Zerstörungsfreie Gleitsystemanalyse an der einkristallinen Hochtemperaturlegierung SC16 bei mittlerer Orientierung der Zugachse

Die Oberflächen von einkristallinen SC16-Proben quadratischen Querschnitts werden im Anschluss an eine Zugbelastung nach Gleitspuren durchsucht, um aus Verlauf und Höhenstufung sowie der Kenntnis der Kristallorientierung in der Probe die aktivierten Gleitsysteme zu bestimmen. Die Proben mit mittiger Orientierung der Zugachse werden mehrfach bis maximal etwa 0,2 % plastischer Restdehnung verformt. Für die Topografie-Untersuchungen findet die Weißlicht-Interferenz-Mikroskopie Anwendung, die die Höhenbestimmung durch Auffinden der Kontrastmaxima der räumlich entstehenden Interferogramme in Form eines Höhenscans für alle OF-Punkte gleichzeitig, aber voneinander unabhängig ermöglicht. Im Wesentlichen ist die Verformung bei den untersuchten Proben auf je ein Gleitsystem konzentriert. Für eine Probe können Spuren weiterer aktivierter Gleitsysteme nachgewiesen werden. Die topografische Gleitsystemanalyse ermöglicht im Rahmen der diskutierten Fehlertoleranzen eine eindeutige Identifizierung der aktiven Gleitsysteme. Bei allen untersuchten Proben lag Oktaedergleiten vom Typ {111} vor. Die nachgewiesenen Gleitsysteme stimmen mit dem Schmid schen Schubspannungsgesetz überein. Der Vergleich mit den Dehnungswerten eines Extensometers zeigt, dass bei der Raumtemperatur-Belastung die Verformung so stark auf einzelnen Ebenenbündeln der primären Gleitsysteme lokalisiert ist, dass die gesamte inelastische Verformung topografisch nachgewiesen werden kann. Zwischen der Breite der Gleitbänder und der jeweiligen Abgleitung besteht probenübergreifend ein linearer Zusammenhang. Im statistischen Mittel gleitet nur aller drei Netzebenen ein Burgersvektor ab.The surfaces of single crystal square sectioned SC16 specimens are investigated for slip traces in sequence of an uni-axial loading to determine the activated slip systems from angles and height steps involving the crystal orientation of the specimen/sample. The specimens with a middle orientation of the loading axis several times are deformed with a maximum inelastic elongation of about 0.2 %. For the topographic investigations White Light Interference Microscopy is used, allowing a height determination of all surface points by means of a single height scan simultaneous but independent of each other. At the examined specimens the deformation essentially is concentrated in respectively one slip system. For one specimen traces of an other activated slip system are proved. The topographic slip system analysis enables an unambiguous identification of octahedral slip systems correlating to the ranking of the Schmid factors. A comparison with strain values of an extensometer shows, that at room temperature full deformation is localized in a few slip plane bundles. Between the widths and the translatory shifts of the single slip traces a linear dependence is showed. In the statistic means at only every third crystal plane one Burgers vector glides off

Time-Dependent Friction Effects on Vibrational Infrared Frequencies and Line Shapes of Liquid Water

From ab initio simulations of liquid water, the time-dependent friction functions and time-averaged nonlinear effective bond potentials for the OH stretch and HOH bend vibrations are extracted. The obtained friction exhibits not only adiabatic contributions at and below the vibrational time scales but also much slower nonadiabatic contributions, reflecting homogeneous and inhomogeneous line broadening mechanisms, respectively. Intermolecular interactions in liquid water soften both stretch and bend potentials compared to the gas phase, which by itself would lead to a red-shift of the corresponding vibrational bands. In contrast, nonadiabatic friction contributions cause a spectral blue shift. For the stretch mode, the potential effect dominates, and thus, a significant red shift when going from gas to the liquid phase results. For the bend mode, potential and nonadiabatic friction effects are of comparable magnitude, so that a slight blue shift results, in agreement with well-known but puzzling experimental findings. The observed line broadening is shown to be roughly equally caused by adiabatic and nonadiabatic friction contributions for both the stretch and bend modes in liquid water. Thus, the quantitative analysis of the time-dependent friction that acts on vibrational modes in liquids advances the understanding of infrared vibrational frequencies and line shapes

Epigenetic regulation of inflammation by microRNAs in post-infectious bronchiolitis obliterans

