Mixture Of Acetone Research Articles

Determination of polycyclic aromatic hydrocarbons in water using dispersive liquid-liquid microextraction-gas chromatography-mass spectrometric

For the extraction of polycyclic aromatic hydrocarbons (PAHs) from water samples, a new sample preparation approach based on dispersive liquid-liquid microextraction (DLLME) was developed. In this procedure, a water sample was injected with a mixture of carbon tetrachloride, CCl4 (extraction solvent), and acetone (disperser solvent) to generate an emulsion in which the PAHs were extracted into fine droplets of extraction solvent. The impacts of several extraction parameters were explored, including extraction solvent type, disperser solvent type, extraction solvent volume, and disperser solvent volume. For phenanthrene and fluoranthene, the calibration curve correlation coefficient (r2) was 0.9993 and 0.9973, respectively. For phenanthrene and fluoranthene, the limits of detection (LODs) were 0.0008 g/mL and 0.0006 g/mL, respectively. For phenanthrene and fluoranthene, the relative standard deviations (RSDs) were 10.69 percent and 9.72 percent, respectively. The analyte recovery rates ranged from 100.5 to 107.8%. Phenanthrene and fluoranthene were discovered in the samples.

Hydrogen-bonded networks in alcohol-acetone binary mixtures: molecular dynamics study.

Our previous studies on various hydrogen-bonded binary systems have shown anomalous physico-chemical properties at lower (10-30%) volume concentrations of either one or both of the components. In order to have a better understanding of this phenomenon, a systematic molecular dynamics study of binary mixtures of acetone with eight primary alcohols (R-OH, with R = 1 to 8) was undertaken. The structure of the binary systems is studied using radial distribution function, hydrogen bond statistics, and graph theoretical approach. Two distinct features are observed. Firstly, the bunching of R = (1, 2), R = (3, 4, 6), and R = (5, 7, 8)-acetone mixture in their hydrogen bond characteristics. Secondly, the number of alcohol-acetone hydrogen bonds is more for R = (3, 4, 6) and the alcohol-alcohol hydrogen bonds for the rest, indicating a preferential bonding of R = (3, 4, 6) alcohols with acetone when compared to the rest. With an increase in acetone concentration, the average degree of association decreases for all systems, showing an overall decrease in hydrogen bond multimer structures. The hydrogen bond networks are visualized using graph theory.

Four Greenness Evaluations of Two Chromatographic Methods: Application to Fluphenazine HCl and Nortriptyline HCl Pharmaceutical Combination in Presence of Their Potential Impurities Perphenazine and Dibenzosuberone

Nowadays, when analysts develop a new method, they are taking into consideration the green aspects of the developed method. Two chromatographic methods were developed for the determination of antidepressant pharmaceutical combination nortriptyline hydrochloride and fluphenazine hydrochloride in presence of their potential impurities and the methods were assessed using four tools; eco-scale, analytical greenness profile (AGP), analytical greenness metric approach (AGREE), and green analytical procedure index (GAPI). Method (A) was RP-HPLC, in which the separation was carried out on C18 column (250 × 4.5 mm, 5 µm) by gradient elution using mobile phase consisting of a mixture of water containing 0.1% H3PO4 (pH 2.25) and methanol, at a flow rate of 2 mL/min with DAD detection at 254 nm. Method (B) was TLC, in which the separation was carried out on silica gel TLC F254 plates. The mobile phase used was a mixture of methanol and acetone (9:1, v/v) with UV detection at 245 nm. The proposed methods agreed with ICH guidelines of method validation and were successfully applied for determination of the proposed components in their dosage form and the results were compared statistically to those obtained by the reported RP-HPLC method with no significant difference; which suggests the application of the developed methods for routine quality control analysis of these drugs.

