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1
Malhiac, Catherine. "Synthèses sélectives à l'aide de réactifs siliciés (Phosphite-Acétals de cétène silylés). Applications à la préparation d'aminophosphonates et d'esters 2,3-difonctionnels". Rouen, 1993. http://www.theses.fr/1993ROUES007.
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Une méthode générale de préparation de 1-dialkylaminophosphonates est proposée. Cette voie d'accès à partir d'aldéhydes et de dérivés silylés d'amine et de phosphite est générale et directe. Les aminophosphonates sont obtenus avec de bons rendements et une pureté très satisfaisante. L'extension à des aldéhydes 2,3-éthyléniques n'a pas fourni les résultats initialement attendus. Une étude de cette réaction complexe a permis de mettre en évidence la formation majoritaire 1,3-dialkylaminophosphonates, composés nouveaux et potentiellement intéressants. La formation et l'utilisation des carbanions dérivés 1-dialkylaminophosphonates ont conduit à des résultats globalement négatifs. Une seconde partie concerne la préparation sélective d'esters 2,3-difonctionnels via un acétal de cétène silylé porteur d'un groupement oxygéné ou aminé. Les conditions de formation des dérivés silylés des alkoxyesters ont été très nettement améliorées par rapport à la littérature. Leur utilisation pour des réactions de type aldolique avec des aldéhydes et des imines a été étudiée. L'emploi de bromure de zinc à 0°C permet un accès stéréosélectif aux 3-hydroxy(amino)-2-alkoxyesters. Un travail similaire a été réalisé à partir d'iminoesters. La préparation et l'isolement des dérivés silylés sont décrits. Un complément d'étude est effectué avec les aldéhydes et les imines
2
Marriott, Robert Edward. "Accelerated cleavage of phosphate esters". Thesis, University of Cambridge, 1994. https://www.repository.cam.ac.uk/handle/1810/272476.
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Cocks, Sarah. "The electrophilicity and chemistry of phosphate esters". Doctoral thesis, University of Cape Town, 1986. http://hdl.handle.net/11427/16377.
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Bibliography: pages 380-395.A series of phosphate esters containing the E.-nitrophenyl moiety as a leaving group were synthesised and their base catalysed hydrolysis and electron impact-induced fragmentations studied. Heterocyclic ester substituents were present in some of the substrates and in-this sense they were considered as models for a nucleotide molecule containing both the 11 energy-rich11 phosphate bond and the nitrogen heterocyclic ring. The relative reactivity of the phosphorus-E,-nitrophenoxide bond was taken as a probe for nitrogen (pyridyl or quinolyl) participation in the substitution reaction. Although the heterocyclic derivatives show that the introduction of the nitrogen centre increases the rate of base catalysed hydrolysis, the reactivity enhancement is. not significant and results probably from polar effects rather than from intra-molecular catalysis. A comparison of the mass spectra of the heterocyclic and carbocyclic analogues, reveal differences which are significant (in the pyridyl substrates) and dramatic (in the quinolyl substrate) with regard to the fragmentation involving the E.-nitrophenoxy radical expulsion and formation of the corresponding phosphorylium ion. Synthetic approaches towards dimethylaryl and dimethyl(arylalkyl) phosphates are discussed. Nucleophilic displacement at the methyl ester carbon, and in particular the oxygen+ nitrogen methyl group transfer in these substrates occurs readily, complicating the synthetic procedures and lowering the stability of products. Dimethyl-(2-pyridylmethyl) phosphate isomerises in water to the zwitterionic N-methylpyridinium derivative via bimolecular methylation. The kinetics of the reaction were studied and no evidence for intra-molecular methyl transfer was obtained. - ii - The isomerisation of dimethyl-(quinolin-8-yl) phosphate in water also provides evidence for the bimolecular methylation. The crystal and molecular structure of dimethyl-(quinolin-8-yl) phosphate was determined and has revealed that the orientation of the CH 3 groups in the crystal provide no indication for the occurrence of methyl transfer in the solid state. The dynamics of the prepared phosphate derivatives studied in solutions were also investigated by means of mass spectrometry. Fragmentation patterns and their relative contributions are presented and discussed. The effect of solvent on the rates of the reaction between trimethyl phosphate and i) pyridine and ii) 4-(dimethylamino)pyridine, was studied at 25 - 65°C using NMR techniques. The solvents used were DzO, CD30D, CD3CN and DzO/CD30D and DzO/CD3CN mixtures. Water (DzO) is the most effective medium for the methyl transfer reaction. We attribute this to the strong hydrogen bonding between water and the departing dimethyl phosphate anion in the transition state. Activation parameters obtained for the reactions in pure solvents confirmed our interpretation of the hydrogen bonding effect operating in the transition state. Fragmentation of S-arylethyl phosphates has been investigated. A novel feature is exhibited by S-arylethyl phosphorochloridates. They easily decompose thermally yielding 1-chloro-2-arylethanes and/or arylethylenes presumably via concerted C-O and P-Cl bond fission involving a phenonium ion intermediate and expulsion of a metaphosphate species.
4
Butt, Afshan Hena. "Syntheses of analogues of some important phosphate esters". Thesis, University of Birmingham, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369394.
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Bond, Dianne Ruth. "A structure-reactivity study of selected phosphate esters". Doctoral thesis, University of Cape Town, 1985. http://hdl.handle.net/11427/22521.
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Bibliography: pages 201-208.A comparative X-ray analysis study of bis(4-nitrophenyl)-8-quinolinyl phosphate (4), 1-naphthyl-bis(4-nitrophenyl) phosphate (5) and 4-nitrophenyl -8-quinolinyl phosphate (5) was undertaken. In compound (4) donor-acceptor nitrogen-phosphorus interactions change the geometry of the molecule from tetrahedral to quasi trigonal bipyramidal, thus the structure may be considered as an "early stage" of the intramolecular displacement of the 4-ni trophenoxide group. In the diester (6) this interaction is replaced by intermolecular N+ -H...O- hydrogen bonding. In addition the intramolecular non-bonded potential energies of (4) and (5) were calculated and the minimum-energy conformations were compared with those determined by X-ray diffraction. These results confirm the differences observed in the intramolecular interactions operative in (4) and (5). The mass spectra of (4) and (5) are dramatically different with respect to the fragmentation involving expulsion of the 4-nitrophenoxy radical and formation of the corresponding phosphorylitum ion by nitrogen participation. Rate measurements for the base-catalysed hydrolysis of the first P-OPNP linkage show that (4) is not significantly more reactive than (5) and provide no evidence for intramolecular nucleophilic catalysis in the hydrolysis of (4). The crystal and molecular structure of 1-naphthyl acetate (7) was determined. Attempts to grow suitable crystals of 8-quinolinyl acetate (8) failed and therefore its structure could not be elucidated. Possible intramolecular nitrogen - carbonyl carbon interactions operative in (8) could therefore not be established.
6
Haffey, Samuel Fraad 1973. "Numerical models of phosphate esters in the Chattahoochee River". Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/29405.
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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2004.Includes bibliographical references (leaves 124-127).
