Search results for "ATAL"
showing 10 items of 10591 documents
Educazione ambientale per la prevenzione delle patologie fetali e neonatali
2018
On the synthesis of functionalized porphyrins and porphyrin conjugates via β-aminoporphyrins
2016
International audience; The synthesis of functionalized porphyrins and their conjugates from meso-tetraarylporphyrins through the acylation and the oxidation of beta-aminoporphyrins was investigated. 2,3-Dioxochlorins were prepared by the oxidation of a variety of beta-aminoporphyrins and subsequently used in a condensation reaction with functionalized aromatic aldehydes and ammonium acetate to form beta-functionalized porphyrins bearing a fused imidazole ring. Under optimized experimental conditions both reactions tolerate various functional groups and afford the products in an appropriate overall yield. The mildness and usefulness of this methodology are illustrated by several examples in…
Struktura i właściwości kopolimerów etylenu z norbornenem otrzymanych wobec katalizatora wanadocenowego
2018
Kopolimery etylenu z norbornenem ze względu na swoje wyjątkowe właściwości pozwalają na ich potencjalnie szerokie zastosowanie. Jednak w zależności od warunków prowadzenia syntezy, a przede wszystkim od zastosowanego katalizatora, właściwości takiego kopolimeru mogą się zmieniać w szerokim zakresie. W prezentowanej pracy zbadano właściwości wybranych kopolimerów etylenu (E) z norbornenem (NB) otrzymanych przy wykorzystaniu homogenicznego katalizatora wanadocenowego Cp2VCl2 aktywowanego tradycyjnym związkiem glinoorganicznym AlEt2Cl. Określono zależność pomiędzy stopniem wbudowania komonomeru w łańcuch kopolimeru a mikrostrukturą, masą molową, rozkładem mas molowych, temperaturą zeszklenia i…
Application of Silsesquioxanes in the Preparation of Polyolefin-Based Materials
2023
This paper is a review of studies on the use of the polyhedral oligomeric silsesquioxanes (POSS) of various structures in the synthesis of polyolefins and the modification of their properties, namely: (1) components of organometallic catalytic systems for the polymerization of olefins, (2) comonomers in the copolymerization with ethylene, and (3) fillers in composites based on polyolefins. In addition, studies on the use of new silicon compounds, i.e., siloxane–silsesquioxane resins, as fillers for composites based on polyolefins are presented. The authors dedicate this paper to Professor Bogdan Marciniec on the occasion of his jubilee.
Wpływ wybranych parametrów na efektywność katalizowanej wanadocenem kopolimeryzacji etylenu z norbornenem i właściwości otrzymanych produktów
2019
W pracy zbadano wpływ parametrów reakcji na kopolimeryzację etylenu z norbornenem wobec katalizatora wanadocenowego (Cp2VCl2) w obecności trichloroctanu etylu (ETA). Przeprowadzono serię reakcji kopolimeryzacji, zmieniając w każdej z nich jeden z parametrów reakcji: temperaturę lub ciśnienie etylenu. Następnie zbadano temperaturę zeszklenia, stopień wbudowania norbornenu i mikrostrukturę otrzymanych kopolimerów, poddając je analizie DSC oraz spektroskopii 13C NMR. Wykazano wpływ badanych parametrów na aktywność katalizatora oraz ilość i sposób wbudowania jednostek norbornenu w łańcuch polimerowy, jak również wartość temperatury zeszklenia produktu. Stwierdzono, że właściwości otrzymanego ko…
Copolymerization of Ethylene with Selected Vinyl Monomers Catalyzed by Group 4 Metal and Vanadium Complexes with Multidentate Ligands: A Short Review
2021
This paper gives a short overview of homogeneous post-metallocene catalysts based on group 4 metal and vanadium complexes bearing multidentate ligands. It summarizes the catalytic behavior of those catalysts in copolymerization of ethylene with 1-olefins, with styrenic monomers and with α,ω-alkenols. The review is focused on finding correlations between the structure of a complex, its catalyst activity and comonomer incorporation ability, as well as the microstructure of the copolymer chains.
Regio- and Stereoselective Chloro Sulfoximidations of Terminal Aryl Alkynes Enabled by Copper Catalysis and Visible Light
2021
Advanced synthesis & catalysis 2552-2556 (2021). doi:10.1002/adsc.202100162
The first catalytic method for Heck alkynylation of unactivated aryl bromides (copper-free Sonogashira) in an ionic liquid: 1 mol-percent palladium/t…
2007
Herein we report the studies of Heck alkynylation (copper-free Sonogashira) with aryl halides (I, Br, Cl) employing various metallic precursors, tertiary phosphanes and bases in [BMIM][BF4] as the solvent. As a result, we provide the first method that allows the coupling of a large array of substrates, either activated or deactivated bromides in an ionic liquid. Furthermore, the system of highest efficiency is unexpectedly the simplest and cheaper combination that employs [Pd(η3-C3H5)Cl]2/PPh3 at only a 1 mol-% loading with pyrrolidine as the base and in the absence of a copper salt. The coupling of sterically and electronically deactivated bromides bearing different functional groups to ar…
The Copper-microRNA Pathway Is Integrated with Developmental and Environmental Stress Responses in Arabidopsis thaliana
2021
As an essential nutrient, copper (Cu) scarcity causes a decrease in agricultural production. Cu deficiency responses include the induction of several microRNAs, known as Cu-miRNAs, which are responsible for degrading mRNAs from abundant and dispensable cuproproteins to economize copper when scarce. Cu-miRNAs, such as miR398 and miR408 are conserved, as well as the signal transduction pathway to induce them under Cu deficiency. The Arabidopsis thaliana SQUAMOSA-PROMOTER BINDING PROTEIN-LIKE (SPL) family member SPL7 binds to the cis-regulatory motifs present in the promoter regions of genes expressed under Cu deficiency, including Cu-miRNAs. The expression of several other SPL transcription f…
La Bottega dei Gagini alla prova dell'architettura
2022
The Gagini atelier in Palermo performed a prevalent task in the field of sculptural production. The essay examines the opportunities and difficulties that two different generations of artists had to go through in a city dominated by strict corporate rules