Sciencemadness Discussion Board - Practical home synthesis for Formaldehyde

Practical home synthesis for Formaldehyde

avi66 - 8-4-2010 at 00:54

i really need to get formaldehyde, to obtain hexamine for my rdx synthesis, so i read about methanol dehydrogenation over heated copper which form formaldehyde "ch3oh -> ch2o + h2" so i decide to build a little reactor which evaporate methanol fumes to a copper pipe which rust inside with his oxide catalyst and heat it to 300c, and i don't know the efficiency of this process.... i heard about it somewhere that the formaldehyde is over react with the copper catalyst to form formic acid and co gas....
someone know the efficiency of methanol dehydrogenation over heated copper?.... or know effective way to get formaldehyde or hexamine?(i don't have access to fuel tablets)

dehydrogenation.jpg - 136kB

hissingnoise - 8-4-2010 at 02:17

Quote:

(i don't have access to fuel tablets)

I've seen hexamine fuel tablets on eBay and other places!
My first hexamine was from formalin and ammonia cleaner - later from a camping-supplies shop!
I get formalin by the gallon from my local pharmacist. . .
Preparation of formalin looks like a real pain when a bit of seaching might suffice!

gnitseretni - 8-4-2010 at 03:52

What about heating paraformaldehyde?

mickelcorleone - 8-4-2010 at 09:49

I think that the best way for formaldehyde synthesis

you can use PCC OR PDC
YOU CAND DIRECT SYNTHESIS BY PCC

CH3OH_____>ADD PCC----->H2C=O

avi66 - 8-4-2010 at 10:58

pcc i carcinogenic and more hard to get then formaldehyde, by the way its made from formaldehyde.

somebody can tell me what he think about the process which i mentioned above please?

if someone know practical way to synthesis this stuff please post it.

[Edited on 8-4-2010 by avi66]

watson.fawkes - 8-4-2010 at 13:30

Quote: Originally posted by avi66

so i decide to build a little reactor which evaporate methanol fumes to a copper pipe which rust inside with his oxide catalyst and heat it to 300c

A couple of comments purely on the engineering.

Assume inefficiency, which means you have plenty of unreacted methanol in your output vapor. The sketch of your apparatus doesn't have a way of separating these two vapors. You should be able to put a temperature controlled condenser in the line, after the catalyst bed and before the water trap, and recycle back the bulk of the methanol back to the boiler. This way, the consequence of catalyst inefficiency is a slower output rate, rather than a second-stage separation procedure. You might not care about this separation step, though.

Also, you'll want more surface area than the inside of a circular pipe, which is a minimal surface. Pack the heated catalyst pipe with copper mesh.

avi66 - 8-4-2010 at 13:45

ן Have lcd hot air gun with temperature control, and about the methanol recycle, its not my problem,i can make condenser and recycle the methanol.
i dont afraid from low efficiency .... i afraid of spending the methanol ... i don't want it to became formic acid and other compounds .... i want most of the methanol 90%+ which will react, will form ch2o.
so here i ask you guys if you know the ratios of compound which form in those conditions.... and about the surface area .... its very long and dense spiral, and i already flat the pipe, so i got a lot of surface area.
Thanks for the helpers

watson.fawkes - 8-4-2010 at 14:03

Quote: Originally posted by avi66

and about the surface area .... its very long and dense spiral, and i already flat the pipe, so i got a lot of surface area.

Less surface area than you think, I'm afraid. Flattening the pipe changes the surface area very little, at most a few percent. It's quite instructive to take apart some copper mesh (it's usually knit and can be undone from one end) and wind it around a cylinder form just to see how much area there is.

Now, as far as your yield question goes, if you don't have any references from when you read about this in the first place, perhaps you might be asking how to find such references rather than asking others to be your librarian.

hissingnoise - 8-4-2010 at 14:30

OTOH, you could (pretend to?) take up taxidermy and legitimately look for formalin in your area.

entropy51 - 8-4-2010 at 16:07

New members who are too lazy to search

Must we have yet another thread on preparing HCHO by oxidation of CH3OH?

There are literally dozens of threads on formaldehyde already, including this one which contains lots of useful information, including references.

Must we clutter up the forum with the latest kid's sad attempt at chemical engineering?

IMHO anyone without the imagination to figure out how to obtain formaldehyde probably (certainly?) won't be able to make it from methanol.

It's one thing to discuss novel synthetic methods that may or may not work. It would be even better if those proposing such methods could present some experimental evidence that these novel methods might work. But it's just a waste of time to entertain the brain farts of everyone who wants to know how to make something that's been discussed ad nauseum, just because they're too lazy to search the forum.

mnick12 - 8-4-2010 at 18:25

Ahh entropy calm down, yes it is annoying and useless to ask to be spoonfed but keep in mind this guy only has 3 posts and obviously not aware of it. Best thing to do is to nicely remind people of what they are doing wrong. Afterall it is very discouraging for new members to join when people are being so nasty, infact I didnt join until two almost 2 1/2 years after I found this sight since I was worried members would be overly critical.

