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Chemistry Forums for Students => Organic Chemistry Forum => Organic Chemistry Forum for Graduate Students and Professionals => Topic started by: Miep on November 24, 2009, 01:32:30 AM

Title: reduction nitro group
Post by: Miep on November 24, 2009, 01:32:30 AM

Hi,

Could someone tell me about the mechanism when reducing a nitro group with Fe/HCl?  I found a mechanism based on single electron transfer, however isn't there H2 formed as a reductor?

Thanks,
Miep

Title: Re: reduction nitro group
Post by: movies on November 24, 2009, 11:53:21 AM

I believe the mechanism you found with SET is probably correct.  You might generate a small amount of H₂, but these reactions are not run under an atmosphere of hydrogen like in other metal reductions, so the hydrogen is probably just lost to the atmosphere.

Also remember that H₂ doesn't act as the direct reductant in catalytic hydrogenation – it is likely a metal hydride or a hydrogen radical that does the reaction.  These intermediates are also possible in nitro reduction, I suppose, but I don't know all the evidence for why the SET mechanism is preferred.