Search Results (74)

The aim of this work was to prepare a large set of variously substituted 3-aminophthalates starting from substituted 3-acylamino-2H-pyran-2-ones acting as dienes in Diels–Alder reactions with dialkyl acetylenedicarboxylates having the role of dienophiles. These thermally allowed [4+2] cycloadditions were taking place with normal electron demand due to rather electron-deficient dienophiles and relatively electron-rich dienes; however, they still required quite harsh reaction conditions: heating in closed vessels at 190 °C for up to 17 h was sufficient in most cases (albeit for a few reactions the time needed was up to 58 h) to achieve conversions above 95%. Such conditions, unfortunately, necessitated the use of a larger excess of dienophiles (as undesired polymerization takes place concomitantly); nevertheless, the straightforward isolation procedures enabled access to the target compounds in moderate to high yields (average yield 56%). All products were characterized by standard analytical and spectroscopic methods. With the goal of changing the reaction conditions to be more environmentally friendly, we investigated the effect of various solvents (water, n-butanol, butyl acetate, xylene, para-cymene, n-nonane, etc.) and the temperature applied (130–190 °C) on the conversion. We found that higher temperatures are necessary in most cases (except for the most reactive 2H-pyran-2-ones) regardless of the solvent used. Relative reactivity was determined for both sets of reactants and the experimentally obtained data show good agreement with the computational results. Full article

Water contamination by heavy metals, including radionuclides, is a major threat to human health and the environment. New methods for their removal are therefore needed. Adsorption is currently a common method for wastewater treatment. It depends on the physical and chemical interactions between heavy metal ions and adsorbents. The main characteristics of suitable adsorption methods are (i) a high adsorption efficiency and ability to remove different types of ions, (ii) a high retention time and cycle stability of adsorbents, and (iii) availability. Chitin is a commercially available biopolymer from marine waste that has several favourable properties: availability, low cost, high biocompatibility, biodegradability, and effective adsorption properties for metal ions. However, the processing of chitin into stable structures, such as chitin-based composites, is difficult due to its high chemical stability and extremely low solubility in most solvents. The central working hypothesis of the present work is that powdered α-chitin can be dissolved in the ionic liquid 1-butyl-3-methylimidazolium acetate and cross-linked with its monomer, N-acetyl-D-glucosamine, in a Maillard-like or caramelisation reaction to produce chitin-based composites. It is further hypothesised that such composites can be used as biosorbents for heavy metal ions. Eu(III) is chosen here as a non-radioactive representative and analogue for other f-elements. Full article

Gynura divaricata (L.) DC is a long-used medicinal and edible plant in China folk. Its hyperglycemic effects have garnered increasing public attention in recent years. This study revealed that the ethyl acetate (EtOAc) and butanol (BuOH) partition fractions of G. divaricata crude extract exhibited significantly higher α-glucosidase inhibition activity and enhanced glucose uptake ability compared to other fractions. Guided by the hypoglycemic bioassay, these two fractions were subjected to isolation of active compounds using high-speed countercurrent chromatography (HSCCC). A two-phase solvent system composed of hexane-methyl tert-butyl ether (MtBE)-methanol-0.1% TFA water was employed for the separation of the EtOAc fraction by conventional HSCCC through a gradient elution strategy. Five major compounds were obtained and identified as chlorogenic acid (1), 3,4-dicaffeoylquinic acid (2), 3,5-dicaffeoylquinic acid (3), 4,5-dicaffeoylquinic acid (4), and kaempferol-3-O-β-D-glucopyranoside (5) by ESI-MS, ¹HNMR, and ¹³CNMR. The chlorogenic acid and the three dicaffeoylquinic acids were found to display higher inhibitory activities against α-glucosidase compared to the flavonoid. Considering their acidic nature, pH-zone-refining CCC (PHZCCC) was then applied for further scale-up separation using a solvent system MtBE: n-butanol: acetonitrile: water with trifluoroacetic acid (TFA) as a retainer and ammonium hydroxide (NH₄OH) as an eluter. A significantly higher yield of chlorogenic acid was obtained from the BuOH fraction by PZRCCC. Molecular docking between the caffeoylquinic acids and α-glucosidase confirmed their hypoglycemic activities. This study demonstrates that CCC is a powerful tool for preparative separation of active constituents in natural products. This research presents a novel and effective method for the preparative isolation of hypoglycemic compounds from Gynura divaricata. Full article

