Bir Sain

Cobalt phthalocyanine catalyzed aerobic oxidation of secondary alcohols: an efficient and simple synthesis of ketones

A variety of activated and non-activated secondary alcohols have been efficiently oxidized to their corresponding ketones in excellent yields with molecular oxygen using cobalt phthalocyanine as catalyst in the presence of powdered potassium hydroxide.

An efficient aerobic oxidative cyanation of tertiary amines with sodium cyanide using vanadium based systems as catalysts

The first report on the use of vanadium-based catalysts for oxidative cyanation of tertiary amines with molecular oxygen in the presence of sodium cyanide and acetic acid to afford the corresponding alpha-aminonitriles in good to excellent yields is described.

Grafting of oxo-vanadium Schiff base on graphene nanosheets and its catalytic activity for the oxidation of alcohols

Graphene oxide was found to be a convenient and efficient supporting material for grafting of oxo-vanadium Schiff basevia covalent attachment. The low dimensionality and rich surface chemistry of graphene oxide play critical roles in order to achieve a good degree of such grafting. Catalytic potential of the so prepared graphene-bound oxo-vanadium Schiff base and comparison with its homogeneous analogue was studied for the oxidation of various alcohols to carbonyl compounds using tert-butylhydroperoxide as oxidant. The structural and chemical nature of the catalyst was characterized by a variety of techniques including XRD, FTIR, TGA, TEM, and ICP-AES. The immobilized complex was found to be highly efficient and showed comparable catalytic reactivity as its homogenous analogue with the added benefits of facile recovery and recycling of the heterogeneous catalyst. The graphene-bound oxo-vanadium Schiff base was successfully reused for several runs without significant loss in its catalytic activity.

PEG-assisted solvent and catalyst free synthesis of 3,4-dihydropyrimidinones under mild reaction conditions

PEG-assisted solvent and catalyst free synthesis of 3,4-dihydropyrimidinones under mild and neutral reaction conditions is described.

An improved high yielding immobilization of vanadium Schiff base complexes on mesoporous silica via azide―alkyne cycloaddition for the oxidation of sulfides

Azide–alkyne [3+2] cycloaddition “click reaction” was found to be a simple yet improved approach for the efficient immobilization of oxo–vanadium(IV) tridentate Schiff base complexes to mesoporous silica via covalent attachment as it occurred under mild reaction conditions and provided high catalyst loading compared to the direct immobilization of oxo–vanadium(IV) tridentate Schiff base complex to 3-chloropropylsilyl functionalized silica support.

Cobalt phthalocyanine immobilized on graphene oxide: an efficient visible-active catalyst for the photoreduction of carbon dioxide.

New graphene oxide (GO)-tethered-Co(II) phthalocyanine complex [CoPc-GO] was synthesized by a stepwise procedure and demonstrated to be an efficient, cost-effective and recyclable photocatalyst for the reduction of carbon dioxide to produce methanol as the main product. The developed GO-immobilized CoPc was characterized by X-ray diffraction (XRD), FTIR, XPS, Raman, diffusion reflection UV/Vis spectroscopy, inductively coupled plasma atomic emission spectroscopy (ICP-AES), thermogravimetric analysis (TGA), Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). FTIR, XPS, Raman, UV/Vis and ICP-AES along with elemental analysis data showed that Co(II) -Pc complex was successfully grafted on GO. The prepared catalyst was used for the photocatalytic reduction of carbon dioxide by using water as a solvent and triethylamine as the sacrificial donor. Methanol was obtained as the major reaction product along with the formation of minor amount of CO (0.82 %). It was found that GO-grafted CoPc exhibited higher photocatalytic activity than homogeneous CoPc, as well as GO, and showed good recoverability without significant leaching during the reaction. Quantitative determination of methanol was done by GC flame-ionization detector (FID), and verification of product was done by NMR spectroscopy. The yield of methanol after 48 h of reaction by using GO-CoPc catalyst in the presence of sacrificial donor triethylamine was found to be 3781.8881 μmol g(-1)  cat., and the conversion rate was found to be 78.7893 μmol g(-1) cat. h(-1). After the photoreduction experiment, the catalyst was easily recovered by filtration and reused for the subsequent recycling experiment without significant change in the catalytic efficiency.

Cobalt phthalocyaninetetrasulphonamide catalyzed aerobic oxidation of α-hydroxyketones: an efficient and simple synthesis of α-diketones

A variety of α-hydroxyketones were efficiently oxidized to α-diketones in near quantitative yields with molecular oxygen, under alkaline conditions, using cobalt phthalocyaninetetrasulphonamide as catalyst. Acyloins in general were found to less reactive than benzoins and required high pH for their oxidation. Among the benzoins, those substituted with electron donating groups were found to be more reactive and required lesser reaction time for their oxidation.

Photocatalytic reduction of carbon dioxide to methanol using a ruthenium trinuclear polyazine complex immobilized on graphene oxide under visible light irradiation

A ruthenium trinuclear polyazine complex was synthesized and subsequently immobilized through complexation to a graphene oxide support containing phenanthroline ligands (GO-phen). The developed photocatalyst was used for the photocatalytic reduction of CO2 to methanol, using a 20 watt white cold LED flood light, in a dimethyl formamide–water mixture containing triethylamine as a reductive quencher. After 48 h illumination, the yield of methanol was found to be 3977.57 ± 5.60 μmol gcat−1. The developed photocatalyst exhibited a higher photocatalytic activity than graphene oxide, which provided a yield of 2201.40 ± 8.76 μmol gcat−1. After the reaction, the catalyst was easily recovered and reused for four subsequent runs without a significant loss of catalytic activity and no leaching of the metal/ligand was detected during the reaction.

Starch Immobilized Ruthenium Trichloride Catalyzed Oxidative Cyanation of Tertiary Amines with Hydrogen Peroxide.

Starch immobilized ruthenium trichloride, easily synthesized by the reaction of silyl functionalized imidazolium chloride and hydroxyl groups of expanded corn starch (ECS) followed by the reaction with ruthenium trichloride, was found to be a highly efficient and recyclable catalyst for the oxidative cyanation of tertiary amines to α‐aminonitriles in high yields using hydrogen peroxide with sodium cyanide in acetic acid.

Copper-catalyzed imination of pyridines using PhINTs as nitrene precursor

Abstract The reaction of PhINTs with pyridines in the presence of a catalytic amount of Cu(II) triflate afforded the corresponding p -tolylsulfonyliminopyridinium ylides in excellent yields.