symboom
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Non reactive Solvent for potassium permanganate
Here is some information I have found.
It has been discovered that potassium permanganate can be a homogenous weak oxidant in organic solvent without the addition of water. If acetone is
employed as the only solvent, among some common organic substrates included alkenes, alcohols, arenes, aldehydes and phenols, secondary alcohols are
converted to the corresponding ketones and aldehydes to the corresponding acid. Compared with oxidation reaction of potassium permanganate in water,
in anhydrous acetone system, potassium permanganate as a weaker oxidant has no influence on the alkyls in benzene rings, double bonds and so on. So
potassium permanganate can exhibit selectivity by solvent controlling. Especially, when aldehydes are oxidized, the oxidation process is a green
organic reaction for nearly all coproducts and solvent can be recycled
Dimethyl polyethylene glycol solubilizes potassium permanganate in benzene or methylene chloride and can thus be used as a phase transfer agent for
permanganate oxidations. ... When methylene chloride is used as the solvent, potassium permanganate may be transferred from either an aqueous solution
or from the solid phase.
some of the lower-chlorinated hydrocarbons (methylene chloride, 1,2-dichloroethane, 1,1,2-trichloroethane) should work. If you can live with a high
boiling point solvent, you might consider chlorobenzene.
Other solvents that fit these criteria include most alkanes (pentane, hexane, cyclohexane, petroleum ether, etc.), benzene (but not toluene), and
diethyl ether
[Edited on 4-12-2020 by symboom]
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rockyit98
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permanganate ions are not the problem it's the K+ ion , so if you can get some Crown ether for K+ (18-crown-6) that will make potassium permanganate
much soluble. what about glacial acetic acid?
"A mind is a terrible thing to lose"-Meisner
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clearly_not_atara
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The one paper I have read using this technique uses methylene chloride. This seems like an excellent choice limited only by availability. Chloroform,
by contrast, sounds concerning due to its oxidation product.
I'm not sure what's the best alternate solvent. Benzene should work if it's not too nonpolar. Toluene is a no. Ether makes me nervous. Chlorobenzene
should work. 1,2-dichloroethane is probably okay.
Crown ethers are not practical for amateurs. Toxic & expensive.
The technique of choice here is just to use a stoichiometric amount of a quaternary ammonium chloride forming the quat permanganate and KCl. To make a
large amount of trimethylbenzylammonium chloride, you can take advantage of the reaction between formaldehyde and NH4Cl to give trimethylamine
hydrochloride:
http://www.orgsyn.org/demo.aspx?prep=CV1P0531
The amine can be combined with benzyl chloride in acetone to precipitate the quat.
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unionised
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It dissolves in acetonitrile to the extent of giving a pinky purple solution.
Not the easiest solvent to find OTC- which is a pity.
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clearly_not_atara
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If you can buy ethyl acetate, it should be pretty easy to make acetonitrile, if slow -- just stir with ammonia water for days (ok annoying) and
distill over alumina (or "insert catalyst here").
If you can't, though, it's work.
[Edited on 3-12-2020 by clearly_not_atara]
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