Toluene Ethanol Research Articles

Phytochemical Study, FTIR and GC-MS Characterization and Evaluation of the Antioxidant Activity of Letestua durissima Extracts

The current study focused on extract content, phytochemical screening, GC-MS analysis, infrared analysis and antioxidant activity evaluation of bark, sapwood and heartwood of Letestua durissima, commonly called Kong Afane in Gabon, using DPPH and ABTS methods. The highest extract contents, reaching 37.3%, were observed in the bark. Phytochemical tests revealed the presence of alkaloids, polyphenols, sterols, terpenes, flavonoids and saponins in the extracts. The quantitative results highlighted high concentrations of polyphenols (95.56 mg GAE g−1 of dry extract in the acetone extract), condensed tannins (113.45 mg CE g−1 of dry extract in the extract toluene–ethanol) and flavonoids (20.26 mg CE g−1 of dry extract in the toluene–ethanol extract) in the bark. Regarding the evaluation of antioxidant activity, the results showed a significant capacity of the extracts to scavenge free radicals. This activity was more pronounced in the toluene–ethanol extracts, with an IC50 of 0.66 for the ABTS method and 2.39 for that of DPPH. The GC-MS identification of phenolic compounds such as hydroxybenzoic acid, protocatechuic acid, gallic acid, catechin and triterpenes could explain the high reactivity of our extracts as antioxidants.

The Chemical Characterisation of the Maritime Pine Bark Cultivated in Northern Portugal

Maritime pine, scientifically known as Pinus pinaster, holds a vital role in Iberian Peninsula forests, primarily as a source of wood for panels, paper, and cellulose production. Recently, there has been a growing interest in utilising agroforestry by-products to yield valuable chemicals for applications in various sectors, including the food, pharmaceutical, and bioenergy industries. This study aimed to assess the value of the primary by-product of Pinus pinaster from the Minho region of northwestern Portugal, i.e., the bark. The research extensively examined the bark’s chemical and thermal characteristics, including ash content, extractives, lignin, cellulose, hemicellulose, fatty acids, and mineral composition. Additionally, various analytical techniques like FTIR, SEM, DSC, DTG, and XRD were used to observe chemical structure differences. The results reveal that the Pinus pinaster bark primarily consists of lignin (51.15%) and holocellulose (46.09%), with extractives mainly soluble in toluene–ethanol, followed by water, and a small amount of them are soluble in ethanol. The bark contained around 0.44% ash, and heavy metals such as Cd and Pb were not found. During degradation, Pinus pinaster experienced a 10% mass loss at 140 °C. In terms of crystallinity, holocellulose and cellulose showed similar percentages at approximately 25.5%, while α-cellulose displayed the highest crystallinity index at 41%.

Extraction and Characterization of Fiber and Cellulose from Ethiopian Linseed Straw: Determination of Retting Period and Optimization of Multi-Step Alkaline Peroxide Process

Flax is a commercial crop grown in many parts of the world both for its seeds and for its fibers. The seed-based flax variety (linseed) is considered less for its fiber after the seed is extracted. In this study, linseed straw was utilized and processed to extract fiber and cellulose through optimization of retting time and a multi-step alkaline peroxide extraction process using the Taguchi design of experiment (DOE). Effects of retting duration on fiber properties as well as effects of solvent concentration, reaction temperature, and time on removal of non-cellulosic fiber components were studied using the gravimetric technique, Fourier transform infrared (FTIR) spectroscopy and thermal studies. Based on these findings, retting for 216 h at room temperature should offer adequate retting efficiency and fiber characteristics; 70% cellulose yield was extracted successfully from linseed straw fiber using 75% ethanol-toluene at 98 °C for 4 h, 6% NaOH at 75 °C for 30 min, and 6% H2O2 at 90 °C for 120 min.

