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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
331

Developement of cycloisomerization reactions for the synthesis of nitrogen or oxygen containing heterocycles / Developement of cycloisomerization reactions for the synthesis of nitrogen or oxygen containing heterocycles

Spina, Rosella 15 December 2011 (has links)
La catalyse, les solvants alternatifs et l'économie d'atome font partie des clés pour le développement de nouvelles stratégies durables de synthèse. Des hétérocycles comme les quinoléines substituées, par réaction de cycloisomérisation catalysée par le cuivre en utilisant les liquides ioniques, et les isoquinoléines carbonylées par réaction de carbonylation oxydante catalysée par le palladium dans le méthanol ont été synthétisées. La formation sélective de 1,3-dihydroisobenzofuranes et/ou 1H-isochromènes a été tentée par réaction de cycloisomérisation catalysée par différent métaux de transition. La synthèse d'hétérocycles à cinq chaînons, par exemple furanes, pyrroles et pyrrolin-4-ones à été mise au point par nouvelle réaction de cycloisomérisation catalysée par de sels de platine ou d'or en utilisant des diols, des amino alcools ou des α-amino-ynones dans le PEG sous activation micro-ondes. Les produits sont récupérés pur après une simple étape de précipitation-filtration. Les α-amino-ynones chiral sont synthétisée à partir de N-protégé carboxyanhydrides des aminoacides (UNCAs). Une réaction de iodocyclisation a été aussi développée pour obtenir de nouvelles structures hétérocycliques. / Catalysis, alternative solvents and atom economy represent key areas for the sustainable development of versatile strategies in organic chemistry. Fused heterocycles, such as substituted quinolines by a cycloisomerization reaction using a recyclable catalytic system copper/ionic liquids and isoquinoline-4-carboxylic esters based on PdI2-catalyzed oxidative carbonylation were prepared. A selective 5-exo-dig or 6-endo-dig cyclization route to obtain 1,3-dihydroisobenzofurans and/or 1H-isochromenes was tested by metal transition cycloisomerization reaction of alkynylbenzyl alcohols in PEG. Five membered ring heterocycles such as furans, pyrroles and pyrrolin-4-ones were successfully obtained by a novel platinum or gold-catalyzed cycloisomerization reaction of diols, aminoalcohols or α-amino-ynones in poly(ethylene glycol) (PEG) under microwave irradiation. The heterocyclic systems were recovered pure after a simple precipitation-filtration work-up. The catalytic systems were studied by using the TEM and XPS techniques. The chiral α-amino-ynone substrates were prepared by an original method starting from N-protected carboxyanhydrides of amino acids (UNCAs). Also unprecedented results are reported in the area of iodocyclization to obtain chiral iodopyrrolin-ones.
332

Karakterizacija, toksičnost i primena novosintetisanih jonskih tečnosti za čišćenje i konzervaciju papirne arhivske građe / Characterization, toxicity and application of newly synthesized ionic liquids for cleaning and conservation of paper heritage artefacts