A numerical model was constructed to assess the magnitude of organophosphoric acid triester sinks in the Chattahoochee River and to identify concentration patterns downstream of point source discharges. The model was built using WASP5 and supporting software packages. The model simulated mass transport of tri-butyl phosphate, tri (2-butoxyethyl) phosphate, and tri (2-chloroethyl) phosphate within a reach of the river bounded by Buford Dam and Northern Atlanta. Several potential mechanisms for the removal of the phosphate esters from the water column were considered. These were biodegradation, sorption to settling solids, volatilization, and oxidation by free radicals. Of the three phosphate esters considered by the model, tri (2-chloroethyl) phosphate was predicted to be the most resistant to degradation by natural attenuation processes. Tri (2- butoxyethyl) phosphate showed the most potential for degradation in surface waters. Biodegradation and sorption to settling solids were predicted to be the most effective processes for the removal of tri (2-butoxyethyl) phosphate. Concentration patterns at several locations downstream of point source discharges were predicted for the three compounds. Concentration patterns were found to be affected by the diurnal flow variation caused by the operation of two hydroelectric dams within the modeled reach.
by Samuel Fraad Haffey.
M.Eng.
7
Iagrossi, Anna. "Stereochemical studies of reactions of phosphate and thiophosphate esters". Thesis, University of Leicester, 1988. http://hdl.handle.net/2381/33748.
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Nucleophilic substitution reactions involving phosphate monoesters have been investigated. Two general syntheses of O-alkyl or O-aryl [16O,18O] thiophosphate monoesters are reported. An independent and general method for the determination of the enantiomeric excess of isotopically chiral thiophosphate monoesters has been developed and the absolute configurations of the diastereoisomers of (2R)-O-(O-ethyl thiophosphoryl)-3, 4S-dimethyl-5S-phenyl-l,3,2-oxazaphos- pholidin-2-one have been assigned. The solvolysis of p-nitrophenyl [R-16O,18O] thiophosphate in ethanol gives rise to ethyl [16O, 18O] thiophosphate with a large degree of racemisation of configuration (~80%). This observation is consistent with the formation of a thiometaphosphate intermediate of finite life-time which is then trapped by ethanol with accompanying loss of stereochemical integrity. This study provides the first direct evidence for a monomeric thiometaphosphate in protic solvent. During the course of developing the stereochemical analysis, it was noted that O-ethyl thiophosphate reacts with cis-2-chloro-3, 4-dimethyl- 5-phenyl-l, 3, 2-oxazaphospholidin-2-one with ca. 10% inversion and 90% retention of configuration. This system also reacts with fluoride ion with complete loss of stereochemistry. Cis-2-chloro-3, 4-dimethyl-5- phenyl-l, 3, 2-oxazaphospholidin-2-one and the corresponding 2-thione are epimerised to the more stable trans isomers by pyridine and other nucleophilic catalysts. These reactions require an in-line exocyclic displacement at a phosphorus centre held in a five-membered ring. Nucleophilic substitution at di- and tri-esters have also been studied. The stereochemical course of the hydrolysis of the 1, 3, 2-dioxaphosphor- inan-2-one system involving good leaving groups such as chloride and fluoride occur with inversion of configuration via an in-line mechanism, whereas hydrolysis of this system involving poor leaving groups occurs with retention of configuration via a pseudorotation mechanism.
8
Tarrat-Iché, Nathalie. "Etude théorique des mécanismes d'hydrolyse des esters de phosphate". Toulouse 3, 2005. http://www.theses.fr/2005TOU30212.
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Les esters de phosphate jouent un rôle fondamental du point de vue biologique. Cependant, les mécanismes d'hydrolyse des monoesters restent encore très controversés (principalement en raison de la grande stabilité de ces derniers en solution). Les méthodes de la chimie quantique moderne constituent une alternative de choix pour élucider, au niveau atomique, les mécanismes de ces réactions. Dans ce mémoire nous avons validé l'utilisation de calculs quantiques (DFT/B3LYP) couplés à un modèle continu de solvant pour étudier les mécanismes d'hydrolyse des tri- et diesters de phosphate, ces derniers faisant intervenir un intermédiaire ou un état de transition de type phosphorane. La même approche est appliquée aux mécanismes d'hydrolyse des monoesters de phosphate. Par comparaison avec les résultats obtenus dans le cas des di- et triesters, cette étude montre que la réactivité d'un ester protoné peut différer de celle de son dérivé méthylé, pour lequel intervient un " intermédiaire " phosphoranePhosphate esters play a fundamental role in many biological processes. Unfortunately, the detailed understanding of how monoesters hydrolysis reactions proceed is still subject of debate (this is largely due to the kinetic stability of phosphate monoesters). Modern quantum chemistry methods seems to be a good alternative to elucidate these reaction mechanisms. In this thesis, we have validated the use of quantum calculation (DFT/B3LYP) coupled with a continuum solvation model by studying hydrolysis mechanism of phosphate tri- and diesters. In these cases, the scientific community is unanimous on the fact that they involve pentacovalent phosphorane intermediate or transition state. The same approach is applied to the hydrolysis mechanism of phosphate monoesters. By comparison with the results obtained in the case of the di- and triesters, it is observed that the reactivity of a protonated ester can differ from that of its methylated derivative, for which a phosphorane “intermediate” is occuring
9
Walsh, Owen Anthony. "Computer simulation of phosphate ester hydrolysis reactions". Thesis, University of Oxford, 2001. http://ora.ox.ac.uk/objects/uuid:bf94b5d1-c550-4af5-849c-4438000450aa.
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Phosphate esters and their hydrolysis reactions underpin many of the most important reactions in biology and have therefore been the focus of continued research. In this thesis, a range of theoretical studies on two phosphate ester hydrolysis reactions is presented. Particular attention is paid to the role of solvent in these reactions. The first reaction studied is the hydrolysis of dimethyl phosphate. A study using density functional theory examines three possible mechanisms for this reaction in the gas phase and the presence of solvent is also considered through the use of reaction field methods. The base-catalysed mechanism for this reaction receives further attention and the reaction energy profile in solution is adiabatically mapped using two different hybrid QM/MM potentials. The use of a QM/MM potential facilitates an atomistic representation of the solvent. Another study determines the potential of mean force for this reaction by simulating the reaction using QM/MM molecular dynamics simulations in conjunction with umbrella sampling methods. Both QM/MM studies demonstrate that, in solution, the rate-determining step for the base-catalysed reaction is the cleavage of the bond between the phosphorous and the leaving group. The QM/MM studies also established that the reaction proceeds via the formation of a short-lived pentacoordinated intermediate species. The second reaction studied was the base-catalysed hydrolysis of methyl ribose phosphate, a realistic model of the nonenzymatic hydrolysis of RNA. Since the hydrolysis of thio-substituted analogues of RNA have been the study of many experimental studies probing the mechanism of RNA hydrolysis, theoretical studies of the hydrolysis of two thio analogues of methyl ribose phosphate are also presented. The results of these studies provide valuable insight into the mechanism of RNA hydrolysis and concludes that the cleavage of P-O5' bond corresponds to the reaction transition state.
10
Lad, Chetan Shantilal. "Mechanics and reactivity of phosphate ester hydrolysis". Thesis, University of Sheffield, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.269339.
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Keita, Ousainou Ansumana. "The synthesis of new phenylhydroxyiodonium phosphates from (diacetoxyiodobenzene) and dialkyl phosphates and their use in the α-phosphorylation of ketones to mono-ketol phosphates". University of Akron / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=akron1197558427.
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Tossell, Katie Jayne. "Catalysis of phosphate ester hydrolysis through hydrogen bonding". Thesis, University of Sheffield, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.578696.
