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Tytuł:
Fabrication of Fe-TiB2 Nanocomposites by Spark-Plasma Sintering of a (FeB, TiH2) Powder Mixture
Autorzy:
Huynh, X.-K.
Kim, B.-W.
Kim, J.-S.
Powiązania:
https://bibliotekanauki.pl/articles/351368.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Fe-TiB2 nanocomposite
mechanical activation
spark plasma sintering
self-propagating high-temperature synthesis reaction
Opis:
Fe-40wt% TiB2 nanocomposites were fabricated by mechanical activation and spark-plasma sintering of a powder mixture of iron boride (FeB) and titanium hydride (TiH2). The powder mixture of (FeB, TiH2) was prepared by high-energy ball milling in a planetary ball mill at 700 rpm for 3 h followed by spark-plasma sintering (SPS) at various conditions. Analysis of the change in relative sintered density and densification rate during sintering showed that a self-propagating high-temperature synthesis reaction occurs to form TiB2 from FeB and Ti. A sintered body with relative density higher than 98% was obtained after sintering at 1150°C for 5 and 15 min. The microstructural observation of sintered compacts with the use of FE-SEM and TEM revealed that ultrafine particulates with approximately 5 nm were evenly distributed in an Fe-matrix. A hardness value of 83 HRC was obtained, which is equivalent to that of conventional WC-20 Co systems.
Źródło:
Archives of Metallurgy and Materials; 2018, 63, 2; 1043-1047
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fe-Al based composite reinforced with ultra-fine Al2O3 oxides for high temperature applications
Autorzy:
Kopec, Mateusz
Jóźwiak, Stanisław
Kowalewski, Zbigniew
Powiązania:
https://bibliotekanauki.pl/articles/2055052.pdf
Data publikacji:
2021
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
cermet composites
reaction synthesis
powder method
electron microscopy
Opis:
In this paper, an Fe-Al based composite reinforced with ultra-fine Al2O3 oxides was obtained through sintering of aluminium, iron and mullite ceramic powders using self-propagated high temperature synthesis (SHS). The powder mixture with a 50%wt. content of the ceramic reinforcement was cold pressed and subsequently subjected to the sintering process in vacuum at 1200◦C for 25 minutes under external loading of 25 kN. The complex microstructure of the Fe-Al matrix reinforced with ultra-fine Al2O3 oxides was found to be desired in high temperature applications since only 3% of the relative weight gain was observed after 100 hours of annealing at 900◦C.
Źródło:
Journal of Theoretical and Applied Mechanics; 2021, 59, 3; 509--513
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Surowiec kaolinowy jako potencjalny materiał do syntezy zeolitu typu A
Raw kaolin as a potential material for the synthesis of a-type zeolite
Autorzy:
Wdowin, M.
Powiązania:
https://bibliotekanauki.pl/articles/216047.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Instytut Gospodarki Surowcami Mineralnymi i Energią PAN
Tematy:
reakcja syntezy
kaolin
Na-A
charakterystyka mineralogiczna
charakterystyka chemiczna
badania teksturalne
synthesis reaction
raw kaolin
mineralogical characteristics
chemical characteristics
textural investigations
Opis:
W pracy przedstawiono możliwość uzyskania materiału zeolitowego typu A z naturalnych surowców ilastych. Materiał wykorzystany do syntezy stanowił wysokiej klasy kaolin pozyskiwany dla celów ceramicznych z piaskowca kaolinowego ze złoża Maria III k. Bolesławca. Surowiec kaolinowy poddano szeregom reakcji celem otrzymania zeolitu typu A. W pierwszym etapie materiał kalcynowano celem uzyskania amorficznego, bardziej reaktywnego produktu (metakaolinu). Następnie metakaolin poddano reakcji hydrotermalnej (w temperaturze 100°C), gdzie materiał ten połączono z roztworem wodnym 3 mol•dm–3 wodorotlenu sodu. W wyniku reakcji otrzymano zeolit Na-A, który scharakteryzowano stosując metody mineralogiczne (XRD, SEM-EDS, DTA/TG), chemiczne (XRF) i teksturalne (ASAP). Badania XRD wykazały, że otrzymany produkt stanowi wysokiej czystości zeolit typu A, gdzie udział fazy zeolitowej w otrzymanym materiale wyniósł (95% wt.), resztę stanowił kwarc. Analizy morfologii ziaren (SEM) potwierdziły dobrą krystalizację zeolitu, gdzie materiał ten formuje bardzo dobrze wykształcone kubiczne kryształy. [...]