N,N′-Dialkylimidazolium-based ionic liquids are capable of completely dissolving lignocellulosic biomass at elevated temperatures and are considered as promising green solvents for future biorefining technologies. However, the obtained ionic liquid lignin preparations may contain up to several percent nitrogen. This indicates strong interactions between the biopolymer and the IL cation, the nature of which has not yet been clarified. The present study investigates mechanisms and pathways of the formation of nitrogen-containing lignin compounds. To achieve this goal, eight monomeric lignin-related phenols bearing different functional groups (ketone, aldehyde, hydroxyl, carbon–carbon double bonds) were treated with 1-butyl-3-methylimidazolium acetate (BmimOAc) under typical conditions of IL-assisted lignocellulose fractionation (80–150 °C). A number of the resulting products were tentatively identified, for all the studied model compounds, by two-dimensional NMR spectroscopy and high-performance liquid chromatography—high-resolution mass spectrometry. They all possess covalently bonded Bmim residues and occur through the nucleophilic addition of an N-heterocyclic carbene (deprotonated Bmim cation) to electron-deficient groups. The reactivity of lignin functional groups in their interaction with Bmim is greatly affected by the temperature and dissolved oxygen. IL’s thermal degradation products act as additional reactive species toward lignin, further complicating the range of products formed. The obtained results made it possible to answer the question posed in this article’s title and to assert that N,N′-dialkylimidazolium-based ILs act as active reagents with respect to lignin during the dissolution of lignocellulose. Full article

The present study reports the ability of a fungal isolate Aspergillus ochraceus DY1, obtained from rotten wood, to degrade alkali lignin (AL) and lignocelluloses in an efficient manner. The efficiency of degradation was monitored by measuring the percentage of decolorization and utilizing GC-MS for identifying degradation products at different time intervals (10, 20, 30, and 40 days). The optimal degradation of alkali lignin (AL) was achieved at 0.01% concentration, 25 °C, and pH 7, resulting in 63.64% degradation after 40 days of incubation. A GC-MS analysis revealed significant degradation products, including n-hexadecanoic acid, octadecane, butylated hydroxytoluene, 2,6,11-trimethyl-dodecane, dibutyl phthalate, oleic acid, 3,5-dimethoxy-phenol acetate, and 2-(phenylmethylene)- cyclohexanone. Structural changes in AL were confirmed through HSQC 2D NMR and size-exclusion chromatography, indicating depolymerization and reduced molecular weight. Furthermore, A. ochraceus DY1 demonstrated substantial biomass loss in corn stover (62.5%) and sugarcane bagasse (50%) after 7 days of solid-state fermentation. Surface morphological depletion was observed in the bio-treated corn stover through SEM and confocal microscopy, which was not seen in the untreated one. These findings underscore the potential of A. ochraceus DY1 for efficient lignin degradation, with promising applications in biofuel production, waste management in the paper and pulp industry, and the synthesis of value-added bioproducts. Full article

Volatile organic compounds (VOCs) are one of significant contributors to air pollution and have profound effects on human health and the environment. This study introduces a detailed analysis of VOC emissions from various industries within an industrial complex using a high-resolution measurement instrument. This study aimed to identify the VOC profiles and their concentrations across 12 industries. Sampling was conducted across 99 facilities in an industrial complex in South Korea, and VOC analysis was performed based on measurement data using a Proton-Transfer-Reaction Time-of-Flight Mass Spectrometry (PTR-ToF-MS). The results indicated that the emission of oxygenated VOCs (OVOCs) was dominant in most industries. Aromatic hydrocarbons were also dominant in most industries, except in screen printing (SP), lubricating oil and grease manufacturing (LOG), and industrial laundry services (ILS) industries. Chlorinated VOCs (Cl-VOCs) showed a relatively higher level in the metal plating (MP) industry than those in other industries and nitrogen-containing VOCs (N-VOCs) showed high levels in general paints and similar product manufacturing (PNT), MP, and ILS industries, respectively. The gravure printing industry was identified as the highest emitter of VOCs, with the highest daily emissions reaching 5934 mg day⁻¹, primarily consisting of ethyl acetate, toluene, butyl acetate, and propene. The findings suggest that the VOC emissions from the gravure printing and plastic synthetic leather industries should be primarily reduced, and it would be the most cost-effective approach to improving air quality. This study can provide the fundamental data for developing effective reduction technologies and policies of VOC, ultimately contributing to enhanced atmospheric models and regulatory measures. Full article

