Sciencemadness Discussion Board

2,5-dimethoxybenzaldehyde question

Snakeforhire - 16-6-2022 at 02:10

Hello all.

I have a 100g flask of this compound that has been stored for the better part of 18 years. It was opened once (by curiosity about the smell it could have) and then recapped tight and stored away from light, but not from heat (not in the fridge or anything).
Do you guys think it would still be usable in a Henry reaction ?

Any opinions much appreciated :)
TY all for reading.

zed - 16-6-2022 at 05:53

Easy enough to find out. Try it.

Snakeforhire - 16-6-2022 at 07:30

Alas, that sadly will have to wait until I manage to source some nitromethane : since february possession of it here is forbidden to individuals as it is considered an energetic precursor... :mad::mad: :(
F'ing stupid, as everyone who knows a bit about energetics knows that it's not that easy to make it detonate as is.
So I'll have to see if a professional friend can buy it for me, or maybe register a small company myself. Big PitA...

mackolol - 16-6-2022 at 12:34

Maybe try producing the nitrometane from chloroacetic acid (if you can obtain it), if not the acid can still be made too.

Rainwater - 16-6-2022 at 14:08

A recrystallization with methanol is suggested in this post
http://www.sciencemadness.org/talk/viewthread.php?tid=12667

Mateo_swe - 17-6-2022 at 03:06

Is all forms of nitromethane banned?
Even the methanol/nitromethane racing fuel for model cars and planes?
Here you can buy the nitro RC-fuel if it is lower than a certain %, but they have lowered the %age quite much.
You could distill the nitro RC-fuel to get a methanol/nitromethane mix that is usable in a Henry reaction.

If RC-fuel is not an option you could make it yourself but buying it would be much easier.
If you are inside EU try one of the sellers in the "Reagents and Apparatus Acquisition" section of this forum.
I woluld guess they can provide it for you, maybe even if outside EU.

clearly_not_atara - 17-6-2022 at 07:24

It would still be usable if it is still an aldehyde. That is the only necessary thing about a Henry reaction. In order to determine this, simply form the bisulfite adduct. This will also allow you to purify it, by removing any fraction which has been oxidized over the years to the benzoic acid.

But if you have no expectation of being able to perform a Henry reaction in the foreseeable future, you might want to think about other things you could do with it. Obviously, it would not be usable in a Henry reaction if you cannot get any nitro-compounds.

monolithic - 17-6-2022 at 09:23

You could try forming the bisulfite adduct, recrystallize, and then convert back to the aldehyde. I believe this would allow you to separate the main impurity from oxidation of the aldehyde i.e. the carboxylic acid.

Snakeforhire - 18-6-2022 at 07:20

Quote: Originally posted by Mateo_swe  
Is all forms of nitromethane banned?
Even the methanol/nitromethane racing fuel for model cars and planes?
Here you can buy the nitro RC-fuel if it is lower than a certain %, but they have lowered the %age quite much.
You could distill the nitro RC-fuel to get a methanol/nitromethane mix that is usable in a Henry reaction.

If RC-fuel is not an option you could make it yourself but buying it would be much easier.
If you are inside EU try one of the sellers in the "Reagents and Apparatus Acquisition" section of this forum.
I woluld guess they can provide it for you, maybe even if outside EU.


Anything that's over 10%. And pre-mixed fuel is pretty expensive. :(
I'd rather not order from outside the EU if I can avoid it : there'd probably be sniffer dogs at the customs, and they're trained to detect nitro compounds...

Snakeforhire - 18-6-2022 at 10:04

Quote: Originally posted by clearly_not_atara  
It would still be usable if it is still an aldehyde. That is the only necessary thing about a Henry reaction. In order to determine this, simply form the bisulfite adduct. This will also allow you to purify it, by removing any fraction which has been oxidized over the years to the benzoic acid.

But if you have no expectation of being able to perform a Henry reaction in the foreseeable future, you might want to think about other things you could do with it. Obviously, it would not be usable in a Henry reaction if you cannot get any nitro-compounds.


and, pray tell, what else might I do with it without any nitroalkenes ?

Snakeforhire - 18-6-2022 at 12:03

Well anyhoo, since it seems my choices are limited I guess I'll go the RC fuel route. :(

One question still lingers in me mind tho : is glacial acetic acid a must for the Henry reaction, or can it be substituted for a less conc. form (80%) ?

[Edited on 18-6-2022 by Snakeforhire]

PirateDocBrown - 18-6-2022 at 14:22

Make a different nitro compound.