The paper presents the obtaining possibility of type A zeolite material from natural clays. The material used for the synthesis was a high-quality kaolin extracted for ceramic needs derived from kaolin sandstones of Maria III deposits near Boleslawiec. Raw kaolin was subjected to a series of synthesis reactions in order to obtain zeolite A. In the first stage a tested material was calcined in order to obtain an amorphous, more reactive product (metakaolin). Next, metakaolin was hydrothermally reacted (at 100°C) where the material was combined with the aqueous solution of 3 mol•dm–3 NaOH. The reaction gave the zeolite Na-A, which was characterized using the mineralogical (XRD, SEM-EDS, DTA/TG), chemical (XRF), and textural (ASAP) methods. XRD studies have shown that the obtained product is of high purity zeolite A wherein content of zeolite phase in the obtained material was 95% wt. The rest was a quartz. Grain morphology analysis (SEM) confirmed the good crystallization of zeolite, wherein the zeolite is formed by very well developed cubic crystals. [...]
Źródło:
Gospodarka Surowcami Mineralnymi; 2015, 31, 3; 45-57
0860-0953
Pojawia się w:
Gospodarka Surowcami Mineralnymi
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
One-pot three component (LaCl3•7H2O) catalysed biginelli reaction for the synthesis of 1,2,3,4-tetrahydropyrimidine
Autorzy:
Murugesan, C.
Sihabudeen, M. Mohamed
Ahamed, A. Asrar
Powiązania:
https://bibliotekanauki.pl/articles/1190119.pdf
Data publikacji:
2016
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
2
3
4-tetrahydropyrimidine; one pot synthesis
Multicomponent reaction; Biginelli reaction; 1
Opis:
A Series of tetrahydropyrimidine has been derived by LaCl3•7H2O catalysed one pot three component biginelli reaction. The compounds have synthesised from an aldehyde, ethyl acetoacetate and urea or thiourea in an ethanolic medium using a catalytic amount of (LaCl3•7H2O). This method provides quantitative yield and the catalysis can be easily recovered from the reaction medium and be re-used.
Źródło:
World Scientific News; 2016, 35; 87-99
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optymalizacja syntezy 1,1-diamino-2,2-dinitroetenu (FOX-7) realizowanej w skali wielkolaboratoryjnej
Optimization and scaling-up of 1,1-diamine-2,2-dinitroethene (FOX-7) synthesis
Autorzy:
Chyłek, Z.
Cudziło, S.
Powiązania:
https://bibliotekanauki.pl/articles/209797.pdf
Data publikacji:
2011
Wydawca:
Wojskowa Akademia Techniczna im. Jarosława Dąbrowskiego
Tematy:
FOX-7
synteza
ciepło reakcji
synthesis
heat of reaction
Opis:
W niniejszej pracy dokonano optymalizacji procesu otrzymywania 1,1-diamino-2,2-dinitroetenu (FOX-7, DADNE ) w wyniku nitrowania jego bezpośredniego prekursora 2-metylopirymidyna-4,6-dionu (MPD). Zaproponowane modyfikacje obejmujące zarówno proces otrzymywania FOX-7 jak i MPD, pozwalają na prowadzenie szybszej i wydajniejszej oraz bezpieczniejszej syntezy tych związków. Dokonano pomiaru efektu cieplnego generowanego podczas procesu nitrowania MPD. Zmodyfikowane parametry procesu mogą być wykorzystane do otrzymywania FOX-7 w skali wielkolaboratoryjnej i półtechnicznej.
In the paper, optimization of 1,1-diamine-2,2-dinitroethene (FOX-7) and its precursor, 2-methylpirymidyne-4,6-dion (MPD), syntheses are presented. The proposed modifications make it possible to synthesize both of the compounds in more efficient, faster, and safer processes. Heat effects of the MPD nitration were measured. The results obtained can be used to design equipment and to formulate procedure of FOX-7 production in a pilot scale process.
