Greener Selective Cycloalkane Oxidations with Hydrogen Peroxide Catalyzed by Copper-5-(4-pyridyl)tetrazolate Metal-Organic Frameworks.
Microwave assisted synthesis of the Cu(I) compound [Cu(µ₄-4-ptz)]n [1, 4-ptz=5-(4-pyridyl)tetrazolate] has been performed by employing a relatively easy method and within a shorter period of time compared to its sister compounds. The syntheses of the Cu(II) compounds [Cu₃(µ₃-4-ptz)₄(µ₂-N₃)₂(DMF)₂]n∙(DMF)2n (2) and [Cu(µ₂-4-ptz)₂(H₂O)₂]n (3) using a similar method were reported previously by us. MOFs 1-3 revealed high catalytic activity toward oxidation of cyclic alkanes (cyclopentane, -hexane and -octane) with aqueous hydrogen peroxide, under very mild conditions (at room temperature), without any added solvent or additive. The most efficient system (2/H₂O₂) showed, for the oxidation of cyclohexane, a turnover number (TON) of 396 (TOF of 40 h(-1)), with an overall product yield (cyclohexanol and cyclohexanone) of 40% relative to the substrate. Moreover, the heterogeneous catalytic systems 1-3 allowed an easy catalyst recovery and reuse, at least for four consecutive cycles, maintaining ca. 90% of the initial high activity and concomitant high selectivity.
Chemical Engineering Departament, Instituto Superior de Engenharia de Lisboa, Instituto Politécnico de Lisboa, R. Conselheiro Emídio Navarro, 1959-007 Lisboa, Portugal. lmartins@deq.isel.ipl.pt.|Centro de Química Estrutural, Complexo I, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal. lmartins@deq.isel.ipl.pt.
Luísa
L
Martins
Department of Chemistry, School of Basic Sciences, Indian Institute of Technology Indore, IET-DAVV Campus, Khandwa Road, Indore 452017, India. nrajendra@iiti.ac.in.
Rajendar
R
Nasani
Department of Chemistry, School of Basic Sciences, Indian Institute of Technology Indore, IET-DAVV Campus, Khandwa Road, Indore 452017, India. phd11113104@iiti.ac.in.
Manideepa
M
Saha
Department of Chemistry, School of Basic Sciences, Indian Institute of Technology Indore, IET-DAVV Campus, Khandwa Road, Indore 452017, India. suman1009@yahoo.com.
Shaikh
S
Mobin
Department of Chemistry, School of Basic Sciences, Indian Institute of Technology Indore, IET-DAVV Campus, Khandwa Road, Indore 452017, India. xray@iiti.ac.in.
Suman
S
Mukhopadhyay
Centro de Química Estrutural, Complexo I, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal. pombeiro@tecnico.ulisboa.pt.
Armando
A
Pombeiro
D002384:Catalysis; D003300:Copper / Q000737:chemistry*; D003510:Cyclohexanes / Q000737:chemistry; D003511:Cyclohexanols / Q000138:chemical synthesis*; D003512:Cyclohexanones / Q000138:chemical synthesis*; D055772:Green Chemistry Technology; D006861:Hydrogen Peroxide / Q000737:chemistry*; D008872:Microwaves; D009942:Organometallic Compounds / Q000737:chemistry*; D010084:Oxidation-Reduction
D003510:Cyclohexanes; D003511:Cyclohexanols; D003512:Cyclohexanones; D009942:Organometallic Compounds; C506365:Cyclohexane; C036468:cyclohexanone; D003300:Copper; D006861:Hydrogen Peroxide
Cu(I or II) MOFs; efficient cycloalkane oxidation; green oxidation; microwave; reusable heterogeneous catalysts; solvent-free