass transfer direction was from nanofluid drops to aqueous continuous phase. Viscosity of nanofluids increases slightly with the size and concentration of the nanoparticles whereas the system interfacial tension remains almost constant. Terminal velocity values were comparable with those predicted by Grace and Vignes equations. The average and maximum mass transfer enhancements of 51.8 and 78.7% were achieved, respectively, with nanofluid drops. The smallest size nanoparticle at nearly the mid concentration of 0.003 wt% provides the highest enhancement. Nanoconvention caused by Brownian motion is the main plausible cause of this behavior. It was demonstrated that enhancement factor of diffusivity coefficient can be reproduced by a quadratic equation of drops’ Reynlods number, and the Newman equation based on effective diffusivity can predict the mass transfer coefficient satisfactorily.

Synergetic formation of secondary inorganic and organic aerosol: effect of SO<sub>2</sub> and NH<sub>3</sub> on particle formation and growth

Abstract. The effects of SO2 and NH3 on secondary organic aerosol formation have rarely been investigated together, while the interactive effects between inorganic and organic species under highly complex pollution conditions remain uncertain. Here we studied the effects of SO2 and NH3 on secondary aerosol formation in the photooxidation system of toluene∕NOx in the presence or absence of Al2O3 seed aerosols in a 2 m3 smog chamber. The presence of SO2 increased new particle formation and particle growth significantly, regardless of whether NH3 was present. Sulfate, organic aerosol, nitrate, and ammonium were all found to increase linearly with increasing SO2 concentrations. The increases in these four species were more obvious under NH3-rich conditions, and the generation of nitrate, ammonium, and organic aerosol increased more significantly than sulfate with respect to SO2 concentration, while sulfate was the most sensitive species under NH3-poor conditions. The synergistic effects between SO2 and NH3 in the heterogeneous process contributed greatly to secondary aerosol formation. Specifically, the generation of NH4NO3 was found to be highly dependent on the surface area concentration of suspended particles, and increased most significantly with SO2 concentration among the four species under NH3-rich conditions. Meanwhile, the absorbed NH3 might provide a liquid surface layer for the absorption and subsequent reaction of SO2 and organic products and, therefore, enhance sulfate and secondary organic aerosol (SOA) formation. This effect mainly occurred in the heterogeneous process and resulted in a significantly higher growth rate of seed aerosols compared to without NH3. By applying positive matrix factorisation (PMF) analysis to the AMS data, two factors were identified for the generated SOA. One factor, assigned to less-oxidised organic aerosol and some oligomers, increased with increasing SO2 under NH3-poor conditions, mainly due to the well-known acid catalytic effect of the acid products on SOA formation in the heterogeneous process. The other factor, assigned to the highly oxidised organic component and some nitrogen-containing organics (NOC), increased with SO2 under a NH3-rich environment, with NOC (organonitrates and NOC with reduced N) contributing most of the increase.

Experimental assessment of the degree of hydrogen loading for the dibenzyl toluene based LOHC system

Liquid Organic Hydrogen Carriers allow for storing hydrogen with high density at ambient conditions. In the LOHC hydrogen storage process, a significant number of different partially and fully hydrogenated species occur on the reaction pathway from the hydrogen-lean to the hydrogen-rich form of the LOHC system. In order to access the amount of hydrogen stored in the carrier system, ways of measuring the degree of hydrogenation are required. A number of physical properties can be correlated with the degree of hydrogenation. However, there are different mixtures of hydrogenated, partly hydrogenated and dehydrogenated derivatives which result in an identical degree of hydrogenation but different properties. In this contribution we report on attempts to correlate physico-chemical properties and spectroscopic data to the degree of hydrogenation of the dibenzyl toluene system by using density, viscosity, refractive index, UV–VIS and Raman spectroscopy measurements. The most reliable correlations were found for density or refractive index.

Quasi-equilibrium distribution of pristine fullerenes C60 and C70 in a water–toluene system

An improved technique of the ultrasound-assisted reversible liquid–liquid transfer of pristine (unmodified) C60 and C70 fullerenes between organic solutions and aqueous fullerene dispersions (AFD; another notation in general use, nC60, nC70) without any additional reagents (media modifiers) was developed. To our knowledge, this is the first report of such a fullerene transfer from an AFD to an organic phase. Based on the observation of this fullerene reversible transfer, their distribution between the aqueous and organic phases was considered. A quasi-equilibrium transfer mechanism was proposed, which makes it possible to estimate distribution constants, KD, as 6 and 2, for C60 and C70 respectively, in a water–toluene system. Under the optimum conditions, AFDs of C60 and C70 with the concentrations 180 ± 20 and 70 ± 20 μM, respectively, were obtained from the corresponding solutions in toluene. Based on UV/vis spectroscopy, total organic carbon, headspace GC–MS, and MALDI measurements, a reliable analytical procedure to measure fullerene concentrations and to monitor the concentration of residual toluene in AFDs was proposed. AFDs of a mixture of fullerenes C60 and C70 were characterized by the developed technique.

ChemInform Abstract: Triethylamine: A Potential N‐Base Surrogate for Pyridine in Knoevenagel Condensation of Aromatic Aldehydes and Malonic Acid.

Cinnamic acids are intermediates with significant potential for synthesis of several industrially important chemicals. Classically, cinnamic acids are produced through Knoevenagel condensation of aromatic aldehydes and malonic acid in the presence of an organocatalyst and large amounts of carcinogenic pyridine. An alternative pyridine free reaction scheme for Knoevenagel condensation of malonic acid and aromatic aldehydes was investigated by replacing pyridine with an aliphatic tertiary amine surrogate in toluene as the reaction medium. Of the three aliphatic tertiary amines used, namely, triethyl amine (TEA), trioctyl amine (TOA) and tributyl amine (TBA), only TEA afforded cinnamic acids in comparable yields to those obtained with pyridine. Validation through a computational analysis is attempted to provide an explanation for the observed role of TEA as an aliphatic N-base instead of TBA and TOA. The use of TEA as a mild base in place of pyridine can be seen as playing the dual role of a base catalyst as well as a phase transfer agent evidenced by the in-process ATR-FITR spectroscopy. Use of the TEA–toluene system in place of pyridine can be seen as resulting in a process that affords ease of handling, separation and recycling of the solvent and the catalyst.