Źródło:
Biuletyn Wojskowej Akademii Technicznej; 2011, 60, 2; 379-391
1234-5865
Pojawia się w:
Biuletyn Wojskowej Akademii Technicznej
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Prolina : pospolity aminokwas wyjątkowy katalizator. Część IV, Reakcja Michaela
Proline as a common amino acid and an exceptional catalyst. Part IV, Michael reaction
Autorzy:
Karczmarska-Wódzka, A.
Studzińska, R.
Kołodziejska, R.
Wróblewski, M.
Dramiński, M.
Powiązania:
https://bibliotekanauki.pl/articles/171840.pdf
Data publikacji:
2014
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
prolina
reakcja Michaela
synteza asymetryczna
proline
Michael reaction
asymmetric synthesis
Opis:
In recent years there has been a dynamic development of asymmetric synthesis. Groups of researchers, particularly the one led by Benjamin List and Carlos Barbas, carried out a number of reactions and showed the effectiveness of the use of small organic molecules such as proline as catalysts. Michael addition catalyzed with proline is a particularly interesting reaction because it can be carried out in two aminocatalytic pathways. The analysis of Michael reaction reveals potential for both forms of aminocatalysis: enamine and iminium catalysis (Scheme 1) [1–14]. Presumably Michael reaction proceeds mainly according to enamine mechanism. The use of proline in Michael reaction with imine activated acceptor is slightly effective. So far the researches have shown that the modification of proline molecule or addition of other catalyst is necessary for condensation to appear. Enamine catalysis concerns the activation of carbonyl compound in situ being a donor. There is no need for enolase anion to be created earlier [2, 15–17]. When, as a result of the reaction of a,b-unsaturated carbonyl compound with proline, Michael acceptor activation appears it means that it is enamine mechanism reaction (Scheme 1) [2, 24]. One of the first examples of direct Michael reaction proceeding through enamine transition state is the reaction of cyclopentanone with nitrostyrene (Scheme 6) [20–23]. Other examples of Michael addition of ketone with nitro olefin catalysed by proline are shown in table 2 and 3 [10, 23, 30]. Nitroketones obtained in that way are useful as precursors for different organic compounds [33], also pyrrolidines [34]. Pyrrolidines are pharmacologically active and they selectively block presynaptic dopamine receptors [34] (Scheme 7). Except for Michael intermolecular reaction, intramolecular condensation adducts were also obtained. Michael intramolecular proline-catalyzed condensation in which inactive ketones transform into α,β-unsaturated carbonyl compounds was described (Scheme 9) [35, 36]. These reactions require a stoichiometric amount of a catalyst and a long time of reaction and they give as a result a little enantiomeric excess [11, 24, 35]. In 1991, Yamaguchi and co-workers carried out malonates Michael addition to α, β-unsaturated aldehydes catalyzed by L-proline [24, 39]. The reaction proceeded according to enamine mechanism, for example dimethyl malonate was reacted with hex- 2-enal in the presence of proline to give Michael adduct in 44% yield. To improve the yield an attempt of a slight modification of a proline molecule was made transforming it into proper salt. Proline lithium salt enabled to obtain the condensation product in 93% yield (Tab. 4). Regardless of a used catalyst the products in the form of racemates were obtained. In order to improve enantioselective properties of a catalyst, Michael addition of diisopropyl malonate to cycloheptenone was carried out in chloroform in the presence of different proline salts. Optimal enantioselectivity and yield was obtained by using rubidium salt (Tab. 5–7) [40, 41]. Rubidium prolinate-catalyzed Michael additions are used in industry e.g. for enantioselective synthesis of the selective serotonine reuptake inhibitior (SSRI) (–)-paroxetine (antidepressant) (Scheme 12) [24].
Źródło:
Wiadomości Chemiczne; 2014, 68, 1-2; 49-65
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Prolina : pospolity aminokwas wyjątkowy katalizator. Część III, Reakcja Mannicha
Proline as a common amino acid and an exceptional catalyst. Part III, Mannich reaction
Autorzy:
Studzińska, R.