Dimitrić Nataša 15 September 2020 (has links)
<p>U okviru ove disertacije uspe&scaron;no je sintetisano 14 novih protičnih jonskih tečnosti na bazi amina. Strukture su potvrđene snimanjem NMR i IC spektra. Izmerena je gustina svih jonskih tečnosti u temperaturnom opsegu&nbsp; T&nbsp; = (293,15&nbsp; &ndash;&nbsp; 353,15) K, kao i gustina njihovih vodenih rastvora u temperaturnom opsegu&nbsp; T&nbsp; = (293,15 &ndash; 313,15) K. Fizičko-hemijska karakterizacija je takođe propraćena merenjem viskoznosti i električne provodljivosti binarnih sme&scaron;a u celom rasponu&nbsp; molarnih frakcija i na različitim temperaturama (T&nbsp; = (293,15&nbsp; &ndash;&nbsp; 313,15) K). Na osnovu dobijenih rezultata utvrđeno je da sve protične jonske tečnosti imaju izražen structure making efekat. Ispitana je antimikrobna aktivnost protičnih jonskih tečnosti na bazi amina prema deset sojeva fungi: Trichoderma sp., Penicillium sp.(1-3), Cladoporium sp., Aspergillus sp. (1,2), A. flavus, F. graminearum i P. citrinium,&nbsp; osam sojeva bakterija:&nbsp; B. subtillis (6633), S. aureus (6538), E. faecalis (19433), K. rhizophila (9341),&nbsp; E. coli (11229), S. enteritidis (13076), P. mirabilis (12453), P. aeruginosa (15692) i dva soja kandida:&nbsp; C. albicans (ATCC 10231) i C. albicans (L) .&nbsp; Rezultati su pokazali da svih četrnaest jonskih tečnosti pokazuju antimikrobno delovanje. Za proučavane protične&nbsp; jonske tečnosti, antimikrobna aktivnost zavisi od dužine alkil lanca, pri tome pokazujući maksimalnu aktivnost sa anjonima koji sadrže 3 i 4 atoma ugljenika u nizu. Rezultati su pokazali da PILs pokazuju bolje antimikrobno dejstvo ako istovremeno sadrži i terminalno hlorovani C atom. Međutim, PILs pokazuju veću aktivnost ako je terminalni C atom monohalogeniran, jer monohalogenirani derivati poseduju veći afinitet za interakciju sa ćelijskom membranom. Najefikasnije PILs (ClA, 3-ClP, 4-ClB, Ac i For) su izabrane da se testiraju kao alternativni rastvarači umesto timola. Svih pet protičnih jonskih tečnosti uspe&scaron;no je testirano kao zelena alternativa za uobičajne organske rastvarače koji se koriste za či&scaron;ćenje i konzervaciju papirne povr&scaron;ine. Značajna antimikrobna svojstva primećena u ovoj doktorskoj tezi sugeriraju da proučavane protične jonske tečnosti mogu imati potencijalnu primenu u radu sa papirnim atifaktima, kao i pri njihovom či&scaron;ćenju i konzervaciji, zamenjujući na taj način primenu konvencionalnih rastvarača i organske supstance otrovne za ljude i životnu sredinu.</p> / <p>In this doctoral thesis the 14 amine based protic ionic liquids were newly synthesized. The validity of all structures were checked and confirmed by NMR and IR spectroscopy. Densities of pure ionic liquids and their diluted aqueous solutions have been measured over the whole composition range at selected temperatures from (293.3 to 353.15) K for pure ionic liquids, and from (293.15 to 313.15) K for diluted aqueous solutions. Physico-chemical&nbsp; characterization was also performed&nbsp; measuring the viscosity and electrical conductivity of binary mixtures in the entire range of mole fractions and at different temperatures (T&nbsp; = (293.15&nbsp; &ndash;&nbsp; 313.15) K). It was concluded that all investigated PILs have structure making tendency. Further, antimicrobial activity of amine based protic ionic liquids has been investigated using ten fungi strains: Trichoderma sp., Penicillium sp. (1-3), Cladoporium sp., Aspergillus sp. (1,2), A. flavus, F. graminearum i P. citrinium, eight ATCC bacterial strains: B. subtillis (6633), S. aureus (6538), E. faecalis (19433), K. rhizophila (9341), E. coli (11229), S. enteritidis (13076), P. mirabilis (12453), P. aeruginosa (15692) and two Candida&nbsp; strains:&nbsp; C. albicans (ATCC 10231) i C. albicans (L). The results indicated that all fourteen ionic liquids showed antimicrobial activity.&nbsp; For the studied PILs, the antimicrobial activity dependent on the alkyl chain length, showing maximal activity with anions containing 3 and 4 carbon atoms. The results revealed that the PILs show better antimicrobial activities if the longer alkyl chain is presented but in the same time contain chlorinated terminal C atom. However, PILs showed higer activity if the terminal C atom is monohalogenated, since the monohalogenated derivatives possess higher affinity to interact with cell membrane. The most effective PILs (ClA, 3-ClP, 4-ClB, Ac and For)&nbsp; were chosen to be tested as alternative solvents instead of thymol. All five PILs were successfully tested as the green alternatives to conventionally used organic solvents for paper cleaning and conservation. The significant antimicrobial properties observed in this doctoral thesis suggest that studied PILs may have potential applications in the paper art and artefact cleaning and conservation replacing thus, conventional solvents and organic substances that are toxic for humans and environment.</p>
333