Post-infectious bronchiolitis obliterans (PiBO) is a rare, chronic disease initiated by severe infection and followed by perpetuating inflammation and obliteration of the small airways. MicroRNAs (miRNAs) have been proposed to play a central role as epigenetic regulators, which control resolution and prevent the uncontrolled progress of inflammation. The aim of this study was to define biomarkers on the level of post-transcriptional gene regulation in order to characterise PiBO. A total of 39 patients with well-defined PiBO and 31 controls from two centres, Barcelona, Spain, and Frankfurt, Germany, were analysed by next-generation sequencing (NGS). The evaluation of the biological targets of the miRNAs was performed by pathway enrichment analysis and protein-protein interaction network analysis respectively. Patients with PiBO had significantly lower lung function values and increased airway inflammation in induced sputum as indicated by total cell counts, neutrophils, IL-1β, IL-6, IL-8 and TGF-β compared to controls. Next-generation sequencing analysis revealed a total of 22 dysregulated miRNAs, which passed significance threshold for P adj ≤ 0.001 with 17 being upregulated and 5 being downregulated. Of these dysregulated miRNAs, miR-335-5p, miR-186-5p, miR-30b-5p and miR-30c-5p were further validated using qRT-PCR. Interestingly, these miRNAs are functionally implicated in cytokine-cytokine receptor interaction, TGF-β signalling and FoxO signalling pathway and significantly correlated with lung function values (FEV1). Our results demonstrate an aberrant miRNA expression profile in PiBO, which impacts pathways responsible for the regulation of inflammation and fibrosis. The defined miRNAs are useful biomarkers and should be assessed as potential target in the field of miRNA therapeutics. We identified dysregulated miRNAs, which impact pathways for inflammatory cytokines and TGF-β signalling in post-infectious bronchiolitis obliterans. The miRNAs reflect bronchial inflammation and fibrosis and could be considered as novel biomarkers supporting diagnosis and treatment options

Epigenetic regulation of inflammation by microRNAs in post-infectious bronchiolitis obliterans

Post-infectious bronchiolitis obliterans (PiBO) is a rare, chronic disease initiated by severe infection and followed by perpetuating inflammation and obliteration of the small airways. MicroRNAs (miRNAs) have been proposed to play a central role as epigenetic regulators, which control resolution and prevent the uncontrolled progress of inflammation. The aim of this study was to define biomarkers on the level of post-transcriptional gene regulation in order to characterise PiBO. A total of 39 patients with well-defined PiBO and 31 controls from two centres, Barcelona, Spain, and Frankfurt, Germany, were analysed by next-generation sequencing (NGS). The evaluation of the biological targets of the miRNAs was performed by pathway enrichment analysis and protein-protein interaction network analysis respectively. Patients with PiBO had significantly lower lung function values and increased airway inflammation in induced sputum as indicated by total cell counts, neutrophils, IL-1β, IL-6, IL-8 and TGF-β compared to controls. Next-generation sequencing analysis revealed a total of 22 dysregulated miRNAs, which passed significance threshold for P adj ≤ 0.001 with 17 being upregulated and 5 being downregulated. Of these dysregulated miRNAs, miR-335-5p, miR-186-5p, miR-30b-5p and miR-30c-5p were further validated using qRT-PCR. Interestingly, these miRNAs are functionally implicated in cytokine-cytokine receptor interaction, TGF-β signalling and FoxO signalling pathway and significantly correlated with lung function values (FEV1). Our results demonstrate an aberrant miRNA expression profile in PiBO, which impacts pathways responsible for the regulation of inflammation and fibrosis. The defined miRNAs are useful biomarkers and should be assessed as potential target in the field of miRNA therapeutics. We identified dysregulated miRNAs, which impact pathways for inflammatory cytokines and TGF-β signalling in post-infectious bronchiolitis obliterans. The miRNAs reflect bronchial inflammation and fibrosis and could be considered as novel biomarkers supporting diagnosis and treatment options