Batch distillation for separating the acetone and n-heptane binary azeotrope mixture: Optimization and simulation

A batch distillation column is one of several approaches that have been developed to improve the distillation process's performance. Batch and specialty chemical industries require quick and reliable process simulations to predict the extent of separation of mixtures such as volatile natural compounds. Acetone and n-Heptane found in wastewater are usually associated with solvents from the pharmaceutical industry. At 329.11 K, acetone and n-Heptane easily combine to form an azeotropic mixture. The different distillation and separation techniques were used to separate the azeotropic mixture which requires several plates and columns. In the current work, batch distillation was used to study the separation of the azeotropic mixture (Acetone and n-Heptane).It was observed that the desired separation was not possible for the Acetone and n-Heptane system. To overcome this, a third component such as Butyl propionate or Benzene is added to the mixture of Acetone and n-Heptane system. This system was simulated using Equinox Software and Services Pvt. Ltd. licensed Multi Batch Distillation Software (MBDS™).Different thermodynamic models have been studied for the azeotropic mixtures, such as NRTL, UNIFAC I, UNIFAC II, and UNIFAC III. The batch distillation system for separating the Acetone and n-Heptane was optimized. Various operating factors such as the number of plates, reflux ratio, batch times, and distillate rates were investigated. Based on simulation studies, the optimal parameters were determined to be a reflux ratio of 2.2, 19 number of plates, and a total time of 1 h to separate >99 wt % Acetone purity from the azeotropic mixture.

Molecular Simulation of Biobutanol Recovery Using LTA and CHA Zeolite Nanosheets with an External Surface

LTA and CHA zeolites with silica and silico-alumino-phosphate (SAPO) composition have been recently proposed by Van der Perre et al. (ChemSusChem2017,10, 2968) to recover butanol from a mixture of butanol, ethanol, acetone, and water. Such a mixture is obtained from biomass fermentation, which is a sustainable alternative for butanol production. Here, we establish a computational methodology to simulate the three-step process, consisting of selective adsorption of butanol, with some ethanol and water, from the initial mixture, using a silica LTA nanosheet; desorption of the adsorbed mixture by increasing the temperature; and adsorption of the desorbed products in a CHA (silica or SAPO) nanosheet. A combination of Monte Carlo simulations, allowing to reproduce or predict single- or multiple-component gas adsorption isotherms, and molecular dynamics, giving the time evolution of the selective adsorption and desorption processes, have been used to model the experimental setup. A recently parameterized force field of general use for zeolites, AlPOs, and SAPOs has been tuned up in order to describe all interactions arising from this model, allowing to capture the thermodynamics of the system, the flexibility of the frameworks, and the effects of surface and bulk in the permeability of the nanosheets.

Tannin-rich tree bark extracts inhibit the development of bacteria associated with bovine mastitis

Condensed tannins were quantified in the barks of selected tree species, and the antibacterial activity of these substances against clinical and subclinical isolates of bovine mastitis were evaluated. Tree barks from Mimosa tenuiflora, Mimosa caesalpiniifolia, Anacardium occidentale, and Stryphnodendron adstringens were used, as well as commercial tannin from Acacia mearnsii. The tannins were extracted using a mixture of ethyl alcohol and acetone. The moisture content (MC), Stiasny index (SI), total solids content (TSC), and condensed tannins (CT) were measured. The evaluation of antimicrobial activity was determined by applying the disk diffusion test. The species that showed the highest CT were M. tenuiflora and A. occidentale, with 37.3% and 37.3%, respectively. The highest SI were obtained by the species A. occidentale and M. caesalpiniifolia, with values above 90%. The bacterium with the lowest resistance to the use of tannins was Streptococcus uberis. A. mearnsii was the only one capable of inhibiting the growth of Escherichia coli, with a mean inhibition halo of 9 mm. All species under study showed high values of condensed tannins in their barks. In addition to showing good performance as antimicrobial agents, these tannins indicated potential applications in the development of natural medicines for the treatment of bovine mastitis.

Modification of the oxygen radical absorbance capacity assay and its application in evaluating the total antioxidative state in fish