Vliv iontových kapalin na funkční části lithium - iontových akumulátorů / The influence of ionic liquids on functional elements in lithium-ion batteries

Meščánková, Veronika January 2016 (has links)
This thesis deals with ionic liquids, their conductivity and the action of the electrode materials, separators and current collectors. The theoretical part is focused on the properties of ionic liquids, Li-ion batteries, corrosion, conductivity and analysis elements. The practical part is focused on the production of graphite electrodes, measuring the conductivity of ionic liquids with different parts of lithium – ion battery and measuring the potential window. Also, there is the effect of ionic liquids described in these parts.
334

Studium elektrických a dielektrických vlastností plynových senzorů na bázi iontových kapalin / The study of the electrical and dielectric properties of gas sensors based on ionic liquids

Maráčková, Lucie January 2017 (has links)
This diploma´s thesis is focused on a study of electrical and dielectric properties of gas sensors based on ionic liquids. Measurements were done on two different types of OECT substrates (0099 and 0160). Three ionic liquids and physiological solution PBS were chosen as electrolytes. Direct current current-voltage characteristic was measured. Switching rations of transistors with this electrolyte were determined by current-voltage characteristic. Alternating resistivity dependence on frequency were measured as well. Better properties showed OECT 0099 substrates.
335

Multifunctional materials based on task-specific ionic liquids : from fundamental to next generation of hybrid electrochemical devices and artifical skin / Matériaux multifonctionnels à base de liquides ioniques à tâches spécifiques : de l’étude fondamentale à la nouvelle génération de dispositifs électrochimiques et de peau artificielle

