Dissertations / Theses on the topic 'Oxygenation Reactions'

O-acyl-N-benzyllactamides are obtained in good yield by reaction of 4-benzyl-5-methyl-1,3-oxazolidine-2,4-diones with Grignards reagents and with lithium alkyls. Three alkanes and two ethers were oxidised with ozone in dichloromethane solution or in aqueous pH 3 suspension. Cyclodecane and cyclododecane were converted into the corresponding cycloalkanones. n-decane was converted into a mixture of isomeric n-decanones and carboxylic acids. An ester was formed from the ethers. Hence, one of the methylene groups of these substrates is generally converted into a carbonyl group. Some of these reactions have preparative value. The oxidation of naphthalene in dichloromethane or acetonitrile with excess ozone gives phthalic aldehyde, 2-formyl benzoic acid and phthalic anhydride. Small amounts of the (E)- and (Z)-isomer of 3-phenyl-(2-formyl)-propenal and are also observed in some cases. The reaction is faster in acetonitrile than in dichloromethane owing to the higher solubility of ozone in the former solvent. The reaction is faster on lowering the temperature because of the increase of the concentration of ozone in solution at lower temperature. With a 1:1 or a 1:2 naphthalene:ozone ratio high conversion and low selectivity for the anhydride is observed. The ozonation of cyclohexane in dichloromethane or acetonitrile gives cycloxexanone, cyclohexanol and acidic material. The influence of solvent, reactant concentration, amount of ozone, temperature, reaction time is studied. A reaction mechanism is proposed based on the results of a simulation of the reaction energetics. The ozonation of N-phenylmorpholine in dichloromethane or acetonitrile produced a lactame and a diformylderivative. These products derive from the attack of ozone at the heterocyclic ring. The reaction mechanism has been investigated by DFT calculations which show that the reaction occurs through the insertion of ozone at the carbon-hydrogen bond of a methylenic group of the morpholine ring. The regioselectivity is due to the to the significantly lower energy barrier calculated for the attack of ozone in α to nitrogen than in α to oxygen. Also, the energy barrier decreases with increasing the polarity of the solvent, accounting for the higher reaction rate observed for the reaction carried out in acetonitrile than in dichloromethane. The ozonation of trans- and cis-decalin in dichloromethane or acetonitrile gives the corresponding 9-hydroxydecalinns, 2- and 3-decalones and acidic material. The influence of solvent, reactant concentration, amount of ozone, temperature, reaction time is studied. A reaction mechanism is proposed based on the results of a simulation of the reaction energetics. The N,N bis(salicylidene)ethylenediaminocobalt(II) catalysed oxidative carbonylation of para-substituted aromatic primary amines at 100 °C in methanol gives carbamates in high yields. In presence of excess dimethylamine also N-aryl-N’,N’-dimethylureas are formed. In methylene chloride moderate yields in isocyanate are obtained. 1-methylbenzylamine gives the carbamate and the urea in high yield. i-propylamine gives only the urea. An α-aminoalcohol gives a 1,3-oxazolidin-2-one. Aliphatic secondary amines react faster and give carbamates in methanol and ureas in methylene chloride. The turnover frequency is also measured in two cases.

Sous l'influence conjuguee de la lumiere et de l'oxygene, une solution de polymere et de bleu de methylene subit plusieurs transformations. La photooxygenation conduit uniquement a des hydroperoxydes allergiques: interaction entre l'etat triplet du bleu de methylene et les groupes hydroperoxydes portes par les chaines macromoleculaires. Cinetique et mecanisme

