Réactions chimiques oscillantes. II. Comportement de la «période d'induction» dans les systémes BrO/Ce⁴⁺/Cyclohexanone et BrO/Ce⁴⁺/Cyclopentanone

Abstract

Oscillating Chemical Reactions. 11. Behaviour of the "induction period" in the BrO~/Ce4+/Cyclohexanon and Br0~/Ce4+/Cyclopentanon systems Summary1) The addition of a-monobromoketone, one of the products of reaction of the BrO~/Ce4+/Cyclohexanon (Sl) and BrO:/Ce4+/Cyclopentanon ( S 2 ) oscillating systems, decreases and even suppresses the induction period (rind) in the case of s 2 .Such is not the case with S1: t i n d , increases and the oscillations can even be completely inhibited.2) The order of addition of the reagents and the time lapse (tad,) preceding the addition of the last of them influences tind., particularly when the last reagent added is Ce4+.3) In our experimental conditions, the inhibition of the oscillatory phenomenon by C1-ions is definite only for IC1-I 35,O. ~O -* M (Sl) and IC1-I > 2 , 5 . 1 0 -3~ (S2); for lower concentrations rind, increases with 1 C1-1 .1. Introduction. -Nous avons montrt, dans une prtctdente publication [l], que des oscillations chimiques pouvaient &tre observkes avec des systkmes analogues a celui de Belousov-Zhabotinskii, mais dans lesquels I'acide malonique etait remplact par un compost cttonique simple (cyclohexanone, cyclopentanone, butanone ou pentanone-3).La pCriode ccprC-oscillatoire)) ou c(pCriode d'inductiom, (tind.), qui prtckde Yapparition des oscillations, est rune des caractkristiques principales des reactions chimiques oscillantes en milieu homogkne.Nous avons signalt [I] des effets difftrents de certains facteurs sur rind,; ainsi rind. avec la cyclohexanone est, toutes choses Cgales, beaucoup moins longue qu'avec la cyclopentanone. Cette difftrence est due a une rCactivitt plus tlevCe de la cyclohexanone tant vis-a-vis de la bromation (la quantitt d'tnol prtsente dans la cyclohexanone &ant de 3,3 . alors que pour la cyclopentanone elle

Mechanism and Phenomenology of an Oscillating Chemical Reaction

“…Sroot, Janjic, Farage [112,113] and Treindl et al [114,115] investigated systems containing just a ketone or diketone as substrate and discovered that such systems display Broscillations, though it is unlikely that the brominated derivatives of the substrates react with the oxidised form of the catalyst to liberate Br -. Under certain initial conditions, the Mn-catalysed acetylacetate or ethyl acetoacetate systems display initial high frequency damped oscillations that give way to longer period, higher amplitude oscillations [116,117], suggesting two different control regimes may be operating.…”

effect of initial reagent concentrations on the oscillatory behavior of the BZ reaction in a batch reactor

“…The overall process of the BZ reaction is the oxidation of an organic substrate such as citric acid or malonic acid by an oxidizing agent (bromate) in the presence of metal ions as catalyst under acidic conditions. Metal ions, such as cerium, iron, and manganese, are widely used as catalysts 7–13. The mechanism of such reactions is explained in detail by Field, Koros, and Noyes (FKN) 3–5.…”

The oscillatory Belousov–Zhabotinsky reaction with flavones in batch systems using aqueous–DMF mixed medium

“…A number of substrates have been used in this system with different catalysts (3)(4)(5)(6)(7)(8)(9). The mechanistic aspects have been presented in detail as the Field-Koros-Noyes (FKN) mechanism (10)(11)(12).…”