[rap35]

Hello,

Been stuck on this issue for some time now.

I am trying to understand the intermediate products for the reaction involving 4-Cyanopyridine (4-CyPr) which condenses to form 2,4,6-Tri(4-pyridyl)-1,3,5-triazine (4-TPT). (see attached image)

Under pressure, 4-CyPr is heated and stirred with Potassium Hydroxide and 18-crown-6. The reaction eventually forms the desired product of 4-TPT.

All I know about the reaction is that it is a condensation reaction and that the 18-crown-ether acts as the ‘phase transfer catalyst’ and coordinates the group 1 ion to deliver the polar KOH into the nonpolar medium (solvent) - making it soluble within the organic reaction conditions.

I can't work out any of the stages between start and finish. I would really appreciate if anybody could tell me what the intermediate products are!

[wildfyr]

So I think its a reaction a little like a polymerization. I drew my best guess. I don't think that nitrogen anion ever really exists as such, but I wanted to show something in the middle there to make my thinking clearer.

Normally this would be pretty wonky, but I think its driven by the fact that A. You probably heat the daylights out of it B. 1,3,5 triazine is a very favorable structure (6 member aromatic ring), more so than nitrile. Happy to discuss it with other organic chemists here!



P.S. I must be the worlds worst mod, because I just now figured out the correct way to attach a picture. Shame on me.

P.P.S Edit* And I didnt cut down my photo. Urgh. It is what it is today, I'm supposed to be working!

[rap35]

So I think its a reaction a little like a polymerization. I drew my best guess. I don't think that nitrogen anion ever really exists as such, but I wanted to show something in the middle there to make my thinking clearer.

Normally this would be pretty wonky, but I think its driven by the fact that A. You probably heat the daylights out of it B. 1,3,5 triazine is a very favorable structure (6 member aromatic ring), more so than nitrile. Happy to discuss it with other organic chemists here!



P.S. I must be the worlds worst mod, because I just now figured out the correct way to attach a picture. Shame on me.

P.P.S Edit* And I didnt cut down my photo. Urgh. It is what it is today, I'm supposed to be working!

Thank you wilfyr for your reply! Hopefully, some more organic chemists will be able to confirm 

I forgot to add that it is stirred in decalin and heated to 200 oC. Here is the reaction method:

4-cyanopyridine (10 g, 96 mmol), 18-crown-6 (1 g,3.8 mmol), potassium hydroxide (225 mg, 4.0 mmol) and decalin (10 cm3) was stirred at 200 "C under argon for 3 h and then evaporated to give a brown solid.

[wildfyr]

Decalin, 200°C and under argon only confirms my suspicions of the mechanism. I did say

You probably heat the daylights out of it

200°C is refluxing decalin.

The best detail here is that its only catalytic KOH, which jibes with my mechanism of OH being a leaving group and not being consumed during the reaction.

[Enthalpy]

Hi rpamenter,

I get identified by this avatar, which is my personal work. I'd like you not to use it. Thanks, cheers!

[wildfyr]

I thought I was talking to you Enthalpy! Didn't even check the username

[Borek]

I get identified by this avatar, which is my personal work. I'd like you not to use it. Thanks, cheers!

You added the avatar to the forum gallery, so anyone can choose it at the moment.