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Reactions of Alcohols and Organophosphonates on Tungsten Trioxide Epitaxial FilmsMa, Shuguo January 2003 (has links) (PDF)
No description available.
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Comparative study for iron mediated hydrolysis of 4-nitrophenyl phosphate in cationic and anionic microemulsion mediaMndubu, Yolisile 30 November 2005 (has links)
The study of rapid cleavage of organophosphate esters by metal ions is of great interest as it is the most important reaction in both biological and environmental sciences. A good understanding of organophosphate hydrolysis by metal ions is important as it can be exploited in formulation of useful detoxifying agents for organophosphate contaminants in the environment. The knowledge can also help in developing effective artificial enzymes.
The hydrolysis of 4-NPP in the presence of Ferrous and Ferric ions in o/w microemulsion media was investigated. The reaction was monitored by measuring the absorbance of the 4-nitrophenolate ion produced in the reaction aliquots with time. The order of effectiveness of the ME media towards the hydrolysis of 4-NPP was found to be CME > AME > aqueous in the presence of Fe(II), Fe(III) and Prussian blue at neutral pH. In comparison with individual metal ions used in the investigation, it was found that polymetallic Prussian blue showed enhanced rate of hydrolysis. The degree of effectiveness is as follows; Prussian blue (insoluble) > Prussian blue (soluble) > Fe(III) > Fe(II). The result of the present investigation enriches our understanding of the possible roles polymetallic ions play in hydrolysis reactions and the effect of different reaction media. The reactions mimic the roles of purple acid phosphatases in the hydrolysis of phosphate esters. The application of the above systems for environmental decontamination of organophosphates is also envisaged. / Chemistry / M.Sc.(Chemistry)
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Conversion of Epoxides to episulfides and episelenidesFinkenbine, John Russell January 1974 (has links)
No description available.
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Development of a model cell culture system in which to study early effects of neuropathy-inducting organophosphatesNostrandt, Amy Carol 20 September 2005 (has links)
Certain organophosphorus (OP) compounds produce a delayed neuropathy in man and susceptible animal species after early inhibition and aging of the enzyme, neurotoxic esterase (neuropathy target esterase, or NTE). In this study, the human neuroblastoma cell line, SY-5Y, was examined for its potential to serve as a nonanimal model for the study of the early effects of neuropathy-inducing OPs. For these investigations, the time course of inhibition and aging of NTE after toxicant treatment in neuroblastoma cells was compared to that in brain tissue from the adult chicken, which is the recognized animal model for organophosphorus ester-induced delayed neuropathy (OPIDN). Concentrations of toxicants to be used for treating neuroblastoma cells were determined after observing viability of treated differentiated SY-SY cells incubated for 24 hours with a range of concentrations of an OP (mipafox) that induces neuropathy, an OP (paraoxon) that does not induce neuropathy, a carbamate (aldicarb), a neurotoxicant (β, β’-iminodipropionitrile, or IDPN) that acts by a different mechanism than the OPs, and a cholinergic agonist (carbachol). Treatment concentrations were chosen that caused less than 30% loss of viability over the 24 hour period.
The time course and extent of detrimental effects of mipafox, which induces OPIDN in hens, and the carbamate, aldicarb, on NTE were similar in the SY-5Y cells to those observed in homogenized chicken brain tissue after the same treatments. Mipafox produced rapid inhibition and aging of NTE, with maximal effects occurring within 10 minutes of exposure. Aldicarb inhibited NTE but did not age the enzyme. Instead, spontaneous reactivation was observed both in SY-5Y cells and in brain tissue. None of the other negative control compounds (paraoxon, IDPN, carbachol) affected NTE activity in either SY-5Y cells or chicken brain tissue.
To determine if the neuroblastoma cells could be used to study early events that could lead to modification of OPIDN, NTE inhibition and aging were determined in the differentiated SY-5Y cell line after mipafox was removed. Removal of mipafox from the cell culture medium at 5 minutes after exposure, or earlier, resulted in essentially no NTE inhibition or aging. NTE inhibition and aging were also determined after treatment of the SY-5Y cells with the neuropathy-inducing OP, mipafox, and representatives of 2 classes of compounds (carbamates and calcium channel blockers) previously demonstrated to modify OPIDN in hens. The modifiers (aldicarb and verapamil) were used as a 5 minute pre-treatment, simultaneous treatment, and a 2 minute post-treatment. Significant prevention of most of mipafox-induced NTE inhibition and aging was observed. Effects on NTE inhibition and aging in differentiated SY-5Y cells after each mipafox-aldicarb combination and mipafox-verapamil combination of treatments were similar to those in chicken brain homogenate. These results indicated that both aldicarb and verapamil protected NTE against the early biochemical effects of mipafox that are thought to initiate OPIDN in vivo.
