Universiẗat, Diss., 2002--Kiel.

University, Diss., 2005--Jena.

The aim of this dissertation is to discover the metathesis of functionalized alkane. The first chapter describes an overview of the catalysis field, the role of surface organometallic chemistry (SOMC) and the history of metathesis. The second chapterstudies the decomposition of the alkane metathesis catalyst precursor based on WMe6 grafted on partially dehydroxylated at 700 °C silica (SiO2-700) [≡Si-O-WMe5] and its activity in the metathesis of non-coordinating substrates. We used thermal programmed desorption (TPD), in situ infrared-mass spectrometry (IRMS) and chemical techniques with nuclear magnetic resonance. We found evidence of decomposition of the catalyst by coordinating substrates (ester and alcohol) and its inactivity in the metathesis of siloxanes and silanes. [≡Si-O-WMe5] catalyzes the disproportionation of n-butyl-ferrocene to ferrocene and dibutylferrocene. The third chapter is dedicated to the strategy of protection of the catalyst active site by modification of the catalyst support. We modified conventional silica which was partially dehydroxylated at 500 °C, and KCC-1 supports by octyltriethoxysilane as well as 1,1,2,2- tetrahydro-perfluorooctyl-triethoxysilane and grafted the alkane metathesis catalyst precursor – W(CH3)6. The obtained materials have been thoroughly characterized and studied in catalysis showing the activity towards metathesis of olefins and alkanes, but were inactive in the metathesis of functionalized alkanes. The fourth chapter provides the strategy with which to design and metathesize a compatible functionalized alkane on well-defined alkane metathesis catalyst. We investigated the weak coordinating pyrrole-based family of substrates. While utilizing [≡Si-O-WMe5] with 1-(alkyl)-2,5-dimethyl-1H-pyrroles, traces of metathesis and isomerization products were observed. With these results, we synthesized a rigid aromatic molecule – 9-hexyl-9H-carbazole and reached 5 % conversion to lower and higher homologs. That result proved to be the first-ever known example of metathesis of a functionalized alkane.

Over the past decades, since the discovery of a single–site silica-supported catalyst for the alkane metathesis reaction by our group, we have been extensively working on the development of supported catalytic systems for the improved alkane metathesis reaction. During these developments, we understand the reaction mechanism and reached a new perspective for the synthesis of various supported bimetallic systems via the surface organometallic chemistry (SOMC) approach. Recently, with this bi-metallic system, we got a very high TON (10000) in propane metathesis reaction. As these catalysts are very efficient for linear alkanes we thought to apply it for cyclo-alkanes specifically, for cyclo-octane metathesis expecting better activity. Besides, the value of the ring alkanes are higher than the linear alkanes. The current work demonstrates a combination of [(ΞSi−O−)W(Me)5] and [(ΞSi− O−)Ti(Np)3 pre-catalyst with several supports (SiO2-700, SBA-15 and MCM-41) for metathesis of cyclooctane. The catalysts have been synthesized and fully characterized by elemental analysis (EA), FT-IR and NMR spectroscopies. After fully characterization the bi-metallic catalyst was tested for metathesis of cyclooctane with highest ever TON 2500 as compared to that of mono-metallic catalyst where we got 430 TON. Which again corroborates our prediction that bimetallic catalysts are better catalysts than monometallic catalysts.

No description available.

Polymers possess bulk elastic properties due to entanglement of the polymer chains, not due to an inherit elasticity found within the monomers. An appropriately disubstituted bicyclo[8.8.8]hexacosane monomer should impart inherit elasticity when utilized in a polymer. A stochastic search of disubstituted bicyclo[m.m.m]alkanes demonstrated that these systems will adopt an out,out configuration and bicycles with medium and large values of m possess variable bridgehead-bridgehead distances. A stochastic search of disubstituted bicyclo[8.8.n]alkanes demonstrated an even-odd effect within the bite-angle of the bicycle. Two model compounds with methyl and hydroxyl groups at the bridgehead carbons were synthesized that demonstrated solid-state structures that correlated extremely well with the computational search. The solid-state structures were observed with both an out,out configuration and variable bridgehead-bridgehead distances. To investigate this hypothesis, polyurethanes will be made from the following diol monomers: 1,10-decanediol, a monocyclic diol, and a bicyclo[8.8.8]hexacosane diol.

Concerns over industrial emissions and nuclear waste have led to the need to study ways to sequester industrial gasses, and recycle nuclear fuel. Two projects were done to study solvent systems for these two problems using computational methods. Current methods for SO₂ sequestration are wasteful in that the gasses cannot be extracted from the solvent, and the solvent cannot be reused. One possible solution, which this work focuses on, is the use of an ionic liquid as a sequestration agent for the adsorption of SO₂. Separation technology for heavy elements has not changed for over 60 years and issues with radiation contamination and low efficiency lead to high solvent waste. Biphasic alkane-water extraction systems are a possible solution as they have been used for the extraction of heavy elements. This work focuses on characterizing the factors that control partitioning in biphasic systems which increase extraction efficiency.

