Informacja

Drogi użytkowniku, aplikacja do prawidłowego działania wymaga obsługi JavaScript. Proszę włącz obsługę JavaScript w Twojej przeglądarce.

English (EN)·Polski (PL)·Yкраїнський (UK)
Przejdź do strony domowej biblioteki Centralna Biblioteka Wojskowa Link otwiera się w nowym oknie Logo biblioteki Prolib Integro - strona głównaCentralna Biblioteka Wojskowa

Wyszukujesz frazę "catalysis" wg kryterium: Temat

  Lista filtrów
Wyrównaj
Wyświetlanie 1-15 z 17
Tytuł:
Kwasy nukleinowe jako katalizatory reakcji chemicznych
Nucleic acids as catalysts in chemical reactions
Autorzy:
Bukowiecka-Matusiak, M.
Sobczak, M.
Powiązania:
https://bibliotekanauki.pl/articles/172466.pdf
Data publikacji:
2012
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
DNA
kataliza
synteza asymetryczna
catalysis
asymmetric synthesis
Opis:
Nucleic acids, due to their specific structure, are effective and durable carriers of genetic information. They have also been used as catalysts in chemical reactions. The right-handed DNA double helix structure has become one of the icons of modern science, and its share in asymmetric catalysis is undeniable. In these reactions, DNA is a source of chirality and proximity between oligonucleotides and complexes of copper during catalysis, what allows a direct transfer of chirality from DNA to the reaction product. Almost complete regioselectivity and excellent enantioselectivity of the aforementioned reactions in water are the evidence of the potential of asymmetry based on DNA. Asymmetric catalysis used in organic synthesis, allows achieving high enantioselectivity. This strategy has been successfully used to create new C-C bonds in Diels- Alder cycloaddition, Friedel-Crafts alkylation and Michael addition using copper complexes with oligonucleotides as catalysts. The important factor to optimize the reaction of asymmetric catalysis in the presence of DNA constitutes its sequence. It has been shown that the use of the double helix DNA can provide the product with higher enantiomeric excess than using the single strand of DNA. In addition, the results of the study suggest that Friedel-Crafts alkylation is accelerated by DNA almost 30-fold. The same correlation is observed in Diels-Alder cycloaddition. Due to promising results, further testing directed at the possibility of using catalytic DNA is being conducted.
Źródło:
Wiadomości Chemiczne; 2012, 66, 1-2; 119-137
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Biomasa - źródło cennych związków organicznych
Biomass a source of valuable organic compounds
Autorzy:
Retajczyk, J.
Wróblewska, A.
Powiązania:
https://bibliotekanauki.pl/articles/172682.pdf
Data publikacji:
2017
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
biomasa
glukoza
glicerol
uwodornienie
kataliza
glucose
glycerol
monoterpenes
hydrogenation
catalysis
Opis:
So far, much attention was paid to processes which allow to obtain biofuels from biomass and less important was receiving from biomass valuable chemical compounds. Biomass is a source of a variety of compounds, such as: hydrocarbons, triglycerides, glycerol, hydroksymetylofurfural, cellulose, hemicellulose and pentoses, lignin and lignocellulose. Taking into account the application of the mentioned above compounds, a large number of articles describing catalytic conversion of biomass to valuable chemical compounds has been written during last 10 years. The articles presented specific types of reactions for compounds contained in biomass, such as: hydrolysis, hydrogenation or isomerization, which allow to obtain valuable products. The reactions are catalyzed among others by: metals deposited on the activated carbon, metal oxides, alloys and zeolites. Researchers still improve processes, adapting them to the structure of highly functionalized particles contained in biomass and process needs. At the same time, scientist focused on cost reduction. Renewable raw materials are converted to the intermediates in physical, chemical and physicochemical processes. Next, obtained intermediates are used for receiving valuable chemicals, such as: lubricants, solvents and products that were previously obtained from petroleum. This work presents the conversion of biomass to compounds which have been already prepared by conventional synthetic methods. Besides chemical pure compounds, catalytic reactions with using metals, lead to obtain mixtures of compounds which can be used for the large volume production: additives for paper, paints, resins, foams, surfactants, lubricants and plasticizers. In the chemical industry for many years it has been placed emphasis on processes that are environmentally friendly. Scientists have also focused on improving the activity of used catalysts and the selectivity of products.
