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- Solvent-free microwave-assisted peroxidative oxidation of alcohols catalyzed by Iron(III)-TEMPO catalytic systemsPublication . Karmakar, Anirban; Martins, Luisa; Guedes Da Silva, M. Fátima C.; HAZRA, SUSANTA; Pombeiro, ArmandoThe iron(III) complexes [H(EtOH)][FeCl2(L)(2)] (1), [H(2)bipy](1/2)[FeCl2(L)(2)].DMF (2) and [FeCl2(L)(2,2'-bipy)] (3) (L = 3-amino-2-pyrazinecarboxylate; H(2)bipy = doubly protonated 4,4'-bipyridine; 2,2'-bipy = 2,2'-bipyridine, DMF = dimethylformamide) have been synthesized and fully characterized by IR, elemental and single-crystal X-ray diffraction analyses, as well as by electrochemical methods. Complexes 1 and 2 have similar mononuclear structures containing different guest molecules (protonated ethanol for 1 and doubly protonated 4,4'-bipyridine for 2) in their lattices, whereas the complex 3 has one 3-amino-2-pyrazinecarboxylate and a 2,2'-bipyridine ligand. They show a high catalytic activity for the low power (10 W) solvent-free microwave assisted peroxidative oxidation of 1-phenylethanol, leading, in the presence of TEMPO, to quantitative yields of acetophenone [TOFs up to 8.1 x 10(3) h(-1), (3)] after 1 h. Moreover, the catalysts are of easy recovery and reused, at least for four consecutive cycles, maintaining 83 % of the initial activity and concomitant rather high selectivity. 3-Amino-2-pyrazinecarboxylic acid is used to synthesize three new iron(III) complexes which act as heterogeneous catalysts for the solvent-free microwave-assisted peroxidative oxidation of 1-phenylethanol.
- Solvent-free microwave-assisted peroxidative oxidation of alcohols catalyzed by iron(III)-TEMPO catalytic systemsPublication . Karmakar, Anirban; Martins, Luisa; Guedes Da Silva, M. Fátima C.; HAZRA, SUSANTA; Pombeiro, ArmandoThe iron(III) complexes [H(EtOH)][FeCl2(L)(2)] (1), [H(2)bipy](1/2)[FeCl2(L)(2)].DMF (2) and [FeCl2(L)(2,2'-bipy)] (3) (L = 3-amino-2-pyrazinecarboxylate; H(2)bipy = doubly protonated 4,4'-bipyridine; 2,2'-bipy = 2,2'-bipyridine, DMF = dimethylformamide) have been synthesized and fully characterized by IR, elemental and single-crystal X-ray diffraction analyses, as well as by electrochemical methods. Complexes 1 and 2 have similar mononuclear structures containing different guest molecules (protonated ethanol for 1 and doubly protonated 4,4'-bipyridine for 2) in their lattices, whereas the complex 3 has one 3-amino-2-pyrazinecarboxylate and a 2,2'-bipyridine ligand. They show a high catalytic activity for the low power (10 W) solvent-free microwave assisted peroxidative oxidation of 1-phenylethanol, leading, in the presence of TEMPO, to quantitative yields of acetophenone [TOFs up to 8.1 x 10(3) h(-1), (3)] after 1 h. Moreover, the catalysts are of easy recovery and reused, at least for four consecutive cycles, maintaining 83 % of the initial activity and concomitant rather high selectivity. 3-Amino-2-pyrazinecarboxylic acid is used to synthesize three new iron(III) complexes which act as heterogeneous catalysts for the solvent-free microwave-assisted peroxidative oxidation of 1-phenylethanol.
- Sulfonated schiff base dimeric and polymeric copper(II) complexes: temperature dependent synthesis, crystal structure and catalytic alcohol oxidation studiesPublication . Martins, Luisa; HAZRA, SUSANTA; Guedes Da Silva, M. Fátima C.; Pombeiro, ArmandoTemperature dependent synthesis and crystal structure of the dicopper(II) complex [Cu2(L-jONO0 )2(l- 4,40 -bipy)(DMF)2] (1) and the dicopper(II) based coordination polymer [Cu2(l-L-1jONO0 :2jO)2(l-4, 40 -bipy)]nnH2OnDMF (2) derived from the acyclic Schiff base 2-[(2-hydroxy-3-methoxyphenyl)methylideneamino]benzenesulfonic acid (H2L) are described. Compounds 1 and 2 crystallize in monoclinic P21/n and P21/c systems, respectively. Crystal structure analysis reveals that the coordination polymer 2 consists of a dimeric building block which is comparable to the basic structure of 1. The compounds are isolated from the same reaction mixture but at different reaction temperatures and 1 can be converted into the coordination polymer 2. They were tested as catalysts for (both primary and secondary) alcohols oxidation. They show good catalytic activity for the solvent- and additive-free microwave (MW) assisted peroxidative (with tert-butylhydroperoxide) oxidation of cyclohexanol (up to 85% yield of cyclohexanone) after 30 min of low power MW irradiation. 2