“Gas and liquid-phase FTIR study of the acylation capacity of supported phosphotungstic Wells- Dawson heteropolyacid”.

SEBASTIÁN E. COLLINS, ADRIÁN L. BONIVARDI, SILVANA R. MATKOVIC, LAURA E. BRIAND.

Washington, DC

Congreso; “238th American Chemical Society National Meeting & Exposition”; 2009

American Chemical Society

<!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";} @page Section1 {size:612.0pt 792.0pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> Undoubtedly, the catalytic processes based on heteropoly-acids are an outstanding contribution in the development of environmental benign technologies. Along with this worldwide trend, our group explores the catalytic activity of phosphotungstic Wells-Dawson HPA in the Friedel-Crafts acylation of p-isobutylbenzene with acetic anhydride toward pisobutylacetophenone, which is an intermediate in ibuprofen synthesis. Infrared spectra collected during the interaction of acetic anhydride with the HPA catalyst between 20-70 ºC, showed the production of IR bands characteristic of molecularly adsorbed acetic acid and adsorbed acetate species. Blank experiments flowing HAc corroborated this last interpretation. Additionally, a weaker band was registered at 1650 cm-1, along side with the production of HAc. This signal could be ascribed to the acetyl [CH3C(O)+] intermediated bonded to the heteropoly-anion, as was reported previously on HZSM5 (1705 cm-1) and Keggin type HPA (1654 cm-1). In order to corroborate this assignment, an additional experiment was performed adsorbing acetyl chloride (CH3COCl). The intermediate-reactive acetyl species partially reacts/desorbs by flowing AA/CCl4 under heating up to 70 ºC. The typical acetyl IR band is also clearly observed during the reaction between p-isobutylbenzene/acetic anhydride (10/1) in the temperature range of 20-70 ºC. Exposición oral de 35 minutos de duración. El congreso contó con 13.000 inscriptos