AN INFRARED SPECTROSCOPIC STUDY OF ACETONE AND MESITYL OXIDE ADSORPTION ON ACID CATALYST

The interactions between the acetone carbonyl and the carbonyl and dou ble bond of mesityl oxide and the Bronsted and Lewis acid sites of aci d catalysts have been studied by Fourier Transform infrared (FTIR) spe ctroscopy. The acetone carbonyl interactions with bridging acidic OH a nd with bridging weakly acidic OH can be distinguished from one anothe r semiquantitatively. This was substantiated by a quasi one-to-one rel ation between the number of bridging OH in a cluster Si-nAl containing only one Al and the number of strongly hydrogen-bonded acetone. The d istinction between Bronsted and Lewis sites is not easy with acetone, while it is with mesityl oxide. The system acetone-mesityl oxide adsor bed an acid catalysts is rather unique, since the reagent and the reac tion product of the condensation reaction are qualitatively and quanti tatively detectable by FTIR spectroscopy. The quantitative determinati on of the coverage of the acid sites by the reagent and the reaction p roduct was a prerequisite to the study of the reaction presented elsew here.