Free radical reactions of the phenothiazine, metiazinic acid

verfasst von

Detlef Bahnemann, Klaus Dieter Asmus, Robin L. Willson

Abstract

Absolute rate constants have been measured for the reaction of the anionic conjugate base of metiazinic acid, MZ^-, in the pH range 8-11, with hydrated electrons (k 1.5 × 10⁹ | mol^-1 s^-1), and for the oxidation of MZ^- by OH^., Br₂^-., (SCN)₂^-., CO₃^-., Tl(OH)₂, N₃,^{. .}CH₂CHO, (CH₃SCH₃)₂^+., CH₃SSCH₃^+. and lipoate^+.. The k values for these oxidations are found to be in the 10⁹-10¹⁰ | mol^-1 s^-1 range, except for k(^.CH₂CHO + MZ^-) 2 × 10⁸ | mol^-1 s^-1. The oxidation of metiazinic acid leads to MZ^±. radical zwitterions with yields ranging from 50 to 100% with the minimum value referring to the oxidation by ^.CH₂CHO. The MZ^±. radical zwitterion is characterized by two strong optical absorption bands with maxima at 530 (ε 11 000 | mol^-1 cm^-1) and 270 nm (51 500). Other primary oxidation products are indicated, but only a transient absorption around 350 nm (OH^. adduct and/or hydrogen abstraction product) could qualitatively be identified in the reaction of metiazinic acid with hydroxyl radicals.

Externe Organisation(en)

Helmholtz-Zentrum Berlin für Materialien und Energie GmbH
Brunel University

Typ

Artikel

Journal

Journal of the Chemical Society, Perkin Transactions 2

Seiten

890-895

Anzahl der Seiten

6

ISSN

1472-779X

Publikationsdatum

1981

Publikationsstatus

Veröffentlicht

Peer-reviewed

Ja

ASJC Scopus Sachgebiete

Chemie (insg.)

Elektronische Version(en)

https://doi.org/10.1039/P29810000890 (Zugang: Unbekannt)