Sciencemadness Discussion Board

formaldehyde from urea?

physics inclination - 4-8-2017 at 23:02

Is there a reasonably simple way to synthesize formaldehyde from urea by somehow removing the amide groups? I've done a bit of searching and have not found any methods yet. If nothing else, I could try to electrolyze the urea and see if that works--seeing as how electrolysis can break down urea all the way to N2 H2 and CO2, perhaps it could also partially break it down into NH3 and CH2O
source: https://www.ohio.edu/engineering/ceer/research/urea.cfm

I think urea would be a more interesting way to get formaldehyde than the usual methanol because it is always readily available in urine, and urea can also produce ammonia from heating to decomposition. And with formaldehyde and ammonia you can make hexamine, so if you can get both of those reagents from urine, that would be really interesting and thrifty. However, one would need to keep in mind to avoid unintended hydrogen cyanide synthesis, which isn't a problem with the typical methanol route.

And if not from urea, then maybe formaldehyde from cyanuric acid? That is another thermal decomposition product of urea.

For what it's worth, there is a kind of "halfway" compound between formaldehyde and urea called formamide.

subskune - 5-8-2017 at 00:29

from pee that is really not an efficient way if so use fertilizer that is even cheaper than the water you drink to piss:D If you try to remove the amide you will likely end wih carbon monoxide and ammoia (if you hydrate)

XeonTheMGPony - 5-8-2017 at 04:10

Best way to make Formaldehyde is by catalytic oxidization of methanol via copper tube furnace.

I been slowly gathering the parts to make said apparatus.

unionised - 5-8-2017 at 04:39

If I was trying to make formaldehyde I'd probably not start from some thing that reacts quickly with formaldehyde and destroys it.

physics inclination - 5-8-2017 at 10:44

Quote: Originally posted by XeonTheMGPony  
Best way to make Formaldehyde is by catalytic oxidization of methanol via copper tube furnace.

I been slowly gathering the parts to make said apparatus.


Yea I saw your thread on that, it was very interesting and probably is the best homemade way of making formaldehyde.
Quote:

If I was trying to make formaldehyde I'd probably not start from some thing that reacts quickly with formaldehyde and destroys it.

(quote from "unionised". idk how to do multiple named quotes)

oh, I was not aware of this reaction between urea and formladehyde, and yea I guess this wouldnt be viable then. Unless under high temperature or some other conditions that might favor the production of formaldehyde, but I cant think of any.

But because I'm bored, stubborn, and curious, I wonder if you can use the electrolysis products of urea N2 H2 and CO2 to make several other things. Like if I removed the N2 and sent the H2 and CO2 through an electrical discharge, maybe compounds like methanol and formaldehyde could form, in a similar way that N2 and O2 from air makes NO/NO2 in an arc.

edit: Actually I just looked on wikipedia and it says industrial methanol production uses catalytic conversion of CO/CO2 and H2, but at high temperature and pressure over metal catalysts--I wonder if an electric arc can do similarly though.

[Edited on 8-5-2017 by physics inclination]

physics inclination - 5-8-2017 at 20:53

Ok so I did a bit of a crude experiment electrolyzing a little bit of urine, just to see what happens. And it did release a kind of fishy smell, which was different from the regular urine smell before electrolysis, so maybe it's a mixture of ammonia and maaaybe formaldehyde? I've smelt formaldehyde before doing a biological dissection in middle school, and it was a bit familiar. But even if formaldehyde is present in the product of the electrolysis, it might not be sufficiently concentrated to be useful.
I did take a video of some of it, but I'd prefer not to post unless someone's reeeeally curious because it's way too large filesize to just upload directly and it has my voice in it--but I can upload a few still frames here
The first picture is the overall setup, second is voltage during electrolysis, and third and fourth are just pictures of the gas bubbles being formed--note I switched the terminal polarity between the last two pictures and the negative (the cathode?) seemed to be the thing that gave off more bubbles.

vlcsnap-2017-08-06-00h39m27s035.png - 2.2MBvlcsnap-2017-08-06-00h42m07s678.png - 1.9MBvlcsnap-2017-08-06-00h42m44s491.png - 1.8MBvlcsnap-2017-08-06-00h44m43s471.png - 1.8MB

subskune - 6-8-2017 at 00:10

maybe its just ammonia maybe an amine from the ton of other ingredients in pee or maybe its really formaldehyde. I dont know how it should be produced (if this works then maybe because of the hydrogen at the cathode). It would be really useful if you would use pure urea to exclude side reactions.

One thing that came in my mind is the high pressure addition of steam to carbon (charcoal powder) at elevated temp. This yields a ton of side products but with the right cat you might get formaldehyde.

unionised - 6-8-2017 at 00:35

Electrolysis of urine is likely to produce traces of chloramines which irritate the eyes and nose much like formaldehyde.

Amines- which smell fishy- tend to react with formaldehyde.

Chemetix - 6-8-2017 at 03:27

IIRC electrolysis of urea was discussed here:
https://www.sciencemadness.org/whisper/viewthread.php?tid=71...

The products are ammonia and CO2, just an accelerated thermal decomposition.

Of all the reactions urea can undergo, generating formaldehyde is not one of them. Once it has seen ammonia, getting formaldehyde back is next to impossible, those two stick like shit to a blanket!
Be prepared for intractable cyanates and isocyanates.

At least you gave something a go!!!
Talking only goes so far.

unionised - 6-8-2017 at 04:59

Urea is not the same as urine.
The latter contains salt as the major electrolyte.
Electrolysis will give chlorine...

XeonTheMGPony - 6-8-2017 at 05:04

Judging by the colour not much of that in there either, think he needs to eat better!

So need to know what it is he's actually trying to electrolyze!

physics inclination - 6-8-2017 at 10:01

Quote: Originally posted by Chemetix  
IIRC electrolysis of urea was discussed here:
https://www.sciencemadness.org/whisper/viewthread.php?tid=71...

The products are ammonia and CO2, just an accelerated thermal decomposition.

Of all the reactions urea can undergo, generating formaldehyde is not one of them. Once it has seen ammonia, getting formaldehyde back is next to impossible, those two stick like shit to a blanket!
Be prepared for intractable cyanates and isocyanates.

At least you gave something a go!!!
Talking only goes so far.



Thanks for all the replies :) and yea I didn't want to be just another "ideas guy" so I did this.
And yea I know ammonia and urea react with formaldehyde, but I'm actually not interested in producing isolated formaldehyde, but rather hexamine from the two. So if NH3 and CH2O react quickly after forming, then I guess that's desirable, assuming they do form hexamine along with other various products which I'll try to separate out.

And yea this was a really crude "what happens?" run, for a real attempt I will either isolate the urea from urine or buy some (the latter being the likely better option :P)

And of course if it still doesn't produce enough formaldehyde/hexamine, I can send all the electrolysis exhaust gases through an electric arc chamber and see what comes out lol--hopefully not any cyanides though :o. If I do this, I'll take precautions to destroy any cyanide produced.

edit: this is the video I was thinking of that shows hexamine from formaldehyde and ammonia solutions
https://www.youtube.com/watch?v=mCCpl08_WjQ

[Edited on 8-6-2017 by physics inclination]