Silica-included tungstophosphoric acid and its Cs salt, zinc ion-excha
nged smectite clays, and montmorillonite K10 could be effectively appl
ied as insoluble, readily recoverable solid acid catalysts to the hydr
olysis of ethyl acetate, liquid-phase Friedel-Crafts reactions, and th
e synthesis of alkylporphyrin derivatives, respectively. They are expe
cted to be alternatives to the environmentally problematic homogenous
acid catalysts such as sulfuric acid, aluminum chloride, and boron tri
fluoride.