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This thesis describes the investigation of the effect of hydrogen bonding on the rate of phosphoryl transfer in the reaction of diethyl 8-dimethylamino-I-naphthyl phosphate 3 with a nucleophile. The study of the hydrolysis of triester 3 is in the literature; triester 3 is catalysed by the dimethylammonium general acid, with a rate acceleration of almost 106 in comparison to the hydrolysis of diethyl I-naphthyl phosphate. 58 To ascertain whether the reactivity of triester 3 is specific to this system, the methylation of the amine in triester 3 was altered. Triesters diethyl 8- amino-I-naphthyl phosphate 6 and diethyl 8-methyIamino-l-naphthyl phosphate 7 were synthesised and their reaction with water and hydroxylamine was studied. It is concluded that the effect of methylation of the amine on the rate of P-O cleavage in triester 3 is insignificant, and that the hydrogen bond donor ability of the amino proton donor is not an important factor in increasing the rate of P-O cleavage; the energy of triesters 6H+, 7H+ and 3H+ are very similar. The hydrolysis of 8-dimethylamino-l-naphthyl phosphate 5m is also known to exhibit general acid catalysis by the dimethylammonium group." To ascertain whether the effect of methylation of the amine on the rate of p-o cleavage in monoester 5mis also insignificant, the hydrolysis of 8- rnethylamino-I-naphthyl phosphate 27m was studied. It is concluded that methylation of the amino general acid in triester 6H+ and monoester 5m has no significant effect on the rate of phosphoryl transfer, regardless of the different transition states that are formed. By studying the hydrolysis of monoester 36d it is concluded that the reactivity of monoester 5m is also dependent on the proton donor ability of the amino group. The elimination of various functionalised 8-amino-I-tetralone-3-sulfonic acids with hydroxide has been studied. There is a clear difference between the rates of elimination of the tetralones upon varying the proton donor ability of the amino group. No apparent trend relating the rate of elimination to the proton donor ability of the hydrogen bond donor, or to the pKa of the conjugate acid of the tetralones is observed.
13
Zaluski, Jordan A. "Improved Synthesis of Bis (2,2,2-trifluoroethyl) Phosphono Esters". Youngstown State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1471443290.
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Chernobryva, Mariya. "Development of metal-based catalysts for phosphate ester hydrolysis". Thesis, Queen Mary, University of London, 2016. http://qmro.qmul.ac.uk/xmlui/handle/123456789/24631.
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The development of artificial metal-based catalytic systems for phosphate ester hydrolysis is the central focus of this work. Currently, significant efforts are concentrated in this field of research as phosphate esters are remarkably stable linkages and are found in the molecules of life DNA and RNA, as well as in toxic compounds, such as nerve agents, pesticides and herbicides. The thesis describes the design and synthesis of a series of N-functionalised azamacrocyclic ligands suitable for metal chelation. An efficient strategy is described, where an aminal precursor is used for the selective N-alkylation of a cyclen moiety, in order to obtain non-bridged and ethylene-bridged cyclen-based ligands. Thereafter, the synthesis of the tetraamine Co(III) and Zn(II) aqua-hydroxo complexes is detailed, followed by a study of the coordination chemistry of Co(III)-based cyclen complexes. Moreover, the redox behaviour of such complexes is investigated by means of cyclic voltammetry. The hydrolytic activity of these complexes towards phosphate ester substrates is then presented. The hydrolytic activity of the cyclen-based Co(III) complexes is shown to be extremely sensitive to modest changes in the ligand structures, even though they do not affect the coordination geometry. Cyclen-based Zn(II) complexes appear to have no appreciable activity towards hydrolysis of phosphate mono- and di-esters under the same experimental conditions. The effect of incorporating polymerisable tetraamine Co(III) complexes into the nanogels on their hydrolytic efficiency is also investigated using molecular imprinting technique. The design and synthesis of structurally similar tripodal 'click' ligands, suitable for the preparation of a range of d-block metal complexes is then presented. The coordination chemistry of the complexes of these structurally similar ligands is explored using a range of techniques including single crystal X-ray crystallography, EPR and UV-Vis spectroscopies and cyclic voltammetry. Due to their poor aqueous solubility various ways to improve this are also examined. Future developments of the metal-based catalysts are then discussed including key issues to be addressed to achieve their potential applications in biological systems.
15
Yun, Joanne W. 1970. "Modelling studies of magnesium-dependent phosphate ester processing enzymes". Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/38776.
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Fry, Fiona Helen 1972. "Metal complexes based on macrocyclic ligands and their ability to hydrolyse phosphate esters". Monash University, School of Chemistry, 2002. http://arrow.monash.edu.au/hdl/1959.1/8279.
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Kramer, Ulrike. "Complexation of divalent copper, zinc and calcium ions by phosphate esters in aqueous solution". Doctoral thesis, University of Cape Town, 1988. http://hdl.handle.net/11427/17083.
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The role of metal ions as catalysts for numerous biochemical reactions has been the subject of many investigations. One of the most important classes of ligands are phosphate esters. In this thesis I describe the investigation of some phosphate ester-metal ion equilibria. Formation constants for the complexation of p-nitrophenyl phosphate, phenyl phosphate, 1-naphthyl phosphate, α-D-glucose-1'-phosphate, glycerol-2-phosphate, methyl phosphate, 8-quinolyl phosphate, 8-quinolyl methyl phosphate, triphosphate and fluorotriphosphate with protons, copper, zinc and calcium ions were determined by potentiometry. In addition, the complexation of 1-naphthyl phosphate, 8-quinolyl phosphate and 8-quinolyl methyl phosphate with nickel and cobalt ions was also studied. Protonation enthalpies and copper complexation enthalpies of p-nitrophenyl phosphate, phenyl phosphate, 1-naphthyl phosphate, α-D-glucose-1'-phosphate, glycerol-2-phosphate and methyl phosphate were determined by calorimetry. A correlation between the nucleophilicity of the ester group and the magnitude of the stability constants of the proton, copper and zinc complexes of p-nitrophenyl phosphate, phenyl phosphate, 1-naphthyl phosphate, α-D-glucose-1'-phosphate, glycerol-2-phosphate and methyl phosphate is found and explained in terms of electronic induction effects, i.e. by polarisation of the phosphate oxygens by the ester group. The calorimetric results show that the desolvation of ligand and metal ion during the complexation plays an important role. The possibility of similar correlations for complexes of triphosphates is also discussed.
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PATOIS, CARL. "Alkylation-metallation des esters et amides phosphoriques : la 1,3-dimethyl-2-oxo-1,3,2-diazaphospholidine precurseur d'acrylates z". Palaiseau, Ecole polytechnique, 1992. http://www.theses.fr/1992EPXX0005.
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L'alkylation-metallation des phosphates par les alkyllithiens permet d'acceder a des carbanions alpha-phosphonyles, qui peuvent etre utilises apres fonctionnalisation comme precurseurs dans la reaction de wittig-horner. Son application a differents composes phosphores cycliques et acycliques est etudiee. La selectivite z:e de la reaction de wittig-horner pour preparer des acrylates est ensuite evaluee en faisant varier l'habillage de l'atome de phosphore. Le choix de diazaphospholidines (bisamides cycliques) permet l'obtention selective d'acrylates z avec de bons rapports z:e (>90:10) dans des conditions specifiques qui ont ete definies: li#+, thf, milieu dilue, rechauffement intermediaire du reactif, basse temperature, emploi eventuel de tetramethylpiperidine. Une comparaison de la selectivite induite est effectuee entre la diazaphospholidine et differents cycles phosphores, ainsi que le reactif de still et gennari (cf#3ch#2o)#2p(o)ch(r)co#2r'
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Williams, Daniel M. "Phosphate ester hydrolysis promoted by lanthanide (III) and transition metal complexes". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0015/NQ55393.pdf.
