Zirconium Phosphate Nanoparticles for Solvent Free Acetylation of Phenols and Salicylic Acid: An Efficient and Eco‐friendly Solid Acid Catalyst for Synthesis of Acetyl Salicylic Acid (Aspirin)

Abstract

A facile synthesis of zirconium phosphate (ZP) nanoparticles as an effective, eco‐friendly and recyclable solid acid catalyst were studied. PVA was used as the organic matrix which is the dispersing agent and acted as a template for the nanoparticle. It seems H‐bonds between ZP and PVA along polymer chains play an important role in the better dispersion of in situ formed ZP. The catalyst was characterized by several instrumental techniques such as BET, ICP‐OES, XRD, FT‐IR, SEM and TEM. The TPD‐NH3 analysis suggests the presence of reasonable amount of Brönsted acid sites. The acidic properties of catalyst were studied in acetylation of phenols by acetic anhydride (AA), specifically synthesis of acetylsalicylic acid (ASA), commonly known as Aspirin, from salicylic acid (SA). The effects of reaction time, reaction temperature, mole ratio of reactants, as well as amount of catalysts on the synthesis of ASA were investigated, and the reaction conditions were therefore optimized. The excellent yield (96%) of the ASA was obtained under optimized reaction conditions. The catalyst was recovered from reaction media and reused for 4 times after that with a consistent high yield.