Pham Truong, Thuan Nguyen 29 November 2018 (has links)
Le développement durable nécessite des investissements massifs pour l'exploration et l'utilisation des sources d'énergie renouvelables dans le bilan énergétique. Parmi diverses formes de l’énergie, l'électricité est sans doute la forme la plus souhaitable pour les usages quotidiens. Cependant, en raison de l'intermittence des sources d’énergie renouvelables, l'électricité doit être stockée sous d'autres formes afin de corréler la production éphémère et la consommation en continue. Malgré la présence des systèmes commerciaux de stockage d'énergie, la recherche de nouveaux matériaux et de nouvelles approches pour résoudre ce problème est toujours en cours et attire également une grande attention. Les récents progrès ont poussé la communauté scientifique vers l'utilisation de matériaux à l'échelle nanométrique pour des systèmes de stockage et de conversion de l'énergie. Bien que ces derniers offrent des avantages pour réduire les émissions de gaz à effet de serre, leurs performances sont encore inférieures aux valeurs théoriques. Dans ce contexte, l’ingénierie à l'échelle moléculaire devient cruciale non seulement pour créer un nouveau type d'entités moléculaires mais aussi pour augmenter les performances des matériaux existants. Dans ce contexte, nous proposons d’utiliser une nouvelle famille de matériaux à base de liquides ioniques pour diverses d’applications, comprenant celles dans le domaine énergétique et pour le long terme, dans la fabrication de la peau artificielle, ces objectifs font l’objet de ces travaux de thèse. Cette dissertation est composée de cinq chapitres. Le chapitre 1 présente différents aspects des liquides ioniques (LIs) et des polymères à base de LI décrites dans la littérature. Via ce chapitre, nous envisageons d’atteindre les points suivants : (1) Décrire les utilisations possibles des liquides ioniques en électrochimie ; (2) Discuter des comportements physico-chimiques de ces composés en solution, (3) Montrer l'immobilisation de liquides ioniques (Redox-actifs) sur différents substrats : de couches minces aux polymères et (4) Mettre en évidence les travaux marquant portant sur l’utilisation des polymères ioniques liquides dans diverses applications. Le chapitre 2 présente différentes approches électrochimiques pour l'immobilisation de liquides ioniques rédox à la surface de l'électrode. De plus, les différentes caractéristiques des nouvelles interfaces seront reportées. Le chapitre 3 se concentre sur l'utilisation des polymères LIs comme catalyseurs émergents et comme matrices pour la génération de matériaux hybrides vers l'activation de petites molécules (ORR, OER, HER). Le chapitre 4 étudie la réactivité à l'échelle micro / nanométrique de divers matériaux, y compris les polymères liquides ioniques électro-actifs, en utilisant la microscopie électrochimique à balayage (SECM). Le chapitre 5 présente les résultats préliminaires de la fabrication de substrats flexibles avec des fonctionnalités intéressantes : possibilité de convertir le frottement en électricité et stockage d'énergie en utilisant des liquides ioniques redox polymériques. Ces études ouvrent de nouvelles opportunités pour élaborer des dispositifs flexibles, portables et implantables. / Increasing demand of energy requires massive investment for exploration and utilization of renewable energy sources in the energy balance. However, due to the intermittence of the current renewable sources, the generated electricity must be stored under other forms to correlate the fleeting production and the continuous consumption. Despite available commercialized systems, seeking for new materials and new approaches for resolving this problem is still matter of interest for scientific researches. Highlighted advancements have recently oriented the community towards the utilization of nanoscale materials for efficient energy storage and conversion. Although the advantages given by existing nanomaterials for diverse applications, especially in the energy field, their performance is still lower than theoretical purposes. Consequently, tailoring the physical-chemical properties at the molecular scale becomes crucial not only for boosting the activities of the existed materials but also for creating a new type of molecular entities for storing and releasing the energy. Accordingly, this PhD work aim to develop new family of materials based on ionic liquid that exhibits a multifunctionality towards energy applications. Our work is based on the knowhow in surface functionalization and material preparation by simple methods to build up electrochemical systems that can be utilized in various applications. Thus, this thesis will report different results obtained by following this direction and is composed of six chapters: Chapter 1 reports an overview of ionic liquid and polymeric ionic liquid. We propose to review the available literature on the redox-IL from solution to immobilized substrates. Through this chapter, we will achieve the following points: (1) Report the possible uses of ionic liquids in electrochemistry; (2) Discuss about the physical-chemical behaviors of these compounds in solution, (3) Show the immobilization of (Redox-active)–ionic liquids onto different substrates: from thin layer to polymer and (4) Highlight recent advances using polymeric ionic liquids for diverse applications. Chapter 2 will be devoted to different electrochemical assisted approaches for the immobilization of (redox)-ionic liquids to the electrode surface. We will focus on generating a thin layer and polymeric film based ionic liquid. Furthermore, the different characteristics of the new interfaces will be reported. Chapter 3 concentrates on the use of the polymer ionic liquid modified electrodes as emerging catalyst and as template for the generation of hybrid materials towards activation of small molecules. Chapter 4 studies the reactivity at micro/nanometer scale of diverse materials, including single layer graphene, polymeric redox – ionic liquid, using the scanning electrochemical microscopy (SECM). Chapter 5 reports the potential applications of redox ionic liquid and focus on providing the preliminary results towards the fabrication of flexible substrates with interesting functionalities: possibility to convert the friction to electricity and energy storage by using polymeric redox ionic liquids. These studies open a new opportunity to elaborate flexible, wearable and implantable devices. Finally, some concluding remarks are given to summarize different results obtained in the previous chapters. Besides, different perspectives will be given by using ionic liquid as main material for developing different energy storage and conversion systems.
336

Structure-Dynamics Relationships in Complex Fluids and Disordered Porous Solids Assessed using NMR: Structure-Dynamics Relationships in Complex Fluidsand Disordered Porous Solids Assessed using NMR