The oxygen radical absorbance capacity (ORAC) assay is widely accepted as a common method for evaluating the total antioxidative activity in animals and food. The ORAC assay can simultaneously detect both hydrophilic (H-) and lipophilic (L-) antioxidants in animal tissues. In the present study, we modified the ORAC assay and estimated the total antioxidative state in two important fish species. The liver was initially extracted using a hexane and dichloromethane (Hex/Dc) mixture to prepare L-antioxidants associated with an L-ORAC value followed by the use of an acetone, water, and acetic acid (A/W/AA) mixture to prepare H-antioxidants as associated with an H-ORAC value, according to the original ORAC procedure. We altered the extraction order and reagents used in the modified ORAC assay. The H-antioxidants were initially extracted using 75 mM phosphate buffer (pH 7.4) instead of A/W/AA followed by Hex/Dc. Surprisingly, the H-ORAC value of the liver in rainbow trout (Oncorhynchus mykiss) measured using our modified ORAC assay was five-fold higher than that measured using the original procedure. In contrast, there were no significant differences in the liver L-ORAC values between the modified and original procedures. In addition, the plasma total antioxidative activity measured using the modified ORAC procedure was ten-fold higher than that measured using the original procedure. Analysis of the modified ORAC assay method revealed that high doses of dietary oxytetracycline, a widely used antibiotic, can affect the total antioxidative state and induce oxidative stress in coho salmon (Oncorhynchus kisutch). The present study suggests that total antioxidative activity, particularly H-antioxidative activity, in animal tissues and food based on the original ORAC assay might be underestimated in the literature. The modified procedure of the ORAC assay was simply and effectively improved to evaluate the total antioxidative state in animal tissues.

Microfluidic-Based Formulation of Essential Oils-Loaded Chitosan Coated PLGA Particles Enhances Their Bioavailability and Nematocidal Activity.

In this study, poly (lactic-co-glycolic) acid (PLGA) particles were synthesized and coated with chitosan. Three essential oil (EO) components (eugenol, linalool, and geraniol) were entrapped inside these PLGA particles by using the continuous flow-focusing microfluidic method and a partially water-miscible solvent mixture (dichloromethane: acetone mixture (1:10)). Encapsulation of EO components in PLGA particles was confirmed by Fourier transform infrared spectroscopy, thermogravimetric analysis, and X-ray diffraction, with encapsulation efficiencies 95.14%, 79.68%, and 71.34% and loading capacities 8.88%, 8.38%, and 5.65% in particles entrapped with eugenol, linalool, and geraniol, respectively. The EO components’ dissociation from the loaded particles exhibited an initial burst release in the first 8 h followed by a sustained release phase at significantly slower rates from the coated particles, extending beyond 5 days. The EO components encapsulated in chitosan coated particles up to 5 μg/mL were not cytotoxic to bovine gut cell line (FFKD-1-R) and had no adverse effect on cell growth and membrane integrity compared with free EO components or uncoated particles. Chitosan coated PLGA particles loaded with combined EO components (10 µg/mL) significantly inhibited the motility of the larval stage of Haemonchus contortus and Trichostrongylus axei by 76.9%, and completely inhibited the motility of adult worms (p < 0.05). This nematocidal effect was accompanied by considerable cuticular damage in the treated worms, reflecting a synergistic effect of the combined EO components and an additive effect of chitosan. These results show that encapsulation of EO components, with a potent anthelmintic activity, in chitosan coated PLGA particles improve the bioavailability and efficacy of EO components against ovine gastrointestinal nematodes.

In-vitro antioxidant evaluation and production of biochar from distillation waste biomass of Mentha arvensis

Extraction of essential oils from aromatic plants generates a large amount of distillation waste, which needs to be managed properly. Conversion of this waste into valuable compounds with different applications will not only reduce environmental pollution but also provide a new avenue for complete utilization. The objective of the present study was to explore the distillation waste of Mentha arvensis for dual utilizations through the extraction of bioactive antioxidant/phenolic compounds and to re-use the exhaustive residues for the fabrication of functional materials like biochar. For the extraction of antioxidants and phenolics, several aqueous polar solvents (methanol, ethanol and acetone) mixture were tried and 75 % aqueous methanol was found to be the best solvent in terms of extraction yield, total phenolic content and flavonoid content. The same extract also showed the highest antioxidant activity for DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS [(2, 2′-azino-bis (3-ethylbenzothiazoline-6sulphonic acid)] assay. After extraction of antioxidant/phenolics, the remaining exhaustive residues was re-used for the production of biochar, which was subsequently used as a potential soil amendment. A short-term soil incubation study was conducted with mentha distillation waste (MDW) biochar. The study indicated that MDW biochar can be used as an effective amendment for degraded soil as evidenced by improvements in soil pH, cation exchange capacity, available nutrients (N, P, and K) status, and soil biological properties in terms of microbial biomass carbon and dehydrogenase activity. Thus, this study helped to develop a strategy for complete recycling of MDW under circular economic model, which may also promote environmental sustainability.

