The solvent-free o-esterification of salicylic acid (SA) with the acetic acid anhydride (AAA) in the acetylsalicylic acid (ASA) was studied over the modified clinoptilolite (CL) and heulandites: natural heulandite itself (HEU) and monomineral natural heulandite (HEU-M) of Dzegvi and Akhaltsikhe (Georgia) deposits, respectively; simultaneously decationized and dealuminated forms of catalysts were prepared by acid leaching of initial zeolites. It was demonstrated using the methods of gravimetric, UV- FTIR-spectral and HPLC analysis, also by catalysts acidity measurements the symbatic change of ASA yield in the amount of proton acid centers (AI-(OH)-Si) of catalysts: H-CL (Si /AI = 10.7)> H-HEU (Si /AI = 5.4) ≥ H-HEU-M (Si /AI = 4.1); yields of ASA on H-CL (Si / AI = 10.7) was about 92% and on heulandites – 75% at 80 °C; these solid acid catalysts were prepared from natural zeolites and therefore they are cheap, have high activity, are easy to prepare and reusable.