Źródło:
Wiadomości Chemiczne; 2017, 71, 3-4; 241-262
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
CO2 zamiast CO : katalityczna konwersja CO2 w syntezie związków karbonylowych
CO2 instead of CO : catalytic conversion of CO2 in the synthesis of carbonyl compounds
Autorzy:
Wójcik, Ewelina
Trzeciak, Anna M.
Powiązania:
https://bibliotekanauki.pl/articles/1410899.pdf
Data publikacji:
2021
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
ditlenek węgla
karbonylacja
kataliza
redukcja
silany
carbon dioxide
carbonylation
catalysis
reduction
silanes
Opis:
Modem industrial carbonylation processes, leading to functionalized carbonyl compounds, are based on the application of highly toxic and flammable carbon monoxide. Recently, carbon dioxide which is non-toxic and abundant, has attracted attention as a perfect C1 source to build new C-C and C-N bonds. From the standpoint of green and sustainable chemistry, it is appealing and challenging to combine the reduction of CO2 with subsequent carbonylation using in situ formed CO. Herein we present the application of CO2 as C1 building block for the carbonylation of different organic compounds in the presence of transition metal catalysts (e.g. Pd, Rh, Ru, Fe). Industrially important organic compounds has been obtained in hydroformylation, dehydrogenation, hydrogenation, aminocarbonylation and carboxylation reactions with CO2. On the other hand, rapid reduction of CO2 to CO could processed in the metal catalyst - free systems, using a catalytic amount of fluoride salt and stoichiometric amount of di- or hydrosilane. In these reactions silyl formate has been identified as an important intermediate formed from silane and carbon dioxide. Also hydrazine and sodium borohydrate have been used for CO2 reduction to formic acid or other products. Obviously, these reactions could be restricted because of their sensitivity to the applied conditions, high cost of reactants as well as the waste generated. The presented examples of catalytic carbonylation reactions with CO2 as a source of CO group illustrate a high technological potential of this strategy.
Źródło:
Wiadomości Chemiczne; 2021, 75, 3-4; 395-422
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
W pogoni za sadzą
The pursuit of soot
Autorzy:
Kopacz, A.
Powiązania:
https://bibliotekanauki.pl/articles/172552.pdf
Data publikacji:
2014
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
kataliza
tlenki żelaza
katalizator
sadza
spalanie
catalysis
iron oxide
catalyst
soot
combustion
Opis:
Soot is produced simultaneously by the incomplete combustion of fossil fuels. Investigations of soot elemination methods are currently focused on light fuel oil boilers. The overview of various transition metal properties points at iron as the most promising cation. The technology of existing oil burners excludes modifications necessary to install additional catalytic conversters. The most feasible way to eliminate soot is to introduce the catalyst in the form of fuel additive. Iron iron oxides and/or hydroxides are suggested as base for production of fuel-borne-catalyst.
Źródło:
Wiadomości Chemiczne; 2014, 68, 9-10; 919-939
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Kwas winowy i jego pochodne we współczesnej chemii organicznej
Tartaric acid and its derivatives in current organic chemistry
Autorzy:
Grajewski, J.
Powiązania:
https://bibliotekanauki.pl/articles/171622.pdf
Data publikacji:
2013
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
kwas winowy
winiany
stereochemia
synteza organiczna
kataliza
tartaric acid
tartrates
stereochemistry
organic synthesis
catalysis
Opis:
The tartaric acid and its salts have been present in chemistry for almost 350 years, since Pierre Seignette isolated Rochelle salt in 1675. Since that time tartaric acid and its derivatives have been often used in chemistry due to their accessibility, enantiopurity, relatively low cost and presence of different functional groups which easily allow to modify the molecule. Many tartaric acid derivatives serve as catalysts in important stereoselective transformations such as Sharpless asymmetric epoxidation or asymmetric Rousch aryloboronation. In many others reactions tartaric acid have been employed as a chiral building block for natural products synthesis, highly functionalized molecules or ligand design such as well known TADDOL or its analogues. Its polar functional groups allow to form crystals with amines and aminoalcohols what is widely used for their enantiopurification and resolution. The relatively new subdiscipline is the use of tartaric acid in chiral recognition and chiral discrimination in nanochemistry and enantioselective chromatography. The other, recent applications of tartaric acid include functionalization of metal layers, antibacterial and antifungal activity among many others. The significance of tartaric acid is evident – since 2000, words “tartaric acid” or “tartrates” can be found in databases over four thousand times. Taking that into account this short review is concentrated on selected applications of tartaric acid and its derivatives in organic chemistry in recent several years.
