Solvents Heptane Research Articles

Mechanism of initiation of ethylene cationic polymerization in the presence of an aluminum chloride aquacomplex in heptane with a stoichiometric composition of 1:1:1:2 at the quantum level

In this paper, the mechanism of ethylene initiation in the presence of an aluminum chloride – water catalyst in a heptane solvent of stoichiometric composition 1:1:1:2 was studied using the ab initio RHF theoretical quantum chemical method. The activation energy and thermal effect of this reaction were obtained. These data can be useful for further research in the field of cationic polymerization, and can also be used in the development of new technological processes of polyethylene with specified physicochemical properties characteristic of fiber optics.

Exploring Whole Cells of Rhizopus oryzae for Efficient Synthesis of Emollient Esters: Bioesters for Cosmetics

Production of esters, organic compounds with emollient, emulsifying, and aromatic properties is growing due to high demand and their applications in the cosmetics industry. The synthesis of these compounds involves the reaction between a carboxylic acid and an alcohol, which can be catalyzed by lipases. In this context, the objective of this study was to produce mycelium-bound lipases of the fungus Rhizopus oryzae through submerged cultivation, with the aim of applying them in the synthesis of ethylene glycol oleate, ethylene glycol stearate, and isoamyl palmitate esters, which are relevant to the cosmetic industry. The influence of solvent usage (heptane), biocatalyst mass, and acid/alcohol molar ratio was evaluated in the esterification reactions. In the synthesis of the three tested esters, and in the presence of heptane solvent, an equimolar ratio (1:1) of each acid and alcohol with a concentration of 0.01 mol L-1 was utilized. The reactions were performed in agitated Erlenmeyer flasks at 40 °C with an agitation speed of 200 rpm. The lipolytic biomass of Rhizopus oryzae showed better performance in the synthesis of isoamyl palmitate, achieving a maximum conversion of 83% in 24 h of reaction using 0.30 g of lipolytic biomass and the solvent heptane. In addition, it was observed that higher concentrations of catalyst biomass (0.45 g) and lower molar ratios (1:1.5) of acid to alcohol resulted in a higher conversion of isoamyl palmitate ester, reaching conversions of 48.59 and 83.11%, respectively.

Deep Dive into Eutectics: On the Origin of Deep and Elevated Eutectics

There is growing interest in deep eutectic solvents (DES) for both chemical synthesis and materials applications. However, there is a general lack of understanding regarding what uniquely defines a system as a deep eutectic, and more importantly, what chemical properties determine unique eutectic behavior. In this work, we identify the thermodynamic basis for ideal eutectics relative to assumptions of ideal solutions. We then articulate the new Solvation Shell-Ionic Liquid (SSIL) and -Liquid Solvate (SSLS) model for solutions which identify the chemical/physical factors that create solution non-ideality and afford the ability to accurately calculate liquiduses, and thus the eutectics, of binary systems. The application of these models is demonstrated using diverse families of materials including aqueous salt solutions (ZnCl2, NaCl, KCl, and NH4NO3), aqueous molecular solutions (sucrose and urea), solutions of naphthalene with aromatic (toluene, benzene, toluene, biphenyl and phenanthrene) and non-aromatic (ethanol, butanol, heptane and acetone) solvents, and the choline chloride:urea system for which the term DES was first introduced. The accurate description of the non-ideal enthalpic and entropic terms affords clear definition and prediction of both deep and elevated eutectics in diverse systems.

Combination of molecular dynamics simulation and COSMO to understand asphaltenes aggregation

ABSTRACT Asphaltenes interaction produces problems in oil transport and recovery, and understanding the association process is vital to improving economic and industrial production. Here, we propose the COSMO model in combination with molecular dynamics (MD) simulations to complement the results obtained by Newtonian mechanics with quantum results to get reliable association data. Four asphaltene molecules were studied with toluene and heptane solvents. COSMO showed molecular interaction tendencies, which were later verified with MD. The average aggregation number was calculated through MD and turned out to be entirely dependent on the aromaticity due to π-π stacking. The aromatic rings are responsible for aggregation, while the sulfur heteroatom plays a less fundamental role. Viscosity is also related to the aggregation process; a higher tendency in aggregation increases the dynamic viscosity. Diffusion coefficients were correlated with the aromaticity, dipole moment, and molecular weight. Finally, a mathematical comparison between COSMO and MD results is accomplished.

