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Topic: mechanism for the reduction of a nitro group using Na2S2  (Read 2783 times)

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Offline hardy5086

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mechanism for the reduction of a nitro group using Na2S2
« on: October 28, 2016, 09:57:29 AM »
im new to organic chemistry and cant for the life of me figure out how to draw out the mechanism for the reduction of m-dinitrobenzene to m-nitroaniline using Na2S2. help would be great.

Offline AWK

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Re: mechanism for the reduction of a nitro group using Na2S2
« Reply #1 on: October 28, 2016, 11:03:13 AM »
Na2S is usually used.
Probably you do not find a specific mechanism fo this reductor. Usually schematic mechanism is written: RNO2 :rarrow: RN(OH)2 :rarrow: RNO :rarrow: RNHOH :rarrow: RNH2
I checked, also Na2S2 may be used for reduction of nitro compounds
ArNO2 + S22− + H2O → ArNH2 +S2O32−
« Last Edit: October 28, 2016, 06:04:59 PM by AWK »
AWK

Offline hardy5086

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Re: mechanism for the reduction of a nitro group using Na2S2
« Reply #2 on: October 28, 2016, 08:48:39 PM »
That looks much simpler. I was approaching it from, how does everything interact and what electrons are moving and where and when. it got confusing very quickly. thanks for you help.

Offline phth

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Re: mechanism for the reduction of a nitro group using Na2S2
« Reply #3 on: October 29, 2016, 09:41:01 PM »
Na2S is usually used.
Probably you do not find a specific mechanism fo this reductor. Usually schematic mechanism is written: RNO2 :rarrow: RN(OH)2 :rarrow: RNO :rarrow: RNHOH :rarrow: RNH2
I checked, also Na2S2 may be used for reduction of nitro compounds
ArNO2 + S22− + H2O → ArNH2 +S2O32−

I don't agree with this, and I speak from experimental experience.  The molecule has to be first reduced to a nitrosyl, then sulfur can reduce it further.  Sulfenamide formation where there is an electrophilic center at sulfur vs nitrogen.  The nitro compound would have to be activated by something first...
Ellis, M.; Hill, S.; Foster, P. L. Chem.-Bio. Interactions, 1992, 82, 151-163.

Offline AWK

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Re: mechanism for the reduction of a nitro group using Na2S2
« Reply #4 on: October 30, 2016, 03:20:06 AM »
The above reference concerns reduction of 1,3-dinitrobenzene and nitrosobenzene by GSH, but not by Na2S2.
AWK

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