Addition Of Acetonitrile Research Articles

Impact of POM's coordination mode and Mo-hybrid constituents on the binding, stability, and catalytic properties of hybrid (pre)catalysts.

The assembly of MoVIO2 2+ and methoxy-substituted salicylaldehyde nicotinoyl hydrazone ligands afforded two classes of hybrid polyoxometalates (POMs). In the Class I architectures, [MoO2(HL1-3)(D)]2[Mo6O19]·xCH3COCH3 (D = CH3COCH3 or H2O, x = 0 or 2, and L1-3 = ligands bearing the OMe group at position 3, 4 and 5, respectively), the main driving force for self-assembly is the electrostatic interaction between the components. Class II architectures are composed of a POM anion covalently linked to two Mo-complex units through the terminal Ot or bridging μ2-OPOM oxygen atoms, as found in Lindqvist-based hybrids [{MoO2(HL1-3)}2Mo6O19]·xCH3CN (x = 0 or 2) and the asymmetrical β-octamolybdate-based hybrid [{Mo2O4(HL2)(H2L)}{MoO2(HL2)}2Mo8O26]·CH3CN·H2O. Quantum chemical calculations were applied to evaluate the impact of the POM hybrid constituents on the hybrid-type stability, showing that it strongly depends on the ligand substituent position and ancillary ligand nature. Hybrids were tested as catalysts for cyclooctene epoxidation using tert-butyl hydroperoxide (TBHP in water or decane) and with or without the addition of acetonitrile (CH3CN) as an organic solvent. The catalytic results provided by the use of TBHP in decane are the best ones and classify all the prepared catalysts as very active, with the conversion of cyclooctene >90%, and high selectivity towards epoxide, >80%. We also examined the influence of the ligand structure, POM's hybrid type, and coordination mode on the Mo-hybrid activity and selectivity.

A comparative evaluation of sample preparation techniques for the therapeutic monitoring of carbamazepine in human plasma by RPLC/DAD

Four sample preparation techniques, namely direct protein precipitation through a) trichloroacetic acid addition (PPA) or b) acetonitrile addition (PPO), c) liquid-liquid extraction in n-octanol followed by the direct injection of the organic layer, and d) supramolecular solvent extraction in a tetrahydrofuran/n-octanol/water coacervate (SUPRAS) were evaluated to be used for the RPLC/DAD assay of carbamazepine in human plasma samples, targeting therapeutic monitoring (TM) purposes. The chromatographic approach to separating carbamazepine from human plasma matrices was designed to be a simple gradient elution with an octadecyl chemically modified silica gel stationary phase, and a mobile phase composed of acetonitrile (organic) and HPLC grade water (aqueous), both with 0.1% formic acid. Monitoring at 290 nm allowed for the detection of carbamazepine. After optimizing both sample preparation procedures and chromatographic separation parameters, LOQ values of 3 µg/mL (PPA), 0.6 µg/mL (PPO), 12 ng/mL (LLE) and 50 ng/mL (SUPRAS) were determined. Detector response functions were studied over an interval up to 20 µg/mL (ULOQ).

Cyanomethylation of imines enabled by a mild deprotonation of acetonitrile using a combination of TMSCF3 and CsF

β-Amino acids are important structural units in chemistry and biology. Herein we reported a method to synthesize β-amino nitriles, the crucial synthetic precursor to β-amino acids. By using a nucleophilic base-complex, in situ generated from TMSCF3 and CsF, addition of acetonitrile to a series of aromatic imines offered the corresponding β-amino nitriles in excellent yields. Moreover, other electron withdrawing group bearing methyl group could be deprotonated to produce a good nucleophile under this mild conditions.

Unveiling the Mysteries: Acetonitrile's Dance with Weakly-Solvating Electrolytes in Shaping Gas Evolution and Electrochemical Performance of Zinc-ion Batteries.

