December 05, 2021, 09:23:02 AM
Forum Rules: Read This Before Posting


Topic: Trying to figure out reaction mechanism for reduction of nitro group.  (Read 261 times)

0 Members and 1 Guest are viewing this topic.

Offline ScarletDemiurge

  • New Member
  • **
  • Posts: 4
  • Mole Snacks: +0/-0
Hey, I'm trying to draw the mechanism for the catalytic hydrogenation of a NO2 group with Pd/C as a catalyst. I've looked at several articles (mostly "Insights into the mechanism of nitrobenzene reduction to aniline over Pd catalyst and the significance of the adsorption of phenyl group on kinetics" and "Studying the Mechanisms of Nitro Compounds Reduction (A-Review)") but they show slightly different paths to how NO2 turns into NH2. I drew the mechanism, but I'm not sure it is correct, could anyone give it a look and let me know if there's something wrong with it?

Note: I'm not sure if it's okay, but I'm assuming the hydrogen atoms that are on the surface of the Pd are able to be taken by other atoms as either protons (H+) or hydrides.

Offline sjb

  • Global Moderator
  • Sr. Member
  • ***
  • Posts: 3603
  • Mole Snacks: +219/-42
  • Gender: Male
Re: Trying to figure out reaction mechanism for reduction of nitro group.
« Reply #1 on: November 19, 2021, 02:09:43 PM »
Looks reasonable. However, nitroso (RNO) and hydroxyamine (RNHOH) functionalities have been isolated under some conditions so it might be more accepted that way?

Offline Orcio_Dojek

  • Full Member
  • ****
  • Posts: 354
  • Mole Snacks: +33/-3
Re: Trying to figure out reaction mechanism for reduction of nitro group.
« Reply #2 on: November 19, 2021, 04:24:25 PM »
In my opinion wrong. Look at the step 2 and 3. Step 2 - R-N+=O and then (step 3) - R-N-O- - molecule change its electric charge.

Offline ScarletDemiurge

  • New Member
  • **
  • Posts: 4
  • Mole Snacks: +0/-0
Re: Trying to figure out reaction mechanism for reduction of nitro group.
« Reply #3 on: November 19, 2021, 07:32:48 PM »
nitroso (RNO) and hydroxyamine (RNHOH) functionalities have been isolated under some conditions so it might be more accepted that way?

Thanks! I'll look into that.

Look at the step 2 and 3. Step 2 - R-N+=O and then (step 3) - R-N-O- - molecule change its electric charge.

That can't happen? Sorry if it's basic knowledge, I'm not that good at organic chemistry. So the molecule can't go from positive to negative (or visceversa), it needs to go through a neutral state before changing its charge?

Offline ScarletDemiurge

  • New Member
  • **
  • Posts: 4
  • Mole Snacks: +0/-0
Re: Trying to figure out reaction mechanism for reduction of nitro group.
« Reply #4 on: November 19, 2021, 09:01:49 PM »
I just drew the mechanism again removing the change in charge and including the hydroxyamine as a precursor of nitroso.

What do y'all think about this one?

Sponsored Links