Towards an efficient liquid organic hydrogen carrier fuel cell concept

The high temperature required for hydrogen release from Liquid Organic Hydrogen Carrier (LOHC) systems has been considered in the past as the main drawback of this otherwise highly attractive and fully infrastructure-compatible form of chemical hydrogen storage. According to the state-of-the art, the production of electrical energy from LOHC-bound hydrogen, e.g. from perhydro-dibenzyltoluene (H18DBT), requires provision of the dehydrogenation enthalpy (e.g. 65 kJ mol-1(H2) for H18-DBT) at a temperature level of 300 °C followed by purification of the released hydrogen for subsequent fuel cell operation. Here, we demonstrate that a combination of a heterogeneously catalysed transfer hydrogenation from H18-DBT to acetone and fuel cell operation with the resulting 2-propanol as a fuel, allows for an electrification of LOHC-bound hydrogen in high efficiency (> 50 %) and at surprisingly mild conditions (temperatures below 200 °C). Most importantly, our proposed new sequence does not require an external heat input as the transfer hydrogenation from H18-DBT to acetone is almost thermoneutral. In the PEMFC operation with 2-propanol, the endothermal proton release at the anode is compensated by the exothermic formation of water. Ideally the proposed sequence does not form and consume molecular H2 at any point which adds a very appealing safety feature to this way of producing electricity from LOHC-bound hydrogen, e.g. for applications on mobile platforms.Fil: Sievi, Gabriel. Forschungszentrum Jülich; AlemaniaFil: Geburtig, Denise. Universitat Erlangen-Nuremberg; AlemaniaFil: Skeledzic, Tanja. Forschungszentrum Jülich; AlemaniaFil: Bösmann, Andreas. Universitat Erlangen-Nuremberg; AlemaniaFil: Preuster, Patrick. Forschungszentrum Jülich; AlemaniaFil: Brummel, Olaf. Universitat Erlangen-Nuremberg; AlemaniaFil: Waidhas, Fabian. Universitat Erlangen-Nuremberg; AlemaniaFil: Montero, María de Los Angeles. Universidad Nacional del Litoral. Instituto de Química Aplicada del Litoral. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Química Aplicada del Litoral.; ArgentinaFil: Khanipour, Peyman. Forschungszentrum Jülich; AlemaniaFil: Katsounaros, Ioannis. Forschungszentrum Jülich; AlemaniaFil: Libuda, Jörg. Universitat Erlangen-Nuremberg; AlemaniaFil: Mayrhofer, Karl J. J.. Forschungszentrum Jülich; AndorraFil: Wasserscheid, Peter. Universitat Erlangen-Nuremberg; Alemani

Epigenetic regulation of inflammation by microRNAs in post-infectious bronchiolitis obliterans

Post-infectious bronchiolitis obliterans (PiBO) is a rare, chronic disease initiated by severe infection and followed by perpetuating inflammation and obliteration of the small airways. MicroRNAs (miRNAs) have been proposed to play a central role as epigenetic regulators, which control resolution and prevent the uncontrolled progress of inflammation. The aim of this study was to define biomarkers on the level of post-transcriptional gene regulation in order to characterise PiBO. A total of 39 patients with well-defined PiBO and 31 controls from two centres, Barcelona, Spain, and Frankfurt, Germany, were analysed by next-generation sequencing (NGS). The evaluation of the biological targets of the miRNAs was performed by pathway enrichment analysis and protein-protein interaction network analysis respectively. Patients with PiBO had significantly lower lung function values and increased airway inflammation in induced sputum as indicated by total cell counts, neutrophils, IL-1β, IL-6, IL-8 and TGF-β compared to controls. Next-generation sequencing analysis revealed a total of 22 dysregulated miRNAs, which passed significance threshold for P adj ≤ 0.001 with 17 being upregulated and 5 being downregulated. Of these dysregulated miRNAs, miR-335-5p, miR-186-5p, miR-30b-5p and miR-30c-5p were further validated using qRT-PCR. Interestingly, these miRNAs are functionally implicated in cytokine-cytokine receptor interaction, TGF-β signalling and FoxO signalling pathway and significantly correlated with lung function values (FEV1). Our results demonstrate an aberrant miRNA expression profile in PiBO, which impacts pathways responsible for the regulation of inflammation and fibrosis. The defined miRNAs are useful biomarkers and should be assessed as potential target in the field of miRNA therapeutics. We identified dysregulated miRNAs, which impact pathways for inflammatory cytokines and TGF-β signalling in post-infectious bronchiolitis obliterans. The miRNAs reflect bronchial inflammation and fibrosis and could be considered as novel biomarkers supporting diagnosis and treatment options

Epigenetic regulation of inflammation by microRNAs in post-infectious bronchiolitis obliterans