Aqueous Zn-metal battery (AZMB) is a promising candidate for future large-scale energy storage with commendable capacity, exceptional safety characteristics, and low cost. Acetonitrile (AN) has been widely used as an effective electrolyte constituent to improve AZMBs' performance. However, its functioning mechanisms remain unclear. In this study, we unveiled the critical roles of AN in AZMBs via comparative in situ electrochemical, gaseous, and morphological analyses. Despite its limited ability to solvate Zn ions, AN-modulated Zn-ion solvation sheath with increased anions and decreased water achieves a weakly-solvating electrolyte. As a result, the Zn||Zn cell with AN addition exhibited 63 times longer cycle life than cell without AN and achieved a 4 Ah cm-2 accumulated capacity with no H2 generation. In V2O5||Zn cells, for the first time, AN suppressing CO2 generation, elevating CO2-initiation voltage from 2→2.44 V (H2: 2.43→2.55 V) was discovered. AN-impeded transit and Zn-side deposition of dissolved vanadium ions, known as "crosstalk," ameliorated inhomogeneous Zn deposition and dendritic Zn growth. At last, we demonstrated an AN-enabled high-areal-capacity AZMB (3.3 mAh cm-2) using high-mass-loading V2O5 cathode (26 mg cm-2). This study shed light on the strategy of constructing fast-desolvation electrolytes and offered insights for future electrolyte accommodation for high-voltage AZMB cathodes.

Unveiling the Mysteries: Acetonitrile's Dance with Weakly‐Solvating Electrolytes in Shaping Gas Evolution and Electrochemical Performance of Zinc‐ion Batteries

AbstractAqueous Zn‐metal battery (AZMB) is a promising candidate for future large‐scale energy storage with commendable capacity, exceptional safety characteristics, and low cost. Acetonitrile (AN) has been widely used as an effective electrolyte constituent to improve AZMBs’ performance. However, its functioning mechanisms remain unclear. In this study, we unveiled the critical roles of AN in AZMBs via comparative in situ electrochemical, gaseous, and morphological analyses. Despite its limited ability to solvate Zn ions, AN‐modulated Zn‐ion solvation sheath with increased anions and decreased water achieves a weakly‐solvating electrolyte. As a result, the Zn||Zn cell with AN addition exhibited 63 times longer cycle life than cell without AN and achieved a 4 Ah cm−2 accumulated capacity with no H2 generation. In V2O5||Zn cells, for the first time, AN suppressing CO2 generation, elevating CO2‐initiation voltage from 2→2.44 V (H2: 2.43→2.55 V) was discovered. AN‐impeded transit and Zn‐side deposition of dissolved vanadium ions, known as “crosstalk,” ameliorated inhomogeneous Zn deposition and dendritic Zn growth. At last, we demonstrated an AN‐enabled high‐areal‐capacity AZMB (3.3 mAh cm−2) using high‐mass‐loading V2O5 cathode (26 mg cm−2). This study shed light on the strategy of constructing fast‐desolvation electrolytes and offered insights for future electrolyte accommodation for high‐voltage AZMB cathodes.

Determination of pesticide residue content in fruits and vegetables from Lagos, Nigeria.

Developing countries like Nigeria are increasingly employing pesticides to boost the productivity of their agriculture and food supply, despite the fact that doing so poses a health risk to the general populace. The purpose of this study was to assess pesticide residue levels in Lagos, Nigeria. A total of 18 samples from three neighbourhood markets were collected, and they were then examined for the presence of organochlorine (Endosulfan I, Pentachlorophenol, Heptachlor epoxide, and Endosulfan II) and organophosphate (Dichlorvos, Dimethoate, Phorate, and methyl parathion) residues. During the pre-treatment, the multi-residue Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS citrate) method with the addition of acetonitrile was used, and then samples were analysed using GC-MS. All of the samples contained dichlorvos, but the orange sample's concentration was below the limit of quantification, making quantification impossible. Dimethoate concentrations were below MRLs except waterleaf sample. With a concentration of 0.043 μg/mL, Waterleaf had the highest quantity of dimethoate in the sample. The findings of this study indicate that in order to safeguard the health of consumers, it is necessary to closely monitor organochlorine and organophosphate use nationwide, along with other related pesticides, and to test for pesticide residues in food products.