The temporal relationship of NTE inhibition and aging to other detrimental effects on neuroblastoma cells was assessed by the capability of mipafox to cause changes in free intracellular calcium ion concentration, measured using fluorescent calcium probes, and by its capability to alter cell morphology as assessed by phase contrast microscopy. NTE inhibition and aging preceded these changes. Capability to inhibit activity of the neural enzyme, acetylcholinesterase, was also determined.
The results of these studies indicate that the SY-5Y model system shows promise for use in the determination of initial mechanisms contributing to the development of organophosphorus-induced delayed neuropathy. / Ph. D.
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Synthesis and reactivity of peri-substituted phosphines and phosphonium cationsRay, Matthew James January 2013 (has links)
The clean reaction of 5-lithio-6-diisopropylphosphinoacenaphthene (1') with dichlorophosphines, RPCl₂ (R = Ph, Fc, NMe₂, iPr), led to the formation of peri-substituted phosphino-phosphonium chloride salts 2-5. The synthetic utility of these salts was demonstrated in a range of reactions. Mixed tertiary/secondary bis(phosphines) (6 and 7) were prepared by the LiAlH₄ reduction of phenyl or ferrocenyl phosphino-phosphoniums (2 and 3), and the bis(borane) adduct of 6 was prepared by reduction of 2 with BH₃•SMe₂. Reaction of 2 and 3 with a large excess of MeOTf at elevated temperature gave 1,2-diphosphoniums (11 and 12), which were subjected to reduction and co-ordination to a molybdenum(0) centre. An investigation into the co-ordination chemistry of 2 revealed three distinct modes of reactivity. In the reaction with [(nor)Mo(CO)₄] the Mo(0) complex [(2)Mo(CO)₄Cl] (18) was isolated, in which monodentate co-ordination was observed. [PtCl₂(cod)] reacts with the chloride and triflate salts of 2 to form [(2Cl)PtCl₂] (19) and [((2Cl)PtCl)₂][TfO]₂ (21) respectively, both of which show co-ordination of 2 as a bidentate phosphine/chlorophosphine ligand. A palladium(II) dimer (22) in which 2 forms a chelating phosphine/phosphide ligand was isolated from the oxidative addition of 2 to a palladium(0) complex. The geminally bis(peri-substituted) tridentate phosphine (27) was prepared by reaction of 1' with half an equivalent of iPrPCl₂. 27 has a rather strained geometry, and displays restricted dynamics on an NMR timescale, which leads to anisochronicity of all three phosphorus nuclei at low temperatures. Strained bis and tris(sulfides) 28 and 29 and the bis(selenide) 30 have been isolated from the reaction of 27 with sulfur and selenium, respectively. A series of co-ordination complexes, [(27)Cu(MeCN)][BF₄] (32), [(27)PtCl][Cl] (33), [(27)FeCl₂] (34) and fac-[(27)Mo(CO)₃] (35), with tetrahedral, square planar, trigonal bipyramidal and octahedral geometries, respectively, were synthesised. In all of these complexes the tris(phosphine) backbone is distorted, but to a significantly smaller extent that in the chalcogenides 28-30.
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Effect of ronnel on growth, ruminal constituents, and ration digestibility of beef steersPlegge, Steven Dudley. January 1979 (has links)
Call number: LD2668 .T4 1979 P6 / Master of Science
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Gas phase reactions of dimethoxy phosphoryl anion ((CH₃O)₂PO⁻)Dewitt, Krisma Deylene. January 1986 (has links)
Call number: LD2668 .T4 1986 D48 / Master of Science / Chemistry
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Gold complexes obtained from gold ylide preparationsCoetzee, Karolien 04 1900 (has links)
Thesis (MSc)--University of Stellenbosch, 2005. / ENGLISH ABSTRACT: This investigation comprised the synthesis and characterisation of new Au(I)
phosphonium ylide complexes and other compounds formed during coordination
reactions. These complexes could exploit the synergism between two
pharmacologically active substances (gold complex unit and phosphorus ylide) to
furnish an even more active substance.
Four phosphonium salts were prepared, [C6H5CH2PPh3]Br (1),
[Ph3P(CH2)3PPh3]Br2 (2a), p-[{Ph3PCH2}2C6H4]Br2 (3a) and m-
[{Ph3PCH2}2C6H4]Br2 (4a), by reacting PPh3 with the corresponding alkylbromides.