Controlling molecular orientation is of great importance in organic thin films due to the fact that the fundamental properties of functional nanomaterials depend on molecular orientation at the nanoscale. However, controlling molecular orientation cannot be achieved without having an extensive understanding about the controlling factors in the organic film growth processes. Most previous studies have been devoted to monolayer structures. The structure of multilayer films has not been well investigated. This study was performed using a phenomenological approach, in which the morphology and orientation of n-alkane thin films were studied as a function of substrate identity, interface treatment, substrate temperature and deposition rate. The experimental techniques that were used include IR-spectroscopy, polarized optical microscopy, and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy and X-ray microscopy. The kinetic and thermodynamic factors that govern the orientation of organic thin films were extracted from the experimental results, and generalized to make a framework by which the morphology and orientation of organic films can be predicted. Epitaxial growth was specifically considered as a method to pattern organic thin films. In epitaxial growth, the oriented crystals of an organic film grow on a crystalline substrate such that the structure of the substrate is copied by the deposit crystals. For epitaxy it is required that the lattice planes of two crystals are parallel and similar in the lattice points spacing. A minor part of this dissertation is devoted to epitaxy in an inorganic system. One of the favorable consequences of epitaxial growth in inorganic systems is lattice strain that alters the electronic properties of semiconductor devices. A synchrotron based experimental method has been developed to quantitatively measure the degree of strain in Si1-xGex alloy films grown epitaxially on the Si(100) substrate.

Over the past decades, since the discovery of a single–site silica-supported catalyst for the alkane metathesis reaction by our group, we have been extensively working on the development of supported catalytic systems for the improved alkane metathesis reaction. During these developments, we understand the reaction mechanism and reached a new perspective for the synthesis of various supported bimetallic systems via the surface organometallic chemistry (SOMC) approach. Recently, with this bi-metallic system, we got a very high TON (10000) in propane metathesis reaction. As these catalysts are very efficient for linear alkanes we thought to apply it for cyclo-alkanes specifically, for cyclo-octane metathesis expecting better activity. Besides, the value of the ring alkanes are higher than the linear alkanes. The current work demonstrates a combination of [(ΞSi−O−)W(Me)5] and [(ΞSi− O−)Ti(Np)3 pre-catalyst with several supports (SiO2-700, SBA-15 and MCM-41) for metathesis of cyclooctane. The catalysts have been synthesized and fully characterized by elemental analysis (EA), FT-IR and NMR spectroscopies. After fully characterization the bi-metallic catalyst was tested for metathesis of cyclooctane with highest ever TON 2500 as compared to that of mono-metallic catalyst where we got 430 TON. Which again corroborates our prediction that bimetallic catalysts are better catalysts than monometallic catalysts.

The objectives of this study were to characterize residual feed intake (RFI) in growing bulls and heifers and in mid-gestation females to examine relationships with performance, body composition, feeding behavior, digestibility (DMD) and heart rate (HR) and evaluate the impact of RFI on bull fertility and cow forage utilization. Additionally, use of the n-alkane method to predict individual animal variations in intake was investigated. To accomplish these objectives, multiple RFI studies were conducted. In all studies RFI was computed as the difference between actual and expected DMI from linear regression of DMI on mid-test metabolic BW and ADG. To evaluate phenotypic relationships between feed efficiency, scrotal circumference (SC) and semen-quality an experiment was conducted with yearling bulls (N=204). Residual feed intake was not correlated with BW and ADG, but was positively associated with 12th-rib back fat (BF) such that the more efficient bulls were leaner. Bulls with low RFI had similar SC and progressive motility of sperm compared to high-RFI bulls. However percent normal sperm were weakly associated with RFI in a negative manner. To examine phenotypic relationships between heifer postweaning RFI, and performance, efficiency, HR, and DMD of mid-gestation cows, RFI was measured in growing Bonsmara heifers (N=175). Forty-eight heifers with divergent RFI were retained for breeding. Subsequently, intake, performance and feeding behavior was measured on mid-gestation females. Pregnant females classified as having low postweaning RFI continued to consume 22% less feed, spent 25% less time eating, and had 7% lower HR while maintaining similar BW, ADG and body composition compared to high RFI females. A moderate association between RFI in growing heifers and subsequent efficiency of forage utilization in pregnant cows was found. Growing heifers identified as efficient had greater DMD, however DMD in mature cows was similar between RFI groups. The n-alkane method of predicting intake detected differences in intake between divergent RFI groups in mid-gestation females. Results from this study indicate that inclusion of RFI as a component of a multi-trait selection program will improve feed efficiency of growing animals and mid-gestation females with minimal impacts on growth, body composition, and fertility traits.