Brønsted acid catalyzed Prins-Ritter reaction for selective synthesis of terpenoid-derived 4-amidotetrahydropyran compounds

A number of SO3H-functionalized solids (biochar, montmorillonites, carbon and halloysite nanotubes) has been studied as catalysts in the cascade Prins-Ritter reaction of (-)-isopulegol with benzaldehyde and acetonitrile for synthesis of octahydro-2H-chromene amides (as 4R- and 4S-isomers). A high selectivity to these products at 30 °C in the presence of H2O was observed on catalysts modified with chlorosulfonic acid (CSA) reaching 84% (4R/4S of 5.7) in the case of biochar, while a relatively large amount of octahydro-2H-chromenols (up to 31%), products of Prins condensation, was formed on the materials functionalized by 2-(4-chlorosulfonylphenyl)ethyltrimethoxysilane (CSP). Although Prins condensation proceeds efficiently on weak acid sites, the Prins-Ritter reaction requires sulfated materials with strong (0.33 – 5.8 mmol/g) Brønsted acidity. Catalysts functionalized by CSP were stable, while for the materials modified with chlorosulfonic acid, leaching of -SO3H groups was observed. Nonetheless, on resistant Bioсhar-CSP, selectivity to the amides at 30 °C (67%) was higher than that with the commercial Amberlyst-15 (47%), and triflic acid at − 25 °C (62%). Similar selectivity to the desired products on Biochar-CSA (-SO3H groups) and H2SO4 (81–84%) as well as on Biochar-CSP (-PhSO3H) and with p-toluenesulfonic acid (67–70%) was observed. DFT calculations and experimental results showed that at 30 °C formation of 4S-amide thermodynamically is more beneficial than of alcohols and dehydration products. However, addition of water results in a sharp increase in the reaction rate and 4R-amide selectivity due to a change to the kinetic control, leading eventually to both high yields and stereoselectivity. The proposed reaction pathways also were confirmed by kinetic modelling.This work is part of the scientific activity of the Institute of Chemistry of New Materials, funded by the National Academy of Sciences of Belarus. Julián E. Sánchez thanks to Pontificia Universidad Javeriana for providing computational powder and to Universidad Jaume I (Pla de Promoció de la Investigació de la Universitat Jaume I) for the Post Doctoral Fellowship. Part of this work (synthesis and charaterization of sulfonic-acid catalysts presented in Fig. 2) was funded by the Portuguese funds through Fundação para a Ciência e a Tecnologia (FCT/MCTES) in the framework of the projects UIDB/50006/2020, UIDP/50006/2020. A.F.P. is also grateful to FCT for funding through the Individual Call to Scientific Employment Stimulus 2020.01614.CEECIND/CP1596/CT0007

Модифицирование линейных полимеров электронно-лучевым диспергированием в вакууме

The features of the molecular structure and morphology of polyethylene (PE) and polyvinyl chloride (PVC) based coatings, deposited from the products of repeated electron beam dispersion of the original polymer, are determined. Macromolecules coatings obtained by repeated dispersing of PE, contain a high concentration of unsaturated bonds and short-chain branching. The coating is formed by highly dispersed lamellar, “spiral” formations. The effect of the electron beam on PVC initiates the processes of dehydrochlorination, the formation of a polyconjugated structure. Recycled PVC-based ratings contain mainly graphite-like structures and polyene fragments, have regular pores of 300-700 nm in size, high abrasion resistance, which determines their effective use as an antibacterial layers matrix.Определены особенности молекулярной структуры и морфологии покрытий на основе полиэтилена (ПЭ) и поливинилхлорида (ПВХ), осажденных из продуктов двукратного (вторичного) электроннолучевого диспергирования исходных полимеров на кварцевые подложки. Макромолекулы покрытия, полученного двукратным диспергированием ПЭ, содержат почти в 3 раза более высокую концентрацию ненасыщенных связей и короткоцепной разветвленности. Оно формируется высокодисперсными пластинчатыми, «спиралевидными» образованиями. Электронно-лучевое воздействие на ПВХ инициирует процессы его дегидрохлорирования, образование полисопряженной структуры. Покрытие на основе «вторичного» ПВХ содержит преимущественно графитоподобные структуры и полиеновые фрагменты, имеет регулярные поры размером 300-700 нм, обладает высокой стойкостью к истиранию, что определяет его эффективное применение в качестве матрицы подложки (носителя) для антибактериальных слоев