The 13C and 1H NMR spectra of the compounds 1 – 4a indicated that many of the
nuclei are magnetically inequivalent. The aromatic units in PPh3 are normally
identical, but multiple, overlapping signals proved that the corresponding ortho,
meta and para carbon and proton nuclei are in magnetically different environments
from each other. Single crystal structures of salts 3a and 4a were determined.
Different methods were followed to deprotonate the phosphonium salts to afford
the corresponding ylides and to coordinate the ylides to gold precursor
compounds. Most of the reactions yielded inseparable mixtures of products and
pure compounds could not be isolated in large enough quantities for
characterisation by all physical methods. Sufficient crystals for structure
determination by X-ray diffraction were obtained. The product mixtures were
characterised by 1H, 13C and 31P NMR spectroscopy and mass spectrometry.
Characteristic downfield chemical shift changes after coordination of the ylides to
Au(I) were observed for the carbon and phosphorus nuclei, while the protons
displayed upfield shifts.
Reaction of (C6F5)Au(tht) with the salts 1 – 4a, and subsequent deprotonation
yielded the gold(I) ylide complexes [C6H5CH(AuC6F5)PPh3] (5),
[{Ph3PCH(AuC6F5)}2CH2] (6), p-[{Ph3PCH(AuC6F5)}2C6H4] (8), and m-
[{Ph3PCH(AuC6F5)}2C6H4] (9). The crystal and molecular structures of compounds
5 and 9 were determined. Deprotonation of 4a with n-BuLi, followed by reaction with (C6F5)Au(tht) yielded
complexes 9 and [{Ph3PCH2}2C6H4][BrAuC6F5]2 (10). The crystal structure of
compound 10 was determined. Two aurocyclic compounds, [μ-
{(Ph3PCH)2CH2}2Au2][BF4]2 (12) and [μ–{(Ph3PCH)2C6H4}2Au2][BF4]2 (13) were
synthesised by deprotonating salts 2b and 3b with n-BuLi and subsequently
reacting the corresponding bisylides with ClAu(tht).
Reaction procedures in which Ag2O was used as deprotonating agent for the
phosphonium salts 2a, 3a and 4a, yielded mixtures of products. Single crystals of
complexes m-[Ph3PCH(AuC6F5)C6H4CH3] (14), [C6F5Au(tht)] (15) and
[(C6F5)2Au][(Ph3PCH2)2C6H4] (16) were isolated from the reaction mixtures and
subjected to X-ray crystal structure determination. The molecular structure of 15
exhibited unusual aurophilic interactions and represents the first example of a
linear gold chain in which the gold···gold distances systematically alternate
between 3.13Å, 3.31Å and 3.20Å.
Salt 2b was reacted with Ph3PAu(acac) to afford the desired compound,
[{Ph3PCH(AuPPh3)}2CH2](BF4)2 (19), along with [CH3C(O)C(AuPPh3)2C(O)CH3]
(17) and some byproducts. Compound 17 was characterised by single crystal Xray
diffraction.
The fluorobiphenylgold(I) complexes, 4,4’-[(AuPPh3)2C12F8] (21) and 2,2’-
[(AuPPh3)2C12F8] (22) were synthesised by reaction of ClAuPPh3 with the lithiated
2,2’-dibromooctafluorobiphenyl and 4,4’-dibromooctafluorobiphenyl respectively.
The molecular structure of 21 revealed that one of the C–Au–P bond angles
deviates from linearity by 12.5°, probably as a result of π-stacking of the
tetrafluorophenyl rings and steric requirements of the bulky PPh3 units. The other
C–Au–P bond angle is linear [177.9(3)°]. / AFRIKAANSE OPSOMMING: Hierdie studie behels die sintese en karakterisering van nuwe fosfoniumylied
goud(I)-komplekse en ander verbindings wat gedurende koördinasiereaksies
vorm. Sulke komplekse kan sinergisme tussen twee farmakologies-aktiewe
entiteite (goud(I) en fosfoniumylied) om ʼn meer aktiewe verbinding te vorm
meebring.
Vier fosfoniumsoute is berei, [C6H5CH2PPh3]Br (1), [Ph3P(CH2)3PPh3]Br2 (2a), p-
[{Ph3PCH2}2C6H4]Br2 (3a) en m-[{Ph3PCH2}2C6H4]Br2 (4a), deur PPh3 met die
ooreenstemmende alkielbromiedes te reageer. Die 13C- en 1H- KMR-spektra van
dié verbindings toon dat ʼn aantal kerne in aromatiese ringe magneties
onekwivalent is. Normaalweg is die koolstowwe in PPh3-eenhede ekwivalent,
maar meervoudige, oorvleuelende pieke het nou getoon dat die
ooreenstemmende orto-, meta- en para-koolstof sowel as die ooreenstemmende
protonkerne in verskillende magnetiese omgewings voorkom. Die kristalstrukture
van die soute 3a en 4a hierbo is met behulp van X-straal tegnieke bepaal.