Chemical Composition and Extraction of Micro Crystalline Cellulose from Outer Skin Isolated Coffee Husk

Coffee husk (CH) is a sustainable and abundantly available cellulosic waste material. Its fiber consists of cellulose as the major structural part which leads to potential utilization for the manufacturing of microcrystalline cellulose (MCC) products that can be utilized for different industrial applications. In the present study, chemical composition of outer skin-isolated coffee husk was determined and sequential treatments of various untreated (UT) sample, ethanol—toluene treated sample through dewaxed (DW) treatment, sodium hydroxide (NaOH)—treated sample through alkali (AT) treatment, and sulfuric acid (H2SO4)—treated sample through bleaching (BL) treatment have been carried out. The Micro Crystalline Cellulose (MCC) has been extracted through hydrogen peroxide (H2O2) after BL treatment. The BL treatment for MCC extraction process was conducted without chlorine and additional harsh acid treatment, respectively. The characterization of chemically treated samples was carried out to investigate their morphological, physico-chemistry, and thermal behavior through a scanning electron microscope (SEM), Fourier transform infrared—ray (FTIR), X-ray diffraction (XRD), thermo gravimetric analysis (TGA), and differential temperature analyzer (DTA). From the chemical composition analysis; the cellulose, hemicellulose, lignin, and extractive content were determined and its values were (52.9%), (12.5%), (24.3%), and (9.4%), respectively. In the morphological examination, the great untreated (UT) fiber sample was greatly reduced into a micro-sized BL sample, revealing that (from FTIR analysis) the lignin and hemicellulose contents were greatly removed during chemical treatments and the presence of a micro crystalline cellulose region with 54.7% yield. Also, the sample AT and BL showed the lowest amorphous region in X-RD due to the removal of hemicellulose and lignin. The highest crystallinity index has been determined for the BL sample, i.e., 89.9%. Additionally, the thermal analysis shows that the AT and BL sample has great thermal stability than other (UT and DW) samples at high temperature. Therefore, the outer skin separated coffee husk was prepared from agricultural waste was subjected to eco-friendly chemical treatments to yield MCC. Thus, the extracted MCC is expected to be reliable for replacing other plant materials for the production of crystalline nanomaterial and reinforcing constituent for the fabrication of bio composite.

Understanding the effect of Intake temperature on the ϕ-sensitivity of toluene-ethanol reference fuels and neat ethanol

The low-temperature combustion (LTC) is an attractive concept that enables the modem combustion engines to move toward sustainability mainly by increasing the efficiency and decreasing the emissions. The modern combustion engines which are working based on the LTC concept have specific fuel requirements. Fuel ϕ-sensitivity is a key factor to be considered for tailoring fuels for these engines. Fuel with a high ϕ-sensitivity are more responsive to thermal or fuel stratifications; the auto-ignition properties of different air-fuel mixtures of these fuels, with different equivalence ratio (ϕ), are more diverse. This diversity provide a smoother heat release rate in stratified condition. In this study 11 different toluene–ethanol reference fuels (TERFs) in three research octane number (RON) groups of 63, 84, and 105 together with neat ethanol are evaluated. The Lund ϕ-sensitivity method is used to evaluate these fuels in a cooperative fuel research (CFR) engine. The effect of variation of intake temperature on pressure sensitivity of fuel at a constant combustion phasing is evaluated. This evaluation is performed at two intake temperature of 373 and 423 K, and the results are compared with the outcome of the Lund ϕ-sensitivity number with the intake temperature of 323 K. This study shows that the CR sensitivity response of different blends to the intake charge temperature variation depends on the fuel composition. Accumulated low temperature heat release and latent heat of vaporization. It proves that the fuel ϕ-sensitivity will vary under different thermodynamic conditions. There was a clear link between the accumulated heat released during the early reaction and CR sensitivity of the blends at different intake temperature of 373 and 423 K but the link with the latent heat of vaporization (HoV) found to be inexplicit.

Development of an empirical test method to quantify the ɸ-sensitivity of liquid fuels

Several researchers are investigating strategies to lower the emissions and increase the efficiency of combustion engines to reduce the negative impact on the environment and the climate from transportation. The low-temperature combustion (LTC) concept is the basis for some of these high-efficiency, low-emission combustion technologies. To maximize the combustion controllability of engines based on the LTC concept, the combustion behavior of fuel both at different equivalence ratios (ɸ) and under ɸ sweeps must be understood and planned precisely. The ɸ-sensitivity of a fuel explains its behavior at different engine loads or stratification levels. In this study, a new test method for empirically evaluating ɸ-sensitivity using a Cooperative Fuel Research (CFR) engine is proposed and the validity of the method is investigated. A modified CFR engine for homogeneous-charge compression ignition (HCCI) combustion is used to investigate the compression ratio (CR) sensitivity of different toluene–ethanol reference fuels (TERFs) in a research octane number (RON) range of 63–105. This study suggests a method to quantify the ɸ-sensitivity of different fuels and blends by measuring the compression ratio required to keep the CA50 constant while varying ɸ. It shows that the fuel composition greatly affects the fuel ɸ-sensitivity even for different blends with the same RON. The results also indicate that the coexistence of ethanol and toluene in a blend can generate the highest ɸ-sensitivity of the blend compared to other blends with the same RON. Fuel composition has a strong effect on emissions. The simultaneous effect of fuel composition and ɸ variation on the emission and stability parameters is nonlinear.