Existant en tant que pratique sportive, l’apnée est également de plus en plus utilisée dans d’autres activités sportives dont la natation, à l’entraînement et/ou en compétition. Toutefois, les réponses à l‘apnée dynamique ont été peu explorées lors d’efforts physiques intenses, en particulier en natation. L’objectif de ce travail de thèse est donc d’étudier sur le terrain en situation de nage (étude 1 et 2) et en laboratoire (étude 3) lors d’un exercice intermittent de pédalage, les réponses physiologiques, psychologiques et ergogéniques à l’apnée aiguë apparaissant lors d’efforts intenses. Le métabolisme a été notamment évalué à partir de la mesure de l’oxygénation tissulaire, de paramètres sanguins et de marqueurs hormonaux. Les principaux résultats de ces études montrent qu’en apnée la performance dépendrait de la capacité des sujets à maintenir leur fréquence cardiaque et que l’effort est globalement perçu comme plus dur. L’apnée n’induisait pas d’augmentation de la lactatémie, sans doute en lien avec l’absence de modification de l’extraction musculaire de l’oxygène. Au niveau cérébral, le maintien de l’oxygénation expliquerait la non modification du temps de réaction en apnée. Enfin toutes nos études ont révélé une désaturation artérielle significative en apnée, dès la première apnée de 10 secondes (étude 3) mais sans effet de la capacité d’apnée (étude 1) ou de l’intensité de nage (étude 2) suggérant que la durée compenserait l’intensité. Il serait donc intéressant d’étudier ultérieurement les effets respectifs du couple intensité/durée et les effets chroniques d’un entraînement comportant un exercice intermittent intense lors d’apnées dynamiques
Existing as a sport practice, apnea is also increasingly used in other sports activities including swimming, training and/or competition. However, responses to dynamic apnea have been little explored during intense physical exercise, especially in swimming. The objective of this thesis is to study, in the field in swimming situations (study 1 and 2) and in the laboratory (study 3) during an intermittent cycling exercise, the physiological, psychological and ergogenic responses to acute apnea appearing during intense exercises. Metabolism was especially assessed by measurement of tissue oxygenation, blood parameters and hormonal markers. The main results of these studies show that in apnea the performance would depend on the ability of the subjects to maintain their heart rate and that the exercise is globally perceived as harder. Apnea did not induce an increase in lactatemia, probably related to the lack of modification of the muscle extraction of oxygen. At the cerebral level, the maintenance of the oxygenation would explain that the reaction time is not altered with apnea. Finally, all our studies revealed a significant arterial desaturation in apnea at the first repetition of the 10-second apnea (study 3) but without the effect of apnea capacity (study 1) or swimming intensity (study 2) suggesting that the duration would compensate for the intensity. It would therefore be interesting to study later the respective effects of the intensity/duration pair and the chronic effects of training involving intense intermittent exercise during dynamic apneas