Karczmarska-Wódzka, A.
Wróblewski, M.
Kołodziejska, R.
Dramiński, M.
Powiązania:
https://bibliotekanauki.pl/articles/172649.pdf
Data publikacji:
2014
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
prolina
reakcja Mannicha
synteza asymetryczna
proline
Mannich reaction
asymmetric synthesis
Opis:
Mannich reaction occuring among ketone, aldehyde, and amine is one of the ways of a synthesis of biologically active compounds. Reactions of this type were carried out in the presence of different catalysts [3–10], however in recent years a lot of attention has been paid to enantioselective Mannich reaction catalyzed with proline. Such reactions were carried out with the use of different compounds containing carbonyl group and the most frequently used amine was p-anisidine. The advantage of the use of p-anisidine is a possibility of conducting the direct Mannich reaction (Scheme 3). In this way β-amino ketones (Tab. 1, 2, 4) [15, 18–20, 23, 24], α-hydroxy-β-amino ketones (Tab. 3) [15, 22], and β-amino alcohols (Tab. 5, 6) [25, 26] were obtained. A possibility of syntheses of β-amino sugars and α-amino acids with their derivatives (Tab. 7) [28, 29] is worth noticing. In a great number of described reactions, the products were obtained with satisfactory yield and enantiomeric excess. Taking into consideration the difficulty of a removal of p-hydroxyphenyl group which protects amine group in the resulting products, the attempts of using different amine compounds in Mannich reactions catalyzed with proline were undertaken. The use of amines blocked by tert-butoxycarbonyl group (Boc) enabled to obtain the products with high yield and ee values (Tab. 12–15) [35–38]. However in the case of the use of Boc the reaction must be carried out in an indirect way (it is necessary to prepare imine blocked by Boc earlier).
Źródło:
Wiadomości Chemiczne; 2014, 68, 1-2; 21-48
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
PEG mediated eco-friendly one pot sunthesis of benzylamine coumarin derivatives using multicomponent reactant
Autorzy:
Viradiya, D. J.
Kotadiya, V. C
Khunt, M. D.
Baria, B. H.
Bhoya, U. C.
Powiązania:
https://bibliotekanauki.pl/articles/412545.pdf
Data publikacji:
2014
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
one pot reaction
benzylamine coumarin derivative
green synthesis
PEG-400
Opis:
A green resourceful, eco-friendly and facile protocol was developed for the synthesis of benzylamine coumarin derivatives by the reaction of 4-hydroxy coumarin, secondary amine and aromatic aldehyde in the presence of PEG400 as a solvent as well as catalyst at room temperature. A wide range of functional groups were tolerated in the developed protocol. The structures of all the synthesized compounds were confirmed by 1H NMR, IR, MASS and Elemental Analysis. The target molecules were obtained in good to excellent yield applying this method.
Źródło:
International Letters of Chemistry, Physics and Astronomy; 2014, 11, 2; 177-184
2299-3843
Pojawia się w:
International Letters of Chemistry, Physics and Astronomy
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
One-dimensional isothermal multicomponent diffusion-reaction model and its application to methanol synthesis over commercial Cu-based catalyst
Autorzy:
Lei, K.
Ma, H.
Zhang, H.
Ying, W.
Fang, D.
Powiązania:
https://bibliotekanauki.pl/articles/778972.pdf
Data publikacji:
2015
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
global kinetics
internal effectiveness factor
diffusion-reaction model
methanol synthesis
Opis:
The present work was a study on global reaction rate of methanol synthesis. We measured experimentally the global reaction rate in the internal recycle gradientless reactor over catalyst SC309. The diffusion-reaction model of methanol synthesis was suggested. For model we chose the hydrogenation of CO and CO2 &enspas key reaction. CO and CO2 &enspwere key components in our model. The internal diffusion effectiveness factors of CO and CO2&enspin the catalyst were calculated by the numerical integration. A comparison with the experiment showed that all the absolute values of the relative error were less than 10%. The simulation results showed that decreasing reaction temperature and catalyst diameter were conducive to reduce the influence of the internal diffusion on the methanol synthesis.