Anyway back OT
Avi there are a couple of things to keep in mind if you try this reaction. First and perhaps most importantly methanol vapor is very flammable and if any sizeable amount of air gets into your setup then you basically have a small FAE. Another thing if you do succeed with carring out this reaction, you will most likely have a large amount of methanol in your formaldehyde solution wich would need to be separated. Oh you shouldnt get any formic acid in your product unless air gets in there somehow, since there is only one oxygen in methanol and formic acid has COOH. And if you dont want to do any of this than I may be willing to send you a link of a supplier who sells 37% formaldehyde for 18.00 a gal, but beggers cant be choosers so I will see.

avi66 - 8-4-2010 at 23:50

i take my idea from this site : http://www.ucc.ie/academic/chem/dolchem/html/comp/methanol.h...
that is all i can find , and i guess that if this process was good, its was published on google more then once.
so after long period of time 6 month that im search in google many many times ... i decide to ask professionals.

watson.fawkes - 9-4-2010 at 06:32

Quote: Originally posted by avi66

i take my idea from this site : http://www.ucc.ie/academic/chem/dolchem/html/comp/methanol.h...
that is all i can find , and i guess that if this process was good, its was published on google more then once.

I just searched for "dehydrogenation methanol formaldehyde" on Google. There are a lot of references. While most of them are in academic literature, some are patents and some are available to read, and by "some" I mean "enough to get started" and "enough to have better questions".

The most striking thing is that there are a large number of catalysts available for this reaction. A lot of what you're asking is irrespective of the catalyst.

Lastly, I notice that you need a way of disposing of the hydrogen you'd be generating. It's not in your diagram, and should not just be assumed to go away safely.

watson.fawkes - 9-4-2010 at 06:38

Quote: Originally posted by entropy51

Must we clutter up the forum with the latest kid's sad attempt at chemical engineering?

Yes.

And "yes", because we want to make more chemists. It's clear that OP has little experience with the engineering issues and just as little experience researching the literature. On the other hand, OP has enthusiasm, which we should not squander.

avi66 - 9-4-2010 at 18:16

i do not have taxidermy shop in my area, and the medical formaldehyde have very tiny amount of formaldehyde ... about 4% .... how can i hell get this stuff ..... i need to explode something dam it !

Sedit - 9-4-2010 at 19:47

I honestly fear for your fingers......

watson.fawkes - 9-4-2010 at 20:01

Quote: Originally posted by avi66

how can i hell get this stuff ..... i need to explode something dam it !

I'm afraid my inclination to assist drops precipitously with this comment, as the presence of explosives in the absence of patience is just dangerous. If you can't be bothered to spend the requisite time learning the theory, building safe equipment, and methodically performing the procedures, I can't be bothered to help you injure yourself. I don't particularly care that you want to make explosions, but I do care if you want to do so heedlessly.

avi66 - 10-4-2010 at 01:39

i am professional with high explosives

don't Worry, i got all the safety equipment i need, so if someone know a practical way to synthesis this stuff at home, or know the ratio of ch3oh->ch2o +h2 this reaction/(global methanol conversion), please post it, because i didn't find a information about the, methanol dehydrogenation over heated copper at 300c.
Thanks and good day.

hissingnoise - 10-4-2010 at 04:50

Check this out. . .

http://cgi.ebay.co.uk/BUY-in-BULK-60-x-Mini-HEXAMINE-Fuel-Ta...

avi66 - 10-4-2010 at 05:16

nice one .... but when its arrived to Israel, the airport will see that i purchased hexamine, they will send the army to my home, because they will think i am a dangerous terrorist, who want to make cyclonite,

joking .... i am combat engineering soldier in Israel .... but the airport still band this material.
nobody heard about someone who succeed, with this formaldehyde synthesis?

hissingnoise - 10-4-2010 at 05:33

Sheesh! Now the 'Avi' registers - but doesn't the IDF provide the excitement you seem to crave?
They certainly seem to have little hesitation in expending their munitions for one reason or another. . .

Sedit - 10-4-2010 at 07:28

Quote: Originally posted by avi66

i am professional with high explosives

BS, you are no professional and I personaly think like the airports that you are a terrorist. And thats saying alot from someone whos from a country that tosses that word around so much it makes my stomach churn.

"i am combat engineering soldier in Israel "

This makes it quite clear your intended use of the formed explosive and I think everyone here should drop you from there mind unless they want the thoughts of other peoples body parts floating thru there dreams knowing theres responsible for helping the man make the stuff that blewup himself or countless others. I say ask yor superiors "soldier" and see what they can do for you.

avi66 - 10-4-2010 at 13:36

don't speak rubbish ... pyrotechnic is only a hobbie for me ...

and yes because this hobbie i join combat engineering unit in Israel army, its stink there i just guard alot.
im trying to make formaldehyde by myself, because there are alot of stupid arabs terrorists in my country which cause a restriction of those chemicals import, and be sure that arabs which want to use the explosives to bad purpose, will not use a forum ... they are know everything from the terror organization, i can tell you that as a soldier who know the ability of the bad guys.

i need high explosive in my fireworks, because i really want to create a mini rockets 1.5 cm inner diameter,which carry 20g of rdx high explosive warheads .... its can be cool, i don't want to hurt people ... Israel army is the most moral army in the world(just to remind you), not all the the peoples here are bad .... most of the arabs are bad, but the jews in israel are very moral ... like all the advanced country's in the world.

and do not ban me from this forum please ...

i like this forum, there is a high level of knowledge here.

[Edited on 10-4-2010 by avi66]