Cette thèse vise à comprendre et modéliser l'usure par fretting à sec d'un contact plan/plan en acier soumis à diverses conditions de chargement, notamment le nombre de cycles de fretting, l'amplitude de glissement, la pression de contact, la fréquence de glissement, la taille du contact et l'orientation du contact par rapport à la direction de glissement. La cinétique d'usure a été étudiée en variant ces conditions qui affectent les mécanismes d'usure, y compris la formation et l'éjection de débris en plus de la tribo-oxydation, de l'abrasion et de l'adhésion. Cette investigation montre que, dans la plupart des cas, une trace d'usure composite est détectée combinant une usure oxydo-abrasive et adhésive. Une formulation de cinétique d'usure a été proposée en étendant empiriquement les lois d'usure classiques existantes en tenant compte des paramètres de chargement susmentionnés. Néanmoins, cette formulation supposait une description du taux d'usure global moyen négligeant la nature composite abrasive-adhésive de l'usure et, par conséquent, les variations locales du taux d'usure le long de la trace d’usure.La réalisation d'une description dynamique de la cinétique d'usure intégrant la répartition de l'usure abrasive et adhésive nécessite de comprendre l'évolution de ces mécanismes. Pour atteindre cet objectif, le Concept d’Oxygénation de Contact (COC) est supposé. Cette approche suggère que l'adhésion apparaît dans le centre de contact si la pression partielle de dioxygène est inférieure à une valeur seuil. Dans les côtés latéraux, où les molécules de dioxygène sont présentes en quantité suffisante, l'oxydation et l'abrasion prévalent. Le COC a été quantifié à l'aide du paramètre «distance d'oxygène» défini comme la largeur moyenne de la couronne d'abrasion externe. L'évolution de la distance d’oxygène a été formalisée par rapport aux conditions de chargement en utilisant une formulation de loi puissance qui a permis de prédire les transitions d'usure pour les surfaces lisses et macro-texturées. Cependant, cette formulation est restée paramétrique; par conséquent, une interprétation plus physique du COC est recherchée.Pour atteindre ce dernier objectif, une approche d'Advection-Dispersion-Réaction (ADR) est introduite pour modéliser le transport d'oxygène dans l'interface de fretting en supposant que le lit de débris est un milieu poreux compact. Cette approche ADR a non seulement prédit la répartition de l'abrasion et de l'adhésion, mais a également capturé la transition de l'usure abrasive pure à l'usure adhésive-abrasive mixte pour différentes conditions de chargement
This PhD thesis aims at understanding and modelling dry fretting wear of a flat-on-flat steel contact submitted to various loading conditions including number of fretting cycles, sliding amplitude, contact pressure, sliding frequency, contact size and contact orientation with respect to the sliding direction. Fretting-wear kinetics was studied by varying these loading conditions which affect wear mechanisms including debris formation and ejection in addition to tribo-oxidation, abrasion and adhesion. This investigation shows that, in most cases, a composite wear scar is detected combining oxidative-abrasive and adhesive wear. A wear-kinetics model was proposed by empirically extending the existing classical wear laws taking into account the aforementioned loading parameters. Nevertheless, this model assumed an averaged global wear-rate description neglecting the composite abrasive-adhesive nature of wear and consequently the inherited wear-rate local variations along the fretting scar.Achieving a dynamic wear-kinetics description incorporating the partition of abrasive and adhesive wear necessitates understanding the evolution of these mechanisms. To attain this goal, Contact Oxygenation Concept (COC) is assumed. This approach suggests that adhesion appears in the contact center if the di-oxygen partial pressure is below a threshold value. In the lateral sides, where di-oxygen molecules are sufficient, oxidation and abrasion prevail. COC was quantified using the “oxygen-distance” parameter defined as the averaged width of the external abrasion-corona. Oxygen-distance evolution was formalized versus loading conditions using a power-law formulation which allowed predicting wear transitions for plain and macro-textured surfaces. However, this formulation remained parametric; hence, more physical interpretation of COC is pursued.To achieve the latter objective, an advection-dispersion-reaction approach (ADR) is introduced to model oxygen transport within fretting interface assuming debris bed as a compact porous medium. This ADR approach not only predicted the partition of abrasion and adhesion but also captured the transition from pure abrasive to mixed abrasive-adhesive wear at different loading conditions

Deux types de générateurs chimiques d'oxygène singulet en milieu aqueux ont été étudiés, en vue d'applications dans les domaines de la biologie et de la synthèse organique. Des substrats naphtaléniques, solubles dans l'eau, permettent de stocker l'oxygène singulet efficacement puisqu'ils fixent (1)O:(2) entre 0 et 20°c, et sont totalement régénérés par thermolyse à 40°c, en libérant l'oxygène dont 50% est à l'état singulet. Ce type de générateur constitue une source douce et "propre" de (1)O(2), permettant l'étude de l'intervention de (1)O:(2) dans les processus biologiques. La "décomposition" de H(2)O(2) par les ions molybdate constitue un moyen pour transformer efficacement H(2)O(2) en oxygène singulet (100%). Sur des considérations cinétiques, nous avons montré que la dismutation s'effectue via l'intermédiaire peroxo MoO(6)(2-). Cette source minérale peut remplacer avantageusement la photo-oxygénation et peut être utilisée pour "charger" en (1)O:(2) les substrats naphtaléniques décrits ci-dessus.

