Sulfated Tin Oxide Research Paper

3. Catalytic application of sulfated tin oxide in organic synthesis
3.1. Synthesis of 7-hydroxy-4-methyl coumarin using Pechmann condensation method Different sulfate content (5 to 30% by weight) containing nanostructure sulfated tin oxides were synthesized from the hydroxylated tin oxide (obtained from precipitation method) and SO42- species of the sulfuric acid. At the temperatures 400, 500, and 600 °C, the so prepared sulfated tin oxide catalysts were calcinated. These catalysts were analyzed in the solvent free synthesis of 7-hydroxy-4-methyl coumarin from ethylacetoacetate:resorcinol (molar ratio 2: 1) at 120 °C by using the Pechmann condensation methodology.49 The FT-IR spectra in pyridine of these catalysts clearly indicated the existance

Corma et al also investiagted the effect of the sulfate content and the calcination temperature on the yield of the reaction. One more advantage of the methodology developed is the reusability of the sulfated tin oxide solid acid catalyst. The acidic properties of the sulfated tin oxide catalyst was analyzed by an in situ FT-IR (CO adsorbed

The catalyst surface acidity was determined by uisng the TGA/Pyridine sample. The acid strength of the catalyst was analyzed with potentiometric titration with n-butylamine in non-aqueous media. As represented in the Scheme 5, the Friedel-Crafts acylation of toluene was achieved with the prepared sulfated catalysts56 to investigate the catalytic activityA higher yields of the acylation products were obtained with sulfated tin oxide than Al3+-impregnated sulfated zirconia, since STO has greater acidity and higher acid strength. It was also observed that the sulfated tin oxide was found to show maximum higher acidity and higher efficiency for the acylation reaction when sulfate loading was 10 wt%. Among the structural characteristics, acidity and catalytic activity,a good relationship is