Questions after synthesis of Phenyl-2-nitropropene (P2NP) (Henry Reaction)

[Edeleanu]

Hi, I attempted this reaction yesterday evening. It was my first synthesis, the whole experience was a bit scary to be honest I made a bunch of mistakes and I have a few questions before I attempt this again. Thanks in advance to anyone who can help me out!

First, when I opened the bottle of n-butylamine, white smoke started coming out. This freaked me out, but I proceeded anyway. Could somebody please clarify if this is expected? Do I need special storage conditions for the n-butylamine? It was stored at room temperature in a garden shed, should I store it in a fridge instead?

When I opened the bottle of benzaldehyde, I was taken aback by how strong the smell is. I left the door open so I could breathe, but the smell was probably noticeable by neighbors. I think next time it would be best to use a respirator and only open the door in the middle of the night when people are asleep, what do you think?

I haven't crystallized the P2NP yet, but I'm wondering how to dispose of the remnants of the solution. I suppose it contains the reagents that haven't reacted, so I should probably avoid flushing it down the drain directly. But then what's left? Is there a way to neutralize the reagents and then flush it?

All 3 bottles of nitroethane, benzaldehyde, and n-butylamine have been opened and closed, so the reagents have been in contact with air. Is there some sort of expiration date before they become unusable?

 

[AgamemnonFromTroy]

Hi,
It's normal for N-butylamine to smoke a little when opened, there's no need to worry. You'll find that there's a handful of reagents that do this with the most famous one being HCl.

Benzaldehyde is commonly used as a flavouring agent and it's not that toxic but slightly irritating. As for the smell there's nothing you can really do about it but if someone asks you about the odor you can just say it's a new air freshener or something along those lines.

Before filtering the P2NP I'd recommend placing the flask containing the P2NP solution into a freezer for some time. This ensures you isolate as much of the P2NP as possible. After the first filtration(when you isolate most of the product )I would leave it in the freezer for some days to see if precipitation continues, if nothing comes out of solution feel free to flush it down the drain as it mostly contains either unreacted nitorethane/benzaldehyde dissolved in the chosen solvent making it safe to flush.

In general exposing reagents to air is fine but try to limit as much of the exposure as possible to prevent contamination and or evaporation of the said reagent. Notably there are some reagents that are higroscopic for example KOH and NaOH as well as MgSO4, all of which will absorb water from the surrounding air compromising their functionality. But document yourself online about the properties of any reagents you plan on using and how should they be stored and the potential hazzard they bring .

 

[Edeleanu]

Hi @HectorFromTroy, thank you for these reassuring words and for your suggestions!

I have left the solution in the freezer for 2 days, and then filtered it on the Buchner funnel.
Good idea, I'll try that.

 

[AgamemnonFromTroy]

You can also try evaporating the solvent

 

[damian.dass]

Hi, can i know what is the freezing temperature for the P2NP solution?

 

[AgamemnonFromTroy]

The point of cooling the solution is to lower the solubility of P2NP so that it comes out of solution

 

[damian.dass]

Thank you for your reply.