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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Aspects of reductive methods in organophosphorus chemistry

Donoghue, Neil, Chemistry, Faculty of Science, UNSW January 1998 (has links)
This study is concerned with the reductive cleavage of tetracoordinated organophos-phorus compounds (either quaternary phosphonium salts R4P+ X??? or tertiary phosphine oxides R3P=O) with either the naphthalene radical (naphthalenide) anion or lithium aluminium hy-dride in THF solution at room temperature (RT). Part 1 examines the reaction of lithium naphthalenide with both phosphonium salts and phosphine oxides. The reaction was dem-onstrated to cleave phenyl groups from both bis-salts and bis-oxides in the presence of 1,2-ethylene bridges; based upon this, parallel syntheses of either 1,4-diphosphabicyclo[2.2.2]oc-tane or its P,P'-dioxide were attempted by using the commercially available ethane-1,2-bis-(diphenylphosphine) as the starting material in each case. Examination of the products ofreductive cleavage of the series of benzylphenylphosphonium bromide [PhnP(CH2Ph)4-n]+ Br???(where n = 0 to 3) with lithium naphthalenide leads to the proposal of a mechanism. Part 2 describes hydridic reductions of both quaternary phosphonium salts and ter-tiary phosphine oxides. Examination of the lithium aluminium hydride reduction of qua-ternary phosphonium salts using 31P-NMR has confirmed tetraorganophosphoranes (R4PH; R = Ph, alkyl) as intermediates in the reaction; in addition, two previously unknown classes of compounds, the triorganophosphoranes R3PH2 and the tetraorganophosphoranates R4PH2???, were also found to be intermediates. The behaviour of bis-phosphonium salts where the phosphonium centres are separated by either 1,2-ethylene or 1,3-propylene bridges are also examined. Formation of a monocation exhibiting a bridging hydride occurs when the cyclic bis-phosphonium salt 1,1,5,5-tetraphenyl-1,5-diphosphocanium dibromide is reacted with li-thium aluminium hydride. Mechanisms are proposed which are consistent with the observed experimental results.
2

Aspects of reductive methods in organophosphorus chemistry

Donoghue, Neil, Chemistry, Faculty of Science, UNSW January 1998 (has links)
This study is concerned with the reductive cleavage of tetracoordinated organophos-phorus compounds (either quaternary phosphonium salts R4P+ X??? or tertiary phosphine oxides R3P=O) with either the naphthalene radical (naphthalenide) anion or lithium aluminium hy-dride in THF solution at room temperature (RT). Part 1 examines the reaction of lithium naphthalenide with both phosphonium salts and phosphine oxides. The reaction was dem-onstrated to cleave phenyl groups from both bis-salts and bis-oxides in the presence of 1,2-ethylene bridges; based upon this, parallel syntheses of either 1,4-diphosphabicyclo[2.2.2]oc-tane or its P,P'-dioxide were attempted by using the commercially available ethane-1,2-bis-(diphenylphosphine) as the starting material in each case. Examination of the products ofreductive cleavage of the series of benzylphenylphosphonium bromide [PhnP(CH2Ph)4-n]+ Br???(where n = 0 to 3) with lithium naphthalenide leads to the proposal of a mechanism. Part 2 describes hydridic reductions of both quaternary phosphonium salts and ter-tiary phosphine oxides. Examination of the lithium aluminium hydride reduction of qua-ternary phosphonium salts using 31P-NMR has confirmed tetraorganophosphoranes (R4PH; R = Ph, alkyl) as intermediates in the reaction; in addition, two previously unknown classes of compounds, the triorganophosphoranes R3PH2 and the tetraorganophosphoranates R4PH2???, were also found to be intermediates. The behaviour of bis-phosphonium salts where the phosphonium centres are separated by either 1,2-ethylene or 1,3-propylene bridges are also examined. Formation of a monocation exhibiting a bridging hydride occurs when the cyclic bis-phosphonium salt 1,1,5,5-tetraphenyl-1,5-diphosphocanium dibromide is reacted with li-thium aluminium hydride. Mechanisms are proposed which are consistent with the observed experimental results.
3

Hyphenation of quantum dots-mediated photodetection and continuous microevaporation with capillary electrophoresis for determination ofpesticide residues and acrylamide in vegetables and food

Chen, Qidan., 陈奇丹. January 2010 (has links)
published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

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