Aggregation of Asphaltene Subfractions A1 and A2 in Different Solvents from the Perspective of Molecular Dynamics Simulations

The aggregation behavior of model molecules of asphaltene subfractions A1 and A2 dissolved in heptane, toluene, and tetrahydrofuran (THF) were studied using molecular dynamics simulations. The proposed asphaltene molecular models are based on previously studied structures with two new models, including a highly aromatic model with a prominent island-type molecule and another molecule with a prominent archipelago-type architecture. The aggregation mechanisms in toluene, THF, and heptane solvents were studied. The results in heptane and toluene were consistent with the solubility of asphaltenes and their subfractions in these solvents. The size of the aggregates is well-correlated with aromaticity. When considering THF, large aggregates are broken down into smaller aggregates. This could lead to the mixture of high, medium, and low molecular weight distribution bands usually observed when gel permeation chromatography (GPC) analyses are conducted on asphaltene samples in THF. The size distribution extracted from the simulations shows a bimodal distribution with profiles similar to the size distribution profiles usually found in GPC analysis for asphaltene samples in THF. The distributions of dipole moments of the aggregates against the number of molecules in aggregates were constructed in both THF and toluene and reveal that the dipole moment of the aggregates vanishes when the number of molecules increases as a result of a random structure of the aggregates. The contributions of different molecular interactions to the aggregation mechanism, such as π stacking, van der Waals, and hydrogen bonds, are described.

Resource Recovery from Crude Oil Sludge Using Solvent Extraction and Delayed Cooking Method

The main objective of this work is to make an economically useful recovery from waste. Crude oil sludge is gotten from the bottom of crude oil storage tank. 100mI (109.2g) of crude oil sludge when treated with 50mI, 100mI, 200mi……400 ml of solvent heptane resulted in the formation of three different layers. The first layer contains the solvent and some extracted crude oil in the oil phase. This is distilled to get different hydrocarbon fractions. The second layer is asphaltic residue which when furnace treated and activated or washed and neutralized with inclusion of additives yields activated coke used as adsorbent and newsprint paste respectively. The third layer is the mud or clay which could be furnace treated to produce activated clay.Results show that petroleum coke is best activated at 800°C and the optimal condition for bleaching red palm oil by the adsorbent is at 130•C.

Determination of diffusion coefficient of C2H6 and CO2 in hydrocarbon solvents by molecular dynamics simulation

In this paper, the diffusion coefficients of C2H6 and CO2 in various hydrocarbon solvents have been determined using molecular dynamics simulation at different temperatures and atmospheric pressure. Effect of force field type and number of cell molecules on MD simulation results were investigated. The optimum number of molecules in amorphous cell was obtained and it was found that COMPASS force field showed the best result in comparison with the other investigated force fields forces (Universal, Dreiding, Cvff, and Pcff). In addition, the diffusion coefficients of ethane and CO2 were found to comply with the Stokes–Einstein equation. These coefficients were calculated from the slope of mean square displacement (MSD) curves. Temperature changes also showed an increasing effect on the diffusion coefficients and the activation energies (Ea) and pre-exponential constants (D0) for C2H6 diffusion in heptane and hexane solvents were obtained using Arrhenius theory. The simulated results indicated a good agreement with the experimental data for C2H6 in heptane, hexane, octane, dodecane, and hexadecane solvents and CO2 in hexadecane solvent.

