What am I doing wrong? (P2NP)

[Rabidreject]

Yeah I have realised that now funnily enough.

So I had tried to make this before and now I have successfully done so, I realise that it wasn’t the actual reaction that was the issue before, it was the crystallisation.

So when I went to make some this time, I assumed it needed longer to react (which it didn’t) - I actually just needed to realise there was acid in the solution which was probably keeping the p2np dissolved. Washing with water, every time has lead to crystallisation so I assume that is what was going wrong when it wouldn’t crash out upon cooling.

Last night I made more in a much simpler manner.
I chucked everything into my round bottom (50ml benzaldehyde, 50ml nitroethane, 6-7ml of cyclohexylamine and 10ml GAA) and put it in a steam bath at 80c for 7 or so hours.
When I came back in the morning, there was a yellow oil layer on the bottom and a small clearer layer on top.
Yesterday I recrystallised my last batch of p2np and didn’t wash up the beaker so it had some crystals around the edge.
I poured my RM in and it instantly crystallised via seed nucleation.

When I filtered there was still some oil come through so I just washed it with more water and it eventually went solid. This happened a few times

So yeah a hot water bath with no condenser worked fine.

It is interesting how much extra heat and time it needs than working with substituted benzaldehyde’s.

 

[w2x3f5]

The bad tone mix benzaldehyde with amin. Either you make a ready -made amine acetate to the reaction, or first mix all the reagents and the last queue add benzaldehyde.

 

[w2x3f5]

What I said concerns the reaction of Henry condensation

 

[OneTensionSkyRed]

Just use polyethylene polyamine. Sold as an epoxy hardener, works like a wonder in Henry reaction. You don't need to heat or reflux, this reaction goes well at RT. Heating just leads to more side products. With polyethylene polyamine this reaction must be done under acidic conditions, dissolve the amine in excess GAA and make sure the solution has acidic pH before adding benzaldehyde or nitroalkane. That's all there is to it

 

[Frenki]

I attempted the synthesis of P2NP but have been unsuccessful so far. I’m using 99% pure benzaldehyde and glacial acetic acid (GAA), also 99% pure. I don’t have access to 100% pure nitroethane, but I’m using Acrifix 1S 0117, which contains nitroethane as the main component. I didn’t distill it, but I heated the mixture to around 107°C to evaporate ethyl formate and ethyl acetate, based on their boiling points. According to the data sheet, the remaining components include trace amounts of 1-butanol and 2-phenoxyethanol.





For the ammonium acetate, I synthesized it myself by bubbling ammonia gas into glacial acetic acid until crystallization occurred, then used it immediately without further purification.





I conducted several small-scale tests, always using a slight excess of nitroethane relative to benzaldehyde. I varied the amount of ammonium acetate in each run, but none of the reactions were successful. The reaction mixture consistently turned brown, rather than the expected red/orange, suggesting that the Henry reaction between benzaldehyde and nitroethane did not proceed properly.





My questions:


• Does nitroethane need to be absolutely pure (100%) for this reaction to work?


• Can the presence of 1-butanol or other impurities significantly interfere with the reaction?


• Are there any critical temperature ranges or conditions I might be overlooking?





Any insight or suggestions would be greatly appreciated. I’d really like to understand where the issue lies and how to get this synthesis to work properly.

 

[w2x3f5]

You do not have laboratory work itself, it is difficult to say that it went wrong without it. It is advisable to highlight the first nitroethan in its pure form. Ammonia acetate is not the best catalyst, but it works, it works very well with microwave irradiation. Also, you have nothing to say about how the P2NP was released from a mixture of ammonium acetate and acetic acid. Usually severe dilution and multiple flushing, after which the mixture needs to be cooled to a negative temperature and it is advisable to throw the crystal of P2NP. If the reaction has passed badly, you will be tired of crystallizing. On a good catalyst and with normal nitroethan and benzaldehyde, the mixture after the reaction is yellow and crystallization begins when cooling

 

[rampage]

did you check out this thread, it's way easier in the microwave and quicker

Microwave (small) scale: 1-Phenyl-2-nitropropene (P2NP)

Has anyone tried this exact recipe lately? I know Jesse_pinkman_ did a few years back. But he then went of on a Gallium tangent... Would love to hear some experiences, lessons, tips, tweaks or tricks? Thanks all in advance. Microwave (small) scale: 1. Benzaldehyde 100 ml, nitroethane 100 ml...

bbgate.com

 

[Frenki]

I’ve read a lot of topics, but I haven’t succeeded—maybe because I don’t have a good catalyst. Anyway, this was my last attempt:


Benzaldehyde, nitroethane distilled from Acrifix 1S0117, and ammonium acetate, heated in the microwave. It immediately turns a strong yellow color, but after some time it becomes clear, and there are no further changes.