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Williams, Daniel M. "Phosphate ester hydrolysis promoted by lanthanide (III) and transition metal complexes". Thesis, McGill University, 1999. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=35551.
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Phosphate ester linkages are omnipresent in nature and are found in many biologically important molecules such as DNA, RNA and ATP. Many enzymes that hydrolyze phosphate esters are activated by metal ions. Since the structure of biological enzymes can be quite complicated, it is often useful to work with simpler artificial metalloenzymes to help elucidate the mechanisms by which phosphate ester hydrolysis is activated by metals.In principle, simple dinuclear metal complexes could hydrolyze phosphate esters by double Lewis acid activation or by a combination of single Lewis acid activation and metal-hydroxide activation. These two mechanisms are kinetically indistinguishable. In this study, two different phosphate substrates are used to distinguish these mechanisms.
Lanthanide (iii) salts have proven extraordinarily effective in accelerating the rate of phosphate ester hydrolysis by several orders of magnitude. Consequently, there has been much effort in recent years to develop a ligand that would bind lanthanides so as to further improve their ability to hydrolyze phosphates. These efforts have met with limited success. Reported here is a dinuclear lanthanide (iii) complex which hydrolyzes BNPP (bis p-nitrophenyl phosphate) with unprecedented reactivity at pH 7.0 and 25°C.
A mononuclear copper (ii) 6,6'-diamino-2,2 '-bipyridyl complex is synthesized which gives one of the fastest rate accelerations reported for hydrolyzing 2',3 '-cAMP. A hydrogen bonding mechanism is proposed for the acceleration of the rate of hydrolysis of the cyclic phosphate.
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Lindner, N. M. "Affinity purification and use of alkaline phosphatase for phosphate ester synthesis". Thesis, Open University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234750.
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Dudaczek, Jürgen. "Oktapeptide als neue Organokatalysatoren zur Hydrolyse von Phosphaten und Estern". kostenfrei, 2009. http://www.opus-bayern.de/uni-wuerzburg/volltexte/2009/3517/.
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Eberhardt, Luc. "New chiral amino-phosphanes : Applications in asymmetric hydrogenation of alpha-dehydroamino acid esters". Université Louis Pasteur (Strasbourg) (1971-2008), 2007. http://www.theses.fr/2007STR13081.
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Ce mémoire est consacré à la synthèse de nouveaux ligands chiraux phosphorés et à l’étude de leur comportement en catalyse homogène d’hydrogénation asymétrique d’esters méthyliques de dérivés d’acide cinnamique. Ces composés de type aminophosphines ou phosphoramidites se comportent soit comme des ligands P(III) monodentate lorsqu’ils sont issus d’acides aminés ou de la dinaphtho[2,1-d:1',2'-f][1,3,2]dihydroazépine, soit comme des ligands P(III) chélatant dans le cas des dérivés d’hydrazine. L’étude des leurs propriétés complexantes a permis de montrer qu’ils sont capables de se coordiner à des ions métalliques de configuration d8 tels que le rhodium(I) ou le platine(II). La mise en œuvre de ces ligands en hydrogénation asymétrique a permis de mettre en évidence quatre propriétés importantes: 1) l’excès énantiomérique dépend principalement du fragment asymétrique substituant l’atome de phosphore à savoir le groupe 1,1’-binaphthalene-2,2’-diyl dans le cas présent; 2) l’utilisation d’un substituant chiral dinaphtho[2,1-d:1',2'-f][1,3,2]dihydroazépino permet cependant d’obtenir des excès énantiomériques plus élevés qu’avec un ligand phosphoramidite comportant un groupement amino achiralThis thesis is devoted to the synthesis of new chiral phosphorus ligands and their study in the homogeneous catalytic asymmetric hydrogenation of cinnamic acid methyl ester derivatives. These aminophosphanes and phosphoramidites behave either as monodentate P(III) ligands when they are derived from amino acids or from dinaphtho[2,1-d:1',2'-f][1,3,2]dihydroazepine, or as P(III) chelating ligands when they are derived from hydrazines. The study of their metal-complexes showed that these compounds are able to coordinate d8 metal ions such as rhodium(I) or platinum(II). The catalytic properties of the abovementioned ligands as regards asymmetric olefin hydrogenation can be summarized as follows: 1) the enantiomeric excess is highly dependant on the nature of the asymmetric fragment substituting the phosphorus atom, in this case the 1,1'-binaphthalene-2,2'-diyl group; 2) the use of a chiral dinaphtho[2,1-d:1',2'-f][1,3,2]dihydroazepino substituent results in higher enantiomeric excesses compared to phosphoramidite ligands containing an achiral amino group
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Mdhlovu, Johan. "Optimisation of water-in-oil microemulsion formulation stabilised by nonylphenol ethoxylated phosphate ester". Diss., Pretoria : [s.n.], 2005. http://upetd.up.ac.za/thesis/available/etd-03062006-093400.
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Åström, Hans. "Studies on phosphate ester cleavage and development of oligonucleotide based artificial nucleases (OBAN's) /". Stockholm, 2004. http://diss.kib.ki.se/2004/91-7349-935-8/.
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Tarico, Daniel Joseph 1965. "Dispersion of alumina powder in secondary butyl alcohol with a phosphate ester surfactant". Thesis, The University of Arizona, 1990. http://hdl.handle.net/10150/277307.
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Most ceramic articles are produced by first dispersing powders in a suitable liquid, forming the dispersion (by casting, molding, extrusion, etc.), drying and then firing the body to its final sintered state. It has been recognized that dispersion characteristics strongly affect the green body which in turn determines properties of fired ceramic, and recently, dispersion science has become quite important in the development of ceramics processes. In this thesis research, colloidal size alumina powder was dispersed in secondary butyl alcohol with a phosphate ester dispersant. Dispersions were produced in an attrition mill and evaluated by viscometry and sedimentation. These dispersions were "optimized" by adjusting surfactant concentration and milling time. Zeta potential measurements indicated stabilization was not purely electrostatic. It was noted that a small amount of water added to the dispersions dramatically affected dispersion rheology. With slight water addition high solids content slurries (40 vol. percent) could be produced with rheological characteristics desirable for casting. Solution conductivity measurements were made to provide insight into the possible mechanism by which water affects dispersion stability.
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Myrex, Ronald Dustan. "Synthesis and characterization of phosphorus-containing inorganic polymers". Birmingham, Ala. : University of Alabama at Birmingham, 2007. https://www.mhsl.uab.edu/dt/2007r/myrex.pdf.
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Thesis (Ph. D.)--University of Alabama at Birmingham, 2007.Additional advisors: Houston Boyd, Tracy Hamilton, Christopher Lawson, Charles Watkins. Description based on contents viewed Feb. 8, 2008; title from title screen. Includes bibliographical references.