Methodical peculiarities of air sampling for detecting contents of low molecular weight organic compounds on the example of furan and methylfuran

Introduction. Variable analytical control methodologies are applied in monitoring over contents of low molecular weight organic compounds in ambient air. Their unification is a vital and serious challenge requiring valid substantiation and selection of optimal air sampling techniques. Our research goal was to substantiate and select an air sampling technique for chemical analysis of furan and methylfuran. Materials and methods. Our research concentrated on developing and optimizing the process of air samples preparation for chemical analysis of furan and methylfuran; examining effectiveness of furan and methylfuran sorption-desorption using various sorbents. Standard furan and methylfuran samples (≥99.0% Sigma-Aldrich), heptane solvents, sorbent tubes with Tenax, Sylochrom C-120, and coal as sorbents were used in the research. All experimental studies were aimed at testing effective procedures for taking and preparing air samples for further furan and methylfuran analysis in them. They were performed on “Kristall-5000” gas chromatographer with mass-selective detection (MSD) and 25-meter long PoraPlotQ-capillary column. Results. We comparatively analyzed the results produced by taking air samples for further detection of furan and methylfuran in them using different techniques. They included low temperature concentration; sorption on filters made of quartz microfiber and a sorbent tube with Nenax TA; sorption on a tube with Tenax TA at t=20-25 °C. The analysis enabled us to reveal an effective procedure for taking ambient air samples for further detection of furan and methylfuran in them. This procedure was low temperature concentration of low molecular weight organic compounds on a sorbent tube with Tenax TA. Limitations. The accomplished study had no limitations. Conclusion. The accomplished study allows us to recommend taking air samples during 10 minutes with consumption being 0.1 l/min for further detection of furan and methylfuran in them using low temperature concentration on a sorbent tube with Tenax TA. The achieved effectiveness is 99.2% for furan and 100% for methylfuran.

Effects of azole rings with different chalcogen atoms on ESIPT behavior for benzochalcogenazolyl-substituted hydroxyfluorenes

ESIPT behavior has attracted a lot of eyes of researchers in recent years because of its unique optical properties. Due to its large Stokes shift and double emission fluorescence, white light can be generated in the fluorophore based on the excited state intramolecular proton transfer (ESIPT) principle. The excited state proton transfer behavior of hydroxylated benzoxazole (BO-OH), benzothiazole (BS-OH) and benzoselenazole (BSe-OH) have been investigated in heptane, chloroform and DMF solvents. By comparing the infrared vibration spectra and the variation of bond parameters from the S0 to S1 states, and analyzing the frontier molecular orbitals, the influence of hydrogen bond dynamics, the solvent polarity, charge redistribution and the effects of different proton acceptors on proton transfer were observed. The only structural difference among the three substituted hydroxyfluorenes is the heteroatom in the azole ring (oxygen, sulfur and selenium, respectively). We have scanned the potential energy curve of the ESIPT process, and compared the potential barrier, it is found that the heavier chalcogen atoms are more favorable for proton transfer. At the same time, the potential application of changing heteroatoms in the azole ring by walking down the chalcogenic group in crystal luminescence color regulation is also discussed.

Microstructural study on low viscosity poly-α-olefin oils synthesized via AlCl3/H2O cationic system in the present of xylene and heptane solvents

It was well established that polyalphaolefin (PAO) synthesis using AlCl3/solvent system can produce low viscosity PAO grades and has potential to be replaced with hazardous BF3 catalyst in commercial scale. The main aim of this research was to study in which extent AlCl3/solvent can produce PAO4 and PAO6 (4 and 6 represent kinematic viscosity of PAO at 100 °C), recognized as the most common PAO grades, and the main characteristic of final products. In this line, first the produced oligomers by AlCl3, AlCl3/xylene and AlCl3/heptane systems and H2O as the co-catalyst (in AlCl3/H2O = 2 M ratio) were fractioned based on their boiling point into 4 samples including low molecular weight byproduct, PAO4, PAO6 and high molecular weight byproduct. Then, the main characteristics of PAO4 and PAO6 fractions were studied by 1H and 13CNMR spectra, Distortion less Enhancement by Polarization Transfer (DEPT, to study CH sub spectra), GPC and viscometry analyses to unravel structure-properties relationships. The results showed using xylene reduces the molecular weight much more than heptane through enhancing the chain transfer reactions. NMR spectra together with viscosity analysis indicated that the oligomers from AlCl3/heptane system had lower short chain branching (SCB) and branching ratio (BR) and higher long chain branching ((CH2)nCH2CH2CH3, with n > 1) and VI values. Furthermore, the microstructural characterization of commercial PAO4 and PAO6 samples revealed slightly lower SCB, BR and VI values than those in the ones produced with optimum amount of xylene. Our obtained results confirmed that 1-decene oligomerization by AlCl3 catalyst in the presence of optimized amount of xylene solvent results PAO4 and PAO6 in good yield (nearly 78%) with the characteristic which is comparable with that of commercial grades.