ПОЛУЧЕНИЕ И СВОЙСТВА ГИДРОГЕЛЕЙ НА ОСНОВЕ НАНОКОМПОЗИТА ПЕКТИН-Ag, СОДЕРЖАЩИХ КАНАМИЦИН

The hydrogels based on nanocomposite pectin-Ag exhibiting the antibacterial activity (MIСAg = 0.02–0.81 mM) were obtained by ionotropic gelation. It was shown that the synthesized hydrogels had a high capacity for kanamycin (up to 70 wt. %). The obtained hydrogels provided a prolonged release of kanamycin in 0.9 % NaCl and enhanced its antibacterial activity (MIC decreased 10–20 times) due to the synergistic effect.Методом ионотропного желирования получены гидрогели на основе нанокомпозита пектин-Ag, обладающие собственной антибактериальной активностью (МИКAg = 0,02–0,81 мМ). Показано, что синтезированные гидрогели имеют высокую емкость по канамицину (до 70 мас.  %). Полученные гидрогели обеспечивают пролонгированное высвобождение канамицина в физиологическом растворе и усиливают его антибактериальное действие (снижение МИК в 10–20 раз) за счет синергетического эффекта

ПОЛУЧЕНИЕ КОМПЛЕКСНЫХ ПРЕПАРАТОВ НА ОСНОВЕ ЛИПОСОМАЛЬНОЙ ФОРМЫ СТРЕПТОКИНАЗЫ И ИХ ФАРМАКОКИНЕТИЧЕСКИЕ ХАРАКТЕРИСТИКИ

It was obtained that liposomal streptokinase (SK) with a hydrodynamic diameter of ~70 nm and a zeta-potential of –6.2 mV contains 14.1 % wt of drug. The complex formulations based on liposomal SK include “associated” and “free” SK in the ratios of 20/80, 40/60 and 50/50. The in vivo experiments on rats showed an increase in the elimination half-time from 1.8 to 31.9 min and in the time to reach the maximum concentration of streptokinase from 15 to 45 min. The decrease in the elimination rate constant by a factor of 18 compared with SK was also found. The optimal ratio of “associated” and “free” SK in the complex formulation was 40 and 60 % respectively. It was used to obtain liposomal fibrin-specific form of thrombolytic with similar physico-chemical and pharmacokinetic parameters. Получена липосомальная форма стрептокиназы (СК) с гидродинамическим диаметром ~70 нм, дзета-потенциалом –6,2 мВ и степенью включения вещества 14,1 %, на основе которой приготовлены комплексные препараты, содержащие «связанную» и «свободную» СК в соотношениях 20/80, 40/60 и 50/50. Для них в эксперименте in vivo на крысах показано увеличение периода полувыведения от 1,8 до 31,9 мин и времени достижения максимальной концентрации стрептокиназы от 15 до 45 мин, а также уменьшение константы элиминации в ~18 раз по сравнению с нативной СК. Оптимальное соотношение «связанной» и «свободной» СК в комплексном препарате составило 40 и 60 % соответственно, что было использовано для получения липосомальной фибрин-специфичной формы тромболитика, который обладает практически такими же физико-химическими и фармакокинетическими параметрами.

Preparation and Characterization of Microfiltration Ceramic Membranes Based on Natural Quartz Sand

The effect of phase and chemical composition of natural quartz sand, binder and burnable additives was studied. The conditions of application of the membrane and biocide layers on the formation of porous ceramic and microfiltration membranes were investigated. It is shown that a crystalline oxide of Si(IV) is determinant for obtaining the ceramic materials. The presence of carbonates (calcite, dolomite, aragonite, etc.) and crystalline aluminosilicates (microcline, albite, phlogopit, etc.) leads to a decrease in mechanical strength of ceramics. The biocide coating designed to protect the ceramic membrane surfaces from biofouling was applied and its anti-bacterial activity was shown

Effect of Nanodisperse Carbon Fillers and Isocyanate Chain Extender on Structure and Properties of Poly(ethylene terephthalate)

The effect of diisocyanate chain extender (CE) on the mechanical, rheological, and relaxation properties, as well as on molecular weight and crystallizability, of starting poly(ethylene terephthalate) (PET) and its composites containing carbon nanomaterials (CNM) such as carbon nanotubes (CNTs) and commercial carbon (CC) has been studied. The composites were compounded in molten PET using twin-screw extruder (screw diameter 35 mm; L/D=40). To improve the distribution of CNM in the polymeric matrix (before introduction into the melt), they were blended with PET powder and subjected to an ultrasonic treatment in methylene chloride. The salient features of the materials structure were estimated based on DSC and relaxation spectrometry (dynamic mechanical analysis) data. It has been found that CNM additives partly suppress the PET-chain extension reactions which take place during interaction between macromolecular end groups and CE. Besides, both CNT and CC favour crystallizability of the modified PET owing to nucleation of the crystallization process. The influence of CNT appears to be more effective than that of CC. Enhancements in true mechanical strength and deformability of PET/CE/CNM composites, as against PET/CE materials, were found to be most clearly exhibited by the CNT-containing composites

Honeycomb polymer films with silver nanoparticles

Employing self-organization technique ordered composite materials with honeycomb-structured geometry containing silver nanoparticles on the surface of polymer matrix were fabricated. By annealing initial honeycomb composite structures thin ordered films of silver nanoparticles were formed. The simulation of optical properties of the obtained structures was carried out and compared to measured spectra