Phosphotungstic Acid Nanoclusters Grafted onto High Surface Area Hydrous Zirconia as Efficient Heterogeneous Catalyst for Synthesis of Octahydroquinazolinones and β-Acetamido Ketones

• Published in: Journal of cluster science 2011-06, Vol.22 (2), p.295-307
• Main Authors: Naik, Mallari A., Samantaray, Satish, Mishra, B. G.
• Format: Article
• Language: English
• Subjects: Acetonitrile; Acetyl chloride; Aldehydes; Aromatic compounds; Catalysis; Catalysts; Chemical synthesis; Chemistry; Chemistry and Materials Science; Chromatography; Condensates; Diffuse reflectance spectroscopy; Ethanol; Hydration; Infrared spectroscopy; Inorganic Chemistry; Ketones; Nanochemistry; Nanoclusters; Original Paper; Oxidation; Physical Chemistry; Purity; Sol-gel processes; Surface area; Transmission electron microscopy; X-ray diffraction; Zirconium; Zirconium dioxide
• ISSN: 1040-7278; 1572-8862
• DOI: 10.1007/s10876-011-0384-4

Phostungstic acid (PWA) nanoclusters grafted onto high surface area polycrystalline hydrous zirconia powder (PWA/ZrO 2 ) was prepared by wet impregnation method. The zirconia particles were synthesized using a modified sol–gel route. The obtained material was characterized by X-ray diffraction (XRD), UV–Vis–diffuse reflectance spectroscopy (UV–Vis–NIR–DRS), infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and sorptometric techniques. XRD study revealed the presence of tetragonal phase of zirconia in the synthesized sample. TEM study indicates presence of small PWA clusters with size in the range of 5–15 nm well dispersed on the surface of the ZrO 2 particles. The characteristic UV and IR absorption feature of the PWA was retained in the PWA/ZrO 2 material. The PWA/ZrO 2 material was used as an efficient catalyst for the preparation of octahydroquinazolinones and β-acetamido ketones. The octahydroquinazolinones were synthesized by the multicomponent condensation of dimedones, urea and aryl aldehydes in ethanol. Similarly, β-acetamido ketones were synthesized with high yield and purity by four component condensation of aryl aldehydes, enolizable ketones, and acetyl chlorides in acetonitrile. The protocols developed in this investigation using the PWA/ZrO 2 catalyst is advantageous in terms of simple experimentation, high yield and purity of the products and recovery and reutilization of the heterogeneous catalyst.