碩士
國立中央大學
化學學系
106
The meso-tetrakis(pentafluorophenyl) N-confused porphyrin (NCTPFPP 1) was synthesized using literature method, and the other meso-tetrakis(pentafluorophenyl) N-confused oxo-porphyrin (NCTPFPOP 2) was firstly isolated and purified from the same reaction. Compound 2 was characterized by NMR and FT-IR spectroscopy methods, ESI-MS techinique and single-crystal X-ray diffraction determination to confirm a unique structure. Solvent-dependent tautomeric forms were studied on compounds 1 and 2. Compound 1 contains one amino NH proton and one inner C-H at an opposite site (2H form) in DMF, while compounds 2 has two amino NH and one inner C-H (3H form). The electron withdrawing and donating meso-substituents of N-confused porphyrin resulted in blue-shift and red-shift, respectively, on the UV-vis absorption spectrum. Cyclic voltammetery studies of 1 and meso-tetrakis(phenyl) N-confused porphyrin (NCTPP) were carried out to elucidate the positive shift on the redox potential for electron withdrawing meso-substituents of N-confused porphyrin. In the case of NCTPP, two reversible wave were observed on the positive side and one reversible and one half-reversible wave were oberserved on the negative side. In the case of 1, no reversible wave was observed on the positive side but two reversible wave were observed on the negative side. In addition, the NH chemical shift varied with concentration of 2 indicated the equilibrium between monmer and dimer. The iron complexes of meso-tetrakis(pentafluorophenyl) N-confused porphyrin, (HCTPFPPH)FeIIBr (1a) and (HCTPFPP)FeIIIBr (1b), were synthesized and characterized by 1H NMR, UV-vis spectra and single-crystal X-ray diffraction technique. The electron withdrawing meso-substituents of 1a resulted in blue-shift on the Soret band and Q band of UV-vis absorption spectrum, while the iron complex of meso-tetrakis(p-methoxylcarbonylphenyl) N-confused porphyrin with electron donating meso-substituent resulted in red-shift on the Soret band and Q band of UV-vis absorption spectrum. The 1a and 2a with electron withdrawing meso-substituents have less amount of peaks found in paramagantic 1H NMR spectrum than (HCTPPH)FeIIBr and (HCTPP)FeIIIBr. The oxidation rate of 1a is slower than (HCTPPH)FeIIBr, which correspond to proposed mechanism. In the proposed mechanism, losing electron is rate determining step. Cyclic voltammetery studies were carried out for 1a, 1b, (HCTPPH)FeIIBr, (HCTPP)FeIIIBr and (HCTPPO)FeIIIBr. There are two, one and two reversible waves in (HCTPPH)FeIIBr, (HCTPP)FeIIIBr and (HCTPPO)FeIIIBr, respectively. Furthermore, (HCTPPH)FeIIBr and (HCTPP)FeIIIBr have one elcetorn transfer in high potential redox processes and two electrons transfer in low potential redox processes. Besides, there are two and four reversible redox steps in 1a and 1b. Finally, we used (HCTPP)FeIIIBr, (HCTPPO)FeIIIBr, 1b and TPPFeIIICl as catalysts to activate dioxygen and compared oxygen atom transfer reactive activity with triphenylphosphine (PPh3). We found almost no triphenylphosphine oxide (OPPh3) product was produced when using TPPFeIIICl as catalyst and blank without any complex. However using N-confused Iron complexes as catalysts could produce OPPh3. In increasing order of reaction rate are (HCTPP)FeIIIBr, (HCTPPO)FeIIIBr and 1b. It means N-confused Iron complexes may undergo oxygen atom transfer reaction catalyzed by high valence FeV=O complexes intermediates during the reaction wih oxygen. In this process, 1b showed highest reactive activity with more stable and higher activity intermediate.

碩士
國立臺灣大學
化學研究所
102
Intramolecular cyclization of propargyl acetate 1 containing a carbonyl group on the aryl ring induced by [Ru]Cl has been investigated. The reaction gives rise to the ruthenium carbene complex 2a in the presence of NH4PF6 in dichloromethane via an exo-dig cyclization of the ketone functionality with the triple bond. Elaboration of this process is revealed by running the reaction at high temperature or other solvents such as acetone, tetrahydrofuran or acetonitrile, yielding only ruthenium carbene complex 2a. This indicates that intramolecular cyclization takes place by