Eco-Friendly Solvent Engineered CsPbI2.77 Br0.23 Ink for Large-Area and Scalable High Performance Perovskite Solar Cells.

The performance of large-area perovskite solar cells (PSCs) has been assessed for typical compositions, such as methylammonium lead iodide (MAPbI3 ), using a blade coater, slot-die coater, solution shearing, ink-jet printing, and thermal evaporation. However, the fabrication of large-area all-inorganic perovskite films is not well developed. This study develops, for the first time, an eco-friendly solvent engineered all-inorganic perovskite ink of dimethyl sulfoxide (DMSO) as a main solvent with the addition of acetonitrile (ACN), 2-methoxyethanol (2-ME), or a mixture of ACN and 2-ME to fabricate large-area CsPbI2.77 Br0.23 films with slot-die coater at low temperatures (40-50 °C). The perovskite phase, morphology, defect density, and optoelectrical properties of prepared with different solvent ratios are thoroughly examined and they are correlated with their respective colloidal size distribution and solar cell performance. The optimized slot-die-coated CsPbI2.77 Br0.23 perovskite film, which is prepared from the eco-friendly binary solvents dimethyl sulfoxide:acetonitrile(0.8:0.2 v/v), demonstrates an impressive power conversion efficiency (PCE) of 19.05%. Moreover, the device maintains ≈91% of its original PCE after 1 month at 20% relative humidity in the dark. It is believed that this study will accelerate the reliable manufacturing of perovskite devices.

Sensitive and Rapid LCMS/MS Method for the Estimation of recently approved Antiviral drugs Maribavir and Fostemsavir in spiked human plasma

In this study, a straightforward, highly sensitive, and selective liquid chromatography/tandem mass spectrometry (LC–MS/MS) method was developed and rigorously validated for the simultaneous quantification of Maribavir and Fostemsavir in human plasma. To ensure precision and reliability, we employed Dolutegravir as the internal standard (IS). The analytical process involved a two-step extraction method. Initially, protein precipitation was induced by the addition of acetonitrile, followed by liquid–liquid extraction using a 1:1 (v/v) mixture of diethyl ether and dichloromethane as the extracting solvent. Separation of the analytes was achieved through reversed phase high-performance liquid chromatography (HPLC) using a Phenomenex C18 Luna column (4.6 mm×100 mm, 5 µm). A simple isocratic mobile phase consisting of acetonitrile, methanol, and 0.1% formic acid (35:55:10, v/v) was used, operating at a flow rate of 0.5 mL/min. Under these optimized conditions, the LC chromatogram of the spiked standard exhibited distinct peaks at retention times of 2.07 min, 2.59 min, and 4.29 min for Fostemsavir, Maribavir, and the internal standard, respectively. Detection was performed using a triple quadrupole mass spectrometer employing electrospray ionization in positive ion mode and multiple reaction monitoring (MRM) mode. The mass transitions monitored were m/z 377 → 110, m/z 584 → 105, and m/z 420 → 142 for maribavir, fostemsavir, and dolutegravir, respectively. This method provided a rapid analysis within 5 minutes, over a linear concentration range of 15-750 ng/mL for both maribavir and fostemsavir. Method validation was conducted following FDA guidelines for bio-analytical methods, and the results consistently fell within the acceptable limits for both analytes. Therefore, our developed method holds promise for the accurate analysis of maribavir and fostemsavir in human plasma, and it has potential applications in pharmacokinetic studies

The Adsorption of 2,4-Dichlorobenzoic Acid on Carbon Nanofibers Produced by Catalytic Pyrolysis of Trichloroethylene and Acetonitrile

