Epoxidation of Olefins over Immobilized Jacobsen Catalysts

2 Epoxidation of Olefins over Immobilized Jacobsen Catalysts 

Epoxidation of cis-ethyl cinnamate, styrene, and 1,2-dihydronaphtalene over MCMIHC, MCM2HC, and MCM3HC materials was carried out using different oxygen sources (e.g., NaOCl, m-CPBA, and DMD generated in situ). The catalyst stability was checked by recording the infrared spectra of the catalyst before and after the reaction. When NaOCl and m-CPBA were employed as oxygen sources. 

Reaction conditions 0.25 mmol substrate, 0.25mmol Oxone , 30mg homogeneous catalyst or 300-500mg heterogeneous catalyst, 0.075mmol 4-PPNO, 4mL CHjCOOH, pH 7-8 by use of aqueous NaHCOj, RT, 25-50min. a cisitrans ratio, b [2R, 3R) (cis-epoxide). c (2S, 3R) (trans-epoxide). 

Different immobilization methods were applied for Jacobsen s catalyst. The entrapment of the organometallic complex in the supercages of the dealuminated zeolite was achieved without noticeable loss of activity and selectivity. The immobilized catalysts were reusable and did not leach. For the oxidation of (-)-a-pinene the system used only O2 at RT instead of sodium hypochloride at 0 °C. There was a disadvantage in the use of pivalic aldehyde for oxygen transformation via the corresponding peracid. This results in the formation of pivalic acid, which has to be separated from the reaction mixture. 

I First cyds ] Second cyde I Third cyde I Fourth cyde 

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