October 24, 2021, 03:33:32 AM
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Topic: Oxidation  (Read 1375 times)

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Offline Justinn343

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Oxidation
« on: July 23, 2021, 12:49:58 AM »
Recently I have been wondering why Acetone is obligatory to use as solvent in oxidation with other oxidising agents, i know it is a mild oxidiser and neutralises hydroxy radicals but could there be another alternative to it in the fields of green chemistry? Maybe Ascorbic Acid in H2O?

Offline rolnor

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Re: Oxidation
« Reply #1 on: July 23, 2021, 01:20:03 AM »
acetone was used from long time ago with Jones reagent, I think you can use other solvents as well. Ascorbic acid reacts fast with KMnO4 so its probably not so good.

Offline Justinn343

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Re: Oxidation
« Reply #2 on: July 23, 2021, 11:47:10 AM »
Which other solvents can be used?
Also is it necessary to use those solvents in combination with the main oxidizer?

Offline Justinn343

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Oxidation
« Reply #3 on: July 24, 2021, 02:36:05 AM »
If Acetone is an oxidant why is it used to reduce over oxidation  ??? ??? And Why is it perferred for indoles to be oxidised in basic conditions and not acidic?

Looking forwards to your replies,

Justin

Offline rolnor

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Re: Oxidation
« Reply #4 on: July 24, 2021, 06:44:09 AM »
It depends on the oxidation reagent. Jones reagent is aqueous so maybe dioxane, DMF (not DMSO), maybe THF, acetonitrile.
KMnO4 is also water-soluble so its similar. I think there is tetrabutylamoniumpermanganate also so this could be used in DCM, EtOAc etc. Acetic acid would also be fine in all cases.  I have no reference to these suggestions, its just my thoughts.
No, you can use just water but often your startingmaterial is not soluble in just water, you need a co-solvent.

Offline billnotgatez

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Re: Oxidation
« Reply #5 on: July 24, 2021, 09:07:50 AM »
@Justinn343
I have combined all your oxidation questions since they are along the same idea

Offline Justinn343

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Re: Oxidation
« Reply #6 on: July 24, 2021, 09:48:54 AM »
Thanks @rolnor for the great reply, that has actually helped me connect the pieces and even answered some of the questions i never even got to ask :)

Also, I noticed u mentioned Acetic Acid would be fine in all cases, would it be a great medium in basic conditions? As an acid?

Offline Justinn343

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Re: Oxidation
« Reply #7 on: July 24, 2021, 09:54:14 AM »
@Justinn343
I have combined all your oxidation questions since they are along the same idea

I started another thread trying to keep it short and sweet, since that one never got any great replies

Offline billnotgatez

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Re: Oxidation
« Reply #8 on: July 24, 2021, 10:37:27 AM »
@Justinn343

I apologize

Offline rolnor

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Re: Oxidation
« Reply #9 on: July 24, 2021, 04:12:02 PM »
I am not sure how you mean, in basic conditions acetic acid will be acetate and not functioning as a solvent? Also I think 90% aquoeous TFA could be used for Jones reagent instead of H2SO4 and act bots as solvent and acid catalyst, it would be interesting to try.

Offline Justinn343

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Re: Oxidation
« Reply #10 on: July 25, 2021, 02:30:17 AM »
@rolnor I will be keeping my options limited to Acetic Acid for now (due to green chemistry purposes) however i was wondering if Acetic Acid can be combined with Ascorbic Acid (vitamin c) to reduce over oxidation when using Oxone as the main oxidising agent?

Offline rolnor

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Re: Oxidation
« Reply #11 on: July 25, 2021, 04:51:34 AM »
Ascorbic acid is in a enol-form so it containes a double-bond, this can react with oxone. It depends on how fast your wanted reaction is if this reaction competes. I also think oxone is not very "green", it can react with ketones and form dioxiranes, these can react with alkenes to form epoxides wich are alkylating. Oxone is a powerful disinfectant and therefore also cytotoxic.
https://en.wikipedia.org/wiki/Potassium_peroxymonosulfate

Offline Justinn343

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Re: Oxidation
« Reply #12 on: July 25, 2021, 05:38:01 AM »
@rolnor You're right but not long ago i was reading about an oxygenation reaction using green chemistry having oxone as the main oxidant, if I'm not mistaken.

It may not be "very green" but its better than thousands of other oxidants when comes to indole oxygenation in my opinion.

I was thinking of a 45min reaction using AcOH as a medium, Ascorbic Acid as a radical quencher and Oxone as the main oxidant.

Let me know what you think

Offline rolnor

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Re: Oxidation
« Reply #13 on: July 25, 2021, 12:20:41 PM »
I would first try without ascorbic acid, if it works, try with. Yes, I agree, chrome and manganese etc. are worse then oxone. I dont know if the oxidation with oxone is possible in slight acidic medium, I have no experience in this reaction.

Offline Justinn343

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Re: Oxidation
« Reply #14 on: July 25, 2021, 03:06:28 PM »
Yes, not a good idea when it comes to Aldehydes but should be fine with non aldehyed indoles in acidic or basic conditions.

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