In this study, carbon nanofibers were synthesized by the catalytic pyrolysis of trichloroethylene (CNF-Cl) and its mixture with acetonitrile (CNF-Cl-N). The addition of acetonitrile resulted in the incorporation of nitrogen in the CNF (0.33 at%), the removal of chlorine, an increase in oxygen-containing functional groups on the surface (from 1.6 to 3.6 at%), and an increase in the volume of mesopores (from 0.35 to 0.41 cm3·g−1) and macropores (from 0.115 to 0.393 cm3·g−1). The study of 2,4-DCBA adsorption on both CNFs revealed that the adsorption capacity showed dependence with a maximum on the 2,4-DCBA concentration in the solution, which was attributed to the electrostatic interactions of adsorbate with adsorbent at various pHs. The adsorption forces were effective over distances greater than the size of the 2,4-DCBA molecule, indicating volume pore filling. The maximum adsorption capacity occurred at 0.7–1.2 mM and a pH of 3.4 ± 0.1. CNF-Cl-N exhibited lower 2,4-DCBA adsorption than CNF-Cl-N due to its lower specific surface area, lower micropore volume, and higher concentration of oxygen-containing groups on the surface. However, these differences were not significant, suggesting that CNFs produced from both chlorine-containing wastes and their mixtures with nitrogen-containing compounds can be effectively used for water treatment to remove 2,4-DCBA.

Validated HPLC-UV method for amphotericin B quantification in a critical patient receiving AmBisome and treated with extracorporeal replacement therapies.

Amphotericin B (AMB) is a polyene macrolide antifungal agent used for treating invasive fungal infections. Liposomal AMB is a lipid dosage form, available as AmBisome, which reduces the toxicity of the drug. A simple HPLC-UV method was developed for the determination of AMB in plasma to study its pharmacokinetic profile in a critical patient receiving AmBisome and treated with extracorporeal replacement therapies. Sample preparation was performed using plasma deproteinization and drug release from liposome by the addition of acetonitrile (ACN)/zinc sulfate and ultrasonication. Chromatographic separation was performed using a C18 column and a mobile phase consisting of phosphate buffer (pH 3.0)/ACN (65/35, v/v). The UV detector was set at 407 nm. The total run time analysis was 23 min. The method was validated according to the standard guidelines and applied to study the pharmacokinetics of AMB in a critical patient. The total run time analysis obtained was shorter than that of the previously reported methods, being useful for therapeutic drug monitoring or pharmacokinetic profile research.

Role of Acetonitrile Additive in Enhanced Performances of Aqueous Zn Anodes

Zinc-ion batteries have been proposed as promising candidates to address ever-growing demands for energy storage and limited resources available for the currently used lithium-battery systems. Despite their promise, the apparent advantages of aqueous zinc-ion batteries (low cost and high energy density) are still overshadowed by uncontrolled water interactions at the zinc metal-electrolyte interface, such as the hydrogen evolution reaction and electrode corrosion. A number of different strategies – e.g., water-in-salt, addition of chelating agents and/or co-solvents – have been proposed to overcome the aforementioned interfacial problems. Among them, the addition of acetonitrile to aqueous ZnSO4-based electrolytes has shown great promise, with reports of improved Coulombic efficiencies and increased cycle life. However, the actual role of this additive remains unclear. In this work, we determine the mechanistic principles behind the participation of acetonitrile in enhancing the performance of aqueous Zn batteries. For this purpose, we utilized a combination of X-ray absorption and Raman spectroscopies, cyclic voltammetry, and galvanostatic coin cell cycling. Our results indicate that the addition of acetonitrile perturbs the interfacial solvation structure, rather than the bulk. Specifically, acetonitrile does not penetrate the first solvation shell of the Zn2+ ion, but does modify interfacial solvation behavior, likely by physisorption to the electrode surface. The Coulombic efficiency of half cells was found to depend on electrode material, employed current density and capacity, and only moderately on acetonitrile concentration. Overall, this works points strongly to the need for systematic evaluation of battery performance in co-solvent systems, and provides a new framework for future efforts to optimize ion transport and performance in zinc-ion batteries._______________________The submitted manuscript has been created by UChicago Argonne, LLC, Operator of Argonne National Laboratory (“Argonne”). Argonne, a U.S. Department of Energy Office of Science laboratory, is operated under Contract No. DE-AC02-06CH11357. The U.S. Government retains for itself, and others acting on its behalf, a paid-up nonexclusive, irrevocable worldwide license in said article to reproduce, prepare derivative works, distribute copies to the public, and perform publicly and display publicly, by or on behalf of the Government. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan. http://energy.gov/downloads/doe-public-access-plan

