Heterogenization of Ketone Catalyst for Epoxidation by Low Pressure Plasma Fluorination of Silica Gel Supports

摘要

Low pressure plasma was used for preparing heterogeneous organocatalysts >2-(>A)-(>C) suitable for dioxirane-mediated epoxidations. Heterogenization was accomplished by adsorption of the methyl perfluoroheptyl ketone (>2) on fluorinated supports (>A)-(>C) deriving from the treatment of commercial C8-silica gel in low pressure plasma fed with fluorocarbons. Catalyst >2-(>C) proved to be the most efficient one, promoting epoxidation of an array of alkenes, including unsaturated fatty esters like methyl oleate (>10) and the triglyceride soybean oil (>11), with the cheap potassium peroxymonosulfate KHSO5 (caroate) as a green oxidant. Notably, the perfluorinated matrix gives rise to the activation of caroate, generating singlet oxygen. Materials were characterized by infrared Attenuated Total Reflectance spectroscopy (ATR-FTIR), X-ray Photoelectron Spectroscopy (XPS ) and Emission Scanning Electron Microscope (FESEM).