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Machairas, Alexandros 1980. "The UV/H2O2 advanced oxidation process in UV disinfection units : removal of selected phosphate esters by hydroxyl radical". Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/29410.
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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2004.Includes bibliographical references (leaves 96-97).
In this work, the issue of how to remove phosphate esters from drinking water is examined. From the various treatment processes available, the oxidation of phosphate esters through hydroxyl radical generated by the UV/H202 process applied at a UV disinfection unit was selected for evaluation. The second-order rate constants of the reactions of two phosphate esters, Tri(2-butoxyethyl) phosphate (TBEP) and Tri-2-chloroethyl phosphate (TCEP) , with hydroxyl radical were estimated from our experimental data to be 2.1000 M-1s-1 and 2 109 M-is-1 respectively A comprehensive kinetic model of the oxidation process was derived. Finally computer simulations were used to exhibit the potential of this treatment process and to examine the effects of pH, total carbonate species concentration, initial hydrogen peroxide dose, and light intensity on its efficiency. The results are not very encouraging when a UV unit designed for disinfection is used. For typical values of pH and total carbonate species (pH=8 and CT=5' 10-4 M) the 1 s order rate coefficients for removal of the phosphate esters are 6.3 10-4 (s-1) for TBEP and 6.3 10-5 (s-1) for TCEP. If higher light intensity is applied in the reactor (50 times higher), and initial hydrogen peroxide dose of 10-3 M and CT remains 5 10-4 M, the 1st order reaction rate coefficients become 2.9 10-2 (s-1) and 2.9-10-3 (s-1) for TBEP and TCEP respectively.
by Alexandros Machairas.
M.Eng.
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Lambert, Emilie. "Préparation de phosphinates difluorés, isostères des diesters de phosphate. Application à la synthèse de dinucléotides modifiés". Rouen, 2013. http://www.theses.fr/2013ROUES040.
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Les oligonucléotides modifiés (ONMs) constituent une classe d'agents thérapeutiques potentiels capables de réguler sélectivement l'expression d'un gène, selon les processus d'ARN interférent ou d'anti-sens. Ainsi, pour améliorer leur comportement en milieu physiologique, il est possible de remplacer le lien phosphate par un isostère. Ce travail de thèse propose ainsi l'étude d'un nouveau motif difluorophosphinyle, complètement non-hydrolysable, en remplacement du groupe phosphate. Dans une première partie, une voie d'accès originale aux difluoro-H-phosphinothioates a été mise au point sur un substrat modèle. Ces composés soufrés se sont avérés plus stables que leurs analogues oxygénés dans les conditions de P-alkylation. Par la suite, les difluorophosphinates ont été obtenus avec succès par une réaction de Mickaelis-Becker. Une oxydation de ceux-ci a permis l'obtention des difluorophosphinates correspondants. La synthèse de deux partenaires furanosiques est ensuite réalisée afin d'accéder, par cette stratégie, à un dérivé bis-furanosique comprenant un lien difluorophosphinate. L'introduction stéréocontrôlée de deux thymines a finalement permis d'accéder à un analogue de dinucléotide, précurseur d'ONM. L'étude conformationnelle par modélisation a mis en évidence le potentiel isostérique de la fonction difluorophosphinate, en tant qu'analogue de phosphateAntisense strategy and small interfering RNAs use modified oligonucleotides (MONs) which specifically recognize and bind ti mRNA strands to modulate genes expressions. To enhance oligonucleotide drug properties, one important strategy is the replacement of the phosphate group by isosters. This PhD work aimed at developing a strategy to obtain a new, essentially non-hydrolysable difluorophosphinyle unit, to replace the diesterified phosphate group. First, a methodology involving thionylated analogues was developed on model substrate. These hitherto unreported compounds are more stable under alkylation conditions. Conversion of phosphinothioyle group delivered successfully the desired difluorophosphinates. The requisite furanosyles units were prepared and the above strategy was applied to generate a fully protected 3,5-bisfuranosyl difluorinated phosphinate. Stereocontroled glycosylation with thymine reactant led to the dinucleotide analogue. Calculation studies highlighted the isosteric potential of difluorophosphinate linkage, as new analogue of diesterified phoshate group
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Conibear, Anne Claire. "Synthesis and evaluation of novel inhibitors of 1-Deoxy-D-xylolose-5-phosphate reductoisomerase as potential antimalarials". Thesis, Rhodes University, 2013. http://hdl.handle.net/10962/d1008282.
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Malaria continues to be an enormous health-threat in the developing world and the emergence of drug resistance has further compounded the problem. The parasite-specific enzyme, 1-deoxY-D-xylulose-S-phosphate reductoisomerase (DXR), has recently been validated as a promising antimalarial drug target. The present study comprises a combination of synthetic, physical organic, computer modelling and bioassay techniques directed towards the development of novel DXR inhibitors. A range of 2-heteroarylamino-2-oxoethyl- and 2- heteroarylamino-2-oxopropyl phosphonate esters and their corresponding phosphonic acid salts have been synthesised as analogues of the highly active DXR inhibitor, fosmidomycin. Treatment of the heteroarylamino precursors with chloroacetyl chloride or chloropropionyl chloride afforded chloroamide intermediates, Arbuzov reactions of which led to the corresponding diethyl phosphonate esters. Hydrolysis of the esters has been effected using bromotrimethylsilane. Twenty-four new compounds have been prepared and fully characterised using elemental (HRMS or combustion) and spectroscopic (1- and 2-D NMR and IR) analysis. A 31p NMR kinetic study has been carried out on the two-step silylation reaction involved in the hydrolysis of the phosphonate esters and has provided activation parameters for the reaction. The kinetic analysis was refined using a computational method to give an improved fit with the experimental data. Saturation transfer difference (STD) NMR analysis, computer-simulated docking and enzyme inhibition assays have been used to evaluate the enzyme-binding and -inhibition potential of the synthesised ligands. Minimal to moderate inhibitory activity has been observed and several structure-activity relationships have been identified. In silica exploration of the DXR active site has revealed an additional binding pocket and information on the topology of the active site has led to the de novo design of a new series of potential ligands.KMBT_363
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Lopes, Shailesh M. "Synthesis, characterization and applications of fats and oil derived phase change materials". Diss., Columbia, Mo. : University of Missouri-Columbia, 2007. http://hdl.handle.net/10355/5938.
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Thesis (Ph. D.)--University of Missouri-Columbia, 2007.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on March 20, 2009) Vita. Includes bibliographical references.
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Eriksson, Ulrika. "Contribution of polyfluoroalkyl phosphate esters (PAPs) and other precursor compounds to perfluoroalkyl carboxylates (PFCAs) in humans and the environment". Doctoral thesis, Örebro universitet, Institutionen för naturvetenskap och teknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-52010.
