• Bulletin of the Korean Chemical Society
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• v.32 no.11
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• pp.4001-4004
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• 2011

Various 5-substituted 1H-tetrazole derivatives were synthesized in a simple and environmentally benign method from the reaction of aryl and benzyl nitriles with sodium azide in solvent-free media using montmorillonite K-10 clay as solid recyclable heterogeneous acidic catalyst and microwave irradiation in good yields and short reaction times.

• Bulletin of the Korean Chemical Society
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• v.33 no.7
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• pp.2140-2144
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• 2012

A polymer support immobilized acidic ionic liquid was prepared by copolymerization of 3-vinyl-1-(4-sulfonic acid)butylimidazolium hydrogen sulfate with styrene in the presence of benzoyl peroxide and its primary application as a solid acidic heterogeneous catalyst to the synthesis of Hantzsch 1,4-dihydropyridines through a one-pot three-component reaction of aromatic aldehydes, ethyl acetoacetate and ammonium acetate was investigated. The results showed that this heterogeneous catalyst has high catalytic activity and the desired products were obtained in good to high yields. Moreover, the catalyst was found to be reusable and a considerable catalytic activity still could be achieved after third run.

• Bulletin of the Korean Chemical Society
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• v.32 no.11
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• pp.3853-3854
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• 2011

• Bulletin of the Korean Chemical Society
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• v.26 no.10
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• pp.1585-1587
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• 2005

• Bulletin of the Korean Chemical Society
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• v.33 no.8
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• pp.2724-2730
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• 2012

A new heterogeneous acidic catalyst was successfully prepared by impregnation of silica (Aerosil 300) by an acidic ionic liquid, named 1-(4-sulfonic acid)butylpyridinium hydrogen sulfate [$PYC_4SO_3H$][$HSO_4$], and characterized using FT-IR spectroscopy, the $N_2$ adsorption/desorption analysis (BET), thermal analysis (TG/DTG), and X-ray diffraction (XRD) techniques. The amount of loaded acidic ionic liquid on Aerosil 300 support was determined by acid-base titration. This new solid acidic supported heterogeneous catalyst exhibits excellent activity in the synthesis of 2-aryl-2,3-dihydroquinazolin-4(1H)-ones by cyclocondensation reaction of 2-aminobenzamide with aromatic aldehydes under solvent-free conditions and the desired products were obtained in very short reaction times with high yields. This catalyst has the advantages of an easy catalyst separation from the reaction medium and lower problems of corrosion. Recycling of the catalyst and avoidance of using harmful organic solvent are other advantages of this simple procedure.

• Bulletin of the Korean Chemical Society
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• v.33 no.2
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• pp.524-528
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• 2012

A kind of nanosized sulfated zirconia was prepared by a hydrothermal method, and full characterized by XRD, TEM, BET, TGA, and FTIR. Its catalytic activity was evaluated in the esterification reactions, including the testing of the catalytic reusability and the optimization of reaction conditions. The obtained catalyst was revealed to be highly efficient solid catalyst for the esterification of acetic acid with n-butanol, presenting the advantages of high conversion and selectivity, easy recovery, and steady reusability.

• Bulletin of the Korean Chemical Society
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• v.32 no.7
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• pp.2243-2248
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• 2011

Carbon-based solid acid catalyst was found to be highly efficient, eco-friendly and recyclable heterogeneous catalyst for the multicomponent reaction of dimedone, aromatic aldehydes, and a nitrogen source (ammonium acetate or aromatic amines) under solvent-free conditions, giving rise to 1,8-dioxodecahydroacridines in high yields. The present methodology offers several advantages, such as a simple procedure with an easy work-up, short reaction times, high yields, and the absence of any volatile and hazardous organic solvents.

• Bulletin of the Korean Chemical Society
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• v.32 no.12
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• pp.4286-4290
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• 2011

A novel catalytic synthesis of biscoumarins from 4-hydroxycoumarin and aromatic aldehydes has been developed. The reaction occurs in ethanol in the presence of tetrabutylammonium hexatungstate $[TBA]_2[W_6O_{19}]$ as catalyst to give the corresponding products in high yields. This new approach has short reaction times, clean reaction profiles, and simple experimental and workup procedures. Moreover, the catalyst can be easily recovered by filtration and used at least three times with only slight reduction in its catalytic activity.

• Bulletin of the Korean Chemical Society
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• v.34 no.11
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• pp.3289-3294
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• 2013

An efficient method for the preparation of 8-benzylidene-4-phenyl-3,4,5,6,7,8-hexahydro-1H-quinazolin-2-ones/thiones from the reaction of aromatic aldehydes with cyclohexanone and urea or thiourea in the presence of Tetrabutylammonium hexatungstate, $[TBA]_2[W_6O_{19}]$, as an efficient, inexpensive catalyst under thermal and solvent-free conditions has been developed. Good yields, short reaction times, straightforward workup, reusability of the catalyst, and green conditions are the most obvious advantages of this procedure.

• Bulletin of the Korean Chemical Society
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• v.31 no.12
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• pp.3653-3657
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• 2010

Silica supported tungstosilicic acid has been used as an effective catalyst for a modified Dakin-West one-pot, four-component condensation of an aryl aldehyde, an aryl ketone, acetyl chloride and acetonitrile for the synthesis of $\beta$-acetamido ketones. This catalytic system can act as an active, inexpensive, recoverable and recyclable catalyst. Some advantages of this system are short reaction times, good to excellent yields, easy work up and the ability to be carried out at the large scale reactions.