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The kinetics and mechanism of trace iridium(Ⅲ) catalyzed oxidation of 1,2-propanediol (PRD) by cerium(Ⅳ) in aqueous sulfuric acid media were investigated by titrimetric technique of redox in the temperature range of 298～313 K. The results show that the reaction is of unity with respect to Ce(Ⅳ), and a positive fractional order with respect to [PRD]. It is found that the pseudo first-order ([PRD]>>[Ce(Ⅳ)]) rate constant kobs increases with the increase of [Ir(Ⅲ)] and [H+], but decreases with the increase of [HSO4-]. Under the protection of nitrogen, the reaction system can initiate polymerization of acrylonitrile, indicating the generation of free radicals. On the basis of the experimental results, a reasonable mechanism was proposed. From the hydrogensulfate dependence, Ce(SO4)2 was found as the kinetically active species. The preequilibrium constants, rate constants for the rate determining step together with the activity parameters were evaluated.
The kinetics and mechanism of trace iridium (Ⅲ) catalyzed oxidation of 1,2-propanediol (PRD) by cerium (Ⅳ) in aqueous sulfuric acid media were investigated by titrimetric technique of redox in the temperature range of 298 ~ 313 K. The results show that the reaction is unity with respect to Ce (IV), and a positive fractional order with respect to [PRD]. It is found that the pseudo first-order ([PRD] >> [Ce (IV)]) rate Under the protection of nitrogen, the reaction system can start of acrylonitrile, indicating the generation of free-radical [HSO4-]. From the basis of the experimental results, a reasonable mechanism was proposed. From the hydrogensulfate dependence, Ce (SO4) 2 was found as the kinetically active species. The preequilibrium constants, rate constants for the rate determining step together with the activity parameters were as