Catalysis Letters, Vol.38, No.1-2, 133-134, 1996
Oxidation of Limonene Catalyzed by Mn-III(SALEN)Cl-Center-Dot-H2O
The cationic Mn-III(Salen) complex was proved to be an effective catalyst for the oxidation of limonene with iodosobenzene as terminal oxidant. For reactions conducted in CH2Cl2 at rt, with molar ratio of 1 : 0.05 : 1 (limonene : catalyst : iodosobenzene) limonene oxidation does occur with an optimal conversion of 60%. The major products according to HRGC-MS and HRGC-IR analyses were cis- and trans-1,2-epoxylimonene (30% and 16.7%, selectivity, respectively), the two diastereoisomers of 1-p-menthen-9-al (20% selectivity), and carvone (10% selectivity). A turnover of 60 was observed at 1 : 0.01 : 1 ratio. The higher selectivity toward epoxide formation supports the rebound oxygen mechanism.