synthesis of formaldehyde?

Quote: Originally posted by S.C. Wack

PREPARATION OF FORMALDEHYDE In the usual way. See original post for attachment here Saw the name H. Adkins in Blazter's document and figured that this is a non-bullshit patent. US19330613 [Edited on 2-8-2009 by S.C. Wack]

I've had great success in separating pure trioxane from fuel tablets. Fill bottom 1/4 of 5 gallon plastic bucket with them, snap on lid, and leave them on a small low power heating pad, such as is used for seed germination or terrarium heating. Pure Trioxane will sublimate and crystallize on the upper sides and top of the bucket over about a 2 week period.

You can also melt them and strain out the wax for initial purification, but it's messy and odorous.

[Edited on 3-7-2010 by Eclectic]

I was asked to sketch the apparatus I proposed above

An electrolytic process to make formaldehyde is disclosed in this
abstract , the product is essentially commercial strength formalin.
Translated below, restating the preceding brief summary is the
excerpt from the cited German Patent Attachment: DE138442.pdf (251kB)
This file has been downloaded 903 times


Beispiel V.
Für die Bildung von Aldehyden mag nachstehendes Beispiel zur Erläuterung dienen:
Als Elektrolyt dient eine Lösung, die in 500 ccm Flüssigkeit ca. 120 g Natriumacetat
und 160 g Natriumchlorat enthält. Die Elektroden bestehen aus Platinblech, die
Stromdichte ist ca. 20 bis 30 Amp. pro Quadratdecimeter, die Temperatur ca.
20 bis 30° C. Die Isolierung geschieht wie bereits beschrieben.
Man erhält bei diesem Versuch wesentlich Formaldehyd.
Die Ausbeute an Formaldehyd und Methylalkohol beträgt etwa 60 pCt. der Theorie,
wobei beide Körper etwa im Verhältnis 2 : 1 sich gebildet hatten.

Example V.
For the formation of aldehydes the following example may serve for explanation:
A solution of 500 cubic centimetres serves as an electrolyte, containing approximately
120 gms of sodium acetate and 160 gms sodium chlorate. The electrodes are of platinum metal,
Current density is approximately 20 to 30 amperes per square decimeter, the temperature
approximately 20 to 30 °C. Isolation is as already described.
One receives with this attempt substantial formaldehyde.
The yield in formaldehyde and methyl alcohol amounts to about 60 percent of the theory,
both form possibly in the proportion 2 : 1

.

Quote: Originally posted by questions

I just thought of an idea, please if anyone has any thoughts, please tell me what you think. I add the right amount of Hcl to hexamine in a thick HDPE container so it will break the hexamine down to a solution of water, formaldehyde and ammonium chloride. I then put in lead electrodes and begin passing electricity through the solution. I then put an air tight lid over the top of the solution and use a vacuum pump to suck all the air out of the container. This will cause the formaldehyde to boil out and into a receiver container with ice and chilled water to collect it. I'm guessing that the ammonium and chlorine ions wont disstill over with the formaldehyde as they would still be bound to the electrodes as electricity would still be passing through it. Do you think this would work in my attempt to separate the ammonium chloride from the formaldehyde solution ?

Why not buy some formadehyde?
It is readily available for treating diseases in Koi carp where I live. The local aquarium shop will sell you a litre without batting an eyelid

formaldehyde

Here in australia the most we can buy from an aquarium is a 3.7% solution. It is just too dilute

formaldehyde

id be looking into the neff reaction with nitromethane.

I belive it would make for some pritty pure formaldehyde

might be a bit pricey but thats never stopped me.

the problem you will get with using hexamine is the formation of methylamine from
imine formation between formaldehyde and ammonium chloride.

with the neff this will not happen.

still I would be using dilute sulfuric acid to work with the nitro salt.
this way when you distill you dont get HCl comming over as well.

make sure you dont use too much acid or you will polymerise the aldehyde.

[Edited on 12-4-2011 by Ephoton]

Quote: Originally posted by azo

Be carefull thinking that portable toilet fluid has formaldehyde in it, this is not the prefured compound these days because of the toxic properties of formaldehyde. is more used because it controls odours better than quaternary ammonium compounds. regards azo [Edited on 13-4-2011 by azo]

Quote: Originally posted by weiming1998

What's with all those complex tube setups? Oxidation of methanol with KMnO4 will do. Traces of formic acid will be formed, but not much, if you control the amount of KMnO4 you put in. If your experiment won't allow any formic acid, then neutralize with a suitable hydroxide/carbonate that forms a formate salt that's not very soluble.

Quote: Originally posted by Lambda-Eyde

Quote: Originally posted by weiming1998   What's with all those complex tube setups? Oxidation of methanol with KMnO4 will do. Traces of formic acid will be formed, but not much, if you control the amount of KMnO4 you put in. If your experiment won't allow any formic acid, then neutralize with a suitable hydroxide/carbonate that forms a formate salt that's not very soluble. Have you tried this method of yours and analyzed the product? Do you have any references for this reaction?

Quote: Originally posted by weiming1998

I have, just on the oxidation of ethanol instead of methanol, and since the two alcohols/aldehydes are very similar, it should work for methanol as well. I haven't done any proper analysis based on testing solutions, but the smell of the acetaldehyde, the bubbling of the solution and the fact that the smell isn't cleared by the addition of a base confirms the fact that it is an aldehyde.

Quote: Originally posted by weiming1998

References? http://en.wikipedia.org/wiki/Alcohol_oxidation The end product of the oxidation is a carboxylic acid, but you see, the aldehyde is an intermediate product. If you use an excess of the alcohol, more aldehydes are going to be produced instead of carboxylic acids.