Tunable polymer microgel particles and their study using microscopy and real‐time deformability cytometry

AbstractWe report the preparation and mechanical properties of highly swellable, spherical polymer microgels synthesized by precipitation copolymerization of divinylbenzene‐55 (DVB), 4‐methylstyrene (4MS), and maleic anhydride (MA) at different cross‐linker contents, in a range of methylethylketone (MEK) and heptane solvent mixtures. Microgels were characterized by optical and confocal microscopy, and their mechanical properties tested using real‐time deformability cytometry (RT‐DC), a technique developed to analyze cell properties by measuring deformation under shear stress. Hydrolysis of anhydride groups gave microgels with diameters ranging from 10 to 22 μm when swollen in saline, depending on vol% MEK and cross‐linker loading. Young's moduli of the microgels could be tuned from 0.8 to 10 kPa by adjusting cross‐linker content and MEK/heptane solvent composition, showing an inverse relationship between the effects of vol% MEK and %DVB on microgel properties. These microgels also show strain‐stiffening in response to increasing shear stresses. Extension of the RT‐DC method to the study of polymer colloids thus enables high‐throughput analysis of microgels with tunable mechanical characteristics.

Lipase‐oxovanadium heterogeneous catalysis system: a robust protocol for the dynamic kinetic resolution of sec‐alcohols

AbstractHerein, we present a robust and eco‐friendly dynamic kinetic resolution (DKR) protocol for secondary alcohols using a combined heterogeneous catalytic CAL−B/VOSO4 system at 50 °C in the relatively green solvent heptane. This catalytic system is active and chemo‐ and enantioselective for up to 5 cycles. A set of 13 aromatic and heteroaromatic secondary alcohols were evaluated to determine the substrate scope. The performance of the combined CAL−B/VOSO4 system was improved by employing a low‐cost, homemade Teflon tube to compartmentalize the catalysts in one‐pot conditions, making this system for up to 8 reaction cycles.

Dynamic Wettability Alteration of Calcite, Silica and Illite Surfaces in Subsurface Environments: A Case Study of Asphaltene Self-Assembly at Solid Interfaces

A fundamental understanding of dynamic wettability alteration at complex solid interfaces in varying fluidic environments representative of the subsurface environments is essential for engineering field-scale strategies to enhance energy recovery while reducing environmental impacts. In this study, we characterize dynamic wettability alteration at solid surfaces (e.g., calcite, silica and illite) resulting from the self-assembly and adsorption of polyaromatic macromolecules known as asphaltenes in heptane and toluene solvents at 200 bar and 313 K using classical molecular dynamics simulations. These conditions are chosen to be representative of the subsurface environments. On adding asphaltenes, the equilibrium contact angles on calcite, silica and illite surfaces which are in the range of 25–34° increased to 69–79°. The adsorption and self-assembly of asphaltene molecules on the solid surfaces and the accumulation on water/hydrocarbon interfaces reduces the spreading distances of water molecules and enhances the hydrophobicity of the solid surfaces. Further, the accumulation of asphaltene molecules at the water/liquid hydrocarbon interfaces results in a reduction of the interfacial tension of water/heptane and water/toluene, thus stabilizing the water droplet. The enhanced surface hydrophobicity contributes to the formation of layered structures of heptane and toluene close to the solid surfaces and reduces the self-diffusivities of these molecules close to the surface.