Post-infectious bronchiolitis obliterans (PiBO) is a rare, chronic disease initiated by severe infection and followed by perpetuating inflammation and obliteration of the small airways. MicroRNAs (miRNAs) have been proposed to play a central role as epigenetic regulators, which control resolution and prevent the uncontrolled progress of inflammation. The aim of this study was to define biomarkers on the level of post-transcriptional gene regulation in order to characterise PiBO. A total of 39 patients with well-defined PiBO and 31 controls from two centres, Barcelona, Spain, and Frankfurt, Germany, were analysed by next-generation sequencing (NGS). The evaluation of the biological targets of the miRNAs was performed by pathway enrichment analysis and protein-protein interaction network analysis respectively. Patients with PiBO had significantly lower lung function values and increased airway inflammation in induced sputum as indicated by total cell counts, neutrophils, IL-1β, IL-6, IL-8 and TGF-β compared to controls. Next-generation sequencing analysis revealed a total of 22 dysregulated miRNAs, which passed significance threshold for P adj ≤ 0.001 with 17 being upregulated and 5 being downregulated. Of these dysregulated miRNAs, miR-335-5p, miR-186-5p, miR-30b-5p and miR-30c-5p were further validated using qRT-PCR. Interestingly, these miRNAs are functionally implicated in cytokine-cytokine receptor interaction, TGF-β signalling and FoxO signalling pathway and significantly correlated with lung function values (FEV1). Our results demonstrate an aberrant miRNA expression profile in PiBO, which impacts pathways responsible for the regulation of inflammation and fibrosis. The defined miRNAs are useful biomarkers and should be assessed as potential target in the field of miRNA therapeutics. We identified dysregulated miRNAs, which impact pathways for inflammatory cytokines and TGF-β signalling in post-infectious bronchiolitis obliterans. The miRNAs reflect bronchial inflammation and fibrosis and could be considered as novel biomarkers supporting diagnosis and treatment options

Transferhydrierung mit flüssigen organischen Wasserstoffträgersystemen als Wasserstoffquelle

