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Kinetic and equilibrium studies involving some acetophenones.

Earls, Derek William. (1972) Kinetic and equilibrium studies involving some acetophenones. Doctoral thesis, University of Surrey (United Kingdom)..

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Abstract

The work is divided into four parts. In part one the pKa values of a series of acetophenones have been determined using a novel method which involved measuring the rate of detritiation of a weak carbon acid in hydroxide-water-dimethylsulphoxide media. The change in the rate due to hydroxide ion removal on ionisation of an added stronger carbon acid enabled the pKa for this acid to be determined. In part two the hydroxide-catalysed rates of detritiation (k[T]) and racemisation (k[H]) of phenylmethylacetophenone have been measured in various dimethylsulphoxide-water mixtures. The isotope effect (k[H]/k[T]) reaches a maximum at an H_ value of 16.5 and the Bronsted B exponent for the reactions is 0.49 +/- 0.02. Arrhenius parameters have been determined and E[T]-E[H] reaches a maximum at an H_ value of 16.8. Anomalous A[H]/A[T], values are discussed in terras of solvent reorganisation contributions. In part three the acid-catalysed rates of detritiation of some acetophenones have been determined in acidic and highly acidic media. Equilibrium protonation studies on the acetophenones have also been made using a nuclear magnetic resonance method. The two studies allowed an appraisal of current mechanistic criteria for reactions in highly acidic media. The equilibrium studies emphasise the elusiveness of true thermodynamic pK[BH][+] values. In part four kinetic and nuclear magnetic resonance studies of ion association effects in alkali-metal ethoxide-ethanol, t-butoxide-t-butanol media have been made. The tendency towards increasing ion-pair formation on going from potassium to sodium to lithium cations is most pronounced in t-butanol. The nuclear magnetic resonance studies suggest a greater tendency towards the formation of solvent-separated rather than contact ion-pairs in ethanol.

Item Type: Thesis (Doctoral)
Divisions : Theses
Authors :
NameEmailORCID
Earls, Derek William.
Date : 1972
Contributors :
ContributionNameEmailORCID
http://www.loc.gov/loc.terms/relators/THS
Additional Information : Thesis (Ph.D.)--University of Surrey (United Kingdom), 1972.
Depositing User : EPrints Services
Date Deposited : 22 Jun 2018 13:00
Last Modified : 06 Nov 2018 16:52
URI: http://epubs.surrey.ac.uk/id/eprint/847387

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