Einfluss elektronischer Faktoren auf die katalytische Aktivität von chiral-at-metal Ruthenium Komplexen

Transition metal complexes with metal centered chirality, also called chiral-at-metal complexes, provide a useful and expandable toolbox for asymmetric catalysis. This thesis focuses on the synthesis of chiralat- metal ruthenium complexes with previously unused substituents to explore the electronic influence concerning reactivity and enantioselectivity. Within the first part of the thesis (Chapter 3.1) the synthesis of bis(pyridinyl-NHC) ruthenium complexes with 5-bromo and 4-dimethyl amino substitution at the pyridine moiety is presented. During the investigation of structural isomers, the formation of a mixed normal/abnormal NHC complex was observed and further investigated. By lowering the temperature and extending the reaction time, a ratio of 9.8:1 in favor of the mixed nNHC/aNHC complex was achieved. Formation of this mixed coordination was only observed for 5-CF3 (62%) and 5-bromo (53%) substituted complexes, while trimethylsilyl as well as 4-dimethyl amino substitution showed selective formation of the nNHC complex. The separation of diastereomeric complexes was realized by application of (tolylsulfonyl)benzamides as chiral auxiliaries. Due to the non–C2–symmetry of the mixed complexes, four diastereomers can be formed. Two of the resulting complexes were stable against silica gel and were found to consist of the same metal-centered chirality. Brùnsted acid induced labilization of the auxiliary ligand under retention of configuration created the corresponding complexes with up to ] 99% ee. The same protocol was applied to di-isopropylphenyl substituted complexes, providing access to sterically more demanding complexes. The second part of this thesis (Chapter 3.2) focuses on the application of the obtained complexes in asymmetric catalysis. In detail, the ring contraction of isoxazoles to 2H-azirines was investigated. Here, the 5-bromo substituted complex allowed a faster conversion at lower temperatures compared to the previously reported rhodium complexes. After a broad screening of reaction conditions, a maximum of 67% ee was obtained. During the investigation, non-linear effects were observed as well as a light induced racemisation of the product catalyzed by the applied ruthenium complexes. For the asymmetric C(sp3)-H amination reaction, the newly obtained mixed nNHC/aNHC complex was found to provide an 160-fold increased turnover frequency compared to the analogus nNHC complex. This allowed a reduction of the reaction time down to 10 min. For the alkynylation of trifluoroacetophenone, the differences between the nNHC and mixed nNHC/aNHC complexes were negligible. For a propargylic substitution, the di-isopropylphenyl substituted complexes showed higher enantioselectivity (up to 55% ee), the mixed nNHC/aNHC complex provided low enantioselectivity (11% ee) while the bis-nNHC complex induced no enantioselectivity. Initial UV-Vis studies with acyl imidazoles indicated a broad absorption around 550 nm. Among the tested complexes, the 4-dimethyl amino substitution showed a maximum at 640 nm, followed by the mixed nNHC/aNHC complexes, while the bis-nNHC complexes showed maxima at 520 nm. This could be used in further studies concerning the potential application of ruthenium complexes in asymmetric photocatalysis

Herbicide-free establishment of short rotation agroforestry systems with different tree species - results from an organic field trial in Bavaria

info:eu-repo/semantics/publishedVersio

WJXT Weather Guide, 1822-1972 : a Weather Handbook

A history and weather guide of Jacksonvill

Erträge von Winterweizen in einem Agroforstsystem zur Energieholzgewinnung im ökologischen Landbau

The study is part of the research project "Development and testing of an agroforestry system combining organic agriculture and short rotation coppice". Cooperation partners are the Bavarian State Institute for Agriculture (LfL) and the Bavarian State Institute of Forestry (LWF). The two experimental sites are located in the northern Munich gravel plain near Freising and in the southern part of the Franconian Jurassic near Kaisheim. Aim of the study was to compare the yield of agricultural crops in an alley cropping system for woody biomass production with a standard cultivation without trees on the field. A positive effect of periodically harvested tree stripes on the yield of the agricultural crops is expected. First results show that there were no significant differences in the overall marketable yield of winter wheat in the agroforestry system compared to the reference site without trees. The spatial distribution of the yield, however, differed significantly. In close proximity to the tree stripes a significant reduction of the marketable yield could be measured. These lower yields were equalized by higher yields in bigger distances of the tree stripes

Schnellwachsende Gehölze zur Energiegewinnung im ökologischen Landbau - Etablierung und Wuchsleistung verschiedener Baumarten

So far there is only little experience with the cultivation of coppicing fast-growing tree species in German organic agriculture. The research project investigated the establishment and the performance of different tree species - black alder (Alnus glutinosa), grey alder (Alnus incana) and two hybrid poplar clones ('Max 1', 'Max 3') under organic conditions. Various strategies to reduce weed competition were examined. Different undersown crops (Medicago lupulina, Trifolium repens, Camelina sativa, Secale cereale) and a self-degradable mulch membrane were compared with an untreated control. The two experimental sites are located in Southern Bavaria (Germany). All tree species could be successfully established on both experimental sites. The results show that during the first three years the trees on self-degradable mulch membrane growd best, and reached the lowest heigth on black medic. A recommendation regarding choice of tree species and strategies of establishment can be given after tree harvest and after an economic evaluation