Shakhov, Alexander 09 February 2014 (has links)
A NMR study of the structure-dynamics relationships in heterogeneous materials is presented. In the first part, transport in soft-matter systems is studied using the pulsed field gradient NMR technique (PFG NMR). The molecular crowding effect in biological matter has been addressed using polymer solutions as model systems. By performing ensemble-based diffusion studies, the earlier obtained data on anomalous diffusion have been complemented. The transition to normal diffusion on a larger time scale has been shown. Taking advantages of the NMR approach, transport properties of microemulsions consisting of micellar colloids dissolved in liquid crystals have been investigated. The self-diffusivities measured under equilibrium conditions have shown weak correlations with microscopic ordering and macroscopic phase transitions occurring in the systems under study. The formation of micelles is shown to be decisive for macroscopic separation at the isotropic-nematic transition. The second part of the thesis covers heterogeneous effects in diffusion for fluids in porous solids, as probed using a combination of NMR diffusometry and structure characterization methods. Ionic liquids have been investigated, revealing a complex behavior under confinement. The attempts to correlate the observed characteristics of the ionic liquids with their internal chemical structure were undertaken. Finally, the series of nanoporous glasses with tunable pore structure characteristics were studied. Strong correlations between their structure and the preparation conditions as well as between the resulting transport properties have been shown.
337

Chirale und redoxaktive (Raumtemperatur-)Ionische Flüssigkeiten basierend auf Ferrocen und S-Prolin

