goldberg - 5-9-2022 at 00:14
While reading about Kolbe electrolysis i came across description of Hofer-Moest reaction.
In short in case where graphite is used instead of platinum (and especially in presence of salts like carbonates or sulfates) radical reacted during
oxidation of carboxylate ion is oxidized to carbocation. Then carbocation reacts with nucleophile.
I'm curious if anybody has practical experience with this reaction.
I read that it is possible to obtain methanol from acetate salts using this reaction but what else can be obtained by electrolysis of acetate salts?
The main problem is that given nucleophile must be very resistant to oxidation so it will be not oxidized instead of acetate ion.
That's why synthesis of methyl iodide by electrolysis of solution of sodium acetate, sodium carbonate(to prevent Kolbe reaction) and potassium iodide
will be rather not succesfull. But how about reaction of methyl radical with elemental iodine in statu nascendi?
Or would be possible to synthesise nitromethane by electrolysis of sodium acetate in presence of sodium nitrite?
Has anybody obtained other substance than metanol or it's esters using Hofer-Moest reaction?
Another line of thought: Electrochemicaly generated carbocation should be able to react with aromatic ring in manner similar to Friedel-Crafts
alkylation. (In Friedel-Crats there is also carbocation involved but it is generated by another mean). Unfortunately i did not managed to find any
information about such reaction in literature.
Etheryfication of phenols would not be rather succefull in described condiitons because phenols are too easily oxidized but maybe there is workaroud?
Say synthesis of anisole from phenol.
I will be very gracefull for any information from literature or your own experience in laboratory with Hofer-Moest reaction.
I'm driven by curiosity because Hofer-Moest reaction looks potentialy usefull and i do not seek route to synhtesise any parcitcular compound right
now, rather i'm checking the waters.
myr - 5-9-2022 at 07:01
Have you seen this paper? https://www.nature.com/articles/s41467-020-18275-1
It discussed the limitations of the H-M reaction, giving a bit of a literature review on these kinds of decarboxylations. The described system is
really interesting synthetically too.
Specifically, I don't think you would get nitro compounds, maybe nitrite esters instead.
goldberg - 5-9-2022 at 23:36
Thank you for this paper i'm analysing it in detail right now. I see that it is about oxygen containing nucleophiles that are also oxidized at anode.
What about graphite anode instead of platinum? It should adsorb radicals and thus reaction will proceed only by carbocations.
Why you think that it instead of nitroalkane nitrite ester would be formed?