IRANIAN JOURNAL OF CATALYSIS
Year:2014 | Volume:4 | Issue:2|Papers Count:9

Reaction between aromatic aldehydes and 3-methyl-1-phenyl-2-pyrazoline-5-one catalyzed by nano-SiO2/HClO4 in water under reflux provided a simple and efficient route for the synthesis of 4- ((5-hydroxy-3-methyl-1-phenyl-1H -pyrazol-4-yl) (aryl) methyl) -3-methyl-1-phenyl-1H-pyrazol-5-ol derivatives in high yields.

Ionic liquids such as 1, 3-dialkylimidazolium salts make excellent catalysts and solvents for synthesis of dialkyl 2- (dialkoxyphosphoryl) -3- (1-oxo-1-H -phthalazin-2-yl) succinates from 2 H -phthalazin-1-one, dialkyl acetylenedicarboxylates, and trialkyl phosphites. Under similar conditions, triphenyl phosphite led to dialkyl 2- (diphenoxyphosphoryl) -3- (1-oxo-1-H phthalazin-2-yl) succinates. The ionic liquid was readily recycled and can be reused four times without significant loss of activity or mass.

Photocatalytic reduction of carbon dioxide to formaldehyde was investigated on four semiconductor photocatalysts (FeS, FeS/FeS2, NiO and TiO2). The reaction was carried out in continues flow of CO2 gas bubbled into the reactor. Semiconductor photocatalysts were characterized by X-Ray diffraction (XRD) and Diffuse Reflectance Spectroscopic (DRS) methods. Sulfide ion was used as hole scavenger. The results show that the TiO2 has greater photocatalytic activity compared to the other photocatalysts, for example, maximum formaldehyde concentration were 720 and 380 ppm on TiO2 and NiO, respectively.Addition of carbonate ion causes an increase (around two times) in the concentration of formaldehyde. The yield of the formaldehyde decreased with decreasing concentration of the sulfide ion and the pH of the reaction mixture (from 700 ppm to 500 ppm). This investigation demonstrates that under ultraviolet radiation, carbon dioxide can be reduced to formaldehyde on semiconductor photocatalysts. This reaction could have been a possible chemical route to photosynthesis on the early Earth.

Eggshell was found to be a versatile heterogeneous catalyst for the synthesis of pyrano [3, 2-c] quinoline derivatives in good yields. This protocol has the advantages of environmental friendliness, short reaction time, low cost and convenient operation.

Efficient and one-pot synthesis of 1, 8-dioxo-octahydroxanthenes was described by Knoevenagel condensation, Michael addition and cyclodehydration of dimedone. This reaction was carried out through condensation of dimedone and various aromatic aldehydes in the presence of task-specific Bronsted acidic ionic liquid under solvent free conditions. The catalyst could be recycled five times without significant loss of its catalytic activity.

An efficient and direct procedure for the synthesis of benzo [h] -indeno [1, 2-b] -quinoline derivatives has been described. The procedure employs a three-component condensation reaction in one-pot using 2H -indene-1, 3-dione, naphthalen-1-amine and aldehydes in the presence of catalytic amount of L-prolinein aqueous media.

Ammonium monovanadate (NH4VO3) has been devoted as an efficient, commercially available, eco-friendly and reusable catalyst for the synthesis of bis (indolyl) methanes (BIMs), oxindole derivatives and also Michael adducts of indoles at 50oC under solvent-free conditions. The reusability of this solid acid catalyst in addition with its selectivity has also been examined.

Cellulose sulfuric acid was used as an efficient biopolymer-based catalyst for the synthesis of tetrahydropyrimido [4, 5- b] quinoline-2, 4, 6-triones and hexahydro-2 H -pyrazolo [5, 4- b] quinoline-6-ones via three component reaction of aldehyde, 5, 5-dimethyl-1, 3-cyclohexadione and 6-amino-1, 3-dimethyluracil or 5-amino-3-methyl-1-phenypyrazole under solvent-free conditions at 90oC. The major advantages of the present method are simple experimentation, use of inexpensive and ecofriendly reusable catalyst with good yields and short reaction times.

Introduction: Rice husk (RH), the outer covering of rice grains that obtained during the milling process, is one of the main agricultural residues. It mainly consists of cellulose, hemicelluloses, lignin, silica and minor other mineral composition. Societies often dispose of the rice husk waste using open burning that leads to environmental pollution and damages to the land and the surrounding area in which it was dumped.