Hooker's oxidation
The Hooker oxidation is a name reaction in organic chemistry . It was named after the English chemist Samuel Cox Hooker (1864-1935). With the help of this reaction it is possible to swap the hydroxy and alkyl (alkenyl) groups within a 2-hydroxy-3- alkyl (or alkenyl ) - 1,4-benzoquinone , with the latter one less methylene group after the reaction contains.
Overview reaction
Instead of potassium permanganate as the oxidizing agent , the reaction can also be carried out with a combination of hydrogen peroxide and sodium carbonate .
R = H , alkyl or alkenyl radical
mechanism
In the following mechanism, the R 1 radical illustrates the alignment of the molecule and shows that the hydroxy group and the alkyl (alkenyl) group actually change positions.
First, the hydroxyl group in molecule 1 is deprotonated and a permanganate ion ( 3 ) approaches the resulting anion 2 . Molecules 4 , 5 and 6 show, like permanganate ion, the carbon atoms at which R 2 and the hydroxyl group were initially located, oxidized and reduced themselves to manganese (IV) oxide . A hydroxide ion can now split off a proton in 7 , which is in the α position to the R 2 radical and a carbonyl group . This is followed by an intramolecular nucleophilic attack by the carbanion 7 on the carbonyl carbon atom and thus the closure of a six-membered ring 8 . The molecule 9 is formed by splitting off a formate anion . After the electrons 10 have been shifted and the subsequent acidic ( H + ) work-up with, the product 11 is formed in that the hydroxyl group and the alkyl or alkenyl radical, which has now been shortened by one methylene group, have switched positions.
Individual evidence
- ↑ a b Z. Wang (Ed.): Comprehensive Organic Name Reactions and Reagents, 3 Volume Set. John Wiley & Sons, Hoboken, New Jersey 2009, ISBN 978-0-471-70450-8 , p. 1477.