Utilizing recycled asphalt shingle into pavement by extraction method

Abstract The recycling of asphalt shingles in pavement construction is beneficial to the environment and industry by reducing the consumption of virgin materials. However, current approaches of utilizing recycled asphalt shingle (RAS) by mixing with soft asphalt or rejuvenator were questionable for the anti-aging problems. This study developed a new approach to recycle asphalt shingles, in which the RAS binder was dissolved and extracted by a mixed solvent of heptane and trichloroethylene (TCE). In the proposed process, the viscosity of the extracted RAS binder was controlled by the polarity and composition of the mixed solvent. Results indicate that heptane dissolved the soft part and trichloroethylene (TCE) could dissolve the stiff part of RAS binder. The use of the mixed solvent of heptane and TCE with a certain proportion through the proposed method could prepare asphalt binder with desired properties. The current approaches of utilizing RAS were compared with the proposed method. Results indicate that the anti-aging properties of extracted RAS binder using the proposed method were better since the soft asphalt could not dissolve RAS binder at 170 °C, and the binder blend of RAS binder and rejuvenator had a potential anti-aging problem because an obvious loss of rejuvenator existed during the aging process. The performance test suggests that the high and low temperature region of the extracted RAS binder was close to 75.2–28 °C, which could be used as a common asphalt in pavement engineering.

Molecular dynamics simulations of asphaltene aggregation under different conditions

Abstract The formation of organic sediments, especially asphaltene in reservoirs, wells and equipment, has a harmful effect on the oil production economy, which reduces oil production and can block oil production facilities. In order to investigate the asphaltene aggregation and solubility, a series of molecular dynamics simulations in different conditions were performed on two famous asphaltene based model, of M1 and VI. VI asphaltene has two high aliphatic side chains, whereas M1 asphaltene has only two methyl groups on its sides. The simulation results show that the solubility parameter increases with increasing number of aromatic rings and decreasing the number of carbon atoms in the side chain. The aggregation of asphaltene molecules in toluene, heptane and isopropyl benzene solvents and also in the mixture of solvents has been investigated. The results show that the aggregation of M1 asphaltene in toluene and isopropyl benzene is lower than that of VI asphaltene. The mixture isopropyl benzene-heptane is appropriate solvent for both asphaltenes M1 and VI which represents less interaction between asphaltene molecules. The effect of six types of inhibitors on the aggregation of asphaltene was investigated. Based on the simulation results, the aggregation of asphaltene with the presence of DETPMP inhibitor significantly decreases due to the delay in the growth of crystals and by increasing the concentration of all used inhibitors, their inhibitory properties were decreased.

Observation of an infrequent enantiomer/conformer substitutional disorder in ethyl 13-ethyl-4-oxo-8,13-dihydro-4H-benzo[5,6]azepino[3,2,1-ij]quinoline-5-carboxylate heptane hemisolvate.

Considering the importance of quinolones due to their broad spectrum of biological activities, the crystal structure of the title compound, C22H21NO3·0.5C7H16, has been determined. Two enantiomers of the benzazepinoquinoline molecule and one molecule of heptane form the asymmetric unit of this centrosymmetric triclinic (P-1) crystal. All the molecules in the crystal present disorder. Substitutional disorder is observed for the benzazepine molecules, where a minority conformer of the R enantiomer replaces the main conformer of the S enantiomer and vice versa. Positional disorder is found for the heptane solvent molecule, which occupies a void left by the independent enantiomers of both conformers.

The role of calcite and silica interfaces on the aggregation and transport of asphaltenes in confinement

The structure and transport of the heavy asphaltene molecules in unconfined bulk fluids and fluids confined in a 4 nm slit-shaped nanopores of calcite and silica were studied using classical molecular dynamics simulations. The pores were filled with 7 wt% of asphaltene dissolved in an equimolar solvent of heptane and toluene. The mixture was considered since asphaltenes are insoluble and soluble in heptane and toluene, respectively. Our studies showed that asphaltene molecules tended to aggregate in unconfined bulk fluids to form a large cluster composed of all the asphaltene molecules. However, the size of nanoaggregates is smaller in the confined fluidic environments due to the adsorption of asphaltenes on silica or calcite surfaces. The aggregation and adsorption of asphaltenes initially located in the bulk fluid occurred at the pore entrances of calcite and silica. However, the asphaltene molecules located within the pore were adsorbed onto the pore surface. Further, confinement influenced the structure of the solvent. Toluene showed preferential adsorption for the calcite and silica surfaces over heptane due to differences in the polarities of these molecules. The adsorption behavior of the asphaltenes and solvents prove that the chemistry of the surfaces and edges have a crucial role in determining the structures of confined hydrocarbons. Further, confined fluids had a significant influence on the diffusivities of the asphaltenes and the solvents. Asphaltene and toluene diffusivities in confined fluids are lower compared to in bulk fluids. Further, the diffusivities of asphaltene with a higher molecular weight in confined and bulk fluids were lower compared to asphaltenes with lower molecular weights. The aggregation of asphaltenes proceeded via π-π stacking arising from the van der Waals affinity between the polyaromatics cores. These findings have important implications for predicting the influence of earth-abundant solid interfaces on the aggregation and transport behavior of complex heavy hydrocarbon molecules such as asphaltenes which are known to cause challenges in flow assurance for the recovery of hydrocarbons at the field-scale.