Molecular Docking Interactions with Mycobacterial ATP and Polyketide-13 Synthase Enzymes of Phytoconstituents Isolated from Entada abyssinica Stem Bark

The search for novel therapies for tuberculosis continues due to the emergence of resistant strains, adverse drug reactions, and potential drug-drug interactions of antitubercular drugs. This study was undertaken to identify compounds from Entada abyssinica, a plant used by herbalists in East Africa for the management of symptoms of tuberculosis. An extract of shade-dried E. abyssinica stem bark was prepared by maceration in a mixture of acetone and methanol in the ratio of 3:2. Column and thin layer chromatography were used to isolate pure compounds. The structures of the compounds were elucidated using nuclear magnetic resonance and infrared spectroscopy. The compounds were further studied using in silico tools to predict their binding affinities, descriptors of pharmacokinetics, and toxicity. Seven known compounds: 2,3-dihydroxypropyltriacontanoate (1), 1',26'-bis-(2,3-dihydroxypropyl) hexacosanedioate (2), stigmasterol 3-O--D-glucopyranoside (3), sitosterol 3-O--D-glucopyranoside (4), Spinasterol 3-O--D-glucopyranoside (5), stigmasterol (6) and spinasterol (7) were isolated. Compounds 1 and 2 had better binding affinities (-27.7374 and -28.5726 Kcal/mol) than the bedaquiline (-22.9042 Kcal/mol) for ATP. All isolated compounds had better binding affinities (between -21.4357 and -18.7809 Kcal/mol) than isoniazid (-10.8307 Kcal/mol) for polyketide-13 synthase enzymes. The compounds showed variable but promising pharmacokinetic properties with minimum toxicity. E. abyssinica stem bark contains phytochemicals with promising antimycobacterial activity via inhibition of the ATP and polyketide-13 synthase enzymes. In vitro and in vivo studies are recommended to validate the predicted antimycobacterial activity as well as the pharmacokinetics and toxicity profiles.

Adsorption onto hybrid hectorite-hydroxyethyl cellulose composite as a pre-concentration method for the spectrophotometric quantification of a cationic organic molecule, irinotecan

This study develops a pre-concentration methodology for pharmaceutical irinotecan, as a model cationic organic molecule. The methodology is based on the adsorption and quasi-desorption of irinotecan onto a hybrid hectorite clay-hydroxyethyl cellulose composite (Bentone LT). Upon incubation of the loaded composite with mixtures of acetone:water or acetonitrile:water, at a specific range of relative volumes, fast and massive composite expansion was observed macroscopically. Ιrinotecan could be assayed in the supernatant, most likely still bound onto delaminated clay (i.e. quasi-released), at concentrations up to about 90% of the loaded compound. Constant quasi-release efficiency was verified, independent of irinotecan concentration in the loading medium. The effect of salt concentration in loading and release medium and of adsorbate-to-adsorbent ratio on irinotecan quasi-release was investigated.Bentone LT adsorption/quasi-release-based methodology was validated as a pre-concentration step for photometric quantification of irinotecan in dilute aqueous solutions. Standard curves were linear over the concentration range of 31 to at least 700 ng/mL. A pre-concentration factor of 76.8-fold was achieved. Pearson's coefficient of determination for calibration curves prepared on different days was ≥0.980 for all 7 replicate irinotecan quantifications in aqueous solutions of 42 mL. Percent Coefficient of Variation (CV%) on all quality control levels was ≤13.03% for repeatability and ≤ 12.83% for intermediate precision. Bias was ≤ ±9.9% on all quality control levels. The Limit of Detection (LOD) and Limit of Quantitation (LOQ) were determined to be 10.38 and 31.44 ng/mL, respectively. This is around 30 times lower than in the hyphenated-assay non-complemented by a pre-concentration step. These results indicate that the proposed pre-concentration method allows quantitative determination of the studied cationic organic with acceptable analytical characteristics, in dilute aqueous solutions.

