[lutesium]

Everytime I read a making of a nitrostyrene I see a different amine used as the catalyst. What is the role of the amines at the making of a nitrostyrene and do we have to use different amines as catalyts???

Thanx a lot!


Lutesium...

[sjb]

If you're making the nitrostyrene via Henry reactions of nitromethane and substituted benzaldehyde you can use base to form the anion of the nitromethane species which then reacts in aldol style to form the nitrostyrene.

edit spell check

[Kryolith]

Of what synthesis are you talking about? The one posted by sjb? Generally amines are often used as mild bases. Mostly pyridine and NEt₃

[lutesium]

Yes! Excatly that! Benzaldehydes + NitroButane... But the point that I cannot understand is that at every example in one of my books they use a different amine as the catalyst! What does this mean???

Thanx


Lutesium...

[Kryolith]

It's a simple Henry reaction. You just need a base as a catalyst. Theoretically it doesn't matter which one.  A different base may influence
*reaction rate
*yield
*cleaning [correct word?]
*etc....

Of course the base should be soluble, else you have to work under phase transfer conditions.

[Borek]

*cleaning [correct word?]

Purification.

Note: I am not native English speaker either

[Kryolith]

Purification.

Thanks. I could have known this, as I read it before in the experimental sections of English papers.

EDIT:
I found a suitable smiley:

[lutesium]

Thanx!!! But the point that I cannot understand is that how can someone predict which amine is the best? By experimenting on my very precious benzaldehyde?


Lutesium...

And my native language isn't English either

[Kryolith]

Thanx!!! But the point that I cannot understand is that how can someone predict which amine is the best?

I guess that's a combination of intuition, experience and/or trial and error. 

[russellm72]

What do you mean your precious benzaldehyde? The stuff is dirt cheap unless you have it labelled with C-14 or something.

If you have experimental procedures then pick one that is a close match and just go for it. The previous post is correct there are a variety of bases used purely to try and increase rate/yield ease of purification etc. People all always investigating the use of new reagents. You'll find this for many reactions you look at. Unless you want to go down this route, just put your reaction on and go for it!!!!!!!

If you want do a few small scale reactions and determine by HPLC/TLC which one is looking most fruitful.

Good luck.

R.

[lutesium]

Ah good! I couldn't realize that I could experiment with plain Benzaldehyde but if I experiment with it I'll find out which amine suits best to Benzaldehyde but if your benzaldehyde is pricey (and sold by 5gr quantities) you can figure out how hard that procedure is!


Lutesium...