Bouvet, Carola 30 May 2016 (has links)
In der vorliegenden Dissertation geht es um die Synthese und Charakterisierung chiraler, redoxaktiver (Raumtemperatur-)Ionischer Flüssigkeiten basierend auf Ferrocen und der natürlich vorkommenden Aminosäure S-Prolin. Diese Baueinheiten sind entweder über eine Ether- oder über eine Esterverbrückung verknüpft. Auch der Anionenaustausch vom I– - zum CF3SO3– - sowie (CF3SO2)2N– -Salz (kurz NTf2–) wird dargelegt und der Einfluss des Anions auf den Schmelzpunkt der Verbindungen untersucht und diskutiert. Die Redoxaktivität wird durch das im Ferrocen enthaltene Fe II eingebracht, das reversibel zu Fe III oxidiert werden kann. Aufgrund des Pyrrolidin-Rings sind die dargestellten Verbindungen stets chiral und bilden nach der Quaternisierung mit Halogenalkanen Diastereomere, soweit die Alkylkette größer als Methyl ist. Das Diastereomerenverhältnis wurde mittels 1H-NMR-Spektroskopie und in einem Fall anhand von Röntgenpulverdiffraktogrammen durch Rietveld-Verfeinerung analysiert. Die Verbindungen wurden thermisch anhand simultaner thermischer Analysenund Tieftemperaturversuchen untersucht, die belegen, dass die Synthese von insgesamt sechs neuen Raumtemperatur-Ionischen Flüssigkeiten gelang. Davon basiert eine Verbindung, (1S2S)- und (1R2S)-2-[(Ferrocenylcarbonyl)oxy]methylen-N-methyl-N-pentylpyrrolidin-1-iumiodid, auf I– und fünf Verbindungen enthalten NTf2– als Gegenion. Das Diastereomerengemisch der Verbindungen (1S2S)- und (1R2S)-N-Butyl-2-[(ferrocenylcarbonyl)oxy]methylen-N-methylpyrrolidin-1-ium NTf2– besitzt den größten Flüssigkeitsbereich von -25 bis +263 °C und auch die höchste Zersetzungstemperatur aller hier dargestellten Verbindungen. Insgesamt werden in dieser Arbeit elf Einkristallstrukturanalysen vorgestellt, wobei es sich um drei Verbindungen des Typs FcCH2N(CH3)2(CnH2n+1)I (Fc = Ferrocenyl, n = 1,2,3), Ferrocenmonocarbonsäurechlorid, zwei ether- sowie fünf esterverbrückte Verbindungen handelt. Mikrokristalline Proben wurden mittels Röntgenpulverdiffraktometrie charakterisiert. Ergänzende Analysen wurden mittels UV-Vis- und IR-Spektroskopie sowie Massenspektrometrie und Elementaranalyse durchgeführt. Ein wichtiger Aspekt bei Ferrocenverbindungen ist das Redoxpotential, welches mittels Cyclovoltammetrie bestimmt wurde. Hierbei liegt das Formalpotential des Fe II /Fe III -Redoxpaars der etherverbrückten Verbindungen bei +0,05 V und bei den esterverbrückten Verbindungen unabhängig vom Anion bei +0,28 V vs. Ferrocen/Ferrocenium in Acetonitril. Bei den iodidhaltigen Verbindungen zeigt das I– -Ion ebenfalls eine Redoxaktivität bei E(0,f,Fc) = -0,18 V und 0,22V. Die Diffusionskoeffizienten der esterverbrückten Triflat- und NTf2– -Verbindungen liegen in der Größenordnung von 7·10−6 cm2/s und die heterogenen Geschwindigkeitskonstanten bei 0,01 cm/s. / The present dissertation deals with the synthesis and characterization of chiral, redoxactive room temperature ionic liquids (RTILs) based on ferrocene and the naturally occurring amino acid S-proline. These building blocks are coupled either via an ether- or an ester-bridge. The anion exchange from I– to CF3SO3– and (CF3SO2)2N– salts (abbreviated as NTf2–) is presented. The influence of the anion on the melting point of the compound is investigated and discussed. The redox activity is introduced into the molecule via the Fe II -containing ferrocenyl groups, which can be oxidized reversibly to Fe III . The synthesized compounds based on the pyrrolidine ring are chiral. After quaternization with alkyl halides, they form diastereomers in case of alkyl chains longer than methyl. The ratio of the different diastereomers was analyzed by 1H NMR spectroscopy and, in one case, by Rietveld refinement of the X-ray powder diffraction pattern. The thermal behavior of the compounds was studied by simultaneous thermal analysis and low temperature experiments. The results show the successful synthesis of six new RTILs. One of them is based on iodide ((1S2S)- and (1R2S)-2-[(ferrocenylcarbonyl)oxy]methylene-N-methyl- N-pentylpyrrolidine-1-ium iodide) and six RTILs contain NTf2– as counter ion. The diastereomeric mixture of compounds (1S2S)- and (1R2S)-N-butyl-2-[(ferrocenylcarbonyl)oxy]methylene-N-methylpyrrolidine-1-ium NTf2– exhibits the widest liquid range from -25 to +263 °C and the highest decomposition temperature of all compounds presented herein. Eleven single crystal structure analyses are presented. Three of them belong to compounds FcCH2N(CH3)2(CnH2n+1)I (with Fc = ferrocenyl and n = 1,2,3), then ferrocene monocarboxylic acid chloride, two of ether- as well as five ester-bridged compounds. Microcrystalline samples were characterized by X-ray powder diffractometry. Supplementary analyses by UV/Vis and IR spectroscopy as well as mass spectrometry and elemental analyses have been carried out. An important feature of ferrocene containing compounds is their redox potential which is determined with cyclic voltammetry. The formal potential of the Fe II /Fe III redox couple in the ether-bridged compounds is at +0.05 V and in the ester-bridged compounds independent from the type of anion at +0.28 V vs. ferro- cene/ferrocenium in acetonitrile. The I– anion shows as well redox activity with formal potentials at E(0,f,Fc) = -0.18 V and 0.22 V. The diffusion coefficients of the ester-bridged triflate and NTf2– compounds are in the order of 7·10−6 cm2/s, the heterogeneous rate constants in the order of 0.01 cm/s.
338

Synthesis of Metal-Rich Compounds of Group 15 Elements in Lewis-Acidic Ionic Liquids