Antibacterial Activity of Carotenoid Pigments Produced by Heterotrophic Bacteria from Seawater in Krakal Coastal Area, Yogyakarta, Indonesia

Investigating natural pigments resulting from marine bacterial secondary metabolites is important because of their broad benefits in the food, pharmaceutical, cosmetic, and textile industries. In this study, 52 isolates of pigmented bacteria were isolated from seawater in the Krakal coastal area, Yogyakarta, Indonesia. Seven bacterial isolates showed high pigment stability. Profiling of pigment extracts using a mixture of acetone and methanol with UV–Vis spectrophotometric reading showed that the compounds produced were carotenoids. The highest total carotenoid content with UV–Vis spectrophotometric reading at 480 nm was produced by the Kral-3 isolate (1800 mg/g), followed by Kral-15 (1698.9 mg/g) and Kral-25 (797.2 mg/g) isolates. Analysis of the antibacterial activity of the carotenoid extracts of Kral-3, Kral-15, and Kral-25 isolates using the agar well diffusion method revealed a very strong inhibition score against Escherichia coli. In addition, the carotenoid extract of the Kral-3 isolate showed a strong inhibition score against Staphylococcus aureus, whereas the Kral-15 and Kral-25 isolates showed moderate inhibition scores. Based on the 16S rRNA gene analysis, the Kral-3, Kral-15, and Kral-25 isolates were identified as Kocuria rhizophilla, Calidifontibacter sp., and Rhodococcus ruber, respectively. Based on the findings, the novel bacterial strains are a potential bioresource for the commercial production of natural carotenoids.

Stability of Terpenoid-Derived Secondary Ozonides in Aqueous Organic Media

1,2,4-Trioxolanes, known as secondary ozonides (SOZs), are key products of ozonolysis of biogenic terpenoids. Functionalized terpenoid-derived SOZs are readily taken up into atmospheric aerosols; however, their condensed-phase fates remain unknown. Here, we report the results of a time-dependent mass spectrometric investigation into the liquid-phase fates of C10 and C13 SOZs synthesized by ozonolysis of a C10 monoterpene alcohol (α-terpineol) in water:acetone (1:1 = vol:vol) mixtures. Isomerization of Criegee intermediates and bimolecular reaction of Criegee intermediates with acetone produced C10 and C13 SOZs, respectively, which were detected as their Na+-adducts by positive-ion electrospray mass spectrometry. Use of CD3COCD3, D2O, and H218O solvents enabled identification of three types of C13 SOZs (aldehyde, ketone, and lactol) and other products. These SOZs were surprisingly stable in water:acetone (1:1) mixtures at T = 298 K, with some persisting for at least a week. Theoretical calculations supported the high stability of the lactol-type C13 SOZ formed from the aldehyde-type C13 SOZ via intramolecular rearrangement. The present results suggest that terpenoid-derived SOZs can persist in atmospheric condensed phases, potentially until they are delivered to the epithelial lining fluid of the pulmonary alveoli via inhaled particulate matter, where they may exert hitherto unrecognized adverse health effects.

Green synthesis of mesoporous Ni-Co layered double hydroxide and its application for removal of 2,4-dinitrophenol from water: A theoretical study complemented by the first principle density functional theory-Monte-Carlo approach

This paper describes the synthesis of a novel mesoporous Ni-Co layered double hydroxide(LDH) and its application for the adsorptive removal of 2,4-dinitrophenol(2,4-DNP) from an aqueous solution. A green synthetic method was used involving a non-aqueous ‘soft chemical' ethanol: acetone mixture in order to avoid intercalation or interlayer contamination by CO2 gas, which is responsible for carbonate formation. The synthesized material was characterized using PXRD, HR-TEM, FESEM, XPS, FT-IR, TGA-DTA, etc. The experimental and model fitting results of adsorption studies showed that equilibrium Freundlich adsorption isotherm and kinetic pseudo-second-order were the best-fitting models. Also, thermodynamic adsorption parameters ∆Ho,∆Soand∆Go were found to be favorable, non-spontaneous, and endothermic. Furthermore, theoretical molecular dynamic simulation (MD) revealed that the nature of adsorbate-substrate (2,4-DNP- Ni-Co LDH) interactions were favorable hydrophobic interactions. DFT-based DMoL3 approach showed that the adsorbate-substrate energy gap (eV) increases with the increase in the interfacial region, explaining the high chemical stability after the adhesion of adsorbate molecules. The regeneration adsorption cycles showed that the Ni-Co LDH acts with an excellent removal affinity towards the 2,4-DNP molecule within 150–180 min from cycles 1–4.

Ferula communis L. (Apiaceae) Root Acetone-Water Extract: Phytochemical Analysis, Cytotoxicity and In Vitro Evaluation of Estrogenic Properties.

