Synthesis Of Methyl Cedryl Ketone Catalyzed By Solid Acid

Methyl Cedryl Ketone (MCK) is a classic spice which has a woody and musky smell, widely used in disinfectants, cosmetics, cleaning products and other household chemical industries. At present, MCK is produced through the acetylation of Cedrene by using acetic anhydride as acylating agent and polyphosphoric acid (PPA) as catalyst in industry. However, this process accompanies many side reactions which lead to low selectivity and low yield, and causes equipment corrosion and environment pollution by polyphosphoric acid. Therefore, the study on the synthesis of MCK catalyzed by solid acid has a very important significance.The main order carrier in MCK is Isomer G, the product of acetylation of Olefin B which is from Thujopsene acid-catalyzed isomerization, by choosing a suitable catalyst and reaction condition, the yield of Olefin B could be maximized selectively. Therefore, this paper firstly studied the isomerization of Thujopsene catalyzed by PW/AC catalyst (load amount of 30%) and determined that it had a high selectivity of Olefin B. The structure of PW/AC catalyst was characterized by BET, IR, XRD, particle size distribution, pore size distribution, etc. The effects of the reaction temperature, solvent ratio, the amount of catalyst, etc on the isomerization reaction were studied and found that the reaction temperature of 40℃, solvent and Thujopsene mass ratio of 2:1, catalyst amount of 40% were the optimum operating conditions.At the same time, this paper through a variety of solid acid catalyst screening and found that macroporous strong acid cationic exchange resin catalyst had a high catalytic activity and selectivity on the acetylation of Cedrene. The structure of resin catalyst was characterized by BET, particle size distribution, pore size distribution, etc. The effects of the reaction temperature, acetic anhydride ratio, the amount of catalyst, the reaction time, etc on the acetylation reaction were studied and the optimum acetylation conditions were determined as follows: the reaction temperature of 90℃, acetic anhydride and Cedrene mole ratio of 2:1, catalyst amount of 40%, reaction time of 3h. Finally, this paper studied on the combination of the isomerization reaction and the acetylation reaction. Firstly Cedrene was catalyzed by PW/AC catalyst for the isomerization reaction of 1h, and then catalyzed by resin catalyst for the acetylation reaction of 3h. It was found that Isomer G in the MCK produced by the new process was 2.76 times as much as the amount catalyzed by polyphosphoric acid in industry, the color was much better, while the conversion and the yield of ketone also were higher than the product catalyzed by polyphosphoric acid. The experimental results in this work provide an important reference for the future industrial application of the synthesis of MCK catalyzed by solid acid.