Kinetic study of the photodegradation of p-hydroxybenzenediazonium ion in polar media

Authors

  • B QUINTERO Depto. de Química Física, Facultad de Farmacia, Universidad de Granada, 18071 Granada, España
  • MC CABEZA Depto. de Química Física, Facultad de Farmacia, Universidad de Granada, 18071 Granada, España
  • MI MARTÍNEZ PUENTEDURA Depto. de Química Física, Facultad de Farmacia, Universidad de Granada, 18071 Granada, España
  • PJ MARTÍNEZ DE LAS PARRAS Depto. de Química Física, Facultad de Farmacia, Universidad de Granada, 18071 Granada, España
  • MP GUTIÉRREZ Depto. de Química Física, Facultad de Farmacia, Universidad de Granada, 18071 Granada, España

Keywords:

p-hydroxybenzenediazonium, Photodecomposition, Aryl cation, Kinetic analysis

Abstract

A study on the photodecomposition of p-hydroxybenzenediazonium ion (PDQ) has been made using chromatographicand spectrophotometric data obtained from UV-irradiated (254 nm) PDQ solutions in acetonitrile and aqueous media.The HPLC and HPLC-mass results indicate that 4-acetamidophenol is the main product formed after the irradiationof PDQ in acetonitrile. This is explained as a consequence of the initial formation of the aryl cation which is laterinvolved in a Ritter’s reaction. A kinetic analysis of the spectrophotometric data reveals that PDQ photodegradation isfaster in acetonitrile (observed rate constant (kobs) = 0.1442 s-1) than in acidifi ed acetonitrile (kobs = 0.009 s-1) indicatinga higher photostability of the protonated species derived from PDQ. The second order constant (0.062 M s-1) found forthe PDQ photodecomposition in phosphate buffer (pH 7) is explained in term of the equilibrium between protonatedand non-protonated species coming from the acid dissociation of PDQ

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Published

2007-09-20

How to Cite

1.
QUINTERO B, CABEZA M, MARTÍNEZ PUENTEDURA M, MARTÍNEZ DE LAS PARRAS P, GUTIÉRREZ M. Kinetic study of the photodegradation of p-hydroxybenzenediazonium ion in polar media. Ars Pharm [Internet]. 2007 Sep. 20 [cited 2025 Apr. 3];48(3):297-310. Available from: https://revistaseug.ugr.es/index.php/ars/article/view/4992

Issue

Vol. 48 No. 3 (2007)

Section

Original Articles

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