Silica gel-supported polyphosphoric acid (PPA/SiO2) as an efficient and reusable catalyst for conversion of carbonyl compounds into oxathioacetals and dithioacetals

A simple and efficient method for the conversion of carbonyl compounds to oxathioacetals and dithioacetals by using polyphosphoric acid supported on silica gel (PPA/SiO2) as an acid catalyst have been developed. PPA/SiO2 is easily recovered from the reaction mixture and reused without a decrease in catalytic activity.