In this thesis the transfer hydrogenation of different substrates with the LOHC compound perhydro-dibenzyltoluene (H18 DBT) was investigated. The applied substrates included aromatic, olefinic and carbonylic compounds. The reactions were carried out to identify suitable catalysts and reaction conditions for rapid and highly selective transformations. Toluene was used as aromatic model compound. A catalyst variation, including Pt/C, Pd/C, Rh/C, Ru/C, Ni/SiOx, Raney nickel and Au/AlOx, was carried out at 270 °C. It was found that only platinum, palladium and rhodium were active for this kind of reaction. Furthermore, a temperature variation was carried out with platinum and palladium catalysts. The temperature was varied between 210 °C and 290 °C. Even at the lowest temperature, where a sole dehydrogenation of the carrier is hardly possible, a significant activity was observed for both catalysts. The activity was always higher when platinum was used as active metal. It was further found that the amount of the hydrogen carrier has a minor influence as long as it is used in excess (threefold hydrogen excess). When stoichiometric ratios of the educts were used, an equilibrium conversion of toluene of 62 % was reached, which indicates a slight exothermicity of the reaction. The transfer hydrogenation proceeded without any noticeable side reactions or the formation of partly hydrogenated compounds. In a next set of experiments olefinic substrates were used for the transfer hydrogenation reaction. To avoid analytical difficulties due to a fast isomerisation of the double bond of linear alkenes, (Z) cyclooctene was used as substrate at temperatures between 210 °C and 290 °C. It was found, however, that the molecule is not stable under the applied conditions and a vast amount of side reactions occurred. Consequently, 1 octene was used for the transfer hydrogenation, despite the analytical problems. The same catalysts were applied as mentioned before and again platinum- and palladium-based catalysts were found most active for the reaction. A fast isomerisation of the double bond occurred, which did not seem to have an influence on the transfer hydrogenation activity. The formation of side products was far less pronounced compared to (Z) cyclooctene, however, a small amount of mostly aromatic C8 molecules formed during the reaction. Furthermore, with Pt/C the release of hydrogen was observed, when the substrate was fully consumed. With palladium as active metal, hydrogen was released to a significant extent during the entire reaction time. Platinum, in contrast, has a high selectivity towards the transfer hydrogenation and the hydrogen evolution only occurred when the substrate was fully consumed.   At last the transfer hydrogenation of oxygen containing carbonyl compounds was studied. The use of aldehydes proved difficult as they are very reactive under the applied reaction conditions. With hexanal as substrate the decarbonylation was very pronounced, which led to the formation of the catalyst poison CO. Furthermore, the aldol condensation occurred. To avoid these side reactions, which are due to the very unstable –COH group, ketones were used for the transfer hydrogenation reaction. Acetone is a very stable molecule and the transfer hydrogenation with Pt/C and Pd/C proceeded without any noticeable side reactions under comparatively mild temperatures (150 °C with Pt/C). The reaction is, however, strongly limited by a reaction equilibrium and reaction conditions needed to be optimised. Furthermore, the release of hydrogen was observed with both catalyst. It could be shown that the gas was not released due to dehydrogenation of H18 DBT but rather through dehydrogenation of the produced isopropanol. The dehydrogenation is in general undesired for transfer hydrogenation reactions, but it opens a new dehydrogenation pathway for H18 DBT under significantly milder reaction conditions. The transfer hydrogenation was furthermore carried out with cyclohexanone as substrate. The reaction was, however, not as straightforward as with acetone due to the formation of side products. Mainly phenol and diethylethers were formed to a high extent. For the transfer hydrogenation with H18 DBT as hydrogen donor very stable substrates have to be used, as the reaction temperatures have to be at least 150 °C for Pt/C and 190 °C for Pd/C. The highest activity was always observed with Pt/C no matter which substrate was used. The activity with Pd/C was lower compared to Pt/C and a minor activity was usually observed with Rh/C. Other applied catalyst did not yield any hydrogenated reaction products. To gain a deeper insight into the reaction mechanism, a deuterium labelled hydrogen carrier was used for transfer hydrogenation reactions. To simplify the analytical evaluation diphenylmethane (DPM) was used as donor molecule, as it is chemically similar to H0 DBT and no structural isomers exist. A method for the complete deuteration of DPM was developed. It was found that palladium is more active for the deuteration of the methyl bridge, whereas platinum is more active for the deuteration of aromatic positions. Furthermore, all catalysts are more active when carbon is used as support instead of alumina. For the complete deuteration of DPM Pt/C proved to be the best catalyst. At higher temperatures and with a higher deuterium excess the H/D exchange proceeds significantly faster. The deuteration was therefore carried out at 150 °C for at least 24 h and with a deuterium excess of 20.   