Źródło:
Wiadomości Chemiczne; 2013, 67, 5-6; 495-519
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Hydroformylacja w środowisku cieczy jonowych
Hydroformylation in ionic liquids medium
Autorzy:
Trzeciak, A.M.
Powiązania:
https://bibliotekanauki.pl/articles/172009.pdf
Data publikacji:
2011
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
kataliza
hydroformylacja
ciecze jonowe
karbeny N-heterocykliczne
catalysis
hydroformylation
ionic liquids
rhodium
N-heterocyclic carbenes
Opis:
The hydroformylation reaction was discovered by Otto Roelen in 1938. He studied the side processes occurring during the Fischer-Tropsch synthesis with a cobalt catalyst and found some amounts of aldehydes formed from the olefin and syngas (H2/CO) [1]. The hydroformylation found application in the chemical industry, mainly for production of n-butanal from propene. Aldehydes obtained by propene hydroformylation are subsequently hydrogenated to alcohols, used as solvents. Butanal can also be condensed to C8 aldehydes and alcohols, 2-ethylhex-2-enal and 2-ethylhexanol, important components for plasticizers such as dioctylphtalate. The hydroformylation reaction can be applied not only for the synthesis of aldehydes but also for other products. In particular, successful synthesis of quaternary carbon centers by hydroformylation has been reported in which the rhodium catalyst was modified with a ligand that serves as a catalytic directing group by covalently and reversibly binding to both the substrate and the catalyst. Ionic liquids have been recognized as a novel class of solvents which can be successfully used for homogeneous catalysis [4]. Application of ionic liquids, non-aqueous and non-volatile solvents, has made it possible to construct biphasic systems in order to efficiently separate catalysts from organic products. It is also important that the properties of ionic liquids, such as solubility, acidity, or coordination ability, can be tuned by the use of different cations and anions. In the ideal case, the ionic liquid is able to dissolve the catalyst and displays partial miscibility with the substrate. If the products have negligible miscibility in the ionic liquid, they can be removed by simple decantation, without extracting the catalyst. If the products are partially or totally miscible in the ionic liquid, separation of the products is more complicated [4e, 4h]. The main problem with catalytic systems for hydroformylation containing ionic liquid phase was a significant leaching of the catalyst out of the ionic liquid phase, which can be overcome by modifying neutral phosphane with ionic groups. Examples of such systems are presented in the article. It was revealed that N-heterocyclic carbenes were formed in the biphasic hydroformylation reactions promoted by Rh complexes in an imidazolium ionic liquid [10]. Consequently, reactivity of the in situ formed Rh-carbene complexes can strongly influence on the hydroformylation reaction course [11]. The best methodology to perform the hydroformylation reaction would be a flow system in which the catalyst remains in the reactor and the substrates and products flow continuously into and out of the reactor. For the construction of such a system with soluble rhodium catalysts, ionic liquids could be considered as media used for the immobilization of the catalyst. The first example of continuous flow hydroformylation was reported by Cole-Hamilton [19, 20]. Different Supported Ionic Liquid Phase (SILP) catalysts have been examined in hydroformylation [15–17]. Interestingly, the neutral ligand can be applied efficiently in a continuous gas-phase SILP process, while in a typical biphasic system containing ionic liquid and organic solvent it would leach into the product phase.
Źródło:
Wiadomości Chemiczne; 2011, 65, 11-12; 1003-1020
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Katalizatory palladowe immobilizowane w materiałach typu MOF aktywne w reakcjach uwodornienia
Palladium catalysts immobilized in MOF materials active in hydrogenation reactions
Autorzy:
Augustyniak, Adam W.
Trzeciak, Anna M.
