Patent ID: 7544831
Filing Date: 2009-06-09
Classification: C07C

Abstract:
1. A green catalytic process for the synthesis of acetyl salicylic acid which comprises reacting salicylic acid with acetic anhydride in a molar ratio of 1:2 to 1:5 in the presence of solid acid catalyst wherein the solid acid catalyst used is selected from the group consisting of nano-crystalline sulphated zirconia, nano-crystalline sulphated titania, zeolite H-beta, H-Y, H-ZSM-5 and K-10 montmorillonite clay catalyst having the surface area in the range of 85-523 m2/g, wherein the salicylic acid to catalyst weight ratio in the range of 10:1 to 250:1, heating the above said reaction mixture at a temperature in the range of 90 to 120° C., for a period of 30 to 240 minutes, followed by filtration to obtain the crude acetyl salicylic and recrystallizing the resultant crude product with ethanol-water mixture to obtain pure crystals of acetyl salicylic acid and regenerating the used catalyst by washing with acetone and activating it in air at a temperature of 350 to 450° C. for a period of 2-4 hrs for further use.