TI(III) oxidation of alkenes and alkynes and Ru(III) catalysis in the oxidation of alkenes: A kinetic and mechanistic study

✍ Scribed by P. S. Radhakrishnamurti; H. P. Panda

• Publisher: John Wiley and Sons
• Year: 1983
• Tongue: English
• Weight: 565 KB
• Volume: 15
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/kin.550150609

✦ Synopsis

Abstract

The oxidation of trans‐stilbene, phenylacetylene, and diphenylacetylene by Tl(OAc)~3~ in aqueous acetic acid medium in the presence of HClO~4~ follows the rate law
in [H^+^] of 0.1–1.0__M__, the [H^+^] dependence below 0.1__M__ being marginal. The reactions are strongly dielectric dependent. The order of reactivity among the substrates is styrene > phenylacetylene and trans‐stilbene > diphenylacetylene. A mechanism involving the oxythallation adduct by the Tl^+^(OAc)~2~ species has been discussed. The use of Ru(III) as a homogeneous catalyst brings a change in the kinetic orders for trans‐stilbene, the rate law being
The formation constants K for the Ru(III)–alkene π complex at 40, 50, and 60°C are 90.14__M__^−1^, 105.2__M__^−1^, and 127.7__M__^−1^, respectively. Interestingly the oxidation of phenylacetylene and diphenylacetylene does not undergo catalysis by Ru(III). The mechanism involving the metal–arene π complex is discussed.