Powiązania:
https://bibliotekanauki.pl/articles/172135.pdf
Data publikacji:
2019
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
sieci metaliczno-organiczne
kataliza
pallad
uwodornienie
selektywność
metal-organic frameworks
catalysis
palladium
hydrogenation
reaction
selectivity
Opis:
Palladium immobilized in metal-organic frameworks (MOF) exhibit promising catalytic properties in hydrogenation of different unsaturated substrates. Due to the specific porous and crystalline structure MOFs can contribute in bonding and activation of organic substrates, increasing catalytic efficiency of Pd@MOF composites. The superior tunability of MOFs structures enables to design highly selective catalysts for hydrogenation of different substrates, such as olefins, esters, ketones, alcohols or alkynes. Due to the synergistic effects of palladium and MOF not only high activity but also high selectivity can be achieved. The article presents representative examples of MOF-based palladium catalysts for hydrogenation to illustrate perspectives, also technological, of their application.
Źródło:
Wiadomości Chemiczne; 2019, 73, 3-4; 221-241
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Katalizowane cynkiem asymetryczne hydrosililowanie ketonów i imin
Zinc-catalyzed asymmetric hydrosilylation of ketones and imines
Autorzy:
Gajewy, J.
Powiązania:
https://bibliotekanauki.pl/articles/172235.pdf
Data publikacji:
2013
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
kataliza asymetryczna
hydrosililowanie
kompleksy cynku
enancjoselektywność
aktywacja asymetryczna
asymmetric catalysis
hydrosilylation
zinc complexes
enantioselectivity
asymmetric activation
Opis:
One of the fundamental research goals in modern chemistry is the development of efficient and selective procedures to access organic compounds. Among all of the methodologies developed so far, catalysis offers an efficient and economical approach to enantiomericaly pure substances. In particular, transition metal catalysts modified by ligands, usually phosphines, are one of most successful examples of practical catalysis. Unfortunately, most of the applied metals (e.g., Pd, Rh, Ru, Ir) are low abundant, toxic and expensive. For this reason, recent research is focusing on their replacement by cheaper and low toxic metals. For example, the use of zinc can be of great interest, due to its abundance (0.0076% in the earth crust), biological relevance and distinct abilities. In the last two decades many scientific group have been working on finding new, high efficient and inexpensive catalytic system based on zinc for enantioselective transformations. It has been found that many of important organic reactions (for example aldol, Diels-Alder, Friedel-Crafts, Henry reactions) in their asymmetric version can be catalyzed by zinc complexes. One of them is also asymmetric reduction of double carbon-heteroatom bonds through addition of hydride (from silane). Hydrosilylation reduction is a promising alternative for the catalytic transformation of organic molecules to other reduction methods such as: hydrogenation and transfer hydrogenation owing to its operational simplicity and mild conditions. This review will give a general overview of the possible applications of zinc-catalyzed hydrosilylation of carbonyl compounds and imines. Since the understanding of mechanism of reaction is crucial for rational planning of new and more efficient ligands, some part of this article was devoted for mechanical considerations.
Źródło:
Wiadomości Chemiczne; 2013, 67, 5-6; 521-562
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Synteza i zastosowanie styrylopochodnych arenów, karbazolu i ferrocenu w projektowaniu e-stereoregularnych krzemoorganicznych materiałów hybrydowych
Synthesis and application of styryl derivatives of arenes, carbazol and ferrocene for designing e-stereoregular organosilicon hybrid materials
Autorzy:
Majchrzak, Mariusz
Powiązania:
https://bibliotekanauki.pl/articles/1413279.pdf
Data publikacji:
2021
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
kataliza
sprzęganie Suzuki
sililujące sprzęganie
materiały hybrydowe
polimery
catalysis
Suzuki coupling
silylative coupling
hybrid materials
polymers
Opis:
The potential for expanding the variety of catalytic methods for carbon-carbon bond formation is being currently explored in many research centres all over the world. An increasing use of selected d-block metals as catalysts in the synthesis has brought new methods of functionalization of organic and organometallic compounds of great importance for development of polymer chemistry and organic chemical technology [5, 6]. This work describes very precise and controlled catalytic transformations as useful tools for the synthesis of new E-conjugated organic, organosilicon molecular and polymeric compounds. The combination of Suzuki-Miyaura coupling and silylative coupling reactions as a simple and efficient method is established for designing new E-stereoregular hybrid materials in the presence of well-defined transition metal (TM) catalysts. All presented compounds can be interesting precursors for a further functionalization that may significantly increase the possibility of their application in the design and synthesis of new functional materials.