Application of the TLC image analysis technique for the simultaneous quantitative determination of L-proline and L-lysine in dietary supplement

A simple and sensitive thin-layer chromatography (TLC) method coupled with an image analysis technique was developed for the simultaneous quantitative determination of L-proline and L-lysine in dietary supplement with good precision and accuracy. Separation was performed on silica gel plates using ethanol‒toluene (2:3, V/V) as the mobile phase. The visualization of chromatograms was based on iodine–azide reaction; therefore, pre-chromatographic derivatization reaction of amino acids with phenyl isothiocyanate was performed. Digital images of TLC plate chromatograms were converted into peak chromatograms, and quantitative analysis was conducted using TLSee software.

Development of a mechanism-dynamic-selection turbulent premixed combustion model with application to gasoline engine combustion and emissions simulation

In order to overcome the drawback (tuning reaction rate coefficients) of using a single mechanism in the chemical-kinetics-based turbulent premixed combustion modelling approach, a mechanism-dynamic-selection turbulent premixed combustion model has been developed, validated, and successfully applied to the combustion and emissions simulation of spark ignition gasoline engines. In this new model, based on the local thermal and turbulent conditions of any preheat cell, a certain chemical kinetic mechanism which can achieve the target ratio of turbulent flame speed to laminar flame speed is selected. To realise this goal, based on the laminar flame speed sensitivity analysis of an improved eTRF (ethanol toluene reference fuel) base chemical kinetic mechanism, a derived mechanism library has been generated. Based on enough experimental and DNS (direct numerical simulation) data of S T/S L, a mechanism selection database (mechanism as a function of Borghi-Peters coordinates) has been constructed and implemented into a CFD (computational fluid dynamics) code, also a classification scheme for identifying unburned, preheat, flame front, and burned zones of a combustion domain has been developed and implemented into the CFD code. The developed mechanism-dynamic-selection turbulent premixed combustion model has been validated using the combustion in a spherical constant volume and applied to the prediction of combustion and emissions of a spark ignition gasoline engine under transient cold start process. Validation results show that, without tuning any model parameters, the base mechanism, the derived mechanism library, the mechanism selection function, the classification scheme, as well as a simulation setup strategy for modelling engine transient cold start process, have good prediction performances and are practical for engine combustion and emissions simulation.

One mol-ecule, three crystal structures: conformational trimorphism of N-[(1S)-1-phenyl-eth-yl]benzamide.

The title compound, C15H15NO, is an enanti-opure small mol-ecule, which has been synthesized many times, although its crystal structure was never determined. By recrystallization from a variety of solvent mixtures (pure aceto-nitrile, ethanol-water, toluene-ethanol, THF-methanol), we obtained three unsolvated polymorphs, in space groups P21 and P212121. Form I is obtained from aceto-nitrile, without admixture of other forms, whereas forms II and III are obtained simultaneously by concomitant crystallizations from alcohol-based solvent mixtures. All forms share the same supra-molecular structure, based on infinite C 1 1(4) chain motifs formed by N-H⋯O inter-molecular hydrogen bonds, as usual for non-sterically hindered amides. However, a conformational modification of the mol-ecular structure, related to the rotation of the phenyl rings, alters the packing of the chains in the crystal structures. The orientation of the chain axis is perpendicular and parallel to the crystallographic twofold screw axis of space group P21 in forms I and II, respectively. As for form III, the asymmetric unit contains two independent mol-ecules forming parallel chains in space group P212121, and the crystal structure combines features of monoclinic forms I and II.

