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Author Topic: Neutralization of Hydrogen Peroxide  (Read 9353 times)

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nancyVIII

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Neutralization of Hydrogen Peroxide
« on: December 03, 2011, 02:18:16 PM »

Hi All,

I am trying to prepare dimethyl sulfoxide (DMSO) from dimethyl sulfide (DMS) by oxidizing it with a 30 wt. % solution of hydrogen peroxide in water (H2O2); for this reaction, I am planning to use 1 mol equivalent of DMS and H2O2.  I don't want any H2O2 in the product, so I'd like to know what the best method is to neutralize any H2O2 that may remain in the solution?

Thanks in advance,

Nancy
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discodermolide

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Re: Neutralization of Hydrogen Peroxide
« Reply #1 on: December 03, 2011, 08:13:10 PM »

Hi All,

I am trying to prepare dimethyl sulfoxide (DMSO) from dimethyl sulfide (DMS) by oxidizing it with a 30 wt. % solution of hydrogen peroxide in water (H2O2); for this reaction, I am planning to use 1 mol equivalent of DMS and H2O2.  I don't want any H2O2 in the product, so I'd like to know what the best method is to neutralize any H2O2 that may remain in the solution?

Thanks in advance,

Nancy


H2O2 decomposes to water and O2 when treated with base.
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Borek

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Re: Neutralization of Hydrogen Peroxide
« Reply #2 on: December 03, 2011, 11:21:56 PM »

H2O2 decomposes to water and O2 when treated with base.

Catalytic decomposition will be much safer - much less risk of contamination of the solution with something you don't want there.
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discodermolide

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Re: Neutralization of Hydrogen Peroxide
« Reply #3 on: December 04, 2011, 12:12:39 AM »

H2O2 decomposes to water and O2 when treated with base.

Catalytic decomposition will be much safer - much less risk of contamination of the solution with something you don't want there.


Catalytic decomposition will cause it to decompose uncontrollably. A regular dosing of base controls the reaction, stop the addition the reaction stops.
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Re: Neutralization of Hydrogen Peroxide
« Reply #4 on: December 04, 2011, 01:53:09 AM »

OP wants to decompose everything, so IMHO it shouldn't be a problem.

Besides, I don't see how NaOH can react with H2O2 the way you state it does, can you elaborate? I fail to see how NaOH can be consumed in such a reaction, so I don't see how the reaction can stop after you stop adding base.
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discodermolide

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Re: Neutralization of Hydrogen Peroxide
« Reply #5 on: December 04, 2011, 02:51:19 AM »

OP wants to decompose everything, so IMHO it shouldn't be a problem.

Besides, I don't see how NaOH can react with H2O2 the way you state it does, can you elaborate? I fail to see how NaOH can be consumed in such a reaction, so I don't see how the reaction can stop after you stop adding base.

I did not mention NaOH.
Think of the Evans chemistry, removal of the oxazolidine chiral aux.
LiOH, THF, H2O2, 90% of the H2O2 vanishes as O2 any H2O. If you stop addition of LiOH the reaction stops. I have done this many times on a very large scale.
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orgopete

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Re: Neutralization of Hydrogen Peroxide
« Reply #6 on: December 04, 2011, 04:22:37 AM »

@OP
I don't think there is a problem here.

Me2S + H2O2  :rarrow: Me2S=O + H2O

Me2S=O + H2O2  :rarrow: Me2SO2 + H2O

How to avoid hydrogen peroxide in product? Stop the addition. Dimethyl sulfide is a pretty good reductant. I don't think you need to do anything else.

@discodermolide
I'm not seeing this. What is the mechanism here? You can make the anion of hydrogen peroxide without decomposition. If you want to do a conjugate addition to an enone, use hydrogen peroxide and (catalytic amount) base.

I can write a balanced equation for the formation of oxygen and water without base. Therefore, a catalyst only need to change the reaction path, not the stoichiometry. As described, this is a stoichiometric reaction, "If you stop the addition of LiOH the reaction stops." I do not understand what is being oxidized.

If you do a Payne oxidation, if the reaction is basic, then oxygen is released.

RCN + H2O2 (base)  :rarrow: RCONH2 + O (bracketed)

2O  :rarrow: O2

If not basic, the peroxy imidate can be intercepted to form an epoxide.
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discodermolide

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Re: Neutralization of Hydrogen Peroxide
« Reply #7 on: December 04, 2011, 04:53:29 AM »

There is not a problem. I am just saying that the H2O2 decomposition is accelerated by base. see measurements attached.
If you stop the base addition the oxygen generation stops. (I don't have that data on this pc). And oxygen generation is dangerous, as we all know.

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nancyVIII

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Re: Neutralization of Hydrogen Peroxide
« Reply #8 on: December 04, 2011, 03:34:52 PM »

I have available an aqueous solution of sodium hydroxide (NaOH), as well as an aqueous mixture of sodium bisulfite (NaHSO3) and sodium metabisulfite (Na2S2O5).  Therefore, I could use either one to neutralize any unreacted H2O2, before purifying the DMSO (by vacuum distillation).  Would one of these choices be preferable for this particular reaction?

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