Imination of N-methylazinium salts by liquid ammonia/potassium permanganate

Treatment of 1-methylquinolinium-, 1,4-dimethylquinolinium- and 1-methyl-1,X-naphthyridinium iodides (X = 5,8) with liquid ammonia/potassium permanganate leads to introduction of the imino group at C-2 forming the 1,2-dihydro-2-imino-1-methylquinolines and 1,2-dihydro-2-imino-1-methyl-1,X-naphthyridines (X = 5,8) respectively. 1,2-Dimethylquinolinium iodide, when subjected to treatment with liquid ammonia/potassium permanganate undergoes an oxo-demethylation reaction, yielding 1-methylquinol-2-one. The nmr-measurements of solutions of the above-mentioned salts in liquid ammonia clearly show the formation of a σ-adduct, strongly suggesting that these σ-adducts are intermediates in the imination reactions.     

C−H Activation of Inert Arenes using a Photochemically Activated Guanidinato-Magnesium(I) Compound

UV irradiation of solutions of a guanidinate coordinated dimagnesium(I) compound, [{(Priso)Mg}₂] 3 (Priso=[(DipN)₂CNPrⁱ₂]⁻, Dip=2,6-diisopropylphenyl), in either benzene, toluene, the three isomers of xylene, or mesitylene, leads to facile activation of an aromatic C−H bond of the solvent in all cases, and formation of aryl/hydride bridged magnesium(II) products, [{(Priso)Mg}₂(μ-H)(μ-Ar)] 4 – 9 . In contrast to similar reactions reported for β-diketiminate coordinated counterparts of 3 , these C−H activations proceed with little regioselectivity, though they are considerably faster. Reaction of 3 with an excess of the pyridine, p-NC₅H₄Bu^t (py^But), gave [(Priso)Mg(py^ButH)(py^But)₂] 10 , presumably via reduction of the pyridine to yield a radical intermediate, [(Priso)Mg(py^But⋅)(py^But)₂] 11 , which then abstracts a proton from the reaction solvent or a reactant. DFT calculations suggest two possible pathways to the observed arene C−H activations. One of these involves photochemical cleavage of the Mg−Mg bond of 3 , generating magnesium(I) doublet radicals, (Priso)Mg⋅. These then doubly reduce the arene substrate to give “Birch-like” products, which subsequently rearrange via C−H activation of the arene. Circumstantial evidence for the photochemical generation of transient magnesium radical species includes the fact that irradiation of a cyclohexane solution of 3 leads to an intramolecular aliphatic C−H activation process and formation of an alkyl-bridged magnesium(II) species, [{Mg(μ-Priso^−H)}₂] 12 . Furthermore, irradiation of a 1 : 1 mixture of 3 and the β-diketiminato dimagnesium(I) compound, [{(^DipNacnac)Mg}₂] (^DipNacnac=[HC(MeCNDip)₂]⁻), effects a “scrambling” reaction, and the near quantitative formation of an unsymmetrical dimagnesium(I) compound, [(Priso)Mg−Mg(^DipNacnac)] 13 . Finally, the EPR spectrum (77 K) of a glassed solution of UV irradiated 3 is dominated by a broad featureless signal, indicating the presence of a doublet radical species.     

Systematic Modulation of Thiol Functionalities in Inexpensive Porous Polymers for Effective Mercury Removal

Through accumulation, mercury contamination in aquatic systems still poses serious health risks despite the strict regulations on drinking water and industrial discharge. One effective strategy against this is adsorptive removal, in which a suitably functionalized porous material is added to water treatment protocols. Thiol (SH) group-grafted structures perform commendably; however, insufficient attention is paid to the cost, scalability, and reusability or how the arrangement of sulfur atoms could affect the Hg^II binding strength. We used an inexpensive and scalable porous covalent organic polymer (COP-130) to systematically introduce thiol functional groups with precise chain lengths and sulfur content. Thiol-functionalized COP-130 demonstrates enhanced wettability and excellent Hg^II uptake of up to 936 mg g⁻¹, with fast kinetics and exceptionally high selectivity. These Hg adsorbents are easily regenerated with HCl and can be used at least six times without loss of capacity even after treatment with strong acid, a rare performance in the domain of Hg-removal research.     

Quantification of allantoin and other metabolites of the purine degradation pathway in human plasma samples using a newly developed HILIC-LC-MS/MS method

The development of a simple HILIC-LC-MS/MS method to quantify the plasma levels of allantoin, inosine, hypoxanthine, and adenosine, using stripped plasma for the bioanalytical method validation, was the purpose of this study. Chromatographic separation conducted using an XBridge BEH Amide column (2.1 × 150 mm, 3.5 μm) was achieved under gradient elution with two mobile phases: 0.1% formic acid–ACN (5:95) and 0.1% formic acid–ACN (50:50). Multiple reaction monitoring MS detection was performed using a triple quadrupole. The method validation experiments were performed according to the European Medicines Agency and the U.S. Food and Drug Administration guidelines. The lower LOQ was 50 nM, 5 nM, 20 nM, and 2 nM for allantoin, inosine, hypoxanthine, and adenosine, respectively. The recovery was repeatable and stable. The intraday precision ranged from 1.6% to 6.5%, while the interday precision ranged from 3.4% to 58.7%. Therefore, it is necessary to make a matrix-matched calibration curve each day to overcome this issue. Since the quality control samples’ stability did not always comply with the guidelines, the samples need to be analyzed soon after collection.     

Stability study and quantitative determination of mebeverine hydrochloride in tablets by means of reversed-phase high-performance liquid chromatography

Summary A rapid and specific reversed-phase high-performance liquid chromatographic method (RPHPLC) is described for the determination of mebeverine hydrochloride in tablets. Elution was performed on an octyl silane column with a methanol-water mixture (75-25), containing 0.05% hexylamine as silanol-blocking agent, adjusted to pH 5.0 with phosphoric acid. The method gave accurate, precise and reproducible results. The mean recovery of the drug from six synthetic tablet mixtures was 100.0% with a relative standard deviation (RSD) of 0.94%. In order to test the specificity of the method, the interference of the degradation compounds of mebeverine hydrochloride and of the intermediates from the synthesis was investigated. None of them did interfere. By means of mass spectrometry and UV-spectrophotometry, the degradation compounds of mebeverine were identified as veratric acid and as 4-|ethyl-[2-(4-methoxyphenyl)-1-methylethyl]amino| 1-butanol. The stability study proved that mebeverine hydrochloride is very stable in tablets; the tablets still contain more than 95% of the declared drug potency after storage for more than one year at 50°C.Colofac; Duspatal; Duspatalin     

Comparison of efficiency calibration techniques of HPGe detector for radioactivity measurement of soil sample in Marinelli geometry

Journal of Radioanalytical and Nuclear Chemistry - To keep the accredited category for the gamma spectrometry test in our laboratory, the efficiency curves of a HPGe detector for soil sample in...     

Non-thermal Plasma Activated Water for Increasing Germination and Plant Growth of Lactuca sativa L

Plasma Chemistry and Plasma Processing - Non-thermal plasma is widely considered as an effective technology for applications in agriculture. Particularly, numerous reports studies have highlighted...     

Chemical Constituents of the Leaves of Artocarpus integer

Chemistry of Natural Compounds -     

Chemical Composition and Antifungal Activity of Essential Oil from the Roots of Tinomiscium petiolare

Chemistry of Natural Compounds -