Determination of five mTOR inhibitors in human plasma for hepatocellular carcinoma treatment using QuEChERS-UHPLC-MS/MS

A fast and reliable QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) method for pre-processing combined with Ultra - high performance liquid chromatography - tandem mass spectrometry (UHPLC-MS/MS) was established for the analysis of five mammalian rapamycin target protein (mTOR) inhibitors (vistusertib, AZD8055, pictilisib, everolimus, temsirolimus)in human plasma. Extraction was achieved by addition of acetonitrile to the sample followed by anhydrous magnesium sulfate and 30 mg C18 for salting out and purification, respectively. MTOR inhibitors were detected using selective response monitoring (SRM) under positive ion electrospray mode. Vistusertib, AZD8055 and pictilisib showed good linearity with a range of 1–80 ng/ml, Additionally, the concentration of everolimus and temsirolimus was 2.5–200 ng/ml and10–800 ng/ml, respectively. The linear correlation coefficient (R2) of each analysis was ≥ 0.9950. The limit of detection (LOD) and Limit of Quantitation (LOQ) were 0.015–0.75 ng/ml and 1–10 ng/ml, respectively. This method showed a high accuracy with high recovery rate and excellent stability. This method is fast, accurate and reliable, suitable for quantitative detection of mTOR inhibitors in human plasma.

Solvent engineering of SnO2 electron transport layer for high-performance perovskite solar cells

Perovskite solar cells (PSCs) show great potential as industrial photovoltaic devices due to their low fabrication cost and high power conversion efficiency. Owing to high electron conductivity and good energy level matching with perovskites, SnO2 is widely used as electron transport layers (ETLs) for PSCs. However, the agglomeration of SnO2 nanoparticles makes them have poor contact with the glass substrate and it is easy to produce defects on the film surface. Herein, acetonitrile (ACN) is used to optimize the conventional solvent of commercial SnO2 colloid to solve these problems. The addition of ACN in solvent resulted in better-performing SnO2 ETLs, thus eliminating the need for long-time ultraviolet ozone (UV-ozone) treatment of the glass substrate, which undoubtedly greatly simplified the fabrication process. The subsequent vacuum treatment of SnO2 films before annealing further improves morphology of the ETLs film and performance of the overall device. Finally, the best devices after the above solvent engineering treatment achieved an efficiency of 22.28%, increased by 16% with respect to the control device fabricated by conventional method. In addition, the long-term stability of devices was also apparently improved. This solvent engineering strategy provides a simple route to prepare high-quality SnO2 ETL for high-performance PSCs.

Molecular Dynamics Studies of Mixtures of a Deep Eutectic Solvent and Cosolvents

All-atom molecular dynamics simulations have been performed on mixtures of tetrabutylammonium chloride-based deep eutectic solvent and two cosolvents — methanol and acetonitrile. Water, a highly polar protic solvent, strongly interacts with the DES components. Herein, we have chosen methanol, a protic solvent but less polar than water, and acetonitrile, an aprotic solvent, to investigate the structural modifications in DES and new interactions arising after the addition of cosolvent based on both polarity and the presence or absence of labile hydrogen. Of the two cosolvents, methanol is found to affect the interactions present in DES significantly. Strong hydrogen bond interaction occurs between the chloride anion and methanol, leading to changes in the behavior of the mixture at the microscopic level. The self-diffusivity of components of the DES increases with the addition of methanol and acetonitrile; however, the increase is relatively more significant in the latter due to fewer average numbers of H-bonds. The amplitudes of the peaks of the structure factor decrease with an increase in the cosolvent concentration, thereby confirming that cosolvent affects the long-range correlations.