Źródło:
Wiadomości Chemiczne; 2021, 75, 1-2; 137-162
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Asymetryczne reakcje pericykliczne katalizowane kompleksami magnezu
Magnesium-catalyzed asymmetric pericyclic reactions
Autorzy:
Czombik, Anna
Powiązania:
https://bibliotekanauki.pl/articles/2200433.pdf
Data publikacji:
2022
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
chiralność
kataliza asymetryczna
reakcja pericykliczna
kwas Lewisa
magnez
chirality
asymmetric catalysis
pericyclic reactions
Lewis acid
magnesium
Opis:
II Group-metals, like magnesium, are one of the most widespread elements in the environment. The abundance of II-group metals in the Earth’s crust is over 108 times greater than the precious metals. For the industrial applications, the important factors are the low costs of production and higher accessibility of their compounds. This puts the spotlight on alkaline-earth metals competing with transition elements as catalysts in organic synthesis. Features of their derivatives, like mild Lewis acidity and strong Brønsted basicity enabled them to catalyze reactions where Lewis-acidactivation of the substrate is essential. In this review the emphasis was put on magnesium-catalyzed pericyclic reactions, which are recognized as one of the most important methods of new carbon-carbon or carbon-heteroatom bonds formation. Using the catalysts based on II-group metal cations and chiral ligands, a highly stereoselective conversion of achiral substrates into enantioenriched products is possible. The Mg-based catalysts have been used in Diels-Alder, ene and 1,3-dipolar additions. Described synthesis methods were characterized by high efficiency (chemical yields and enantiomeric excesses). Where applicable, the relationships between the structure of catalyst/substrates, conditions and efficiency were discussed. Just now there are a few applications, for example in synthesis of alkaloid (–)-manzacidine or antibiotic of algal origin – (–)-malyngolide.
Źródło:
Wiadomości Chemiczne; 2022, 76, 9-10; 755--788
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Reakcje asymetrycznego otwierania pierścienia azyrydyn
Asymmetric aziridine ring opening reactions
Autorzy:
Prusinowska, N.
Powiązania:
https://bibliotekanauki.pl/articles/171513.pdf
Data publikacji:
2013
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
azyrydyny
desymetryzacja
kataliza asymetryczna
rozdział kinetyczny
reakcje otwierania pierścienia
aziridines
desymmetrization
asymmetric catalysis
kinetic resolution
ring opening reaction
Opis:
Aziridines, the nitrogenous analogues of epoxides, are useful building blocks for the synthesis of various functional materials and biologically active compounds. The reactivity of aziridines toward ring opening and expansion is dependent upon their extremely strained ring structures. Among the procedures of ring opening of aziridines, a nucleophilic ring-opening reaction is one of the major routes to highly functionalized compounds (Scheme 2). This short review focused on essentiac asymmetric ring opening reactions of aziridines including enantioselective ring opening of meso-aziridines and kinetic resolution of racemic aziridines with various hetero and carbon nucleophiles towards the synthesis of highly enantiomerically enriched 1,2-difunctionalized fine chemicals.
Źródło:
Wiadomości Chemiczne; 2013, 67, 5-6; 585-618
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Kataliza procesów hydrosililowania z udziałem cieczy jonowych
Catalysis of hydrosilylation processes with the participation of ionic liquids
Autorzy:
Bartlewicz, Olga
Szymańska, Anna
Jankowska-Wajda, Magdalena
Dąbek, Izabela
Maciejewski, Hieronim
Powiązania:
https://bibliotekanauki.pl/articles/1413312.pdf
Data publikacji:
2021
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
hydrosililowanie
kompleksy Rh
kompleksy Pt
ciecze jonowe
SILPC
kataliza heterogeniczna
hydrosilylation
Rh complexes
Pt complexes
ionic liquids
heterogeneous catalysis
Opis:
Hydrosilylation is a fundamental and elegant method for the laboratory and industrial synthesis of organosilicon compounds. The hydrosilylation reaction is usually performed in a single-phase homogeneous system. A major problem, particularly in homogeneous catalysis, is the separation of catalyst from the reaction mixture. The presence of metals in the reaction products, even in trace quantities, is unacceptable for many applications, therefore efforts have been made at applying heterogeneous catalysts or immobilised metal complexes in order to obtain high catalytic activity and easy product isolation at the same time. One of the methods for producing such catalysts is the employment of ionic liquids as agents for the immobilization of metal complexes. Biphasic catalysis in a liquid-liquid system is an ideal approach through which to combine the advantages of both homogeneous and heterogeneous catalysis. The ionic liquids (ILs) generally form the phase in which the catalyst is dissolved and immobilized. In our research we have obtained a number of catalytic systems of such a type which were based on rhodium and platinum complexes dissolved in phosphonium, imidazolium, pyridinium and ammonium liquids. Currently, there has a common trend to obtain heterogenized systems that combine advantages of homogeneous and heterogeneous catalysis, which makes the hydrosilylation process more cost- effective. Such integration of homo- and heterogeneous