Hygrothermal Treatment of Tepa (Laureliopsis philippiana Looser) Fibers

The present study consisted in determining the effects of a hygrothermal treatment on wood fibers from the Laureliopsis philippiana Looser species. The fibers were treated in autoclave at 150 °C for 90 minutes at a pressure of 430 kPa, which was generated during the evaporation process of the water in autoclave. Physical properties, color, and water retention capacity of hygrothermically treated and untreated fibers were analyzed. The chemical properties determined were the extractable amount in sodium hydroxide, toluene ethanol, hot and cold water, the cellulose, holocellulose and lignin contents, the pH value, the percentage of volatile and washable acids, and the buffer capacity. In hygrothermically treated fibers, a change of color was detected as well as a reduction in the water retention capacity and an increase in the percentage of extractable, cellulose, lignin and a decrease of holocellulose. Also an increase in acidity, amount of volatile and washable acids and buffer capacity were determined. Due to the chemical changes observed in the treated fibers, these would present advantages in the manufacture of fiberboards, facilitating the setting of the amino resins.

Computational Insight into the Mechanism of Ruthenium(II)-Catalyzed α-Alkylation of Arylmethyl Nitriles Using Alcohols.

The ruthenium(II)-catalyzed α-alkylation reaction of arylmethyl nitriles (phenylacetonitrile) using alcohols (ethanol) in toluene has been extensively investigated by means of SMD-M06-2X/6-311G(d,p)-LANL2dz (LAnL2dz for Ru, 6-311G(d,p) for other atoms) calculations. Detailed mechanistic schemes have been proposed and discussed. The catalytically active Ru(II) complex was generated by the base-induced KCl elimination from the catalyst precursor [(PNPPh)RuHCl(CO)]. The overall Ru(II) catalytic cycle consists of three basic processes: (1) ethanol-to-aldehyde transformation catalyzed by the 16-electron unsaturated ruthenium pincer catalyst; (2) a 16-electron unsaturated ruthenium pincer catalyst catalyzed condensation reaction of arylmethyl nitrile with aldehyde, which leads to PhC(CN)=CHCH3; (3) hydrogenation of PhC(CN)=CHCH3, which leads to the formation of the α-alkylated arylmethyl nitrile product (PhCH(CH2CH3)CN). The DFT results revealed that the rate-determining barrier of the overall reaction was 23.9 kcal/mol of the H-transfer step in the third process. The reaction of PhC(CN)=CHCH3 with the dihydride Ru complex, which is generated in the ethanol-to-aldehyde transformation process, is the more preferable hydrogenation mechanism than hydrogenation of vinyl nitrile-Ru complex by H2. Using alcohol as the reactant not only fulfills the requirement of the borrowing-H strategy but also lowers the barriers of the H-migration steps.

Valorization of Ethiopian Sugarcane Bagasse to Assess its Suitability for Pulp and Paper Production

This research provides an assessment of the Ethiopian sugarcane bagasse (ESCB) and examines its suitability for the pulp and paper production. The study is focused toward carrying out the physical fractionation pretreatment on the ESCB aiming at the reduction of its lignin, extractive, silica and ash content. A measurement on the chemical composition was carried out to determine the cellulose, lignin, holocellulose, ash and silica content. Furthermore, cold and hot water solubility, 1% NaOH solubility and the presence of ethanol–toluene extractives were measured. Chemical composition analysis of sugarcane bagasse revealed a good level of cellulose (≈ 50%) and Klason lignin content (< 30%). The measurement of the ESCB fiber dimensions (fiber length of 1.86 mm, fiber diameter of 30.02 µm, cell-wall thickness of 2.53 µm) advocates its application in the paper and pulp industry. The physical fractionation pretreatment had a significant effect on reducing the lignin, extractive, ash and silica content in the ESCB, as could be evidenced from the FTIR analysis. These results demonstrate the efficacy of Ethiopian sugarcane bagasse and validate it as a suitable raw material for pulp and paper industry.