Źródło:
Polish Journal of Chemical Technology; 2015, 17, 1; 103-109
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Nowoczesne metody pozyskiwania substancji biologicznie aktywnych przy zastosowaniu reakcji wieloskładnikowych ze szczególnym uwzględnieniem reakcji Ugi
New methods of receive biologically active substances in multicomponent reactions with particular focus on Ugi reaction
Autorzy:
Ryng, S.
Jęśkowiak, I.
Powiązania:
https://bibliotekanauki.pl/articles/172211.pdf
Data publikacji:
2017
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
reakcja wieloskładnikowa
reakcja Ugi
synteza organiczna
synteza ukierunkowana na różnorodność
multicomponent reaction
Ugi reaction
diversity-oriented synthesis
Opis:
In the last decade a change of thought has taken place in the pharmaceutical industry which has led to a renaissance of the Multicomponent reactions (MCRs) [1]. Under the inspiration of diversity-oriented-synthesis (DOS), numerous efforts have been devoted to find powerful synthetic tools for rapidly accessing maximum molecular diversity with minimum cost. In the toolbox enabling DOS for generating molecular libraries, MCRs are now recognized as one of the most useful and powerful strategies [2], which provide the highest number of compounds for the least synthetic effort [3]. Following the rapid progress in the research area of MCRs, widespread application has been found in many different areas such as chemical biology, natural product synthesis, pharmaceuticals as well as agrochemistry [2]. The overall aim of a DOS is to generate a small-molecule collection with a high degree of structural, and thus functional, diversity that interrogates large areas of chemical space simultaneously [4]. In Targed-Oriented Synthesis (TOS) a complex target is transformed into a sequence of progressively simpler structures by formally performing chemical reactions in the reverse-synthetic direction [3]. Special subclasses are isocyanide based MCRs (IMCRs). They are particularly interesting because they are more versatile and diverse than the remaining MCRs. Today most MCRs chemistry performed with isocyanides relates to the classical reactions of Passerini and Ugi (Scheme 1)[5]. In Ugi four-component reaction (U-4CR), carboxylic acids, primary amines and oxo components (aldehydes or ketones) react with isocyanides in polar solvents to obtain -amino carboxamides (Schemes 2 and 3). Occasionally however, selective conversion of amide groups into other functional groups is desirable for an increase of diversity of the IMCR-derived compounds [6]. In this reaction two substituted amide groups are formed under release of one equivalent of water. Thus, the U-4CR is an atom-economic and environmentally friendly reaction. It was also shown that water can be used as the solvent. This reaction is typically performed by stirrling the components for approximately 1 day in small quantities of a protic solvent (e.g. methanol or trifluoroethanol) [7]. The examples of Ugi reactions are described in the Schemes 4–10. Multicomponent reactions have become attractive tools in modern synthetic organic chemistry. Among their many advantages, they allow the creation of large chemical libraries of diverse, complex molecular structures, starting from simple materials within a short time frame. Not surprisingly, these particular features have made MCRs especially appealing to medicinal chemists [8].
Źródło:
Wiadomości Chemiczne; 2017, 71, 1-2; 45-63
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Generating Organic Compounds by Retrosynthetic Pathway via Typical Corey’s Synthesis
Autorzy:
Ononiwu, Chinonso Godwin
Enwereuzo, Onyekachi Oluchi
Akakuru, Obinna Chigoziem
Ejiogu, Chukwudima Benaiah
Onumah, Chinonso Uchenna
Achukee, Chinedu Kingsley
Umaefulam, Tobechukwu Nnamdi
Abaekwume, Nkechi Nancy
Akakuru, Ozioma Udochukwu
Powiązania:
https://bibliotekanauki.pl/articles/1031449.pdf
Data publikacji:
2021
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
Corey’s synthesis
aldehydes
alkanes
alkynes
ketones
organic compounds
organic reaction mechanism
Opis:
Several methods exist for the synthesis of alkanes including Corey’s synthesis, Wurtz reaction, reduction of alcohols and aldehydes, Kolbe’s electrolysis, hydrogenation of alkenes, and Grignard reaction. Among the available methods, the age-long Corey’s synthesis presents robust advantages of yielding symmetrical, unsymmetrical, straight chain and branched chain alkanes. Moreover, it allows of generating high yields of alkanes by utilizing primary alkyl halide and an array of lithium dialkyl copper ranging from primary, secondary to tertiary. Corey’s synthesis has also been implicated in the synthesis of various organic compounds such as (+)-taylorione, terminal alkynes, caribenol A, ketones, and aldehydes. In this work, an explanation of the general concept in the Corey’s synthesis is provided. Furthermore, specific examples of Corey’s reactions and modifications are discussed. Finally, an outlook into the benefits of the Corey’s synthesis in present-day organic synthesis is provided, which is expected to enhance the understanding of organic reaction mechanisms for the development of various organic compounds as drugs for treating diseases.
