부산대학교 도서관

Mechanistic studies on catalytic alkane hydroxylation by Murahashi's O2/copper(ii)/aldehyde system have been conducted to show that the autoxidation of an aldehyde (RCHO) by an O2generating acyl radical intermediate (RC(O)) is involved as an initiation step of the catalytic cycle. The generated RC(O) is trapped by O2to give an acylperoxyl radical intermediate RC(O)OO, which may react with another RCHO to generate an adduct intermediate RC(O)OOC(R)(H)O. The following O–O bond homolytic cleavage of this intermediate will give acyloxyl intermediate RC(O)O and RCOOH, in which the former acts as a reactive species for hydrogen atom abstraction (HAA) from alkane substrates (R1R2CH2; R1and R2are alkyl groups or hydrogen atoms), giving R1R2CH. The generated R1R2CH reacts with O2to generate alkylperoxyl radical intermediate R1R2CHOO, which then undergoes the Russell reaction to give R1R2CHOH (alcohol) and R1R2CO (ketone) in a 1 : 1 ratio as the oxidation products. The acyloxyl intermediate RC(O)O also reacts with RCHO to give carboxylic acid RC(O)OH and RC(O), constructing the catalytic cycle. The role of copper(ii) ions in the above catalytic process is also investigated using a series of copper(ii) complexes. Furthermore, Murahashi's system was adopted in the catalytic oxidation of methane.