catalysts is realized in several variants, as supported IL phase catalysts (SILPC) and solid catalysts with ILs layer (SCILL). Although all the above systems show high catalytic activities, their structure is unknown. This is why we have made attempts to modify selected ionic liquids (corresponding to our most effective systems) and we have applied them as ligands in the synthesis of platinum and rhodium complexes. Another group of catalysts comprises anionic complexes of rhodium and platinum which were obtained by reactions between halide complexes of metals and a respective ionic liquid. Most of the obtained complexes are solids insoluble in hydrosilylation reagents and are characterized by a high catalytic activity. A considerable development of heterogeneous catalysts of this type and their application in many hydrosilylation processes can be expected in the future. This mini-review briefly describes the recent progress in the design and development of catalysts based on the presence of ionic liquids and their applications for hydrosilylation processes.
Źródło:
Wiadomości Chemiczne; 2021, 75, 1-2; 5-29
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Kompleksy platyny typu Markó zawierające n-heterocykliczne ligandy karbenowe O właściwościach supersterycznych
Markó-type platinum complexes containing bulky n-heterocyclic carbene ligands
Autorzy:
Bolt, Małgorzata
Żak, Patrycja
Powiązania:
https://bibliotekanauki.pl/articles/1413313.pdf
Data publikacji:
2021
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
N-heterocykliczne ligandy karbenowe
kompleksy platyny
kataliza homogeniczna
hydrosililowanie
dimeryzacja
N-heterocyclic carbene ligands
platinum complexes
homogeneous catalysis
hydrosilylation
dimerization
Opis:
Progress in technology implying increasing demand for advanced materials dedicated for specific application has become a driving force stimulating research in different branches of science. It has been estimated that over 90% highly processed compounds have been obtained by the methods whose pivotal processes take place in the presence of catalysts based on transition metal complexes. Although these processes permit obtaining desired products, they are often charged with numerous drawbacks that prevent their implementation in industry. That is why the search for new catalytic systems ensuring high efficiency of final products and a possibility of reaction control is still an important direction of studies. Markó complexes are a group of platinum(0) coordination compounds of type [(NHC)Pt(dvtms)]. Although much attention has been recently attracted to these class of compounds, their number reported in hitherto literature is still limited. Owing to the possibility of wide modification of NHC carbene ligand attached to metal, the structures, and thus also properties, of the final complexes can be relatively easily matched to the requirements of individual catalytic reactions. It is particularly interesting in view of permanent development of new technologies and still increasing demand for new synthetic methods of more sophisticated materials dedicated to specific applications. In this paper, the synthesis and characterization of Markó type platinum(0) complexes containing bulky N-heterocyclic carbene ligands is described and their applications in the synthesis of new and unknown organic and organosilicon compounds are discussed. The main advantages of these complexes are highlighted providing an overview of this fascinating area of research.
Źródło:
Wiadomości Chemiczne; 2021, 75, 1-2; 31-53
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Functional materials based on carbon : encapsulated iron nanoparticles
Materiały funkcjonalne oparte na magnetycznych nanokapsułkach węglowych
Autorzy:
Kasprzak, Artur
Popławska, Magdalena
Koszytkowska-Stawińska, Mariola
Powiązania:
https://bibliotekanauki.pl/articles/2057908.pdf
Data publikacji:
2021
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
nanomateriały węglowe
magnetyczne nanokapsułki węglowe
nanomedycyna
elektrochemia
kataliza heterogeniczna
adsorpcja
carbon nanomaterials
carbon-encapsulated iron nanoparticles
nanomedicine
electrochemistry
heterogeneous catalysis
adsorption
Opis:
The chemistry of carbon nanomaterials attracts continuous attention of scientists because of their promising properties and applications. Carbon-encapsulated iron nanoparticles (CEINs) are subgroup of carbon nanomaterials. CEINs are the core-shell nanostructures including the metallic phase permanently encapsulated in a tight carbon coating. The carbon shell protects CEINs against oxidation of metal into a corresponding oxide, as well as prevents them from spontaneous aggregation. It has been documented that the magnetic properties of CEINs are superior in comparison with the respective materials comprising metal oxides. Additionally, the presence of the carbon shell enables surface functionalization of CEINs by means of various synthetic routes, both covalent and non-covalent ones. Chemical functionalization enables tuning the materials’ properties and applications, for example toward introducing catalytically active sites or improving colloidal stability. One may conclude that CEINs combine physicochemical properties of graphene and iron nanoparticle. Therefore, this is prospective material for many applications. In this article, we discuss the properties, chemistry and selected applications of CEINs.
