Kinetic and Mechanistic Study of the Reaction of 2,6-Dichlorophenol Indophenol and Cysteine (Journal article)

Konidari, C. N./ Tzouwarakarayanni, S. M./ Bowman, L. E./ Karayannis, M. I.


In this work the reaction of cysteine (H2Q) with 2,6-dichlorophenolindophenol (D) is studied kinetically in the pH range 2.5-9.0. Taking into consideration the distribution diagrams for the species H3Q+, H2Q, HQ-, Q2- for cysteine and DH2+, DH, D- for 2,6-dichlorophenolindophenol the reaction mte constants k(i) for all possible combinations of the reacting species were determined. The maximum reactivity appears at pH 6.88 with an overall reaction constant k = 306 1.mole-1.sec-1 at 22-degrees. The effect of the concentrations of the reagents and the ionic strength on the reaction rate is also given. From Arrhenius plots an activation energy E(a) = 8.1 kcal/mole was calculated. Working curves for the determination of cysteine in aqueous solutions are also presented applying the reaction rate method. Finally the paper includes important analytical information for the calculation of the errors due to interference of cysteine by the kinetic determination of ascorbic acid, using its reaction with 2,6-dichlorophenolindophenol.
Institution and School/Department of submitter: Πανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών. Τμήμα Χημείας
Keywords: ascorbic-acid
URI: http://olympias.lib.uoi.gr/jspui/handle/123456789/8312
ISSN: 0039-9140
Link: <Go to ISI>://A1992HY96700021
http://ac.els-cdn.com/003991409280107O/1-s2.0-003991409280107O-main.pdf?_tid=4fedd6739ccc064d8954429ace050825&acdnat=1333030760_362a944f1fee3b37e8a2d2b41621ec52
Publisher: Elsevier
Appears in Collections:Άρθρα σε επιστημονικά περιοδικά ( Ανοικτά)

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