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Title: Mechanistic studies of electrophilic reactions involving nitrous acid and bromine
Author: Haine, H. D.
Awarding Body: University of Wales Swansea
Current Institution: Swansea University
Date of Award: 2000
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A fair amount of research has been carried out on the reactions of nitrous acid with aryl hydrazines, with marked differences in mechanism between the reaction of nitrous acid with 2,4-dinitrophenylhydrazine, and the reaction of nitrous acid with alkyl and halogen substituted aryl hydrazines. It was hoped that study of the electrophilic nitrosation of 2-nitrophenylhydrazine would serve as a link between the two sets of results. A large range of electrophilic nitrosating agents are known, and the spectra of two of these; dinitrogen trioxide (N2O3) and nitrosyl thiocyanate (ONSCN), have been studied using stopped flow spectrophotometry. Earlier studies of the nitrosation of hydrazine using sodium acetate/acetic acid buffers, produced discrepancies between observed rates compared to a rate calculated from measurements made in much more acidic conditions in HC1O4. Consequently the original study has been re-investigated and extended. There is considerable current interest in the electrophilic nitrosation of sulfur compounds, which leads to the formation of sulfur-nitroso intermediates, and in the subsequent decomposition reactions of these intermediates. Preliminary work on the reaction of nitrous acid with tetramethylthiourea (NMe)2CS, showed some unexpected 1H NMR spectra for the products. A likely product of the decomposition of the S-nitrosothiouronium ion intermediate (NMe2)2CSNO+ is [(NMe2)2CSSC(NMe2)2]2+ and this species should also be formed in the oxidation of tetramethylthiourea by bromine. This led to an investigation of the reaction of (NMe2)2CS with bromine in aqueous solution, with a comparison made between the products gained by bromination and nitrosation, using 1H NMR.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available