Ferula communis L. (F. communis) belongs to the Apiaceae family and is a herbaceous plant with various pharmaceutical properties, due to the different contents of bioactive compounds extracted mainly from its roots, as well as its leaves and rhizome. To date, this plant extract has demonstrated estrogenic, anti-inflammatory, antiproliferative, cytotoxic, antimicrobial and anti-neoplastic properties. Its estrogenic activity is justified by the presence of ferutinin, an ester of a sesquiterpenic alcohol that acts as an agonist for estrogen receptors, with a chemical formula equal to C22H3O4. The component present in F. communis responsible for the toxicity of the plant is ferulenol, a prenylated coumarin with the chemical formula C24H30O3. This compound is capable of inducing mortality via its strong anti-coagulant properties, leading to a lethal hemorrhagic syndrome, ferulosis, in animals that feed on a chemotype of F. communis containing a high amount of ferulenol. The removal of the component ferulenol makes extracts of Ferula non-toxic. In fact, the remaining prenylated coumarins are not present in concentrations sufficient to induce toxicity. The intake of high concentrations of the extract of this plant leads a double dose-dependent effect that is typical of sesquiterpenes such as ferutinin. Here, we assessed the cytotoxicity and the estrogenic properties of the F. communis phytocomplex obtained through extraction using a mixture of acetone and water. Among the active constituents of F. communis, the identification of ferutinin and ferulenol was performed using HPLC. The effects of the extract were evaluated, following the removal of ferulenol, on three cell lines: human breast cancer MCF-7, human cervical cancer HeLa and human osteoblastic sarcoma Saos-2. The choice of these cell lines was justified by the need to mimic certain processes which may occur in vivo and which are estrogen-dependent. The obtained results demonstrated that F. communis extract, in addition to possessing an estrogenic-like property, showed a dose-dependent effect. Low concentrations (0.1–0.8 μM) demonstrated a hyperproliferative effect, whereas higher concentrations (1.6–50 μM) were toxic. Therefore, this extract could be an excellent candidate to make up for a reduction or lack of estrogen.

Bioacaricidal effects of three volatile oils on cattle ticks

Use of synthetic chemicals in addressing livestock attacks by ticks has negative effects on animals, handlers and the environment. These problems necessitate search for potent alternatives in bioacaricides particularly volatile oils. Acaricidal effects of hydro-distilled volatile oils from the fresh leaves of Eucalyptus citriodora, Ocimum gratissimum (OG) and Callistemon citrinus were evaluated on ticks obtained from infested cattle using topical method at varying concentrations in acetone. For each concentration, ten ticks of similar species were placed in Petri dishes and administered 20μL of the mixture of volatile oil and acetone. Acetone (20μL) was used as control and the effects were observed for 24 h. Out of three tick species identified, Rhipicephalus microplus was most abundant and most sensitive to the oils. Others are Amblyomma hebraeum and Hyalomma rufipes (most resistant). The volatile oil of OG was the most potent with LC50 of &lt; 2 % (&lt; 0.4 μL), &lt; 2 % and 7.97% (1.59 μL) on the organisms respectively. The 5% of OG produced 100% mortality on R. microplus in 10-25 min while 20% concentration produced 100% mortality on H. rufipes in 24 h. Volatile oils of these plants particularly OG can serve as potent alternative bio-acaricidal agents to chemicals.

Thermodynamic Excess Properties of Binary Mixtures of Acetyl acetone and Ethyl Acetate

The density (ρ), viscosity (η), surface tension (σ), and refractive index (R) of binary mixtures of acetylacetone (acac) with ethyl acetate (Etac) were determined at atmospheric pressure over the entire composition range of mixtures. The values of mixtures and pure liquids have been used to calculate the excess volume (VE), deviation in viscosity (Δη), and deviation in surface tension. The computed results were fitted to the Redlich–Kister polynomial equation. The excess molar volume (VE) for the binary system investigated exhibits a positive deviation at 298.15 K, and the positive deviation at 303.15 K becomes too negative as the mole fraction Xacac increases. The deviation in viscosity (Δη) and deviation in surface tension (Δσ) show negative values from the ideality at 303.15 The negative magnitude suggests the presence of strong intermolecular interactions between unlike molecules in the binary mixtures.