Groh, Matthias Friedrich 21 December 2016 (has links)
Chemical synthesis of materials is facing enormous challenges at the present time. The necessary transition toward more sustainable economic processes requires new materials as well as optimized production of well-established materials. However, inorganic materials (e.g., ceramics or alloys) are typically produced industrially by high-temperature processes at up to 2000 °C. A relatively new approach for inorganic synthesis is based on so-called ionic liquids. Ionic liquids (ILs) — often defined as salts with melting points below 100 °C[1] — are usually composed of sterically demanding organic cations and (often) polyatomic anions, which can be selected in order to tune the properties of the IL. Owing to the distinctive physicochemical properties of ILs (e.g., wide liquidus range, high redox and thermal stability, (usually) negligible vapor pressure, tunable polarity), they have gained interest for a wide range of applications. Among the numerous inorganic materials accessible in ILs have been remarkable examples, especially in main-group element chemistry. For instance, a new metastable modification of germanium in the clathrate-II structure[2] or the largest known naked, main-group element cluster [Sn36Ge24Se132]24– (“Zeoball”).[3] The introduction of Lewis-acidic ILs has enhanced the convenience of polycation syntheses and enabled substitution of carcinogenic or toxic substances like benzene, SO2, or AsF5.[4] A considerable number of polycations of group 15 or 16 elements has been synthesized in ILs. The utilization of an IL as reaction medium can be decisive for the composition, structure, and physical properties of the (polycationic) reaction product.[5] In order to broaden the knowledge on synthesis techniques for inorganic materials near ambient temperature based on ILs, this thesis aimed at two goals: • Explorative synthesis of new inorganic compounds in ILs • Elucidating the influence of ILs on product formation For these two goals, metal-rich (polycationic) compounds of group 15 were chosen as promising chemical system, owing to the effectiveness of alkylimidazolium-based Lewis-acidic ILs for the synthesis of this class of compounds. A variety of new polycationic compounds has been successfully synthesized in Lewis-acidic ILs based on 1-n-butyl-3-methylimidazolium (or 1-ethy-3-methylimidazolium) halides and halogenido-aluminates. Determination of the crystal structures by single-crystal X-ray diffraction enabled analysis of their bonding situation supported by quantum-chemical calculations. In general, the employed ILs enabled syntheses with a high selectivity for the yielded polycation. Depending on the investigated chemical system, the following parameters were pinpointed to have significant influence: • Choice of starting materials • Choice of cation as well as anion of the IL • Reaction temperature • Concentration of starting materials in the IL The investigations were supported by NMR spectroscopy, which led to the discovery of nanoparticles of red phosphorus. This finding may stimulate the development of an easily accessible, reactive form of phosphorus without the hazardous drawbacks of the white allotrope. In addition, in situ NMR measurements in ILs were proven a viable option for mechanistic investigations. Conventional solid-state reaction as well as ionothermal syntheses yielded the new layered compounds M2Bi2S3(AlCl4)2 (M = Cu, Ag), which can be interpreted as Bi2S3 molecules embedded in MAlCl4 salts. The choice of starting materials was found to have a crucial influence on the crystallized polytype. Omitting the IL hindered the formation of crystals suitable for single-crystal structure determination. The three new main-group element heteropolycations [Bi6Te4Br2]4+, [Bi3S4AlCl]3+, and [Sb13Se16]7+ as well as known [Bi4Te4]4+ has been synthesized under ionothermal conditions. The Lewis-acidic ILs proved to be exceptional solvents for elements and their halides, and likewise for Bi2S3 and Bi2Te3. Hence, these solvents are not only advantageous reaction media for pnictogen and chalcogen chemistry but also potential (selective but expensive) ore-processing agents. These excellent solvent capabilities extend to complex ternary compounds including heavy transition metals such as Bi16PdCl22 and elemental platinum. This gave rise to the synthesis of metal-rich salts containing [Bi10]4+ antiprisms with an endohedral palladium or, for the first time, platinum atom. Furthermore, the filled bismuth polycation [Rh@Bi9]4+ or the complex cluster [Rh2Bi12]4+ could be obtained from dissolution and conversion of Bi12−xRhX13–x (X = Cl, Br) depending on the employed IL. Real-space bonding analysis revealed that [Rh2Bi12]4+ acquires a unique standing between dative bonding by bismuth polyions and mixed clusters following Wade-Mingos rules. References [1] J. S. Wilkes, P. Wasserscheid, T. Welton, in Ionic Liquids in Synthesis (Eds.: P. Wasserscheid, T. Welton), Wiley-VCH Verlag GmbH & Co. KGaA, 2007, pp. 1–6. [2] A. M. Guloy, R. Ramlau, Z. Tang, W. Schnelle, M. Baitinger, Y. Grin, Nature 2006, 443, 320–323. [3] Y. Lin, W. Massa, S. Dehnen, J. Am. Chem. Soc. 2012, 134, 4497–4500. [4] E. Ahmed, D. Köhler, M. Ruck, Z. Anorg. Allg. Chem. 2009, 635, 297–300. [5] E. Ahmed, J. Beck, J. Daniels, T. Doert, S. J. Eck, A. Heerwig, A. Isaeva, S. Lidin, M. Ruck, W. Schnelle, et al., Angew. Chem. 2012, 124, 8230–8233; Angew. Chem. Int. Ed. 2012, 51, 8106–8109.
339

