Fast reversible oxidative addition of demanding aryl chlorides to Pd under real conditions of catalysis in the Mizoroki-Heck reaction: The kinetic proof

• Published in: Molecular catalysis 2022-05, Vol.524, p.112260, Article 112260
• Main Authors: Schmidt, Alexander F., Kurokhtina, Anna A., Larina, Elizaveta V., Vidyaeva, Elena V., Lagoda, Nadezhda A.
• Format: Article
• Language: English
• Subjects: Aryl chlorides; Mechanism; Mizoroki-Heck reaction; Oxidative addition; Palladium
• ISSN: 2468-8231; 2468-8231
• DOI: 10.1016/j.mcat.2022.112260

•Quasi-equilibrium character of the oxidative addition of ArCl to Pd was demonstrated.•Quasi-equilibrated oxidative addition cannot be therefore the RDS.•Low reactivity of ArCl is caused by another reason not related to oxidative addition.The retarded oxidative addition of aryl chlorides to palladium is commonly believed to be the main obstacle for their successful conversion in cross-coupling reactions. However, this point has been fairly challenged in several papers, including those published recently, by providing experimental data obtained under both model and real catalytic conditions. Here, we provide proof of the fast and reversible character of the oxidative addition elementary step with aryl chlorides in the catalytic cycle of the Mizoroki-Heck reaction. The results have been obtained by the original kinetic approach using the differential selectivity of the competing Mizoroki-Heck reaction with two aryl chlorides. The kinetic data obtained in the real phosphine-free catalytic system unambiguously disproved the rate-determining character of the oxidative addition of aryl chloride as the key factor for lowering the catalytic activity when using aryl chlorides instead of aryl iodides and aryl bromides in the Mizoroki-Heck reaction. [Display omitted]