TY - JOUR
T1 - Sonocatalysis and alkaline-doped carbons: an efficient method for the synthesis of chalcones in heterogeneous media
AU - Durán-Valle, Carlos Javier
AU - Fonseca, Isabel M.
AU - Calvino-Casilda, Vanesa
AU - Picallo, María
AU - López-Peinado, Antonio José
AU - Martín-Aranda, Rosa María
N1 - V.C.C. thanks the Universidad Nacional de Educación a Distancia (U.N.E.D.) for a Ph.D. fellowship. Authors thank Prof. J.L.G. Fierro for the XPS fruitful discussion. Financial Support of this work by Spanish CICYT (project MAT2001-0319) is gratefully acknowledged. Norit pristine carbon has been kindly supplied by Norit Company.
PY - 2005/10/30
Y1 - 2005/10/30
N2 - The Claisen-Schmidt condensation between benzaldehyde and acetophenone has been carried out for the preparation of chalcones. Two basic activated carbons (Na- and Cs-Norit) have been used as catalysts. The order of activity is Na-Norit < Cs-Norit. Chalcones have been synthesized by sonochemical irradiation. The effect of the ultrasound activation has been studied. Cs-doped carbon is presented as the optimum catalyst, giving excellent activity for this type of condensation. A substantial enhancing effect in the yield was observed when the carbon catalyst was activated under ultrasonic waves. This "green" method (combination of alkaline-doped carbon catalyst and ultrasound waves) has been applied to the synthesis of several chalcones with antibacterial properties achieving, in all cases, excellent activities and selectivities. 4′-Hydroxy and 4′-carboxy-chalcones have been prepared under mild conditions by sono-activation of the carbon catalyst. A comparative study under non-sonic activation has showed that the yields are lower in silent conditions, indicating that the sonication exerts a positive effect on the activity of the catalyst. Cs-Norit carbon catalyst can compete with the traditional NaOH/EtOH when the reaction is carried out under ultrasounds. The role of solvent in this reaction was studied with ethanol. High conversion was obtained in absence of solvent. The carbons were characterized by thermal analysis, nitrogen adsorption and X-ray photoelectron spectroscopy.
AB - The Claisen-Schmidt condensation between benzaldehyde and acetophenone has been carried out for the preparation of chalcones. Two basic activated carbons (Na- and Cs-Norit) have been used as catalysts. The order of activity is Na-Norit < Cs-Norit. Chalcones have been synthesized by sonochemical irradiation. The effect of the ultrasound activation has been studied. Cs-doped carbon is presented as the optimum catalyst, giving excellent activity for this type of condensation. A substantial enhancing effect in the yield was observed when the carbon catalyst was activated under ultrasonic waves. This "green" method (combination of alkaline-doped carbon catalyst and ultrasound waves) has been applied to the synthesis of several chalcones with antibacterial properties achieving, in all cases, excellent activities and selectivities. 4′-Hydroxy and 4′-carboxy-chalcones have been prepared under mild conditions by sono-activation of the carbon catalyst. A comparative study under non-sonic activation has showed that the yields are lower in silent conditions, indicating that the sonication exerts a positive effect on the activity of the catalyst. Cs-Norit carbon catalyst can compete with the traditional NaOH/EtOH when the reaction is carried out under ultrasounds. The role of solvent in this reaction was studied with ethanol. High conversion was obtained in absence of solvent. The carbons were characterized by thermal analysis, nitrogen adsorption and X-ray photoelectron spectroscopy.
KW - Activated carbons as catalysts
KW - Basicity
KW - Chalcone synthesis
KW - Claisen-Schmidt condensation
KW - Sonocatalysis
UR - http://www.scopus.com/inward/record.url?scp=26844445720&partnerID=8YFLogxK
U2 - 10.1016/j.cattod.2005.07.063
DO - 10.1016/j.cattod.2005.07.063
M3 - Article
AN - SCOPUS:26844445720
SN - 0920-5861
VL - 107-108
SP - 500
EP - 506
JO - Catalysis Today
JF - Catalysis Today
ER -