Źródło:
Wiadomości Chemiczne; 2021, 75, 11-12; 1211--1233
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ditlenek węgla w syntezie organicznej
Carbon dioxide in organic synthesis
Autorzy:
Burczyk, B.
Powiązania:
https://bibliotekanauki.pl/articles/172758.pdf
Data publikacji:
2013
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
wiązanie ditlenku węgla
surowce odnawialne
synteza organiczna
kataliza
kompleksy metali przejściowych
carbon dioxide fixation
renewable resources
organic synthesis
catalysis
transition metal complexes
Opis:
Carbon dioxide is an abundant, cheap, almost nontoxic, thermodynamically stable, inert electrophile. Exploitation of CO 2 as a chemical feedstock, although will almost certainly not reduce its atmospheric concentration significantly, aims to generate high-value products and more-efficient processes. In recent years efficient transition-metal complexes have been used to perform homogeneously catalyzed transformations of CO 2 . This paper presents an overview of available catalytic routes for the synthesis of carboxylic acids, lactones, urea and carbamates, linear and cyclic carbonates as well as polycarbonates. Reduction processes of CO 2 are shortly men - tioned as well. C arboxylic acids have been synthesized via : (i) carboxylation of organolithium, organomagnesium (Scheme 2 [35]), organoboron (Scheme 3 [40 -42]), organozinc (Scheme 4 [43, 44]) and organotin (Scheme 5 [45, 46]) compounds; (ii) oxidative cycloaddition of CO 2 to olefins and alkynes (Scheme 6 -10 [47 -50, 57]) catalyzed by Ni(0)-complexes; (iii) transition-metal catalyzed reductive hydrocarboxylation of unsaturated compounds (Scheme 11, 12 [64 -67]); (iv) carboxylation of C-H bond (Scheme 13 [69 -71]). Telomerization of dienes, for instance 1,3-butadiene, and CO 2 in the presence of Ni(II) and Pd(II) complexes leads to lactones and esters of carboxylic acids (Scheme 14, 15 [73 -79]). Nucleophilic ammonia, primary and secondary amines react with CO 2 to give, respectively, urea and carbamic acid esters - carbamates and isocyanates (Scheme 16 -18 [94, 95]), thus eliminating the use of phosgene in their synthesis. CO 2 reacts with alcohols, diols and epoxides in the presence of transition-metal complexes (Fig. 2) and the reaction products are: linear carbonates (Scheme 20, 21 [110 -118]), cyclic carbonates (Scheme 22 -24 [153 -170]) and polycarbonates (Scheme 25, 26, Fig. 3, Tab. 1 [179 -186]). Finally, hydrogenation of CO 2 , leading to the formation of CO, HCOOH, CH 3 OH, CH 4 , C 2 H 6 and C 2 H 4 (Scheme 27), as well as electrochemical and photochemical reductions in the pre - sence of homogeneous and heterogeneous catalysts have been shortly reviewed.
Źródło:
Wiadomości Chemiczne; 2013, 67, 1-2; 1-53
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 17

Ta witryna wykorzystuje pliki cookies do przechowywania informacji na Twoim komputerze. Pliki cookies stosujemy w celu świadczenia usług na najwyższym poziomie, w tym w sposób dostosowany do indywidualnych potrzeb. Korzystanie z witryny bez zmiany ustawień dotyczących cookies oznacza, że będą one zamieszczane w Twoim komputerze. W każdym momencie możesz dokonać zmiany ustawień dotyczących cookies