An investigation of reactions directed towards the synthesis of 2-methyl-2-(methylthio)propanal oxime
- Authors: Whittaker, Ruth Eleanor
- Date: 1995
- Subjects: Pesticides -- Synthesis , Insecticides , Aldicarb -- Synthesis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4322 , http://hdl.handle.net/10962/d1004980 , Pesticides -- Synthesis , Insecticides , Aldicarb -- Synthesis
- Description: The processes leading to the formation of 2-methyl-2-(methylthio)propanal oxime, known industrially as aldicarb oxime, have been studied. The three stages of the synthesis, viz., chlorination, thiomethylation and oximation have been thoroughly investigated, with the aim of optimising the yield and purity of aldicarb oxime. Attention has been focused on the chlorination step, and the effects of altering various conditions have been determined; the reaction has been carried out in the absence and presence of heat, solvent and buffer, and the extent of chlorine addition has also been varied. These studies have led to some improvement in the yield for this step. Several simple and inexpensive methods for purifying contaminated batches of aldicarb oxime have also been examined. Possible aldicarb oxime contaminants, identified by GLC and GC-MS analysis, have been synthesised for use as chromatographic and spectroscopic standards, and confirmation of the presence of a number of these contaminants has been achieved. Aldehyde trimers have been found to be the primary contaminants present in aldicarb oxime and the thermal stability of these trimers, their corresponding monomers and aldicarb oxime itself has been studied using variable temperature ¹H NMR spectroscopy. Novel pyridine derivatives, with potential as aldicarb analogues, have been synthesised and characterised using spectroscopic methods.
- Full Text:
- Authors: Whittaker, Ruth Eleanor
- Date: 1995
- Subjects: Pesticides -- Synthesis , Insecticides , Aldicarb -- Synthesis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4322 , http://hdl.handle.net/10962/d1004980 , Pesticides -- Synthesis , Insecticides , Aldicarb -- Synthesis
- Description: The processes leading to the formation of 2-methyl-2-(methylthio)propanal oxime, known industrially as aldicarb oxime, have been studied. The three stages of the synthesis, viz., chlorination, thiomethylation and oximation have been thoroughly investigated, with the aim of optimising the yield and purity of aldicarb oxime. Attention has been focused on the chlorination step, and the effects of altering various conditions have been determined; the reaction has been carried out in the absence and presence of heat, solvent and buffer, and the extent of chlorine addition has also been varied. These studies have led to some improvement in the yield for this step. Several simple and inexpensive methods for purifying contaminated batches of aldicarb oxime have also been examined. Possible aldicarb oxime contaminants, identified by GLC and GC-MS analysis, have been synthesised for use as chromatographic and spectroscopic standards, and confirmation of the presence of a number of these contaminants has been achieved. Aldehyde trimers have been found to be the primary contaminants present in aldicarb oxime and the thermal stability of these trimers, their corresponding monomers and aldicarb oxime itself has been studied using variable temperature ¹H NMR spectroscopy. Novel pyridine derivatives, with potential as aldicarb analogues, have been synthesised and characterised using spectroscopic methods.
- Full Text:
Synthetic and spectrometric studies of benzodioxepinone derivatives
- Authors: Gelebe, Aifheli Carlson
- Date: 1995
- Subjects: Benzodiazepines -- Research Flavonoids -- Research
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4382 , http://hdl.handle.net/10962/d1005047
- Description: An extensive range of oxygen and sulphur substituted benzodiazepine analogues has been synthesised via Baeyer-Villiger and Schmidt reactions of specially prepared flavanone and N-acetyl-4-quinolone precursors. Alternative, cyclisation routes have also been used to prepare some of these compounds. Ring-opening reactions of 1,5-benzodioxepinones have been investigated and a detailed kinetic-mechanistic study of the Baeyer-Villiger reaction of flavanones has been carried out using 1 H NMR spectroscopy to explain the observed regiochemistry of oxygen insertion. The electron-impact mass spectrometric fragmentation patterns of series of 4-aryl-l ,5-benzoxathiepinones, 3-aryl-4, I-benzoxathiepinones and 3-aryl-4,1-benzoxathiepines have been studied using a combination of low-resolution, highresolution and metastable-peak analyses. The 170 NMR spectroscopic properties of various oxygenated analogues have also been studied. The binding affinities of selected benzodiazepine analogues for rat brain benzodiazepine receptors have been evaluated using a radioreceptor assay technique; at certain concentrations, some of test compounds exhibited remarkable potentiation of diazepam binding, others the ability to displace diazepam from benzodiazepine receptors. A conformational analysis of the 7-membered ring systems has been undertaken, using lH NMR spectroscopic, computer modelling and x-ray crystallographic techniques, and certain conformational preferences have been identified.
- Full Text:
- Authors: Gelebe, Aifheli Carlson
- Date: 1995
- Subjects: Benzodiazepines -- Research Flavonoids -- Research
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4382 , http://hdl.handle.net/10962/d1005047
- Description: An extensive range of oxygen and sulphur substituted benzodiazepine analogues has been synthesised via Baeyer-Villiger and Schmidt reactions of specially prepared flavanone and N-acetyl-4-quinolone precursors. Alternative, cyclisation routes have also been used to prepare some of these compounds. Ring-opening reactions of 1,5-benzodioxepinones have been investigated and a detailed kinetic-mechanistic study of the Baeyer-Villiger reaction of flavanones has been carried out using 1 H NMR spectroscopy to explain the observed regiochemistry of oxygen insertion. The electron-impact mass spectrometric fragmentation patterns of series of 4-aryl-l ,5-benzoxathiepinones, 3-aryl-4, I-benzoxathiepinones and 3-aryl-4,1-benzoxathiepines have been studied using a combination of low-resolution, highresolution and metastable-peak analyses. The 170 NMR spectroscopic properties of various oxygenated analogues have also been studied. The binding affinities of selected benzodiazepine analogues for rat brain benzodiazepine receptors have been evaluated using a radioreceptor assay technique; at certain concentrations, some of test compounds exhibited remarkable potentiation of diazepam binding, others the ability to displace diazepam from benzodiazepine receptors. A conformational analysis of the 7-membered ring systems has been undertaken, using lH NMR spectroscopic, computer modelling and x-ray crystallographic techniques, and certain conformational preferences have been identified.
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