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Per-and polyfluoroalkyl substances (PFAS) are anthropogenic compounds that have been spread all over the world. The use of fluorotelomer compounds, short-chained homologues, and other PFASs with perfluorinated moieties has emerged recent years. One of these emerging compound classes is polyfluoroalkyl phosphate esters (PAPs), which have the ability to degrade into persistent PFCAs. The aim of this thesis was to assess the contribution of PAPs and other precursors to the exposure of PFCAs to humans and the environment. The main objective was to analyze a wide range of PFAS in human serum, wild bird eggs, indoor dust, waste water, and sludge. There was a significant contribution from selected precursors to the total amount of PFASs in the abiotic compartments indoor dust, waste water, and sludge. Levels of PAPs found in house dust exceeded those of PFCAs and perfluorosulfonic acids (PFSAs), revealing PAPs as a world-wide important exposure source. A net increase was during waste water treatment was observed for several PFASs in Swedish waste water treatment plants. Together with presence of precursor compounds and intermediates in the influent water and the sludge, this suggest that degradation of PFCA precursors contributed to the increase of PFCAs. Detection of precursors in human serum, together with slow declining trends of PFCAs, revealed an ongoing exposure of PFCAs to the general population of Australia. The diPAPs and the FTSAs were also detected in raptor bird eggs from Sweden from both the terrestrial and the freshwater environment. The precursors concentrations and patterns observed reveal that current regulatory measures are insufficient for the purpose of protecting humans and the environment from PFASs exposure.
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Jubian, Vrej. "Relationship between ligand structure and reactivity for copper (II) complex mediated hydrolysis of phosphate diesters, carboxylic esters, and amides". Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=74656.
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The efficiencies of several Cu(II) complexes in promoting the hydrolysis of bis(2,4-dinitrophenyl) phosphate (BDNPP) have been compared. Copper complexes of the type ((L)Cu(OH$ sb2$)$ sb2$) $ sp{2+}$, where L represents a bidentate diamine ligand, can be effective in promoting the hydrolysis of BDNPP. Furthermore, the activity of the Cu(II) complex is sensitive to the ligand structure. The structure-reactivity relationship has been explained in terms of a detailed mechanism of the reaction.The complex (Cu(2,2$ sp prime$-dipyridylamine)(OH$ sb2$)$ sb2$) $ sp{2+}$ efficiently catalyzes the hydrolysis of carboxylic esters (4-nitrophenyl acetate, methyl trifluoroacetate, and methyl acetate). Methyl acetate, when bound to the copper complex, is hydrolyzed at a rate that is comparable to the k$ sb{ rm cat}$ values for chymotrypsin catalyzed hydrolyses of esters. The hydrolysis of N,N-dimethylformamide by (Cu(2,2$ sp prime$-dipyridylamine)(OH$ sb2$)$ sb2$) $ sp{2+}$ at neutral pH, 100$ sp circ$C, proceeds at least two hundred times faster than that by (Cu(2,2$ sp prime{:}6 sp prime,2 sp{ prime prime}$-terpyridine)(OH$ sb2 ) rbrack sp{2+}.$ A detailed mechanism of the reaction has been given to explain the structural requirements of a metal catalyst necessary for hydrolyzing esters and amides, and a mechanism for Carboxypeptidase A catalyzed hydrolysis of peptides has been proposed.
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Seifert, Gabrielle Victoria. "Amorphous Calcium Phosphate Composites of a Phenylalanine-based Poly(ester urea) Poly(1-PHE-6)". University of Akron / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1460388339.
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Le, Guevel Eric. "Substitution nucléophile de composés organophosphorés par les ions oximate : application en décontamination douce". Versailles-St Quentin en Yvelines, 1997. http://www.theses.fr/1997VERS0017.
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La particularité du comportement nucléophile des ions oximate est mise en évidence dans plusieurs réactions de substitution avec des centres phosphorés. Celle-ci est conforme aux résultats publiés dans la littérature concernant l'attaque, par ces oxyanions, de composés électrophiles modèles à centres carbones. Ces résultats indiquent clairement que : - conformément al̀eur nature de nucléophile alpha, la réactivité nucléophile des ions oximate est très supérieure à celle mesurée avec des nucléophiles classiques de même basicité. - l'extra réactivité nucléophile de la fonction oximate est pratiquement maximale des que l'on atteint une basicité de pka 8,3-8,6 et ce, quelle que soit la nature de l'électrophile mis en jeu. Au-delà, la nucléophile apparaît au mieux constante ou même décroit à des basicités de l'ordre de pka 10. Nous proposons d'expliquer ce comportement en terme d'effet d'énergétique de de solvatation. La mise au point d'une nouvelle méthode de suivi cinétique, basée sur l'utilisation d'une électrode spécifique, a permis d'élargir nos travaux à la destruction de composés organophosphorés toxiques. Les résultats recueillis soulignent le grand intérêt des ions oximate pour la décontamination douce d'agents organophosphorés toxiques. En effet, la réactivité élevée de ces nucléophiles à des niveaux d'acidité proches de la neutralité permet la destruction complète des toxiques dans des conditions peu agressives pour l'environnement. La meilleure compréhension de la particularité du comportement des ions oximate vis-à-vis de centres phosphorés nos permet donc une critique objective des conditions dans lesquelles elles ont été jusqu'à présent utilisées et nous proposons que les solutions décontaminantes soient désormais basées sur l'efficacité d'oximes faiblement basiques.
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Campagne-Mina, Jean-Marc. "Synthèse de phosphino et phosphonopeptides haptènes pour la production d'abaymes à activité protéolytique". Montpellier 2, 1994. http://www.theses.fr/1994MON20254.
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Les peptides incluant un motif phosphinique ou phosphonique, analogues de l'etat de transition d'une liaison peptidique, sont utilises dans la conception d'inhibiteurs d'enzymes et dans la production d'anticorps catalytiques. Dans l'optique de produire des anticorps a activite proteolytique, ce travail est consacre a la synthese de divers phosphino et phosphonopeptides. L'etude de la reactivite des fonctions phosphiniques et phosphoniques avec les reactifs de la famille du bop, a permis de developper une strategie de synthese originale, en phase solide, des phosphino et phosphonopeptides. Dans le cas des acides phosphoniques, nous avons, en outre, mis au point une nouvelle voie de synthese des phosphonates mixtes. L'etude du mecanisme de cette reaction a mis en evidence la formation d'un ester de benzotriazole, dont la reactivite, vis a vis des amines et des alcools, est inversee par rapport a celle des esters de benzotriazole d'acides carboxyliques. Les premiers resultats immunologiques, concernant les caracteristiques des serums obtenus, sont egalement rapportes dans ce travail. L'activite catalytique des anticorps est en cours d'evaluation
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Issenhuth, Jean-Thomas. "Catalyse énantiosélective et polymérisation : Etude de la réactivité de complexes de cuivre et d'aluminium". Université Louis Pasteur (Strasbourg) (1971-2008), 2008. https://publication-theses.unistra.fr/public/theses_doctorat/2008/ISSENHUTH_Jean-Thomas_2008.pdf.
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Baudouin, Jacky. "Synthèse et réactions sélectives d' α oxoesters β fonctionnels et de leurs dérivés : nouveaux synthons et réactifs dans les séries du phosphore, du soufre et de l'azote". Rouen, 1987. http://www.theses.fr/1987ROUE5050.
