Main content area

Allylic oxidation of olefins with a manganese-based metal–organic framework

Chen, Jingwen, Chen, Minda, Zhang, Biying, Nie, Renfeng, Huang, Ao, Goh, Tian Wei, Volkov, Alexander, Zhang, Zhiguo, Ren, Qilong, Huang, Wenyu
Green chemistry 2019 v.21 no.13 pp. 3629-3636
catalysts, catalytic activity, cost effectiveness, cyclohexanones, cyclohexenes, green chemistry, ligands, manganese, oxidants, oxidation, oxygen
Selective oxidation of olefins to α,β-unsaturated ketones under mild reaction conditions has attracted considerable interest, since α,β-unsaturated ketones can serve as synthetic precursors for various downstream chemical products. The major inherent challenges with this chemical oxidation are chemo- and regio-selectivity as well as environmental concerns, i.e. catalyst recycle, safety and cost. Using atmospheric oxygen as an environmentally friendly oxidant, we found that a metal–organic framework (MOF) constructed with Mn and a tetrazolate ligand (CPF-5) showed good activity and selectivity for the allylic oxidation of olefins to α,β-unsaturated ketones. Under the optimized conditions, we could achieve 98% conversion of cyclohexene and 87% selectivity toward cyclohexanone. The combination of a substoichiometric amount of TBHP (tert-butylhydroperoxide) and oxygen not only provides a cost effective oxidation system but significantly enhances the selectivity to α,β-unsaturated ketones, outperforming most reported oxidation methods. This catalytic system is heterogeneous in nature, and CPF-5 could be reused at least five times without a significant decrease in its catalytic activity and selectivity.