A combined experimental and computational approach for the rationalization of the catalytic activity of lipase B from Candida antarctica in water–organic solvent mixtures

AbstractBackgroundThe addition of organic solvents to an aqueous medium for enzymatic reactions offers several advantages, as they can increase the solubility of substrates but can also lead to enzyme inactivation and/or aggregation.ResultsThe effect of adding 30% of several water‐soluble organic solvents on the catalytic activity of lipase B from Candida antarctica (CalB) was studied and the results showed that the highest activity was obtained with the addition of t‐butanol. t‐Butanol and acetonitrile were selected and the kinetic parameters, determined to deepen their effect on CalB activity, showed that the addition of acetonitrile improved the enzyme–substrate affinity, while water–t‐butanol mixtures led to a more than ninefold increase in kcat. To rationalize at a molecular level the kinetic results, molecular dynamic simulations were performed. Analysis of the accessibility of the active‐site cavity, solvent occupancy in the site and in the oxyanion hole, and the stability of the catalytic triad in the two solvent mixtures, provided insight into their effects on the catalytic properties of CalB.ConclusionThe lower occupancy in the oxyanion hole of water molecules and a shorter residence time in the active site of acetonitrile molecules in the acetonitrile–water mixture contribute to the higher enzyme–substrate affinity found experimentally. Conversely, the higher kcat in the t‐butanol mixture is explained by the higher stability of the catalytic triad and by an increase in the nucleophilicity of the catalytic serine due to the persistent presence of t‐butanol molecules in the active site. © 2023 The Authors. Journal of Chemical Technology and Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry (SCI).

Simultaneous determination of maltol and maltol glucuronide in human plasma and urine by HPLC–MS/MS: Application in clinical study in patients with iron deficiency

Ferric maltol has been used as an oral drug for iron deficiency. This study developed and fully validated the novel HPLC–MS/MS methods to determine maltol and maltol glucuronide simultaneously in plasma and urine. The protein precipitation was performed by addition of acetonitrile in the plasma samples. The dilution was performed for the urine samples to reach the suitable concentrations for injection. The multiple reaction monitoring (MRM) with an electrospray ionization (ESI) positive ion detection mode was used for the quantification. The maltol concentration linear ranges were 6.00–150 ng/mL and 0.100–10.0 μg/mL for the plasma and urine samples, respectively. The maltol glucuronide concentration linear ranges were 50.0–15000 ng/mL and 2.00–2000 μg/mL for the plasma and urine samples, respectively. These methods were applied to a single dose clinical study at a dose of 60 mg ferric maltol capsule in the patients with iron deficiency. The half-lives of maltol and maltol glucuronide were 0.90 ± 0.40 h and 1.02 ± 0.25 h in the iron deficiency patients, respectively. 39.52 ± 7.11 % maltol were excreted in urine in the form of maltol glucuronide.

Methodical approaches to scale-up measurement of glyphosate concentration using HPLC-FLD

Introduction. Traditionally, the hygienic assessment of working conditions when using glyphosate preparations, an extremely popular herbicide in the world, is based on the use of thin layer chromatography. In this paper, alternative approaches are considered. On the basis of experimental data, the conditions for the analysis of glyphosate content in air by high performance liquid chromatography were optimized. Material and methods. All work with glyphosate solutions was carried out in polypropylene vessels. Sampling from the air medium was carried out on a medium filtration filter (“blue ribbon”). Subsequent extraction was carried out with water. The measurements were performed by high performance liquid chromatography with a fluorimetric detector at an excitation wavelength of 270 nm and an emission wavelength of 313 nm. To transfer glyphosate to a molecule with fluorimetric properties after derivatization of glyphosate in an alkaline medium using 9-fluorenylmethyl chloroformate by heating and washing off the excess of the reagent with toluene. A C18 reverse phase column was used; ammonium acetate with the addition of acetic acid and acetonitrile were used as eluents. Results. Approbation of the developed technique was carried out on real samples taken during ground treatment of fallow fields and lands of industrial territories with glyphosate preparations. The detected levels of glyphosate did not exceed the lower limit of quantitative determination: 0.5 mg/m3 in the air of the working area and 0.025 mg/m3 in the atmospheric air (with maximum allowable concentrations of 1.0 and 0.1 mg/m3, respectively). Limitations. The study considers a limited number of chromatographic columns. The study is performed on 25 model samples of the air of the working area and atmospheric air. Conclusion. Based on the results of the work performed, methodological instructions “Measurement of glyphosate concentrations in the air by high-performance liquid chromatography” were formed and sent for metrological certification in the approved manner.