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L'étude de différentes voies d'accès à la structure phosphonopyruvate a été réalisée. Cette dernière est obtenue après réaction des α diméthylphosphates α , β époxy alcanoates de méthyle (produits nouveaux) avec un trialkylphosphite. La synthèse de phosphates d'énol dérivés des esters pyruviques a été reprise et généralisée; son extension aux dérivés fonctionnels des esters pyruviques a permis de préparer deux séries nouvelles (soufrée et azotée) de phosphates d'énol fonctionnels. Le comportement de ces différents composés en présence de réactifs nucléophiles usuels a été étudié et a permis de mettre en évidence, dans le cas du méthylate de sodium, la réaction de formation d'une structure nouvelle correspondant aux orthoesters pyruviques et à leurs homologues soufrés; le mécanisme de cette transformation est étudié et discuté. Enfin, la préparation des β dialkylamino oxo esters a été reprise, étudiée et étendue à quelques termes nouveaux. La réduction de ces composés a été réalisée et les conditions de réduction sélective de la fonction carbonyle ont été mises au point. Une étude de la stéréosélectivité de cette réaction et du mécanisme de celle-ci sont proposés en accord avec les résultats relevés dans la littérature
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Chung, Yongseong. "Diene substituent effects on the retro Diels-Adler reaction and dimeric Co(III) complex promoted phosphate ester hydrolysis /". The Ohio State University, 1989. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487671108308264.
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Coulombeau, Agnès. "Synthèse de phosphinodipeptides". Montpellier 2, 2000. http://www.theses.fr/2000MON20147.
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Intervenant dans de nombreuses pathologies humaines, les metalloproteases sont, aujourd'hui, considerees comme des cibles therapeutiques de premiere importance. Dans la recherche de nouveaux inhibiteurs de metalloproteases a zinc, nous avons etudie la synthese d'analogues phosphinodipeptidiques dont l'interet reside d'une part dans la tres forte analogie existant entre leur structure et celle des substrats des metalloproteases a zinc dans leur etat de transition tetraedrique, et d'autre part, dans la possibilite d'incorporation en syntheses paralleles dans des structures peptidiques plus etendues. Afin d'obtenir des esters phosphores aussi stables que possible, nous avons d'abord effectue la synthese pas-a-pas de phosphinates d'ethyle. Mais, a cause de la difficulte a purifier les intermediaires hydrogenophosphinates d'ethyle, instables a divers traitements, nous n'avons pas poursuivi dans cette voie. Nous avons alors effectue une etude de la reaction conduisant au reactif de depart, l'hypophosphite d'alkyle, pour l'obtenir avec la meilleure purete possible. Une methode generale de synthese one-pot a ainsi ete elaboree pour la preparation des phosphinates de methyle obtenus sous forme protegee impliquant l'addition de l'hypophosphite de methyle sur des imines puis celle des hydrogenophosphinates resultants sur des esters ,-insatures. Cette methode permet de faire varier les substituants aliphatiques ou aromatiques sur les carbones en et en du phosphore avec de bons rendements en produits isoles. Des deprotections totale ou selectives fournissent les produits de depart pour des syntheses peptidiques ulterieures par elongation du cote n-, p-, ou c-terminal. Enfin, quelques essais de synthese asymetrique ont ete realises a titre exploratoire, visant a diminuer le nombre de diastereoisomeres obtenus lors de la synthese.
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Sang, Yijun. "Cross-linked resistant starch from high-amylose corn starch, and structures of phosphate esters in cross-linked resistant wheat starch determined by ³¹P NMR spectroscopy /". Search for this dissertation online, 2004. http://wwwlib.umi.com/cr/ksu/main.
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PRADINES, ANTOINE. "Phosphorylation enzymatique de polyols par la phosphatase alcaline optimisation de la synthese de glycerol-1-phosphate". Toulouse 3, 1989. http://www.theses.fr/1989TOU30015.
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Mise au point et optimisation d'une nouvelle methode de phosphorylation enzymatique, utilisant la phosphatase alcaline. Cette methode permet la monophosphorylation de nombreux derives mono ou polyhydroxyles avec des rendements et une regioselectivite eleves. Pour ce faire, un bioreacteur enzymatique a ete utilise contenant l'enzyme immobilise sur support
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Sadik, Mourad. "Étude ultramicroélectrochimique des esters phosphoriques comme solvant : application a la détermination de l'indice d'acide des lubrifiants par amperométrie à une ultramicroélectrode de platine". Nancy 1, 1992. http://www.theses.fr/1992NAN10245.
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Les techniques ultramicroélectrochimiques engageant des électrodes de très faibles dimensions ont été appliquées à l'analyse des réactions dans les esters phosphoriques comme solvants; ces milieux réactionnels sont largement utilisés comme lubrifiants ou comme solvants d'extraction liquide/liquide (ex. Tbp). Les caractéristiques électrochimiques du trimethylphosphate (tmp), du tributylphosphate (tbp), et des solvants industriels de lubrification (fyrquels) ont été précisées (domaines d'electroactivité, systèmes de référence. . . ). Compte-tenu des très faibles chutes ohmiques (dues à l'utilisation des ultramicro-électrodes), il est possible de faire des mesures in situ sans ajout délibéré d'électrolyte. Le comportement des acides hcl, hclo#4, ch#3so#3h, adpp ainsi que celui des amines a été précisé. Le coefficient de transfert de solvatation des ions cl#, agcl#2#, ag#+, cu#2#+, zn#2#+, fe#2#+ et fe#3#+ ont permis de caractériser les propriétés solvatantes de ces milieux qui se rapprochent du dmf. Les conditions de détection ampérométrique de l'indice d'acide résultant de l'hydrolyse des esters phosphoriques industriels ont été précisées et la mise au point d'un dispositif de détection in situ et contrôle de la dégradation des lubrifiants fyrquels a été préconisée
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Borges, Larissa Braga Bueno. "Aplicação de catalisador químico heterogêneo na transesterificação de miscelas etanólicas de óleo de soja". Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/11/11141/tde-10112014-113518/.