Źródło:
World News of Natural Sciences; 2021, 36; 88-98
2543-5426
Pojawia się w:
World News of Natural Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Reakcje i procesy katalityczne. Cz. XV a. Proces Fischera-Tropscha
Autorzy:
Sarbak, Z.
Powiązania:
https://bibliotekanauki.pl/articles/273930.pdf
Data publikacji:
2014
Wydawca:
Roble
Tematy:
reakcja katalityczna
procesy katalityczne
gaz syntezowy
synteza Fischera-Tropscha
catalytic reaction
catalytic processes
syngas
synthesis gas
Fisher-Tropsch synthesis
Źródło:
LAB Laboratoria, Aparatura, Badania; 2014, 19, 2; 16-22
1427-5619
Pojawia się w:
LAB Laboratoria, Aparatura, Badania
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Doświadczalne i teoretyczne badanie efektów cieplnych oraz kinetyki reakcji dla procesu nitrowania 2-metylopirymidynu-4,6-dionu (MPD)
Calorimetric and theoretical investigation of heat effects and reaction kinetics for nitration of 2-methyl-4,6-dihydroxy-pyrimidine
Autorzy:
Chyłek, Z.
Trzciński, W. A.
Powiązania:
https://bibliotekanauki.pl/articles/209630.pdf
Data publikacji:
2012
Wydawca:
Wojskowa Akademia Techniczna im. Jarosława Dąbrowskiego
Tematy:
DADNE
ciepło reakcji
kinetyka
modelowanie syntezy
heat of reaction
kinetics
modelling of synthesis
Opis:
W pracy badano efekty cieplne towarzyszące procesowi nitrowania 2-metylopirymidynu- 4,6-dionu (MPD). Pomiary wykonano za pomocą kalorymetru reakcyjnego. Zmierzono ciepło rozpuszczania MPD w stężonym kwasie siarkowym (95%), ciepło mieszania kwasu azotowego (100%) z kwasem siarkowym (95%) oraz efekt cieplny nitrowania MPD w mieszaninie kwasów azotowego i siarkowego. Analiza danych literaturowych i wyników badań własnych umożliwiła zaproponowanie modelu i matematyczne sformułowanie problemu kinetyki nitrowania MPD. Model zastosowano do symulacji zjawisk przebiegających w kalorymetrze reakcyjnym. Porównano dane doświadczalne z wynikami modelowania. Określono parametry stałych szybkości reakcji przebiegających w kalorymetrze.
The thermal effects accompanying the process of nitration of 2-methyl-4,6-dihydroxypyrimidine (MDP) were investigated. Measurements were performed using a reaction calorimeter DRC Evolution delivered by Setaram. The heat of solution of MDP in concentrated sulfuric acid (95%), the heat of mixing of nitric acid (100%) with sulfuric acid (95%) and the heating effect of nitration of MDP in a mixture of nitric and sulfuric acids were measured. The heat of solution of MDP was 95±3 kJ/mol, while the total heat effect of nitration MDP was 392±9 kJ/mol. The measured heat of solution of acids was 34±2 kJ/mol HNO3. Analysis of literature data and own research allowed us to propose the model of kinetics for nitration of MDP. The model was used to simulate phenomena and reactions running in the reaction calorimeter. The experimental data were compared with modelling results. The parameters of the rate constants of reactions running in the calorimeter were determined.