Intermolecular interactions in binary mixtures of formamide and acetone

Trajectories from molecular dynamics simulations of binary mixtures of formamide (FA) and acetone (AT) have been analyzed across the entire concentration range by means of various pair distributions and topological network analysis techniques to probe the structure of the intermolecular interaction networks existing in these mixtures. Radial pair distributions clearly indicated H-bonding interactions between the two molecule types through acetone oxygen and the cis- and/or trans-hydrogens of formamide. Decomposition of pair energy distributions into possible intermolecular interaction types revealed that the most stable formamide-acetone dimers existing in the binary mixtures interact via an H-bonding. Orientational pair distributions have shown that both the AT-AT and the FA-FA pairs tend to adopt an antiparallel dipole orientation, as their respective pair interaction energies get smaller. And, the FA-AT pairs interacting stronger than −6.3 kcal/mol are found to adopt an orientation such that the angle between the dipole of AT and the C-N bond of FA is larger than 130°. Network neighborhood analysis evidently revealed that the formamides do not show a strong preference for either molecule types. As acetone mole fraction of the mixture is increased, the added ATs are found to be capable of substituting the formamides, to a great extent, in the region spanning their second-order neighborhood. Conversely, as formamide content of the mixture is increased, the added FAs fail to adequately substitute the ATs in the region spanning their second-order neighborhood. Guided by our molecular dynamics based observations regarding the different types of intermolecular interactions existing between formamide and acetone, five FA-AT dimeric structures are highlighted. Their interaction energies are computed with density functional theory at the mPW2PLYP/def2-TZVP level. The most stable dimer is found to have an interaction energy of −7.5 kcal/mol, to involve an O⋯HC hydrogen-bonding, and to have nearly coplanar formamide and acetone. In addition, the DFT structures and interaction energies of trimers of the form AT⋯FA⋯AT and FA⋯AT⋯FA are also reported.

Synthesis of monometallic macrostructured catalysts for bromate reduction in a continuous catalytic system

The last few years have seen great leaps in the use of mechano-chemically modified carbon nanotubes in catalysis. While high improvements in catalytic performance have been achieved, the nature of the technique is not compatible with typical strategies for CNT coating of macro-structured catalysts by chemical vapor deposition. Developing macro-structured catalysts is a key step towards the sustainability of multi-phase catalysis and requires a methodology for coating with mechano-chemical modified CNT metallic catalysts. Preparing water-based slurries is not straightforward due to the CNT’s hydrophobicity, and the use of organic solvents is unsustainable. A novel methodology for the washcoating of macro-structures with pre-modified monometallic CNT catalysts was assessed. A compromise between surfactant use, post-coating treatment, and the catalyst activity/integrity, was achieved by solubilisation of the surfactant in a isopropanol:acetone mixture. The activity of the prepared catalysts was affected by the metallic dispersion, surfactant coverage, and distribution of the palladium throughout the catalytic layer. Palladium centers in the bottommost layers were found to be unavailable for liquid phase reaction. The activity of the catalysts prepared with pre-formed carbon monometallic powders was improved by adopting a coating strategy to maximize the availability of the metallic particles near the surface of the catalytic layer.

Completely Computational Model Setup for Spectroscopic Techniques: The Ab Initio Molecular Dynamics Indirect Hard Modeling Approach.

The spectroscopic quantification of mixture compositions usually requires pure compounds and mixtures of known compositions for calibration. Since they are not always available, methods to fill such gaps have evolved, which are, however, not generally applicable. Therefore, calibration can be extremely challenging, especially when multiple unstable species, for example, intermediates, exist in a system. This study presents a new calibration approach that uses ab initio molecular dynamics (AIMD)-simulated spectra to set up and calibrate models for the physics-based spectral analysis method indirect hard modeling (IHM). To demonstrate our approach called AIMD-IHM, we analyze Raman spectra of ternary hydrogen-bonding mixtures of acetone, methanol, and ethanol. The derived AIMD-IHM pure-component models and calibration coefficients are in good agreement with conventionally generated experimental results. The method yields compositions with prediction errors of less than 5% without any experimental calibration input. Our approach can be extended, in principle, to infrared and NMR spectroscopy and allows for the analysis of systems that were hitherto inaccessible to quantitative spectroscopic analysis.