Kinetic studies on 2,6-lutidine catalyzed peroxyoxalate chemiluminescence in organic and aqueous medium: Evidence for general base catalysis
| Autor: | Wilhelm J. Baader, Fernando H. Bartoloni, Maidileyvis Castro Cabello, Ana Paula Fileno dos Santos, Felipe A. Augusto |
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| Rok vydání: | 2019 |
| Předmět: |
Chemistry
General Chemical Engineering Inorganic chemistry General Physics and Astronomy 02 engineering and technology General Chemistry CATÁLISE 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences Peroxyoxalate 0104 chemical sciences Catalysis law.invention Solvent chemistry.chemical_compound Reaction rate constant Nucleophile law 2 6-Lutidine Light emission 0210 nano-technology Chemiluminescence |
| Zdroj: | Repositório Institucional da USP (Biblioteca Digital da Produção Intelectual) Universidade de São Paulo (USP) instacron:USP |
| ISSN: | 1010-6030 |
| DOI: | 10.1016/j.jphotochem.2019.111967 |
| Popis: | The peroxyoxalate reaction, base catalyzed perhydrolysis of activated aromatic oxalate esters in the presence of chemiluminescence activators, has widespread analytical and bioanalytical applications and is one of the most efficient chemiluminescence transformations known. We report here a kinetic study on this reaction using 2,6-lutidine as catalyst in organic (1,2-dimethoxyethane) and aqueous medium. In both media, experimental conditions can be designed which lead to reproducible results important for analytical applications. Observed rate constants (determined by observing the light emission intensity as well as absorbance variation due to phenol releases) show dependence on both the 2,6-lutidine and the hydrogen peroxide concentration, indicating their participation in the rate-limiting step of the transformation. The rate constants obtained from these kinetic studies proved to be at least one order of magnitude higher in water than in 1,2-dimethoxyethane as solvent. Kinetic experiments designed to distinguish between three different types of catalysis (nucleophilic, specific base and general base catalysis) clearly indicate that the role of 2,6-lutidine in this reaction is as general base catalyst in water as well as most likely in organic medium. |
| Databáze: | OpenAIRE |
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