Chaenomeles speciosa (Sweet) Nakai (C. speciosa) is a traditional Chinese herbal medicine that possesses not only abundant nutritional value but also significant medicinal properties. The extracts of C. speciosa fruits effectively reduce urate levels, but the specific chemical constituents responsible for this effect in C. speciosa fruits are still unknown. Therefore, this study aims to investigate and analyze the structure–activity relationships of these constituents to better understand their ability to lower uric acid. Activity-guided fractionation and purification processes were used to isolate compounds with xanthine oxidase (XO) inhibitory activity from C. speciosa fruits, resulting in three extracts: petroleum ether, ethyl acetate, and n-butanol. The ethyl acetate and n-butanol fractions showed strong activity and underwent further separation and purification using chromatographic techniques. Twenty-four compounds were isolated and identified, with nine showing potent activity, including chlorogenic acid, methyl chlorogenate, butyl chlorogenate, ethyl chlorogenate, cryptochlorogenic acid methyl ester, caffeic acid, p-coumaric acid, benzoic acid and protocatechuic acid. The docking analysis showed that these compounds interacted with amino acid residues in the active site of XO through hydrogen bonding and hydrophobic interactions. These findings suggest that these compounds help reduce uric acid in C. speciosa, supporting further investigation into their mechanism of action. Full article

Sol LeWitt, a pioneer of conceptual art, created during his career over 1350 wall drawings, including the Wall Drawing #736 (1993) at the Center for Contemporary Art Luigi Pecci in Prato (Prato, Italy). The painting, executed by Andrea Marescalchi and Antony Sansotta under LeWitt’s instructions, features a grid of coloured rectangles obtained by overlapping different layers of inks. During a 2021 restoration by the Wall Paintings and Stuccoes Department of the Opificio delle Pietre Dure (Firenze, Italy), an in-depth investigation of the composition and the materials used by LeWitt’s assistants in producing Wall Drawing #736 was performed. A multi-analytical approach entailing Raman spectroscopy, high-performance liquid chromatography coupled to diode array and high-resolution mass spectrometry, gas chromatography–mass spectrometry (GC–MS), and pyrolysis coupled with GC–MS was applied. Our results revealed the use of animal glue, shellac resin, paraffin wax, linseed oil, and various organic pigments. The binder in the preparation layer was identified as poly(vinyl acetate), while poly(n-butyl methacrylate) was determined as a fixative. This research provided valuable insights into LeWitt’s techniques. The acquired knowledge on the paint technique is highly relevant in supporting conservators in restoration and consolidating the many wall drawings produced exploiting the same technique all over the world. Full article

Bis(1-butyl-1-methypyrrolidinium) perthiodicarbonate was obtained by the reaction of carbon disulfide with 1-butyl-1-methypyrrolidinium acetate ([BmPyrro][Ac]) in the liquid phase. Structural characterization of this original complex was achieved by single-crystal X-ray diffraction (SCXRD) analysis. The asymmetric unit of the title compound, C₂S₆·2C₉H₂₀N, consisted of two crystallographically 1-methyl-1-butyl pyrrolidinium cations and one perthiodicarbonate anion. The complex C₂S₆·2C₉H₂₀N crystallized in the monoclinic space group, C 2/c, and possessed the following cell parameters: a = 16.0970(10) Å, b = 14.7140(9) Å, c = 12.3280(8) Å, α = 90°, β = 112.3730(12)°, γ = 90°, V = 2700.11 ų, and Z = 8, Z’ = 0.5. Full article

Acoustic levitation can provide significant benefits for many fundamental research questions. However, it is important to consider that the acoustic field influences the measurement environment. This work focuses on the dissolution of immobilised drops using acoustic levitation in liquid–liquid systems. Previous work demonstrated that the acoustic field of standing waves impacts mass transfer by affecting the spread of dissolved substances in the continuous phase in two distinct ways: (I) solutes may either pass through nodal planes of the standing waves or (II) not pass. The binary systems examined for case (I) are 1-hexanol–water and 1-butanol–water, and for case (II), n-butyl acetate–water and toluene–water. This work quantifies the intensification effect of acoustic levitation on dissolution for the two types of behaviour, by comparing them with reference measurements of mechanically attached dissolving drops. The system was designed to ensure minimal intensification. The minimum intensification of mass transfer for levitating drops in the used setup of case (I) was 25%, and for case (II), it was 65%, both increasing with decreasing surface-equivalent diameter. With this understanding, acoustic levitation can be used more accurately in the field of mass transfer studies. Full article

