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No description available.

No description available.

abstract: Hydrothermal systems are not the typical environments in which organic chemistry is studied. However the organic reactions happening there are increasingly implicated in non-trivial geochemical processes. For example, the origins of life, the formation and degradation of petroleum, and feeding the deep biosphere. These are environments where water is heated and pressurized until it has a polarity more typical of an organic solvent and an increased dissociation constant that decreases its pH. In addition, these environments host many transition metal oxide and sulfide minerals that are not inert bystanders to the chemistry happening around them. This thesis takes from the environment the complicated matrix of hot pressurized water, organic material, and minerals, and breaks it down, systematically, in the laboratory to probe the effects hydrothermal conditions and minerals have on the reactivity of model organic compounds. I conducted experiments at 300°C and 100 MPa using water, organic reactants, and minerals. Methyl- and dimethyl-cyclohexane based reactants provided regio and sterio-chemical markers to indicate reaction mechanisms. Without minerals, I found that the cyclic alkanes undergo a series of reversible stepwise oxidation and hydration reactions forming alkenes-alcohols-ketones, and alkenes-dienes-aromatic rings. I also found the reactions to be reversible; the ketone was readily reduced to the alkane. When the reactions were carried out in the presence of minerals, there were sometimes dramatic effects including reaction rate enhancement and changes in product distributions. Minerals pushed the reaction in the direction of oxidation or reduction depending on the type of mineral used. The hydration reaction could be essentially “turned off” using pyrite (FeS2) and troilite (FeS), which eliminated formation of ketone products. In contrast, hematite (Fe2O3) and magnetite (Fe3O4) favored the hydration reaction and enhanced ketone production. Sphalerite (ZnS) was shown to act as a heterogeneous catalysis for alkane isomerization by activating the C-H bond and increasing reaction rates until thermodynamic equilibrium was reached. This suggests that the types of minerals present in hydrothermal environments will affect the functional group composition of organic material. Minerals and hot pressurized water may also have useful applications in organic chemistry as “green” reactants and catalysts. / Dissertation/Thesis / Ph.D. Chemistry 2013

No description available.

Unresolved Complex Mixtures (UCMs) of hydrocarbons are found in crude and refined oils and in water, sediments and biota polluted with oils. The concentrations of UCMs in oils are significant (e.g. >65% of the aliphatic hydrocarbons in fresh Kuwait crude) and it is perhaps surprising that virtually nothing is known about UCM composition. The present study sought to redress this paucity of information in three main ways: First, following two recent studies of aliphatic UCMs, an investigation of the composition of the "aromatic" UCM of Venezuelan Tia Juana Pesado crude oil was made by spectroscopic (IR, NMR, MS) and oxidative (CrO3, Ru04) methods. These showed that the UCM was, in fact, highly aliphatic. The major compounds identified were alkyl substituted naphthenoaromatics with one and two aromatic rings. Chemical oxidation indicated that the alkyl branched side chains extended to at least twenty three carbon atoms. Second, an investigation into the origins of UCMs was made. The products of hydrous pyrolysis of man-made (polythene) and biogenic (cutan) polymers under conditions proposed previously to simulate catagenesis, included, in the hydrocarbons, high proportions of UCMs (50% - >70%). Hydrous pyrolysis of polythene produced a mixture of saturated (56%) and olefinic (44%) hydrocarbons, whilst pyrolysis of cutan produced hydrocarbon (aliphatic and aromatic; 30-75%) and nonhydrocarbon (70-25%) fractions, both with >60% unresolved components. Oxidative characterisation of these UCMs produced mainly n-acids with somewhat similar results to those found when oil UCMs were oxidised. However, the laboratory generated UCMs are not perfect oil UCM models since some oil UCM oxidation products were not observed in the laboratory models. Finally, an attempt was made to release the geochemical information contained within UCMs. Replicate oxidations of milligram quantities of oil UCMs followed by quantitative GCMS characterisation and multivariate statistical analysis of the resolved oxidation products gave reproducible distributions with >80% similarity. Application of this method to two oil spill incidents where the source oil was known (Milford Haven and the Humber Estuary) gave good correlations between sediment and source. In contrast analysis of Mersey Estuary sediments contaminated with heavy asphaltic oil and of Sullom Voe sediments contaminated with UCMs failed to show any correlation between the sediments and the source oils. However, subsequent re-analysis of the data excluding the major UCM oxidation products (n-carboxylic acids) produced better correlations which indicated that the greatest correlation potential for these UCMs was contained within the minor oxidation products. A similar study of UCMs from two oil seeps from the Siljan Ring region of Sweden failed to show any correlation with potential source rocks, in agreement with biomarker data. This study has extended present knowledge of UCM composition and suggested a mechanism for UCM formation. Furthermore, quantitative and statistical analysis of UCM oxidation products has been shown to be useful for oil identification. There is still much to be learned about UCMs and the subject should provide a fruitful area for further research. Some possible approaches are suggested. Parts of this work have been published (Revill et al. 1991), Organic Geochemistry: Advances and Applications in Energy and the Natural Environment, Manchester University Press

Thesis (Ph. D.)--University of California, San Diego, 1997. / Vita. Includes bibliographical references (leaves 271-300).

Thesis (M.Sc.)-- Memorial University of Newfoundland, 1992. / Restricted until May 1993. Typescript. Bibliography: leaves 131-145. Also available online.

Thesis (Ph. D.)--Earth and Atmospheric Sciences, Georgia Institute of Technology, 2006. / Taillefert, Martial, Committee Member ; Weber, Rodney, Committee Member ; Stack, Andrew, Committee Member ; Benner, Ronald, Committee Member ; Ingall, Ellery, Committee Chair. Includes bibliographical references.

