Low molecular weight, polymeric, and covalently bound cobalt(II)-phthalocyanines for the oxidation of mercaptans

A planar binuclear cobalt(ii) phthalocyanine as a highly efficient catalyst for the oxidation of a mercaptan

This paper reports on a binuclear Co(ii)Pc which exhibits a previously unknown extremely high catalytic activity for the oxidation of a thiol to the corresponding disulfide. The high activity is explained by an electronic contact between the two Co centres in the complex.

FeCl3-diorganyl dichalcogenides promoted cyclization of 2-organochalcogen-3-alkynylthiophenes: synthesis of chalcogenophene[2,3-b]thiophenes

We report here our results on the FeCl3-diorganyl dichalcogenides intramolecular cyclization of 2-organochalcogen-3-alkynylthiophenes. The cyclization reaction proceeded cleanly under mild reaction conditions giving the (S)-Se-, (S)-S- and (S)-Te-heterocycles in good yields. In addition, the obtained chalcogenophenes were readily transformed into more complex products using the palladium cross-coupling reaction with boronic acids. Conversely, using a metal-halogen exchange reaction with n-BuLi, the chalcogenophenes produced the lithium-intermediate which was trapped with aldehyde furnishing the desired secondary alcohol in good yield.

Catalytic Properties of Cobalt Phthalocyanines Chemically Bonded to Polymer Anchored onto Silochrome Surface

Catalytic systems consisting of cobalt phthalocyanine grafted to maleic anhydride-styrene copolymer chemically linked with γ-aminopropylated silochrome have been prepared. In the process of sulfide oxidation with air oxygen the specific catalytic activity of these systems depends strongly on the phthalocyanine concentration in the catalyst. At low phthalocyanine concentrations (below 0.4 × 10−6 mol g−1) the catalytic activity is more than an order of magnitude larger than that of homogeneous catalysts and cobalt phthalocyanine adsorbed on a silochrome surface. The different ways of preparing the catalysts are reflected in the kinetic characteristics of the oxidation process.

Catalytic Oxidation of 2-Mercaptoethanol by Cationic Water-soluble Phthalocyaninatocobalt(II) Complexes

The cationic amphiphilic cobalt(II) phthalocyanines have been prepared, and are characterized by UV-absorption spectra in water and organic solvents and in their mixtures. The monomer–dimer transformation equilibrium was affected by solvent polarity and the length of the alkyl chains in the amphiphilic parts. All complexes are efficient catalysts for the oxidation of 2-mercaptoethanol in the presence of dioxygen. The positive charge around the complex increases the acceleration of the dissociation of 2-mercaptoethanol under neutral pH. The catalytic activity is affected by the length of the alkyl chain; consequently the stability of aggregation between cobalt(II) phthalocyanines, as catalysts for the oxidation of 2-mercaptoethanol, can be changed.

Synthesis of a Monofunctional Phthalocyanine on Silica

Silica of different surface area and grain size modified by aminopropyl groups reacted with 4-(3,4-dicyanophenoxy)benzoic acid chloride. The reaction of these benzamidophenoxydicarbonitrile modified silica gels with 4-(4-tert-butyl-phenoxy)-1,2-benzenedicarbonitrile in the presence of a zinc(II) salt results in covalently bonded phthalocyanine zinc(II) complexes with a loading between 1.8 × 10−5 and 1.7 × 10−6 mol g −1 silica. UV/vis reflectance spectra show that the phthalocyanines on the surface exist in a monomeric state. Cleavage at the amide bond between the silica and the phthalocyanine led to the corresponding monocarboxylic acid phthalocyanine derivative.

Conjugated di- and trinuclear phthalocyanines and their analogs

Extended π-electron delocalization is the most important property of phthalocyanines and structurally related systems. The position of the longest wavelength absorption (Q-band) is influenced by the kind of substituents and by additional fused benzene rings at the ligand. Very large wavelength shifts are obtained with planar annulated di- and trinuclear phthalocyanine analogs sharing a common benzene ring which are the main point of this review. In addition, condensed di- and trinuclear phthalocyanines, and di- and trinuclear phthalocyanines linked via one or two carbon atoms of the macrocycles are discussed for comparison.

Efficient oxidations and photooxidations with molecular oxygen using metal phthalocyanines as catalysts and photocatalysts

Metal phthalocyanines can be very efficient as catalysts and photocatalysts in oxidation reactions using molecular oxygen as oxidant. Different types of soluble low molecular weight or oligomeric and insoluble heterogeneous catalysts and photocatalysts were developed. The heterogeneous metal phthalocyanines exist either impregnated on SiO 2, Al 2 O 3, charcoal and TiO 2 or covalently and coordinatively bound on SiO 2 and organic polymers or ionically bound on an organic ion exchanger. The catalytic oxidations of toxic sulfide and thiol derivative are studied. In addition, toxic phenols were employed as substrates for the photooxidation. Heterogeneous catalysts can exhibit higher activities then low molecular weight phthalocyanines. These systems exhibit a good stability for re-use. Photooxidations are more efficient than oxidations. A Si(IV) phthalocyanine derivative on a polymer ion exchanger is most active and stable. Also some examples for photooxidations in the direction of photochemical synthesis are given.