H0 DPM and D0 DPM were subsequently loaded with either hydrogen or deuterium gas. The hydrogenation proceeded faster compared to the deuterogenation, which might be explained by a higher bond strength between deuterium atoms. Similar results were achieved for the dehydrogenation of H12 DPM and D12 DPM. It was again found that the reaction with hydrogen containing compounds showed a higher reaction rate. The H/D exchange was investigated between both loaded and both unloaded DPM species. With Pd/C and Pt/C a fast isotope exchange was observed between the unloaded DPM species under the applied reaction conditions. The H/D exchange was more pronounced between the loaded species, when Pt/C was used, even though palladium is commonly known to favour the isotope exchange of aliphatic positions. Finally the transfer hydrogenation of acetone h6 or acetone d6 with either H12 DPM or D12 DPM was investigated. It was found for all experiments that an H/D exchange between donor and acceptor molecule took place. A detailed retracement of the course of the reaction was therefore not possible. It is assumed that the catalytic surface gets covered with hydrogen/deuterium atoms before either the reduction of acetone or an isotope exchange occurs. With platinum a higher selectivity towards the transfer hydrogenation was shown, whereas with palladium a higher H/D exchange activity was observed. To gain more insight into the reaction mechanism further surface science studies are necessary. It could be shown in this thesis that platinum on carbon is by far the most active and selective catalyst for the transfer hydrogenation with H18 DBT as hydrogen donor molecule. This work has opened up the interesting research field of using LOHC-bound hydrogen for preparative hydrogenation reactions. This field promises further developments for applying the chemical hydrogen storage and transport vector H18-DBT directly for synthetic purposes. Following this work, these options are currently under even broader investigation at the Institute of Chemical reaction engineering in Erlangen.  In dieser Arbeit wurde die Transferhydrierung verschiedener Ausgangsstoffe mit dem LOHC perhydro Dibenzyltoluol (H18 DBT) untersucht. Die eingesetzten Stoffe waren Aromaten, Olefine und Carbonylverbindungen. Die Reaktionen dienten der Identifizierung geeigneter Katalysatoren und Reaktionsbedingungen für eine schnelle und selektive Umsetzung. Als aromatische Verbindung wurde Toluol eingesetzt. Eine Katalysatorvariation wurde bei 270 °C mit Pt/C, Pd/C, Rh/C, Ru/C, Ni/SiOx, Raney Nickel und Au/AlOx durchgeführt. Es konnte gezeigt werden, dass ausschließlich Platin, Palladium und Rhodium in dieser Reaktion aktiv waren. Des Weiteren wurde eine Temperaturvariation mit Platin und Palladium durchgeführt. Die Temperaturen lagen zwischen 210 °C und 290 °C. Für beide Katalysatoren wurde sogar bei der niedrigsten Temperatur, bei der eine reine Dehydrierung des LOHCs kaum möglich wäre, eine deutliche Transferhydrieraktivität festgestellt. Die Aktivität war bei gleicher Temperatur mit dem Platin Katalysator deutlich größer. Es konnte weiter gezeigt werden, dass die eingesetzte Menge an LOHC nur einen geringen Einfluss auf die Reaktionsrate hat, so lange dieser im Überschuss verwendet wird. Bei einem stöchiometrischen Verhältnis der Ausgangsstoffe, wurde ein Toluolumsatz von 62 % erzielt, was auf eine leichte Exothermie der Reaktion hindeutet. In einer weiteren Reihe von Experimenten wurden Olefine in der Transferhydrierung eingesetzt. Wegen analytischer Schwierigkeiten und der schnellen Isomerisierung der Doppelbindung von linearen Olefinen, wurde (Z) Cycloocten als Ausgangsstoff bei Temperaturen zwischen 210 °C und 290 °C eingesetzt. Allerdings ist dieses Molekül unter den Reaktionsbedingungen nicht stabil genug und eine Reihe an Nebenreaktionen traten auf. Daher wurde trotz der analytischen Probleme 1 Octen als Substrat eingesetzt. Es wurden dieselben Katalysatoren getestet und wiederum waren die Platin und Palladium Katalysatoren am aktivsten für diese Reaktion. Eine sehr schnelle Isomerisierung der Doppelbindung trat auf, was allerdings keinen Einfluss auf die weitere Transferhydrierung hatte. Die Nebenproduktbildung war deutlich geringer verglichen mit dem zyklischen Octen, dennoch konnten aromatische C8 Verbindungen nachgewiesen werden. Weiterhin konnte festgestellt werden, dass mit Platin als Katalysator bei Vollumsatz des Olefins Wasserstoff aus dem LOHC freigesetzt wurde. Mit Palladium hingegen, wurde während der gesamten Reaktionszeit Wasserstoff freigesetzt. Dieses Ergebnis zeigt, dass Platin Katalysatoren wesentlich selektiver in der Transferhydrierung sind.   