University of Surrey

Test tubes in the lab Research in the ATI Dance Research

Kinetics of oxidation of amino-acids by chloramine-T and related compounds.

Salman, Noori Yousif. (1988) Kinetics of oxidation of amino-acids by chloramine-T and related compounds. Doctoral thesis, University of Surrey (United Kingdom)..

[img]
Preview
Text
10804443.pdf
Available under License Creative Commons Attribution Non-commercial Share Alike.

Download (5MB) | Preview

Abstract

Studies of the kinetics and mechanism of the oxidation of amino-acids by chloramine-T, bromamine-T, di-chloramine-T, N-chlorosuccinimide and N-bromosuccinimide in the range pH 2-9 at 25 or 30°C in aqueous solution are described in this thesis. The effects of added p-toluenesulphonamide, chloride ion, or bromide ion on the rates have been studied. All the previous work on the chloramine-T oxidations of amino-acids was carried out at either pH 9 and the reactions were followed by iodometric titration. In the present work, UV spectrophotometry was used successfully to follow the reactions of all the above oxidants. Some runs were followed by iodometry for comparison. In general the kinetics of the oxidation by CAT (chloramine-T) with respect to the oxidant were first order ([CAT]=1x10[-4]M) or consecutive first order ([CAT]=3x10[-3]M). At pH's > 3 the oxidations were generally first order with respect to amino-acid, except for the oxidation of valine and arginine which showed Michaelis-Menten kinetics. Below pH 3 there was little dependence on amino-acid concentrations and it is suggested that the active species is HOCl or H[2]OCl[+] formed in a partly rate-determining step from CAT. At high pH's, the dependence of rate on pH suggests that the CAT anion is the active oxidant. Agreement was observed between the rates of the second stages of the oxidations by CAT and N-chlorosuccinimide, suggesting that these oxidations proceed via the same intermediate which is probably the chloroester. Spectroscopic evidence indicates the formation of the imine as another intermediate in the N-chlorosuccinimide reaction. In the oxidations by dichloramine-T the rate constants for the second stage agree with the rate constants for the CAT oxidations ([oxidant]=1.0x10[-4]M). Clearly CAT formed in the first stage oxidises the amino-acid in the second stage. A product analysis of the oxidations of amino-acids by CAT has been carried out by NMR and GLC. Formation of an aldehyde or a nitrile (depending on the conditions) has been confirmed. Improved calculations of the different species present in CAT solutions at various pH's have been carried out.

Item Type: Thesis (Doctoral)
Divisions : Theses
Authors :
NameEmailORCID
Salman, Noori Yousif.
Date : 1988
Contributors :
ContributionNameEmailORCID
http://www.loc.gov/loc.terms/relators/THS
Additional Information : Thesis (Ph.D.)--University of Surrey (United Kingdom), 1988.
Depositing User : EPrints Services
Date Deposited : 22 Jun 2018 14:26
Last Modified : 06 Nov 2018 16:53
URI: http://epubs.surrey.ac.uk/id/eprint/847982

Actions (login required)

View Item View Item

Downloads

Downloads per month over past year


Information about this web site

© The University of Surrey, Guildford, Surrey, GU2 7XH, United Kingdom.
+44 (0)1483 300800