Catalytic activity of iron and cobalt phthalocyanine complexes towards the oxidation of cyclohexene using tert-butylhydroperoxide and chloroperoxybenzoic acid

Substituent effect on iron phthalocyanines as cyclohexene oxidation catalysts

Two iron phthalocyanines peripherally octasubstituted either with electron-withdrawing isobutylsulfonyl moities or electron-donating isobutoxy moieties were designed to investigate the effect of the substitution pattern on their oxidation catalytic activity, and were then tested in oxidation of cyclohexene as a reaction model. For both catalysts, the main product of oxidation was 2-cyclohexen-1-ol which is an allylic oxidation product. The electron-withdrawing isobutylsulfonyl substituted iron phthalocyanine 1exhibited better catalytic activities than the electron-donating isobutoxy substituted iron phthalocyanine 2.

Synthesis and Characterization of New Imidazole Phthalocyanine for Photodegradation of Micro-Organic Pollutants from Sea Water

In this study, a series of new metal phthalocyanines with imidazole function MPc(Imz) (M: Cd, Hg, Zn and Pd) were synthesized to improve the photocatalyst performances. All physical properties such as total energy, HOMO, LUMO energies of MPc(Imz), as well as their vibrational frequencies have been determined by DFT method using B3LYP theory level at 6-311G (d, p) and sdd basis set. The gap of energy level between work function (WF) of ITO and LUMO of PdPc(Imdz) was 1.53 eV and represents the highest barrier beneficial to electron injection compared to WF of ZnPc(Imz), HgPc(Imz), and CdPc(Imz). Furthermore, the PdPc(Imdz) thin films on indium tin oxide (ITO) glass were prepared by spin coating and vacuum evaporation technique, and were characterized by X-ray diffraction (XRD), surface electron morphology (SEM), atomic force microscopy (AFM), and UV–Vis spectroscopy. The photocatalytic activity of the ITO/glass supported thin films and degradation rates of chlorinated phenols in synthetic seawater, under visible light irradiation were optimized to achieve conversions of 80–90%. Experiments on synthetic seawater samples showed that the chloride-specific increase in photodegradation could be attributed to photochemically generated chloride radicals rather than other photoproduced reactive intermediates [e.g., excited-state triplet PdPc(Imz) (3PdPc(Imz)*), reactive oxygen species]. The major 2,3,4,5-Tetrachlorophenol degradation intermediates identified by gas chromatography-mass spectrometry (GC/MS) were 2,3,5-Trichlorophenol, 3,5-dichlorophenol, dichlorodihydroxy-benzene and 3,4,5-trichlorocatechol.

Cobalt(II) Complexes with N,N,N-Scorpionates and Bidentate Ligands: Comparison of Hydrotris(3,5-dimethylpyrazol-1-yl)borate Tp* vs. Phenyltris(4,4-dimethyloxazolin-2-yl)borate ToM to Control the Structural Properties and Reactivities of Cobalt Centers

Scorpionate ligands Tp* (hydrotris(3,5-dimethylpyrazol-1-yl)borate) and ToM (tris(4,4-dimethyloxazolin-2-yl)phenylborate) complexes of cobalt(II) with bidentate ligands were synthesized. Both Tp* and ToM coordinate to cobalt(II) in a tridentate fashion when the bidentate ligand is the less hindered acetylacetonate. In crystal structures, the geometry of cobalt(II) supported by the N₃O₂ donor set in the Tp* complex is a square-pyramid, whereas that in the ToM complex is close to a trigonal-bipyramid. Both Tp*- and ToM-acac complexes exhibit solvatochromic behavior, although the changing structural equilibria of these complexes in MeCN are quite different. In the bis(1-methylimidazol-2-yl)methylphenylborate (LPh) complexes, Tp* retains the tridentate (к³) mode, whereas ToM functions as the bidentate (к²) ligand, giving the tetrahedral cobalt(II) complex. The bowl-shaped cavity derived from the six methyl groups on ToM lead to susceptibility to the bulkiness of the opposite bidentate ligand. The entitled scorpionate compounds mediate hydrocarbon oxidation with organic peroxides. Allylic oxidation of cyclohexene occurs mainly on the reaction with tert-butyl hydroperoxide (TBHP), although the catalytic efficiency of the scorpionate ligand complexes is lower than that of Co(OAc)₂ and Co(acac)₂. On cyclohexane oxidation with meta-chloroperbenzoic acid (mCPBA), both ToM and Tp* complexes function as catalysts for hydroxylation. The higher electron-donating ToM complexes show faster initial reaction rates compared to the corresponding Tp* complexes.