Chromatographic methods for determination of finasteride and tamsulosin hydrochloride and in presence of finasteride degradation product

Two sensitive and selective chromatographic methods were developed for determination of finasteride and tamsulosin hydrochloride in bulk powder and a pharmaceutical formulation. The first method was based on high-performance liquid chromatography (HPLC) separation of the cited drugs in the presence of the acid degradation product of finasteride. The separation was achieved using a C18 column (300 mm × 3.9 mm; 10-μm particle size) and a mobile phase consisting of 0.04 M ortho-phosphoric acid (pH 3.5 ± 0.2 adjusted with triethylamine) and acetonitrile (50:50, v/v). Quantification was achieved with ultraviolet (UV) detection at 215 nm. Linearity was in the range of 10.00–110.00 μg/mL and 2.00–44.00 μg/mL for finasteride and tamsulosin hydrochloride, respectively. Thin-layer chromatography (TLC)–densitometric method was achieved on an aluminum plates pre-coated with silica gel 60 F254 using toluene–ethanol–diethylamine (8:2:1.5, by volume) as eluent, and the RF values of tamsulosin hydrochloride and finasteride were 0.57 and 0.64, respectively. Quantification was achieved with UV detection at 250 nm for finasteride and 280 nm for tamsulosin hydrochloride. Linearity was in the range of 1.00–40.00 and 0.2.00–20.00 μg per spot for finasteride and tamsulosin hydrochloride, respectively. The results obtained were validated according to the International Conference on Harmonisation (ICH) guidelines. A statistical comparison between the obtained results and the results of a reported method was carried out.

Reduction of Parasitic Capacitance of A PDMS Capacitive Force Sensor.

Polymer-based flexible micro electro mechanical systems (MEMS) tactile sensors have been widely studied for a variety of applications, such as medical and robot fields. The small size and flexibility are of great advantage in terms of accurate measurement and safety. Polydimethylsiloxane (PDMS) is often used as the flexible structural material. However, the sensors are likely subject to large parasitic capacitance noise. The smaller dielectric constant leads to smaller influences of parasitic capacitance and a larger signal-to-noise ratio. In this study, the sensor underwent ultraviolet (UV) exposure, which changes Si–CH3 bonds in PDMS to Si–O, makes PDMS nanoporous, and leads to a low dielectric constant. In addition, we achieved further reduction of the dielectric constant of PDMS by washing it with an ethanol–toluene buffer solution after UV exposure. This simple but effective method can be readily applicable to improve the signal-to-noise ratio of PDMS-based flexible capacitive sensors. In this study, we propose reduction techniques for the dielectric constant of PDMS and applications for flexible capacitive force sensors.

Development and validation of a high-performance thin-layer chromatographic method for the quantitative assessment of topiramate from human serum: Application in therapeutic drug monitoring

A simple and reliable high-performance thin-layer chromatographic (HPTLC) method has been developed and validated for the determination of topiramate in human serum which will help in therapeutic drug monitoring that aids in the clinical management of patient therapy. This method uses dipping method of derivatization to make the non-chromophore topiramate visible for detection. Pre-coated silica gel F254 HPTLC plates were used to carry out chromatographic separation using a mixture of toluene–ethanol (9:1) as the mobile phase. Derivatization was carried out using dipping method. Betamethasone was used as internal standard. Densitometric detection was carried out at 417 nm. The method was validated for linearity, precision, selectivity, limit of detection and limit of quantification and accuracy. Linear calibration curves in the range of 0.25 to 40 μg band−1 gave a correlation coefficient of 0.9963. The intra-day (n = 6) and inter-day (n = 18) precision, expressed as the relative standard deviation, were i...

Identification of odorous constituents of southern yellow pine and China fir wood: the effects of extractive removal

In this study, the odors of two types of softwood species, namely southern yellow pine (Pinus spp.) and China fir (Cunninghamia lanceolata (Lamb.) Hook.), were identified and extracted with ethanol–toluene for the removal of extractives.

Transparent Silk Fibroin Microspheres from Controlled Droplet Dissolution in a Binary Solution.