Źródło:
Biuletyn Wojskowej Akademii Technicznej; 2012, 61, 3; 304-317
1234-5865
Pojawia się w:
Biuletyn Wojskowej Akademii Technicznej
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Reaction Kinetics and Morphological Study of TiNb2O7 Synthesized by Solid-State Reaction
Autorzy:
Choi, S. H.
Ali, B.
Choi, K. S.
Hyun, S. K.
Sim, J. J.
Choi, W. J.
Joo, W.
Lim, J. H.
Lee, T. H.
Kim, T. S.
Park, K. T.
Powiązania:
https://bibliotekanauki.pl/articles/355326.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
solid state reaction
kinetic analysis
quantitative phase analysis
TiNb2O7 synthesis
Opis:
Although TiNb2O7 is regarded as a material with high application potential in lithium-ion batteries (LIBs) and solid-oxide fuel cells (SOFCs), it has been difficult to find suitable cost-effective conditions for synthesizing it on a commercial scale. In this study, TiNb2O7 compounds were synthesized by a solid state synthesis process. For stoichiometrically precise synthesis of the TiNb2O7 phase, the starting materials, TiO2 and Nb2O5 were taken in a 1:1 molar ratio. Activation energy and reaction kinetics of the system were investigated at various synthesis temperatures (800,1000,1200, and 1400°C) and for various holding durations (1,5,10, and 20 h). Furthermore, change in the product morphology and particle size distribution were also evaluated as a function of synthesis temperature and duration. Additionally, quantitative phase analysis was conducted using the Rietveld refinement method. It was found that increases in the synthesis temperature and holding time lead to increase in the mean particle size from 1 to 4.5 μm. The reaction rate constant for the synthesis reaction was also calculated.
Źródło:
Archives of Metallurgy and Materials; 2017, 62, 2B; 1051-1056
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Metody syntezy pochodnych organicznych zawierających wiązanie potrójne węgiel-węgiel
Methods for the synthesis of organic derivatives containing the triple bond carbon-carbon
Autorzy:
Bylińska, I.
Guzow, K.
Powiązania:
https://bibliotekanauki.pl/articles/171636.pdf
Data publikacji:
2012
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
wiązanie potrójne
acetylen
synteza
homosprzęganie
heterosprzęganie
reakcja Glasera
reakcja Haya
reakcja Cadiota-Chodkiewicza
reakcja Sonogashiry-Hagihary
triple bond
acetylene
synthesis
homocoupling
heterocoupling
Glaser reaction
Hay reaction
Cadiot-Chodkiewicz reaction
Sonogashira-Hagihara reaction
Opis:
Compounds containing triple bonds are lately in the centre of interest of many research groups. This is mainly connected with their usefulness as substrates to obtain complex compounds with various applications in different areas of science, industry and medicine [1–5]. Because of that many researchers are interested in methods of synthesis of such compounds. As the demand for derivatives with triple bonds is quite big and the one universal method of synthesis does not exist, the new ones are developed or these already known are improved. To enable choosing the best method for synthesis of acetylene derivatives, this review is presented. The oldest methods based on elimination reaction are mentioned [6–9], whereas those enabling incorporation of acetylene unit into more complicated compounds are described more thoroughly [10–92]. The latter methods based on homo- or heterocoupling lead to symmetrical [10–25] and unsymmetrical acetylene and bisacetylene derivatives [26–92]. The most popular reactions such as Glaser reaction (Scheme 1) [10–12], Cadiot-Chodkiewicz reaction (Schemes 11 and 12) [26–49], Hay reaction (Scheme 13) [13, 14] as well as Sonogashira-Hagihara reaction [50–69] and their modifications (Tab. 3) [57] are described. Moreover, the influence of main parameters such as type of substrate used, ratio of reagents, catalyst, base, solvent, reaction time and temperature on the reaction yield is presented (Tabs 1–4) [14, 18, 23, 25, 50–58, 69–78].
Źródło:
Wiadomości Chemiczne; 2012, 66, 9-10; 935-961
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
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