Oscillator acetylacetone

Fig. 8.10. Plot of oscillator strength P of the 1 1 complexes of Ho3 with monobasic (+) and dibasic ( ) ligands vs. the pXa of the ligand acid (from ref. [741) (a) fluoride, (b) glycolate, (c) acetate, (d) propionate, (e) of-picolinate, (f) tropolonate, (g) kojate, (h) acetylacetonate, (I) IMAD, (2) dipicolinate, (3) methyl succinate, (4) malonate, (5) maleate, (6) fumarate, (7) sulfate.

Dutt and Banerjee (1982) studied temperature dependence of the B-R reaction with substrates such as, malonic acid, acetone, acetylacetone [Acetylacetone was first used in Dutt and Banerjee (1980)] and ethylacetoacetate within 280-320 K range. With increased temperature faster oscillations were observed. 

Rastogi and Rastogi (1980) investigated the oscillatory reaction in acetylacetone/ K.Br03/Mn(III)/H2S04 system and reported oscillations in Br and Mn(III)/Mn(II) and rate of temperature rise,... 

Even the simplest case of one-to-one entrainment at a common frequency offers a surprisingly rich array of possibilities. Crowley and Epstein (1989) studied the behavior of two coupled BZ oscillators in the experimental configuration shown in Figure 12.2. They used acetylacetone instead of malonic acid to prevent the formation of carbon dioxide bubbles. The compositions of the feedstreams (sodium bromate, cerous nitrate, sulfuric acid, acetylacetone) were the same for the two CSTRs, except that the acetylacetone concentration was 0.015 M for one reactor and 0.016 M for the other. This difference gave rise to a difference in uncoupled frequencies of about 15%, with tq = 99.6 s for one reactor and 112 s for the other. In Figure 12.7, we see what happens as the coupling parameter p, the ratio of the mass fiow between reactors to the mass flow through each CSTR, is increased. 

Zhabotinsky (1964b) noticed that the oscillating reaction is completely inhibited by traces of chloride ions. This inhibition was also observed by Janjic et al. (1974) for systems where the dicarboxylic acid is replaced by acetylacetone. Jacobs and Epstein (1976) reported that the inhibition of the concentration oscillation by trace amounts of chloride ions is only of temporary duration, provided that the initial chloride concentration is below a threshold value. High concentrations of chloride ions suppress the oscillations completely. The inhibition is caused by the oxidation of chloride ions to chlorous acid, which then reduces cerium(IV) to cerium(III). 

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