The paper shows the expediency of supplementing the balance simplex method by calculating the number of free variables of separation flowsheets containing recycle flows. The need to determine and set the free variables that provide lower energy consumption when calculating the material balance of flowsheets with recycling is justified. The problem of material balance multivariance is illustrated, and ways to solve it are shown with the example of separation flowsheets for two ternary mixtures: n-butanol + water + toluene and n-butanol + butyl acetate + water. Separation flowsheets containing three distillation columns and a liquid–liquid separator are proposed for both systems. The dependence of the recycle flow values and the energy consumption of distillation columns and separation flowsheets on the selection and setting of values of free variables in solving the balance problem is shown. The dependence of energy consumption on the composition of the original mixture is studied for an n-butanol + butyl acetate + water system. Recommendations for setting free variables for flowsheets of the separation of ternary mixtures with three binary (and one ternary) azeotropes are formulated. The technique of highlighting the region of separation flowsheet operability is illustrated. The column operating parameters that ensure the production of products of a given quality with minimal energy consumption are determined. It is shown that with the incorrect selection and setting of variables (during balance task solvation), the energy consumption for mixture separation can be overestimated by more than 40%. Full article

An overview of solvent replacement strategies shows that there is great progress in green chemistry for replacing hazardous di-polar aprotic solvents, such as N,N-dimethylformamide (DMF), 1-methyl-2-pyrrolidinone (NMP), and 1,4-dioxane (DI), used in processing active industrial ingredients (APIs). In synthetic chemistry, alcohols, carbonates, ethers, eucalyptol, glycols, furans, ketones, cycloalkanones, lactones, pyrrolidinone or solvent mixtures, 2-methyl tetrahydrofuran in methanol, HCl in cyclopentyl methyl ether, or trifluoroacetic acid in propylene carbonate or surfactant water (no organic solvents) are suggested replacement solvents. For the replacement of dichloromethane (DCM) used in chromatography, ethyl acetate ethanol or 2-propanol in heptanes, with or without acetic acid or ammonium hydroxide additives, are suggested, along with methanol acetic acid in ethyl acetate or methyl tert-butyl ether, ethyl acetate in ethanol in cyclohexane, CO₂-ethyl acetate, CO₂-methanol, CO₂-acetone, and CO₂-isopropanol. Supercritical CO₂ (scCO₂) can be used to replace many organic solvents used in processing materials from natural sources. Vegetable, drupe, legume, and seed oils used as co-extractants (mixed with substrate before extraction) can be used to replace the typical organic co-solvents (ethanol, acetone) used in scCO₂ extraction. Mixed solvents consisting of a hydrogen bond donor (HBD) solvent and a hydrogen bond acceptor (HBA) are not addressed in GSK or CHEM21 solvent replacement guides. Published data for 100 water-soluble and water-insoluble APIs in mono-solvents show polarity ranges appropriate for the processing of APIs with mixed solvents. When water is used, possible HBA candidate solvents are acetone, acetic acid, acetonitrile, ethanol, methanol, 2-methyl tetrahydrofuran, 2,2,5,5-tetramethyloxolane, dimethylisosorbide, Cyrene, Cygnet 0.0, or diformylxylose. When alcohol is used, possible HBA candidates are cyclopentanone, esters, lactone, eucalytol, MeSesamol, or diformylxylose. HBA—HBA mixed solvents, such as Cyrene—Cygnet 0.0, could provide interesting new combinations. Solubility parameters, Reichardt polarity, Kamlet—Taft parameters, and linear solvation energy relationships provide practical ways for identifying mixed solvents applicable to API systems. Full article