Weiterhin wurde die Transferhydrierung sauerstoffhaltiger Carbonylverbindungen untersucht. Aldehyde haben sich als schwierige Ausgangsstoffe herausgestellt, da deren Reaktivität unter den gegebenen Reaktionsbedingungen zu groß ist. Mit Hexanal als Substrat wurde eine deutliche Tendenz zur Decarbonylierung festgestellt, was zur Freisetzung des Katalysatorgifts CO führt. Außerdem konnte die Aldol Kondensation nachgewiesen werden. Um diese Nebenreaktionen zu unterdrücken, die durch die sehr instabile –CHO Gruppe verursacht werden, wurden Ketone als Ausgangsstoffe verwendet. Aceton ist ein sehr stabiles Molekül und die Transferhydrierung mit Pt/C und Pd/C verlief ohne Nebenproduktbildung unter sehr milden Bedingungen (150 °C mit Pt/C). Die Reaktion ist allerdings stark gleichgewichtslimitiert, so dass die Reaktionsbedingungen optimiert werden müssen. Mit beiden Katalysatoren wurde während der Reaktion Wasserstoff freigesetzt. Es konnte nachgewiesen werden, dass dieser Wasserstoff nicht direkt aus dem LOHC freigesetzt wurde, sondern vielmehr aus dem entstandenen Reaktionsprodukt Isopropanol. Im Allgemeinen ist Freisetzung von Wasserstoff während der Transferhydrierung eine unerwünschte Reaktion. In diesem Fall eröffnet es einen neuen Weg für die Dehydrierung von H18 DBT unter relativ milden Bedingungen. Die Reaktion wurde außerdem mit Cyclohexanon als Substrat durchgeführt, wobei allerdings eine Reihe von Nebenreaktionen auftraten, die zur Bildung von Phenol und Diethylethern führten. Für die Transferhydrierung mit H18 DBT werden sehr stabile Substrate benötigt, da die Reaktionstemperaturen über 150 °C für Pt/C und über 190 °C für Pd/C liegen. Mit Pt/C wurde in jedem Fall eine deutlich größere Aktivität festgestellt als mit Pd/C. Rh/C zeigte in einigen Reaktionen eine sehr geringe Aktivität. Andere Katalysatoren führten nicht zur Umsetzung der Substrate. Um einen Einblick in den Reaktionsmechanismus zu bekommen, wurde die Transferhydrierung mit einem Deuterium-markierten Wasserstoffträger durchgeführt. Um die analytische Auswertung zu vereinfachen wurde DPM als Donormolekül verwendet, da es sich chemisch ähnlich verhält wie DBT aber als Reinstoff verfügbar ist. Es wurde ein Verfahren entwickelt, um DPM vollständig zu deuterieren. Es konnte gezeigt werden, dass Palladium sehr selektiv die Methylbrücken deuteriert, wohingegen Platin eine größere Aktivität bei der Deuterierung der Aromaten zeigt. Die Katalysatoren zeigen eine größere Aktivität, wenn Kohle als Trägermaterial verwendet wird anstelle von Aluminiumoxid. Pt/C zeigte die besten Eigenschaften, um DPM vollständig zu deuterieren. Höhere Reaktionstemperaturen, sowie ein größerer Deuteriumüberschuss begünstigen den H/D Austausch. Die Deuterierungen wurden daraufhin mit Pt/C bei 150 °C für mindestens 24 h durchgeführt. H0 DPM und D0 DPM wurden anschließend mit Wasserstoff- bzw. Deuteriumgas beladen. Die Hydrierung verlief deutlich schneller als die Deuterogenierung, was wahrscheinlich mit einer größeren Bindungsstärke der D D Bindung erklärt werden kann. Ähnliche Ergebnisse wurden auch für die Dehydrierung von H12 DPM sowie die Dedeuterogenierung von D12 DPM erzielt. Der H/D Austausch zwischen den beiden beladenen und unbeladenen DPM Spezies wurde untersucht. Mit beiden Katalysatoren wurde ein rascher Isotopenaustasch beobachtet. Bei den beladenen DPM Spezies war der H/D Austausch mit Pt/C deutlicher zu erkennen, obwohl Palladium normalerweise besser für den Isotopenaustausch an aliphatischen Positionen geeignet ist. Zum Schluss wurde die Transferhydrierung von Aceton h6 und Aceton d6 mit H12 DPM bzw. D12 DPM untersucht. Bei allen Experimenten konnte ein rascher H/D Austausch zwischen Donor- und Akzeptormolekülen festgestellt werden. Eine detaillierte Nachverfolgung des Reaktionsverlaufs war dadurch nicht möglich. Es kann angenommen werden, dass die Katalysatoroberfläche mit Wasserstoff-/Deuteriumatomen bedeckt wird, bevor die Reduktion von Aceton oder ein Isotopenaustausch stattfindet. Mit Pt/C konnte eine größere Selektivität zur Transferhydrierung beobachtet werden, wohingegen Palladium eher zum Austausch der Isotope neigt. Um mehr Einblick in den Reaktionsverlauf zu bekommen, wären detailliertere Studien nötig. In dieser Arbeit wurde gezeigt, dass Platin auf Kohle der selektivste und aktivste Katalysator für die Transferhydrierung mit H18 DBT als Wasserstoffträger ist. Diese Arbeit hat ein weiteres interessantes Forschungsfeld eröffnet, bei dem LOHC gebundener Wasserstoff für Hydrierprozesse verwendet werden kann. Nachfolgend zu dieser Arbeit wurden weitere Forschungsarbeiten zu diesem Thema am Lehrstuhl für Chemische Reaktionstechnik in Erlangen begonnen