Baeyer-Villiger oxidation of myrtenal over hydrotalcites based catalysts: The role of structure type, metal content, preparation method and acid-base properties

Nopinone is a fine chemical used in many areas of the chemical industry. A relatively new method of its synthesis is Baeyer-Villiger oxidation of myrtenal to 6,6-dimethyl-bicyclo[3,1,1]-hept-2-en-2-ol formate and its subsequent hydrolysis to nopinone. This study deals with preparing mixed oxides modified with tin and tested them as catalysts for this reaction. Besides the influence of different reaction conditions, the research was aimed at the influence of the catalyst type, the method of its modification and the amount of metal incorporated into its structure. The possibility of repeated use of the prepared catalysts was also tested. Total conversion of myrtenal and selectivity to nopinone of 93% was achieved after 2 h of the reaction using the catalyst based on mixed oxide with the molar ratio of Mg/Al ions equals 2 modified by 5 wt% of tin. This catalyst can be used repeatedly in at least three reaction cycles.