Oxidation mechanism of molecular oxygen over cyclohexene catalyzed by a cobalt l-glutamic acid complex

We introduce a new strategy towards the cyclohexene oxidation reaction, which is driven by molecular oxygen with a cobalt(ii)/amine acid complex as the catalyst without any solvents.

Magnetically separable chicken feathers: a biopolymer based heterogeneous catalyst for the oxidation of organic substrates

Magnetically separable chicken feather nanoparticles were found to be efficient, green and heterogeneous catalyst for selective oxidation of alcohols to carbonyls and sulfides to sulfoxides using t-butyl hydroperoxide (TBHP) as oxidant.

A Mild Catalytic Oxidation System: FePcOTf/H2O2 Applied for Cyclohexene Dihydroxylation

Iron (III) phthalocyanine complexes were employed for the first time as a mild and efficient Lewis acid catalyst in the selective oxidation of cyclohexene to cyclohexane-1,2-diol. It was found that the catalyst FePcOTf shown excellent conversion and moderate selectivity relative to other iron (III) phthalocyanine complexes. The optimum conditions of the oxidation reaction catalyzed by FePcOTf/H₂O₂ have been researched in this paper. Iron (III) phthalocyanine triflate (1 mol %) as catalyst, hydrogen peroxide as oxidant, methanol as solvent, and a mole ratio of substrate and oxidant (H₂O₂) of 1:1 were used for achieving moderate yields of 1,2-diols under reflux conditions after eight hours.

Carbonylation of cyclohexene to 2-cyclohexene-1-one by montmorillonite-supported Co(II) catalysts

A novel environmentally-friendly catalytic system for the carbonylation of cyclohexene with molecular oxygen under conditions of mild temperature, and under an atmospheric oxygen pressure is presented. In this system, a series of readily-prepared cobalt complexes of 2-aminophenol and its derivatives immobilised onto montmorillonite were used as catalysts. The catalysts were characterised by FT-IR, elemental analysis, thermogravimetric analysis, powder X-ray diffraction, diffuse reflectance ultraviolet visible spectra, scanning electron microscopic measurements, transmission electron microscopic measurements and the Brunauer-Emmett-Teller method. The effects of various reaction conditions such as catalyst dosage, temperature and time were optimised, obtaining an 88.7 % conversion with 72.0 % selectivity of 2-cyclohexene-1-one in 6 h. The results show that the catalytic activity of the cobalt complexes encapsulated in montmorillonite is higher than those of the free complexes. In addition, the heterogeneous catalysts were stable and can be recycled up to five times without any noticeable change in the catalytic activity.

Stability and catalytic properties of μ-oxo and μ-nitrido dimeric iron tetrasulfophthalocyanines in the oxidation of Orange II by tert-butylhydroperoxide

A study of catalytic activity of μ-nitrido- and μ-oxo-dimeric iron tetrasulfophthalocyanines in the oxidation of Orange II by tert-butylhydroperoxide in aqueous solutions has been performed. It is shown that though in one catalytic cycle activity of μ-oxo-dimer is higher, stability of this complex in oxidative conditions is poor. μ-nitrido-dimer combines relatively good catalytic activity with very high stability in the presence of tert-butylhydroperoxide. The mechanisms of oxidative decomposition of dimers and catalytic oxidation of Orange II have been proposed on the base of kinetic results. The products of catalytic processes are shown to be bio-degradable non-toxic small organic compounds.