Basic aspects when using ionic liquids as a hydraulic fluid

Lovrec, Darko, Kalb, Roland, Tič, Vito 25 June 2020 (has links)
Hydraulic development engineers and tribology specialist still exert substantial effort, time and resources into finding a hydraulic fluid that would be near an ideal fluid. In addition to its basic physicochemical properties, it must meet a number of other requirements related to its practical use within hydraulic system and the materials used therein. Ionic Liquids, as novel lubricants, offer the solution in this regard. The paper gives an overview of the basic properties of selected and tested Ionic Liquids suitable for use as hydraulic fluids. The practically obtained data refer to the basic physico-chemical properties of Ionic Liquids and properties important for practical use within hydraulic system, e.g. compatibility with materials. The results are given in a comparison with common mineral oil based hydraulic oil.
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Fluide supercritique et liquide ionique comme plastifiants de polymères biosourcés : application à l'amidon et à l'acétate de cellulose / Supercritical fluid and ionic liquid as plasticizes on natural-based polymers

Bendaoud, Amine 13 November 2014 (has links)
Les biopolymères constituent une alternative crédible à l’utilisation des plastiques issus de ressources pétrolières. Dans cette étude, la transformation de l’amidon et de l’acétate de cellulose en présence de liquides ioniques en voie fondue (par extrusion) a été réalisée. Les caractéristiques physico-chimiques des formulations obtenues ont montré une dépendance vis-à-vis du type et de la concentration de plastifiant utilisé, mais aussi de l’humidité relative appliquée. De manière générale, les liquides ioniques ont présenté comparativement à des plastifiants usuels: une interaction plus privilégiée avec les deux polymères, une réduction beaucoup plus importante de la cristallinité, une diminution significative de la température de transition vitreuse et une plastification efficace des deux matrices polymères étudiées. Dans un deuxième temps, on s’est intéressé à associer le pouvoir de solvatation et de plastification du dioxyde de carbone supercritique (CO2Sc) sur la mise en oeuvre de l’amidon par les liquides ioniques. Les résultats les plus importants ont montré que le CO2Sc est capable d’interagir sur l’amidon et sur les liquides ioniques, de sorte qu’il peut induire une diminution de la température de la transition vitreuse de l’amidon plastifié / Biopolymers are viable alternatives to the use of conventional plastics derived from fossil fuels resources. In this study, our objective, beyond doing the melt processing ionic liquids plasticized starch and cellulose acetate in laboratory scale microcoumpounder which simulate the performance of a co-rotating twin screw extruder, are to investigate the effects and influence of ionic liquids and water on the intrinsic properties of the materials which are prepared. In general ways, processing with ionic liquids compared with conventional plasticizers, presents: a better interaction with starch and cellulose acetate, a more efficient depressor of glass transition temperature and allows the production of processed materials with efficient crystallinity destruction and plasticization. In the second step, we investigate the effects of supercritical carbon dioxide on the processing of starch with ionic liquid and the effects of the processing pressure, temperature and duration of supercritical carbon dioxide (ScCO2), which is an environmentally-friendly component, on the properties of plasticized starch. The significant results show that ScCO2 is capable of interacting with starch chains and with ionic liquids, so that it may induce a decrease in the glass transition temperature of the plasticized starch

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