Nitroethane is pretty straight forward.

React silver nitrate with sodium nitrite, to get silver nitrite.

Make ethyl iodide with ethanol and iodine.

React silver nitrite and ethyl iodide to get nitroethane.

Victor Meyer reaction.

Doesn't work with methanol, it makes methyl nitrite.

If you want nitro methane in large quantities, you need a tube furnace. Use propane as your carrier gas, and just lead nitric acid vapor in to react with it. 400 C should do it.

It destroys the propane, and you can condense a mixture of 1- and 2- nitro propane, nitro ethane, and nitro methane out. Frac distill out the compound you want.

For smaller amounts, reaction of chloro acetic acid and sodium nitrite.

karlos³ - 19-6-2022 at 09:11

Quote: Originally posted by Snakeforhire  
Quote: Originally posted by clearly_not_atara  
It would still be usable if it is still an aldehyde. That is the only necessary thing about a Henry reaction. In order to determine this, simply form the bisulfite adduct. This will also allow you to purify it, by removing any fraction which has been oxidized over the years to the benzoic acid.

But if you have no expectation of being able to perform a Henry reaction in the foreseeable future, you might want to think about other things you could do with it. Obviously, it would not be usable in a Henry reaction if you cannot get any nitro-compounds.


and, pray tell, what else might I do with it without any nitroalkenes ?

Have you ever heard about cinnamic acids?
Because they exist.

Snakeforhire - 19-6-2022 at 12:20

Quote: Originally posted by PirateDocBrown  
Make a different nitro compound.

Nitroethane is pretty straight forward.

React silver nitrate with sodium nitrite, to get silver nitrite.

Make ethyl iodide with ethanol and iodine.

React silver nitrite and ethyl iodide to get nitroethane.

Victor Meyer reaction.

Doesn't work with methanol, it makes methyl nitrite.

If you want nitro methane in large quantities, you need a tube furnace. Use propane as your carrier gas, and just lead nitric acid vapor in to react with it. 400 C should do it.

It destroys the propane, and you can condense a mixture of 1- and 2- nitro propane, nitro ethane, and nitro methane out. Frac distill out the compound you want.

For smaller amounts, reaction of chloro acetic acid and sodium nitrite.


Thx for the info.
But "semi-industrial" is out of the question for me, way too expensive, no place to do it and overkill for the amount of MeNO2 I need... :(
And NaNO2 is also restricted here now (only a business can buy it), even though I indeed happen to have some iodine just lying about unused... :mad:

Snakeforhire - 19-6-2022 at 12:22

Quote: Originally posted by karlos³  
Quote: Originally posted by Snakeforhire  
Quote: Originally posted by clearly_not_atara  
It would still be usable if it is still an aldehyde. That is the only necessary thing about a Henry reaction. In order to determine this, simply form the bisulfite adduct. This will also allow you to purify it, by removing any fraction which has been oxidized over the years to the benzoic acid.

But if you have no expectation of being able to perform a Henry reaction in the foreseeable future, you might want to think about other things you could do with it. Obviously, it would not be usable in a Henry reaction if you cannot get any nitro-compounds.


and, pray tell, what else might I do with it without any nitroalkenes ?

Have you ever heard about cinnamic acids?
Because they exist.


Sure. But AFAIK their chemistry requires acetic anhydride, which is about as hard to get as virgin ass in TJ... ;)

Snakeforhire - 19-6-2022 at 13:07

Anyway, thx for all your replies. Topic can be consired closed now AFAIC :)
I'll think about all that for a long, long time before deciding on doing anything.

clearly_not_atara - 19-6-2022 at 14:56



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PirateDocBrown - 20-6-2022 at 05:32

Quote: Originally posted by Snakeforhire  

And NaNO2 is also restricted here now (only a business can buy it), even though I indeed happen to have some iodine just lying about unused... :mad:


Extract it from Prague powder pink curing salt. The #1 type is about 6% NaNO2.

Snakeforhire - 21-6-2022 at 06:33

Quote: Originally posted by PirateDocBrown  
Quote: Originally posted by Snakeforhire  

And NaNO2 is also restricted here now (only a business can buy it), even though I indeed happen to have some iodine just lying about unused... :mad:


Extract it from Prague powder pink curing salt. The #1 type is about 6% NaNO2.


Nah, too expensive and tedious.
I'll just ask a friend who has a business to order it for me when I see him. It's nothing suspicious so he wouldn't risk anything.
Anyway, nitroethane isn't the priority. First I needs to distill me some RC fuel. :D