Poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) is one of the most important engineering plastics commonly utilized in various fields. Herein, chemical recycling of PPO was performed via oxidative depolymerization to form 2,6-diemthyl-p-benzoquionone (26DMBQ) as a sole aromatic product in 66% yield using nitronium ions (NO2+) as a mild oxidant. Mechanistic studies revealed that PPO is oxidized by NO2+ generated from the combination of a silicotungstic acid and nitrate salts, and then subsequently attacked by H2O to achieve C–O bond cleavage, resulting in the formation of 26DMBQ, which was sublimed at the headspace of the reaction vessel in pure form. 26DMBQ was applied to polymerization with dianilines to form polyimides. Thus, an upgrade recycling process of PPO was demonstrated.
Monthly Archives: September 2023
Detection of Per‐ and Polyfluoroalkyl Substances in High‐Protein Food Products
Abstract
Per- and polyfluoroalkyl substances (PFAS) belong to the emerging class of persistent organohalogenated contaminants in the environment. We determined the levels of 10 PFAS in selected samples representing different food types, with a special focus on those rich in protein such as fish, meat and meat preparations, liver, eggs, and leguminous vegetables. Such determinations were based on the Quick Easy Cheap Effective Rugged Safe extraction procedure followed by micro-high-performance liquid chromatography–tandem mass spectrometry. The most frequently found was perfluorooctanoic acid, in 84% of the food samples. However, its maximum measured concentration was 0.50 ng g–1, in a herring sample. The highest concentrations were for perfluorobutanoic acid (35 ng g–1 measured in a pork liver sample) and perfluorooctane sulfonate (12 ng g–1 measured in a herring sample). Because these compounds may bioaccumulate in human tissues by dietary intake, further research into their impact on human health is called for. Environ Toxicol Chem 2023;00:1–10. © 2023 SETAC
Implementation of machine learning protocols to predict the hydrolysis reaction properties of organophosphorus substrates using descriptors of electron density topology
Abstract
Prediction of catalytic reaction efficiency is one of the most intriguing and challenging applications of machine learning (ML) algorithms in chemistry. In this study, we demonstrated a strategy for utilizing ML protocols applied to Quantum Theory of Atoms In Molecules (QTAIM) parameters to predict the ability of the A17 L47K catalytic antibody to covalently capture organophosphate pesticides. We found that the novel “composite” DFT functional B97-3c could be effectively employed for fast and accurate initial geometry optimization, aligning well with the input dataset creation. QTAIM descriptors proved to be well-established in describing the examined dataset using density-based and hierarchical clustering algorithms. The obtained clusters exhibited correlations with the chemical classes of the input compounds. The precise physical interpretation of the QTAIM properties simplifies the explanation of feature impact for both supervised and unsupervised ML protocols. It also enables acceleration in the search for entries with desired properties within large databases. Furthermore, our findings indicated that Ridge Regression with Laplacian kernel and CatBoost Regressor algorithms demonstrated suitable performance in handling small datasets with non-trivial dependencies. They were able to predict the actual reaction barrier values with a high level of accuracy. Additionally, the CatBoost Classifier proved reliable in discriminating between “active” and “inactive” compounds.
Pyocyanin biomarker imprinted polydopamine for rapid and simple indirect detection of Pseudomonas aeruginosa
Chemistry Letters, Ahead of Print.
The Effect of Mixed Ligands on the Polymerization Rate of SET-LRP in Aqueous Solution
Chemistry Letters, Ahead of Print.
Hydrothermal pretreatment of Platanus orientalis Linn fallen leaves: effects of process conditions on anaerobic digestion
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[ASAP] Detection, Clinical Application, and Manipulation of RNA Modifications
Accounts of Chemical Research
DOI: 10.1021/acs.accounts.3c00395
[ASAP] Identification of Chemical and Structural Characteristics of Acrylic Paint Layer Using Terahertz Metasurfaces
Analytical Chemistry
DOI: 10.1021/acs.analchem.3c02727
Synthesis, theoretical, in silico and in vitro biological evaluation studies of new thiosemicarbazones as acetylcholinesterase and carbonic anhydrases inhibitors
Eleven new thiosemicarbazone derivatives (1-11) were designed from nine different biologically and pharmacologically important isothiocyanate derivatives containing functional groups such as fluorine, chlorine, methoxy, methyl, and nitro at various positions of the phenyl ring, in addition to the benzyl unit in the molecular skeletal structure. First, their substituted-thiosemicarbazide derivatives were synthesized from the treatment of isothiocyanate with hydrazine to synthesize the designed compounds. Through a one-step easy synthesis and an eco-friendly process, the designed compounds were synthesized with yields of up to 95% from the treatment of the thiosemicarbazides with aldehyde derivatives having methoxy and hydroxyl groups. The structures of the synthesized molecules were elucidated with elemental analysis and FT–IR, 1H NMR, and 13C NMR spectroscopic methods. The electronic and spectroscopic properties of the compounds were determined by the DFT calculations performed at the B3LYP/6-311++G(2d,2p) level of theory, and the experimental findings were supported. They exhibited a highly potent inhibition effect on acetylcholinesterase (AChE) and carbonic anhydrases (hCAs) (KI values are in the range of 23.54±4.34 to 185.90±26.16 nM, 103.90±23.49 to 325.90 ±77.99 nM, and 86.15±18.58 to 287.70±43.09 nM for AChE, hCA I, and hCA II, respectively). Furthermore, molecular docking simulations were performed to explain each enzyme-ligand complex's interaction.
Phosphine‐catalyzed [4+3] annulation reaction of indole derivatives with MBH carbonates: A facile access to indole‐1,2‐fused 1,4‐diazepinones and azepines
Comprehensive Summary
A phosphine-catalyzed [4+3] annulation between dinucleophilic indole derivatives and Morita−Baylis−Hillman (MBH) carbonates was discovered by using the N1 and N4′/C4′ nucleophilicities of the indole precursors, in which indoles act as four atom synthons. This protocol provides an efficient and facile access to indole-1,2-fused 1,4-diazepinones and azepines in good to high yields in one step, which illustrates potential synthetic utilities in drug discovery.
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