As dithionites are oxidized to hydrogensulfites, I thought that dithionates might be oxidized to hydrogensulfates.
Title: The reduction half reaction is: R-NO 2 + 6 H +
Post by: Megatherium on April 15, 2003, 12:10:00 PM
The reduction half reaction is: R-NO2 + 6 H+ + 6 e-__> R-NH2 + 2 H2O
The oxidation half reaction is: S2O62- + 2 H2O __> 2 SO42- + 4H+ + 2 e-
Hence, the total reaction is: R-NO2 + 3 S2O62- + 4 H2O __> R-NH2 + 6 SO42- + 6 H+
EDIT: GC_MS, you got to it first. You're right: NaHSO4 will bee the product (screwed up the oxidation half reaction, lost track of the damned sodium ions LOL :) )
Then the oxidation half reaction should be:
Na2S2O6 + 2 H2O __> 2 NaHSO4 + 2 H+ + 2 e-
By multiplying the oxidation half reaction by three and adding it to the reduction half reaction, we obtain: R-NO2 + 3 Na2S2O6 + 4 H2O __> R-NH2 + 6 NaHSO4
Title: Megatherium is a bit confused over here ...
Post by: Megatherium on April 15, 2003, 12:59:00 PM
Megatherium is a bit confused over here ... the mass balances of both equations seem to bee correct ... GC_MS: Na2S2O6 + 2 RNO2 + 10H+ --> 2 NaHSO4 + 2 RNH2 + 2 H2O Mega : R-NO2 + 3 Na2S2O6 + 4 H2O --> R-NH2 + 6 NaHSO4
Is Megatherium doing too many drugs & is he losing his mind ?
HELP ...
Title: what about the electrons?
Post by: hypo on April 15, 2003, 01:17:00 PM
GC_MS has 10 positive charges on the left, but none on the right!? that isn't ok, is it?
Title: Indeed, you 're right: it isn't.
Post by: Megatherium on April 15, 2003, 01:53:00 PM
What is nice here is that the reaction seems to be auto-catalyzed: the protons that are created in the oxidation are used in the reduction. However, I think the addition of some acid (1 eq. during the reactiton) would be required since: R-NH2 + H+ --> R-NH3+
Oeff, what a relief: I can continue with my old habits ;)
Title: Whoops
Post by: Barium on April 15, 2003, 02:05:00 PM
I mistook dithionate S2O62- for dithionite S2O42-. Feeling really silly :-[ Dithionite is the reducing agent I'm curious about. But what is the oxidation product?
Bisulfate, HSO4- or Sulfate, SO42-
Title: shit
Post by: GC_MS on April 15, 2003, 02:29:00 PM
Oeff, what a relief: I can continue with my old habits
Yes, recalculated after hypo said my ion balance was way out. Have something like 2 S2O62- + 4 H2O + RNO2 --> 6 HSO4- + RNH2 Shit, and that while wasn't on my drugs... ::)
Title: oxidation product of dithionite
Post by: starlight on April 15, 2003, 04:53:00 PM
when dithionite is oxidised by Fe3+ or CrO42-the oxidation product is SO32- (sulfite)
not sure what the oxidation product is when reducing nitro groups tho'.
Title: When dithionite is oxidised by Fe3+ or ...
Post by: Megatherium on April 15, 2003, 05:52:00 PM
Dithionite is the reducing agent I'm curious about. But what is the oxidation product?
Bisulfate, HSO4- or Sulfate, SO42-
When dithionite is oxidised by Fe3+ or CrO42-the oxidation product is SO32- (sulfite)
not sure what the oxidation product is when reducing nitro groups tho'.
It seems indeed more reasonable to expect that the oxidation product here will be SO32- instead of SO42- or HSO4-.
I can't imagine that R-NO2 would be a better oxidant than CrO42-, and has the power to oxidate the sulfur from Na2S2O4 to an oxidation state +VI (like in SO42-). It is indeed pretty sure that the oxidation state from the sulfur in dithionite will change from +III to +IV in the oxidation half reaction.
Hence, we get for the oxidation half reaction: S2O42- + 2 H20 --> 2 SO32- + 4 H+ + 2 e-
The reduction half reaction remains the same (cfr supra), so after multiplying the oxidation half reaction by three and adding it to the reduction half reaction, we obtain: R-NO2 + 3 S2O42- + 4 H20 --> R-NH2 + 6 SO 32- + 6 H+, which can be rewritten as: R-NO2 + 3 Na2S2O42- + 4 H20 --> R-NH2 + 6 NaHSO 3
OK, enough redox chemistry for today already. Now, its time for a good joint :) .
Title: Thank you all
Post by: Barium on April 15, 2003, 07:03:00 PM
This will hopefully be very beneficial to all of us. Just give me some time to get dirty in the lab :P
Title: No prob. Are you going to reduce a ...
Post by: Megatherium on April 15, 2003, 07:53:00 PM
No prob. Are you going to reduce a aryl-2-nitropropane with the Na2S2O4? That would bee rather cool :) .
Title: Naah
Post by: GC_MS on April 16, 2003, 10:30:00 AM
Naaaaaah, no way he is going to try that cheap OTC product on nitroalkanes ;) Might be nice thing if it worked. It works for phenyl-1-propanone -> phenyl-1-propanol.