CO₂ capture, applied in CO₂ separation from natural gas or in CO₂/N₂ separation from power plant flue gas streams, is of great importance for technical, economic, and environmental reasons. The latter seems important because CO₂, as a greenhouse gas, is considered the main contributor to global warming. Using polymeric membranes for CO₂ separation presents several advantages, such as low energy demand, small equipment volume, and the absence of liquid waste. In this study, two ionic liquids (ILs) were used for the preparation of cellulose acetate (CA)–IL blend membranes for potential CO₂ capture applications, namely, 1-butyl-3-methylimidazolium hydrogen sulfate ($[{\mathrm{Bmim}}^{+}]$[${\mathsf{H}\mathrm{SO}}_4^{-}$]) and choline glycine ($[{\mathrm{Ch}}^{+}]\left[{\mathrm{Gly}}^{-}\right]$), as they present adequate CO₂ dissolution ability. The first IL is commercially available, whereas the latter was synthesized by a novel route. Several composite membranes were prepared through the solvent casting technique and characterized by a variety of methods, including thermogravimetry, calorimetry, FTIR spectroscopy, and X-ray diffraction. The CO₂ sorption in the composite membranes was experimentally measured using the mass loss analysis (MLA) technique. The results showed that the ILs strongly interacted with the C=O groups of CA, which exhibited high affinity with CO₂. In the case of $[{\mathrm{Bmim}}^{+}]$[${\mathsf{H}\mathrm{SO}}_4^{-}$], a reduction in the available sites that allow strong intermolecular interactions with CO₂ resulted in a decrease in CO₂ sorption compared to that of pure CA. In the case of $[{\mathrm{Ch}}^{+}]\left[{\mathrm{Gly}}^{-}\right]$, the reduction was balanced out by the presence of specific groups in the IL, which presented high affinity with CO₂. Thus, the CA-$[{\mathrm{Ch}}^{+}]\left[{\mathrm{Gly}}^{-}\right]$ blend membranes exhibited increased CO₂ sorption capability, in addition to other advantages such as non-toxicity and low cost. Full article

Eruca sativa is a commonly used edible plant in Italian cuisine. E. sativa 70% ethanol extract (ES) was fractionated with five organic solvents, including n-hexane (EHex), chloroform (ECHCl₃), ethyl acetate (EEA), n-butyl alcohol (EBuOH), and water (EDW). Ethyl acetate fraction (EEA) had the highest antioxidant activity, which was correlated with the total polyphenol and flavonoid content. ES and EEA acted as PPAR-α ligands by PPAR-α competitive binding assay. EEA significantly increased cornified envelope formation as a keratinocyte terminal differentiation marker in HaCaT cells. Further, it significantly reduced nitric oxide and pro-inflammatory cytokines (IL-6 and TNF-α) in lipopolysaccharide-stimulated RAW 264.7 cells. The main flavonol forms detected in high amounts from EEA are mono-and di-glycoside of each aglycone. The main flavonol form of EEA is the mono-glycoside of each aglycone detected, and the most abundant flavonol mono-glycoside is kaempferol 3-glucoside 7.4%, followed by quercetin-3-glucoside 2.3% and isorhamnetin 3-glucoside 1.4%. Flavonol mono-glycosides were shown to be a potent PPAR-α ligand using molecular docking simulation and showed the inhibition of nitric oxide. These results suggest that the flavonol composition of E. sativa is suitable for use in improving skin barrier function and inflammation in skin disorders, such as atopic dermatitis. Full article

Bactrocera dorsalis (Hendel) (Diptera: Tephritidae) (B. dorsalis) is an important agricultural, major invasive, and quarantine pest that can cause significant damage to the economic value of the fruit and vegetable industry. Male bait is one of the most effective methods of surveying, monitoring, and controlling B. dorsalis. In our study, we constructed cDNA libraries using total RNA extracted independently from the antennae, mouthparts, and thoracic legs of male and female adults and the ovipositors of female adults and screened out four aldehyde-oxidase-related genes (AOX-related), C58800, C66700, C67485, and C67698. Molecular docking predictions showed that eight compounds, including 3,4-dimethoxycinnamyl alcohol, 3,4-dimethoxy-cinnamaldehyde, deet, ethyl N-acetyl-N-butyl-β-alaninate, n-butyl butyrate, n-butyl butyrate, ethyl butyrate, methyl eugenol, and ethyl acetate, could combine with proteins encoded by the four B. dorsalis AOX-related genes. Furthermore, QPCR was performed to confirm that four compounds, including 3,4-dimethoxy cinnamic aldehyde, butyl levulinic acid ethyl ester (mosquito repellent), butyl butyrate, and methyl eugenol, induced significant changes in the AOX-related genes of B. dorsalis. These results provide useful information and guidance for the batch screening of potentially useful compounds and the search for effective attractants of B. dorsalis. Full article