O objetivo deste trabalho foi descrever as principais características da matéria orgânica contida em rochas sedimentares do Jurássico da Unidade Tectono-Estratigráfico Placetas, compreendendo as Formações Constancia e Cifuentes da Bacia Marginal do Norte de Cuba. A combinação do estudo óptico e químico provê uma importante compreensão sobre o tipo de matéria orgânica (material amorfo derivado de algas marinhas versus material de plantas superiores), uma detalhada informação sobre as variações de diferentes fácies sedimentares e o potencial de geração de petróleo em ambas as formações. As análises da matéria orgânica indicaram uma composição diversa para o intervalo estudado. Predominando matéria orgânica amorfa com outros componentes, tais como liptinita foram identificados na Formação Cifuentes. Na Formação Constancia foi identificado material lenhoso (vitrinita e inertinita). A matéria orgânica lenhosa da Formação Constancia está composto por fitoclastos estruturados, a matéria orgânica amorfa é rara. Para a Formação Constancia os dados de pirólise Rock-Eval indicam um baixo teor de índice de hidrogênio, variando desde 36 a 128 mg hidrocarbonetos/g TOC. Os dados plotados no gráfico de índice de hidrogênio versus oxigênio correspondem a matéria orgânica Tipo III. Os valores de temperatura máxima (oC) geralmente corresponderam com outros parâmetros, e indicam algumas variações, causadas pelos precursores da matéria orgânica. O índice de hidrogênio versus índice de oxigênio e parâmetros óticos indicou na parte superior da Formação Constancia uma mistura de querogênio Tipo II e III. Os parâmetros obtidos desde a reflectância de vitrinita, índice de esporos e propriedades da fluorescência sugeriram um estagio imaturo. Os dados de índice de hidrogênio para a Formação Cifuentes mostraram valores médios a altos, variando desde 411 a 929 mg hidrocarbonetos/g TOC. O Índice de hidrogênio versus índice de oxigênio e parâmetros óticos indicou nesta formação uma mistura de querogênio Tipo I e II. Os extratos na Cromatografia líquida mostraram uma predominância dos compostos NSO sobre os hidrocarbonetos saturados e aromáticos para a Formação Cifuentes. Os parâmetros obtidos desde as análises de CG-EM sugerem um estágio imaturo para a Formação. Os biomarcadores refletiram a composição do material gerador e a possibilidade de geração de hidrocarbonetos desde matéria orgânica Tipo I e II em estágios imaturos. A caracterização geoquímica dos extratos orgânicos das rochas geradoras da Bacia Marginal de Cuba permitiu identificar dois grupos de Petróleo, geradas em fácies diferentes do intervalo Kimmeridgiano- Titoniano. Fácies geradoras de afinidade marinha produziram petróleo em cozinhas de geração localizadas na Província gaso-petrolíferas Norte durante o Eoceno. Embora o processo de geração seja responsável por diferenças na composição e nas características na composição do petróleo expulso pelas rochas, observou-se que as maiores modificações nas propiedades dos fluidos foram causadas por processos pósgenéticos. / The purpose of this thesis was to describe the principal characteristic of organic matter contained in sedimentary rocks of the Jurassic Placetas Tectono-Stratigrafic Unit (TSU), comprising of Constancia Formation and Cifuentes Formation (northern Marginal Basin of Cuba). The combined optical/chemical studies have provided important insight on the types of organic matter (amorphous material derived from marine algae versus vascular plant material), detailed information on its variations in different sedimentary facies, petroleum generation potential in both formations. In order to evaluate organic matter content and the type 115 samples were crushed and homogenized to be submitted to total organic carbon determination (TOC %), Rock-Eval pyrolysis, liquid and gas-chromatography, mass spectrometry and determination of optical parameters (vitrinite reflectance, spore color index and fluorescence properties), and semi-quantitative maceral identification. The organic matter analyses indicated a diverse composition for the studied intervals. Predominant amorphous organic matter with other liptinitic component was identified in the Cifuentes Formation and woody material (vitrinitie and inertinitie for the Constancia Formation). The woody organic matter of Constancia Formation is composed primarily of structured phytoclasts, amorphous organic matter is rare. For Constancia Formation Rock-Eval/TOC data indicate that an overall low Hydrogen index, ranging from 36 to 128 mg hydrocarbons/g TOC. Hence they plot in the Type III kerogen area of the oxygen index versus hydrogen index graph. The Tmax (oC) values of the organic matter generally correlate with other maturity parameters, and indicate some variations that appeared to be caused by differences in the precursor organic matter. Hydrogen and Oxygen indices and optical parameters indicate in the upper part of Constancia Formation a mixture of kerogen Type II and III. Parameter obtained from vitrinite reflectance, spore index and fluorescence properties suggest an immature stage. TOC and Rock-Eval data for the Cifuentes Formation show that all have medium to relatively high Hydrogen indices, ranging from 411 to 929 mg hydrocarbons/g TOC. Hydrogen versus Oxygen indices and optical parameters indicate in this formation a mixture of kerogen Type I and II. In the liquid chromatography extracts NSO hydrocarbons are more abundant then saturated and aromatic hydrocarbons for Cifuentes Formation. Parameters obtained from GC-MS analysis suggest an immature stage for Cifuentes Formation strata. Biomarker parameters reflect the composition of the original source material and the possibility of hydrocarbon generation from the organic matter Type I and II in the immature stage. The geochemestry caracterists of petroleum into Bacia Marginal of Cuban was generated by two different fácies os Kimmeridgian-Tithonian source rocks. Oils Kitchens of marine source rocks were developed in the Província gaso-petrolíferas Norte during Eocene. The type of organic matter and the level of thermal evolution of the source rocks produced the compositional differences in the expelled petroleum. However postgenetic processes are the main controls on the current fluid properties in the study área.