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A produção de biodiesel em larga escala deve impulsionar a pesquisa e desenvolvimento de tecnologias mais limpas e de menor custo relacionadas à obtenção e controle de qualidade desse combustível. A extração de óleo de soja com o solvente etanol resulta na produção de uma miscela rica em óleo, semi-refinada, que pode ser diretamente esterificável para produzir ésteres etílicos, sem a necessidade de evaporação do solvente. A transesterificação de miscelas por catálise heterogênea pode adicionar os benefícios do reaproveitamento do catalisador. O objetivo deste trabalho foi promover a otimização da transesterificação de miscelas etanólicas ricas em óleo de soja sob catálise heterogênea do fosfato de potássio tribásico (K3PO4), analisar o rendimento obtido com reutilizações do catalisador recuperado e promover sua regeneração. Foi realizada a adequação de uma técnica para quantificação do teor de ésteres, envolvendo separação por cromatografia em camada delgada associada à análise de coloração por espectrofotometria. Amostras de biodiesel de teor de ésteres conhecido foram oxidadas pela ação do dicromato de potássio em ácido sulfúrico, quantificando-se a mudança de cor do reagente de laranja para verde. O dicromato ácido foi capaz de oxidar completamente a fração isolada de ésteres, determinando os teores corretamente, à variação máxima de 2,05%, estabelecendo uma relação fixa de 0,08?g de dicromato consumido para cada ?g de biodiesel. A transesterificação com K3PO4 foi otimizada, alcançando rendimentos de 96,4% nas condições de RM 1:12, catalisador 5% e agitação 400rpm em 100 minutos de reação. O K3PO4 é um catalisador prático, pois sua utilização não requer etapas de preparação, no entanto apresentou indícios de solubilização no meio reacional. Os rendimentos obtidos com catalisador reutilizado foram baixos para todos os tratamentos de lavagem, sendo a lavagem moderada o escolhido devido a menor variabilidade de massa recuperada após as reutilizações. O catalisador regenerado resultou em rendimentos de 58,72%, equivalente a 84% do obtido com catalisador novo. O K3PO4 teve sua atividade prejudicada pelos fenômenos de saponificação e emulsificação, exigindo que mudanças sejam realizadas para que sua reutilização seja viável. A utilização de catalisadores heterogêneos e miscelas etanólicas lipídicas tem o potencial para redução dos custos de produção devido a obtenção de óleo vegetal sem a necessidade de refino e ao reaproveitamento de catalisador.Large scale biodiesel production motivates research and development of cleaner low cost technologies related to the manufacture and quality control of this fuel. The extraction of soybean oil with the solvent ethanol results in the production of a rich in oil semi-refined miscella that can be directly esterified to produce ethyl esters, without the need of solvent evaporation. The transesterification of micellae by heterogeneous catalysis can add the benefits of reusing the catalyst. The aim of this work was to promote optimization of the transesterification of ethanolic soybean oil miscellae under heterogeneous catalysis of tripotassium phosphate (K3PO4), analyze the yield of reaction with reused catalyst and promote its regeneration. A technique for quantification of the ester content involving separation with thin layer chromatography and color analysis by spectrophotometry was also performed. Biodiesel samples of known ester content were oxidized by the potassium dichromate in sulfuric acid, and the change in color of the reagent from orange to green was quantified. The acid dichromate was able to completely oxidize the isolated fraction esters, correctly determining their content with a maximum variation of 2.05%, and revealing a fixed relation of 0,08?g of dichromate consumed per ?g of biodiesel. The transesterification with K3PO4 was optimized, reaching yields of 96.4% under the conditions of 1:12 molar ratio, 5% catalyst and 400rpm stirring in 100 minutes of reaction. The use of K3PO4 does not require preparation steps, but showed evidence of solubility in the reaction medium. Yields obtained with reused catalyst were low for all treatments, being the moderate washing (LM) chosen due to lower variability of mass recovered after reuses. The regenerated catalyst resulted in yields of 58.72%, equivalent to 84% of that obtained with fresh catalyst. The K3PO4 had its activity impaired by saponification and emulsification phenomena, requiring changes to make its reuse feasible. The use of heterogeneous catalysts with ethanolic rich in oil miscellae has the potential to reduce production costs due to the production of vegetable oil without the need of refining and the reuse of solid catalyst.
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Roux, Philippe. "Rôle de l'estérase neurotoxique dans les polyneuropathies rétardées induites par les organo-phosphores". Paris 5, 1994. http://www.theses.fr/1994PA05P235.
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Lakhrissi, Mohammed. "Dichloromethylenation de lactones et d'esters : synthèse et réactivité". Nancy 1, 1993. http://www.theses.fr/1993NAN10176.
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La dichloromethylenation des lactones et d'esters a été mise au point par l'utilisation d'un nouveau système de réactifs: triphenylphosphine-tetrachlorure de carbone. Ce système permet de transformer les lactones en présence des groupements o-benzyl, o-methylmethylether et d'esters encombres comme les pivaloyles et 4-phenylbenzoyles. Les nouvelles conditions que nous avons mises au point permettent la transformation des lactones -1,4; 1,5 et des acétates. Le motif dichloromethylene se prête bien à des transformations chimiques telles que la réduction, la chloration, la coupure oxydante ainsi que la cyclopropanation
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Chan, Wing-sum. "Resonance Raman, time-resolved resonance Raman and density functional theory study of Benzoin diethyl phosphate, selected P-Hydroxy and P-methoxy substituted phenacyl ester phototrigger and model compounds". Click to view the E-thesis via HKUTO, 2005. http://sunzi.lib.hku.hk/hkuto/record/B36198821.
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Chan, Wing-sum, i 陳穎心. "Resonance Raman, time-resolved resonance Raman and density functional theory study of Benzoin diethyl phosphate, selected P-Hydroxy and P-methoxy substituted phenacyl ester phototrigger and model compounds". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2005. http://hub.hku.hk/bib/B36198821.
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Goumain, Sophie. "Application de l'activation électrochimique du magnésium à l'électrosynthèse d'alcènes chlorés et de cyclopropylphosphonates fonctionnels : perspectives et limitations". Rouen, 1999. http://www.theses.fr/1999ROUES065.
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Les deux premières parties de ce travail concernent la réactivité des carbanions issus de la réduction électrochimique du dichlorophosphonoacétate de triéthyle et du dichlorométhylènediphosphonate de tétraéthyle vis-à-vis de composés carbonylés et d'accepteurs de Michael. Des esters carboxyliques et phosphoniques α-chloro-α,β-insaturés ont ainsi été synthétisés en utilisant le phénomène d'activation électrochimique du magnésium selon une réaction de Horner-Wadsworth-Emmons. La technique utilisant une cellule à compartiments séparés a été utilisée pour l'électrosynthèse de cyclopropylphosphonates α-carboxylates et de 1,1cyclopropanediylbis(phosphonates) 2-fonctionnalisés. Dans la troisième partie, le phénomène d'activation électrochimique du magnésium a été mis en oeuvre pour l'électrosynthèse de cyclopropylphosphonates α-fluorés et α-arylés. La quatrième partie aborde l'électrosynthèse asymétrique de ces composés à partir d'inducteurs chiraux phosphorés.
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Milde, Bianca. "(Ethynyl-)Ferrocenyl Phosphine Palladium Complexes and (Bis-)Phosphinoimidazol(e/ium) Compounds and their Application in Homogeneous Catalysis". Doctoral thesis, Universitätsbibliothek Chemnitz, 2012. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-90521.
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Die vorliegende Dissertation beschäftigt sich mit der Synthese, der Charakterisierung und der Anwendung neuartiger Phosphane in homogenkatalytischen Reaktionen. Dabei wurden die Ferrocenyl- und Ferrocenylethinylphosphan-Palladium und Ferrocenylethinylphosphan-Ruthenium Komplexe in der Palladium-vermittelten Mizoroki-Heck- und Suzuki-Miyaura-Reaktion sowie der Ruthenium-katalysierten Synthese von β-Oxopropylestern verwendet. Der Schwerpunkt lag dabei auf der Untersuchung des Einflusses der elektronischen und räumlichen Eigenschaften der Phosphanliganden auf die Aktivität und Produktivität der entsprechenden Katalysatoren in den homogenkatalytischen Reaktionen.
Weiterhin beschäftigt sich die vorliegende Arbeit mit der Synthese und Charakterisierung von funktionalisierten (Phosphino)Imidazol und (Phosphino)Imidazolium Salzen und deren Anwendung in der Suzuki-Miyaura-Reaktion. Dabei wurde neben der Untersuchung des Einflusses der Position der Phosphanylgruppe und der unterschiedlichen Substituenten ebenfalls die Auswirkung von elektronenziehenden und -schiebenden Gruppen am Phosphanrest untersucht. Die neutralen Mono- und Diphosphane wurden außerdem in der Kreuzkupplung von Arylhalogeniden und in der Synthese räumlich anspruchsvoller Biaryle verwendet. Des Weiteren wurden die (Phosphino)Imidazolium-Salze als Liganden in der Suzuki-Miyaura-Reaktion in ionischen Flüssigkeiten als Reaktionsmedium angewendet, um die Möglichkeit des Recyclings der Katalysatorphase zu untersuchen.