Anbauwürdigkeit von Blauer Lupine im Gemenge mit Getreide

Zur Verbesserung der Anbauwürdigkeit der Blauen Lupine, insbesondere der Beikrautunterdrückung, wurde im Jahr 2017 in einem Feldversuch am Standort Hohenkammer bei Freising der Anbau im Gemenge mit verschiedenen Getreidearten und verschiedenen Saatstärken geprüft. Der Gesamtertrag war im Gemenge höher als in Lupinenreinsaat. Beide Getreidearten sowie beide Lupinensorten kombiniert mit Hafer zeigten im Gemenge höhere Rohproteingehalte als in Reinsaat. Die verzweigte Lupinensorte 'Boregine' war konkurrenz- und ertragsstärker als die endständige Sorte 'Boruta', Hafer war mit einem signifikant höheren Getreideertrag konkurrenzstärker als Weizen. Der Unkrautdruck war bei 'Boruta', aber nicht bei 'Boregine', im Gemenge signifikant geringer als in Reinsaat

Wirkung legumer Zwischenfrüchte auf legume Hauptfrüchte hinsichtlich bodenbürtiger Krankheitserreger

Um die Verträglichkeit zwischen verschiedenen legumen Zwischenfrüchten und drei Körnerleguminosen (Futtererbse, Ackerbohne und Blaue Lupine), speziell in Hinblick auf fruchtfolgebedingte Schaderreger, zu untersuchen, wurden in den Jahren 2016 und 2017 an zwei Standorten in Bayern Feldversuche durchgeführt. Zwischen den verschiedenen Vorfruchtvarianten waren sowohl bei Ackerbohne als auch bei Erbse keine signifikanten Unterschiede in der Befallsstärke mit Fußkrankheiten erkennbar. Die Lupine zeigte im gesamten Versuchszeitraum keine Krankheitssymptome. Für die einzelnen Vorfruchtvarianten zeigten sich auch keine signifikanten Unterschiede im Kornertrag. Da die Fragestellung aufgrund der nicht zu kontrollierenden Bedingungen für Krankheiten in diesen Feldversuchen nicht beantwortet werden konnte, werden die Versuche im Gewächshaus fortgeführt

Die kausale Klasse im Deutschen

Die kausale Klasse des Deutschen zeigt eine facettenreiche Kategorie. Die verschiedenen Markierungen von Kausalzusammenhängen, insbesondere Kausalkonjunktionen, haben jeweils unterschiedliche Gebrauchspräferenzen und Abbildungsbereiche. Kein Mittel gleicht dem anderen und wenn dem doch einmal so ist, findet sich das Sprachsystem bzw. der Mensch einen Weg, um einer Synonymität vorzubeugen. So entstehen immer feinere und nuanciertere Möglichkeiten, die Welt kommunikationsangemessen und zweckoptimiert sprachlich wiederzugeben. Dabei sind nicht nur sprachgeschichtliche Aspekte der Semantik einzelner Formen einflussnehmend, sondern es können ebenso auf syntaktischer oder suprasegmentaler Ebene bedeutungsgebende Nuancierungen beobachtet werden. Diese sind vor allem im Bereich der Pragmatik anzusiedeln. Von der strukturalistischen Bedeutung ausgehend sind die Konsequenzen für die kausale Klasse allerdings schwerwiegend: Kausalsätze haben nur in einem sehr geringen Bereich eine Beziehung zur „natürlichen“ Kausalität. Die unternommenen Vergleiche zeigen, dass die kausale Klasse mit der anderswo gängigen Kategorie nur dann deckungsgleich wäre, wenn der Kausalitätsbegriff anderer Wissenschaftsdisziplinen geöffnet werden würde

Zur Produktionstechnik bei Weißen Lupinen

Die Weiße Lupine ist aufgrund unzureichender Toleranz gegen Anthraknose (Colletotrichum lupini) aktuell nicht für Anbau in Deutschland empfohlen. Wenn neue Sorten mit verbesserter Toleranz in 2019 für den Anbau zur Verfügung stehen, sind Empfehlungen für geeignete Anbautechniken nötig. Deshalb haben wir verschiedene Aussaattechniken, Saatstärken und Reihenabstände geprüft. Erste Ergebnisse zeigen bei der Drillsaat höhere Kornerträge als bei der Einzelkornsaat. Eine höhere Aussaatstärke erhöhte den Kornertrag nicht

Adolescents' and young adults' experiences of childhood cancer: descriptions of daily life 5 years after diagnosis

Background: Survivors of childhood cancer are a growing population in society. These young people have a high risk of developing chronic health problems with a potential strong impact on their lives. How a childhood cancer experience affects survivors in adolescence has only been studied to a limited extent, and an increased understanding of this young group is needed to improve follow-up care. Objective: The aim was to gain a deeper understanding of how childhood cancer affects the lives of survivors by exploring adolescents' and young adults' views of what it is like living with this experience. Methods: Fifty-nine people 11-22 years old were interviewed a median of five years after diagnosis (response rate 66%). Data was collected through telephone interviews and analysed with qualitative content analysis. Results: Three groups of informants were identified according to their descriptions of influence on daily life: ‘Feeling like anyone else’ (the informants who described that the cancer experience had almost no influence on current life) (49%), ‘Feeling almost like others’(those who described some influence) (44%) and ‘Feeling different’ (those describing a great influence on current life) (7%). Conclusions: Most of the adolescents and young adults appear to get along well, although many informants described that life was affected to some extent by having had cancer. Implications for Practice: Necessary follow-up care that can identify those young survivors of childhood cancer having trouble with daily life and offer them support to strengthen their resources in managing difficulties in relation to having had cancer