Verskillende metodes is gevolg om die fosfoniumsoute te deprotoneer na die
ooreenstemmende yliede en om die yliede dan aan goud-bevattende
uitgangstowwe te probeer koördineer. Die meeste reaksies het nie-skeibare
mengsels gevorm en enkelprodukte kon nie in groot genoeg konsentrasies
geïsoleer word om hulle afsonderlik te karakteriseer nie. Kristalle vir X-straal
kristalstruktuur bepalings is verkry. Die produkmengsels is gekarakteriseer met
behulp van 1H-, 13C- en 31P- KMR-spektroskopie en massaspektrometrie.
Karakteristieke veranderinge in chemiese verskuiwings na laer veldsterktes vir die
koolstof en fosfor kerne is waargeneem na koördinasie van die yliede aan Au(I),
terwyl die protone na höer veldsterktes verskuif het.
Die reaksie tussen (C6F5)Au(tht) (tetrahidrotiofeen) en soute 1 – 4a gevolg deur
deprotonering, vorm die goud-yliedkomplekse [C6H5CH(AuC6F5)PPh3] (5),
[{Ph3PCH(AuC6F5)}2CH2] (6), p-[{Ph3PCH(AuC6F5)}2C6H4] (8), en m-
[{Ph3PCH(AuC6F5)}2C6H4] (9). Die kristalstrukture van komplekse 5 en 9 het al die
molekulêre interaksies daarin blootgelê. Deprotonering van 4a met n-BuLi, gevolg deur reaksie met (C6F5)Au(tht) lewer
komplekse 9 en [{Ph3PCH2}2C6H4][BrAuC6F5]2 (10). Die kristal- en molekulêre
struktuuur van kompleks 10 is bepaal. Twee aurosikliese verbindings, [μ-
{(Ph3PCH)2CH2}2Au2][BF4]2 (12) en [μ–{(Ph3PCH)2C6H4}2Au2][BF4]2 (13) is
gesintetiseer deur gedeprotoneerde bisyliede verkry van 2b en 3b met substitusie
van tht aan die ClAu-eenheid te koördineer.
Reaksieprosedures waarin Ag2O vir deprotonering van die fosfoniumsoute 2a, 3a
en 4a gebruik is, het tot mengsels van produkte aanleiding gegee. Enkelkristalle
van komplekse [Ph3PCH(AuC6F5)C6H4CH3] (14), [C6F5Au(tht)] (15) en
[(C6F5)2Au][(Ph3PCH2)2C6H4] (16) is geïsoleer uit die reaksies en
kristalstruktuurbepalings is uitgevoer. Die molekulere struktuur van 15 toon
ongewone aurofiliese interaksies en verteenwoordig die eerste voorbeeld van ʼn
linieêre goudketting; met goud···goud afstande wat sistematies varieër tussen
3.13Å, 3.31Å en 3.20Å.
Sout 2b is met Ph3PAu(acac) gereageer om die gewenste produk,
[{Ph3PCH(AuPPh3)}2CH2](BF4)2 (19), saam met [CH3C(O)C(AuPPh3)2C(O)CH3]
(17) en ander byprodukte te vorm. Verbinding 17 is as enkelkristalle Xstraalkristallografies
gekarakteriseer.
Die fluorobifeniel goud(I)-komplekse, 4,4’-[(AuPPh3)2C12F8] (21) en 2,2’-
[(AuPPh3)2C12F8] (22), is gesintetiseer deur koördinasie van AuPPh3 aan die
gelitieërde 2,2’-dibromooktafluorobifeniel en 4,4’-dibromooktafluorobifeniel
respektiewelik. Die molekulere struktuur van 21 het getoon dat een van die C-Au-
P bindingshoeke met 12.5º afwyk van 180º, waarskynlik as gevolg van π-
interaksie van die tetrafluorofenielringe en die steriese vereistes van die groot
PPh3-eenhede. Die ander C-Au-P bindingshoek is linieêr [177.9(3)°].
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The pyrolysis of phosphorus-based flame retardants姚世民, Yiu, Sai-man. January 1974 (has links)
published_or_final_version / Chemistry / Master / Master of Philosophy
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Synthesis and applications of polystyrene-supported phosphine and arsine reagentsHe, Song, Helen, 何松 January 2006 (has links)
published_or_final_version / abstract / Chemistry / Doctoral / Doctor of Philosophy
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