Effect of the vapor diffusion and improved light harvesting for Perovskite-Cu2ZnSnS4 hybridized solar cells

Abstract In this study, a novel hybridized perovskite-Cu2ZnSnS4 solar cell has been demonstrated. The CH3NH3PbI3 layer was synthesized using a facile one-step solution process under ambient conditions. The precursor solution consists of an equimolar methylammonium ion [MA+] and [PbI3−] anion in heptane solvent. The vapor-assisted crystal growth at the grain boundaries occur due to the methylamine (CH3NH2, MA). Moreover, 1 wt% Cu2ZnSnS4 (CZTS) nanoparticles (NPs) was added to the solution to enhance not only the absorption from visible to infrared regions and but also the transfer of the photogenerated charge carriers, leading to reduced charge recombination. The device structure was glass/ITO/1 wt% CZTS NPs hybrid poly (3,4-ethylenedioxythiophene) poly (styrene-sulfonate) (PEDOT:PSS)/CH3NH3PbI3 (MAPbI3)/C60/BCP/Al. The obtained MAPbI3 perovskite-based solar cell shows a short-circuit current density of 19.00 mA/cm2, an open-circuit voltage of 0.84 V, a fill factor of 0.47, and a power conversion efficiency (PCE) of 7.55%.

Effect of Hydrophilic-lipophilic Balance (HLB) Values of PEG-based Non-ionic Surfactant on Reverse Micellar Dyeing of Cotton Fibre with Reactive Dyes in Non-aqueous Medium

The effect of hydrophilic-lipophilic balance (HLB) of polyethylene glycol-based non-ionic surfactants of polyoxyethylene stearyl ether and polyoxyethylene tridecyl ether series of seven types on reverse micellar dyeing system of cotton was studied in non-aqueous heptane solvent medium. The relationships between HLB values of surfactants and reflectance, K/Ssum value and levelness of the dyed samples were investigated. The experimental results reveal that reflectance percentage increases and K/Ssum value decreases with increase of HLB value while good levelness and visual appearance of dyed samples can be achieved only with optimum HLB value. The most suitable HLB value for reverse micelle dyeing of cotton ranges from 12 to 14 since there is stable formation of reverse micelle under this range. Fastness to washing of dyed cotton samples was also evaluated. The results show that samples dyed by both non-ionic surfactant series can achieve excellent washing fastness supporting reproducibility of K/Ssum value, reflectance percentage and levelness of reverse micelle dyed samples with various surfactants.

Thermodynamic prediction of the solvent effect on a transesterification reaction

This work focuses on the thermodynamic prediction of solvent effects on the transesterification of butyl acetate with ethanol to butanol and ethyl acetate in the solvent heptane at 293.15 K and 303.15 K. Both, the reaction equilibrium and the reaction kinetics have been investigated experimentally by Schmidt et al. (1999). They found that the solvent heptane does not affect the reaction equilibrium but significantly influences the reaction kinetics. They described the solvent effect on the reaction kinetics by empirically correlating the experimentally-observed apparent rate constants with the dielectric constants of the different reaction mixtures.In this work we re-evaluated the experimental data and now present a thermodynamic approach to consistently predict the solvent effect on both, the reaction equilibrium and the reaction kinetics. Accounting for the activity coefficients of the reactants/products obtained from the Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT) allowed for considering the interactions of the reactants/products among themselves and also with the solvent heptane. Accounting for those, it is shown that the solvent effect on the reaction equilibrium as well as on the reaction rate can even be predicted in very good agreement with the experimental data.