In:
Catalysis Science & Technology, Royal Society of Chemistry (RSC)
Abstract:
Mechanistic studies on catalytic alkane hydroxylation by Murahashi's O 2 /copper( ii )/aldehyde system have been conducted to show that the autoxidation of an aldehyde (RCHO) by an O 2 generating acyl radical intermediate (RC(O)˙) is involved as an initiation step of the catalytic cycle. The generated RC(O)˙ is trapped by O 2 to 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 (R 1 R 2 CH 2 ; R 1 and R 2 are alkyl groups or hydrogen atoms), giving R 1 R 2 CH˙. The generated R 1 R 2 CH˙ reacts with O 2 to generate alkylperoxyl radical intermediate R 1 R 2 CHOO˙, which then undergoes the Russell reaction to give R 1 R 2 CHOH (alcohol) and R 1 R 2 CO (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.
Type of Medium:
Online Resource
ISSN:
2044-4753
,
2044-4761
Language:
English
Publisher:
Royal Society of Chemistry (RSC)
Publication Date:
2023
detail.hit.zdb_id:
2595090-3
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