Thermodynamic Analysis of the Solubility of Sulfadiazine in (Acetonitrile 1-Propanol) Cosolvent Mixtures from 278.15 K to 318.15 K

Drug solubility is one of the most significant physicochemical properties as it is related to drug design, formulation, quantification, recrystallization, and other processes, so understanding it is crucial for the pharmaceutical industry. In this context, this research presents the thermodynamic analysis of the solubility of sulfadiazine (SD) in cosolvent mixtures {acetonitrile + 1-propanol} at 9 temperatures (278.15 K–318.15 K), which is a widely used drug in veterinary therapy, and two solvents of high relevance in the pharmaceutical industry, respectively. The solubility of SD, in cosolvent mixtures {acetonitrile + 1-propanol} is an endothermic process where the maximum solubility was reached in pure acetonitrile at 318.15 K and the minimum in 1-propanol at 278.15 K. Although the solubility parameters of acetonitrile and propanol were similar, the addition of acetonitrile to the cosolvent mixture leads to a positive cosolvent effect on the solubility of DS. As for the thermodynamic functions of the solution, the process is strongly influenced by enthalpy, and according to the enthalpy–entropy compensation analysis, the process is enthalpy-driven in intermediate to rich mixtures in 1-propanol and entropy-driven in mixtures rich in acetonitrile.

Advanced Tool for Chiral Separations of Anionic and Zwitterionic (Metalla)carboranes: Supercritical Fluid Chromatography.

The continuous expansion of research in the field of stable carboranes and their wide potential in the drug design require carrying out fundamental studies regarding their chiral separations. Although supercritical fluid chromatography (SFC) is a viable technique for fast enantioseparations, no investigation concerning boron cluster compounds has been done yet. We aimed at the development of a straightforward method enabling chiral separations of racemic mixtures of anionic cluster carboranes and metallacarboranes that represent an analytical challenge. The fast gradient screening testing nine polysaccharide-based columns was used. The key parameters affecting the selectivity were the type of chiral selector, the type of alcohol, and the base in cosolvent. Moreover, the addition of acetonitrile or water to the cosolvent was identified as an effective tool for decreasing the analysis time while preserving the resolution. After the optimization, the chiral separations of 19 out of 20 selected compounds were achieved in less than 10 min. These results demonstrate the clear advantage of SFC over chiral separations using HPLC in terms of both analysis time and structural variety of successfully separated compounds.

A New Sustainable Multistep Catalytic Process from Benzene to Caprolactam: Amination, Hydroximation and Beckmann Rearrangement Promoted and Catalyzed by Trifluoroacetic Acid.

Here we report some results on a 3 steps benzene caprolactam process via amination, aniline Hydroxymation and Beckmann rearrangement. The amination proceeds with hydroxylamine trifluoroacetate, with 97% of conversion and selectivity of 90%, catalyzed by V compounds. We achieve 98% of conversion and 95% of selectivity in the hydroxymation of aniline in the presence of hydroxylamine trifluoroacetate, sulfonic resin and Pd/C. While in the absence of the resin, hydrogenation of hydroxylamine trifluoroacetate occurs readily to the ammonium salt. The reaction occurs likely by the exchanged hydroxylamine and the aniline reduction intermediate. The use of hydroxylamine trifluoroacetate, instead of the chloride, favors the sustainability of the process by avoiding the ammonium chloride formation. The absence of salt except those derived from the trifluoroacetic acid allows a complete reuse of the trifluoroacetic acid and the only byproduct is ammonium nitrate obtained by resin regeneration. Beckmann rearrangement of the so produced cyclohexanone oxime occurs easily after diethyl ether evaporation and additions of a solution trifluoroacetic acid acetonitrile in high yield and selectivity.Graphical New three steps caprolactam process via benzene amination and aniline hydrogenation. Supplementary InformationThe online version contains supplementary material available at 10.1007/s10562-022-04207-9.