Silk is a natural polymer with a broad range of potential applications in textiles, advanced materials, biomedical devices, and drug delivery. The ability to control the morphology and assembly of silk fibroin is essential for the fabrication of silk-based structured materials. Here, we report an effective and simple approach based on droplet dissolution for weaving silk fibroin into spheres of several hundred micrometers in diameter. The spheres possess regular wrinkled microstructures on the surface and switchable transparency for visible light. To produce these silk spheres, we immersed a sessile microdrop of the silk fibroin aqueous solution in a surrounding phase of ethanol in toluene at low concentration (<10%). The droplet experienced a two-phase process: the first phase of volume expansion due to the intake of organic solvents from the surrounding phase and the second phase of droplet dissolution. The dissolution rate is closely related to the dynamics of the droplet, while the resulting microstructure of the silk microsphere is simply adjusted by the composition of the surrounding solution. At high concentrations of ethanol, silk fibroin formed a thin shell around the droplet during the initial expansion of the droplet in volume. As the droplet shrank at a later stage, the shell around the droplet wrinkled and crumpled, leading to regular ridges and crevices on the microsphere surface. This work demonstrates that controlled droplet dissolution may be explored as a novel and effective way to tailor microstructures of silk assemblies. The as-prepared silk microspheres may be potentially used as optical units or microcarriers.

Characterization of bark extractives of different industrial Indonesian wood species for potential valorization

Barks are available as waste material and by-product of wood industry. They have been reported to contain interesting molecules and show some bioactivity such as antioxidant and antifungal. This study aimed at evaluating the amounts of extractives in Acacia mangium (acacia), Paraserianthes falcataria (sengon) and Swietenia mahagoni (mahoni) barks, to evaluate their extractive contents and the presence of potential valuable molecules. The extraction method used soxhlet with four different solvents. Antioxidant activity assays were carried out using methyl linoleate and 2,2-diphenyl-1-picrilhidrazyl (DPPH) and the antifungal activity was determinate by fungal growth inhibitions assays. 5.3%–18.5% extraction yields were obtained. All acetone and toluene ethanol extracts show high antioxidant activity by DPPH. The highest antioxidant value obtained by DPPH was obtained for mahoni bark acetone extract with 3.9mg/L of EC50, followed by mahoni bark toluene ethanol 6.8mg/L, acacia bark acetone 7mg/L, and acacia bark toluene ethanol extract 7.4mg/L. Sengon bark extracts had the greatest antifungal activity inhibition. The greatest antioxidant and antifungal activity were obtained with phenolic compounds which were contained in the extracts.

Brick by brick computation of the gibbs free energy of reaction in solution using quantum chemistry and COSMO‐RS

The computational modeling of reactions is simple in theory but can be quite tricky in practice. This article aims at the purpose of providing an assistance to a proper way of describing reactions theoretically and provides rough guidelines to the computational methods involved. Reactions in liquid phase chemical equilibrium can be described theoretically in terms of the Gibbs free energy of reaction. This property can be divided into a sum of three disjunct terms, namely the gas phase reaction energy, the finite temperature contribution to the Gibbs free energy, and the Gibbs free energy of solvation. The three contributions to the Gibbs free energy of reaction can be computed separately, using different theoretico‐chemical calculation methods. While some of these terms can be obtained reliably by computationally cheap methods, for others a high level of theory is required to obtain predictions of quantitative quality. To propose workflows which can strike the balance between accuracy and computational cost, a number of benchmarks assessing the precision of different levels of theory is given. As an illustrative example, the low‐temperature hydrogenation reaction of acetaldehyde to ethanol in solvent toluene is shown. © 2017 American Institute of Chemical Engineers AIChE J, 63: 3944–3954, 2017

Supercritical Flow Synthesis of Pt1–xRux Nanoparticles: Comparative Phase Diagram Study of Nanostructure versus Bulk

The thermodynamic stability of nanocrystals is different from that of bulk systems, and nanoscale phase diagrams are to a large degree unknown. Here we present a systematic investigation of the Pt1–xRux phase diagram through supercritical flow synthesis of Pt1–xRux nanoparticles across the entire compositional range. The synthesis was done in stoichiometric steps of 0.1 using an ethanol–toluene mixture as solvent at 450 °C and 200 bar. The products were characterized by high-resolution synchrotron powder X-ray diffraction, transmission electron microscopy, and elemental mapping of individual particles using energy-dispersive X-ray spectroscopy. The diffraction data revealed a single-phase face-centered cubic (fcc) alloy for x ≤ 0.2, while an additional hexagonal close-packed (hcp) phase emerges as x approaches 1. This behavior deviates significantly from the bulk phase diagram, where a biphasic region is only observed for 0.62 < x < 0.8. Thus, compositional design of Pt–Ru alloys is more flexible on the n...