Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.638250
Title: Competing alcoholyses and hydrolyses of reactive dyes for cellulose
Author: Morris, P. J.
Awarding Body: University of Wales Swansea
Current Institution: Swansea University
Date of Award: 2000
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Abstract:
This project is primarily concerned with the reactions of halotriazine reactive dyes for cellulose, in aqueous solution. The effect of small amounts of added alcohol (~ 0.05M) on the rates of hydrolysis of a dichlorotriazine dye has been analysed by study of the individual contributions towards rate, of the concurrent alcoholysis and hydrolysis reactions. Kinetics and products studies were all carried out using ion-pair reverse-phase HPLC. Of the alcohols studied; methanol, ethane-1,2-diol and propargyl alcohol, provided rate-product correlations; whilst α- and β-methylglucopyranoside, mannitol, sorbitol and trifluoroethanol all produced rate enhancements of hydrolysis in the region of 10-50%. Medium effects of the added alcohols were found to be negligible and most likely explanation of the rate enhancements has been proposed to be the presence of a third-order, alkoxide-assisted mechanism for hydrolysis. The viability of this proposal was investigated using Bronsted and KSIE analysis. Bronsted plots for second order alcoholyses and third order hydrolyses are linear, with plausible slopes, with the exception of hydroxide which exhibits a 100-fold negative deviation in all cases. Furthermore, significant evidence exists that the hydrolysis of the dye also undergoes a hydroxide-assisted mechanism, analogous to that observed in the presence of alkoxides. Salt effects on the reactions of these dyes were found to be substantial; Five-fold rate enhancements were observed in the presence of ~ 0.1M sodium sulfate, sodium carbonate and some tetraalkylammonium salts. Hence, no buffer catalysis could be observed. Method development of HPLC and HPLC-MS analysis of sulfonated dyes and their reaction products has been optimised. Finally, a survey of homogeneous chemistry of compounds containing a dinitrofluorobenzene reactive group was carried out. Model compounds were synthesised, on which rate and product studies were conducted in aqueous and methanolic solution.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.638250  DOI: Not available
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