What does formaldehyde turn into when incinerated?

Simple chemistry question - I can’t find the answer - what does formaldehyde turn into when exposed to high heat, such as a flame or hot coil?

Since it’s a byproduct of combustion, and has already been exposed to high heat, the answer seems to be it doesn’t turn into anything- it continues to be formaldehyde.

There are quite a lot of reactions when exposed to combustion conditions / temperatures. This paper has a good summary : https://www.sciencedirect.com/science/article/abs/pii/S001021801200020X

These are some of the reactions (note
Many of these are free radicals)

  1. CH2O+M=HCO+H+M
  2. CH2O+M=CO+H2 +M
  3. CH2O+O2 =HCO+HO2
  4. CH2O+O=HCO+OH
  5. CH2O+OH=HCO+H2O
  6. CH2O+H=HCO+H2
  7. CH2O+HO2=HCO+H2O2

Just a word of warning – were you planning on doing this as a practical, rather than a theoretical, experiment, I think that an awful lot of the formaldehyde will end up evaporating rather than cumbusting. Gaseous formaldehyde in quantity will cause your eyes to sting something awful. We speaks from experience. (Formaldehyde, by the way, used to be the basis of Air-Wick and other solid room deodorizers. Formaldehyde polymerizes into a sort of soapy solid form, paraformaldehyde, which depolymerizes slowly at room temperature. If you bury perfumes in the mass, it’ll slowly release them. They stopped using paraformaldehyde as a base when it turned out to be a carcinogen. Now solid deodorizers use something else.

If you make the polymer chains extra long and terminate them in something other than hydroxides, you get acetal plastic – a pretty tough and useful plastic (they make K’NEX building toys out of it)

When I worked for the NHS, it was a regular job for one of my drivers to transport organs (body parts not musical instruments) from a hospital to the main Path Lab. They were put in formaldehyde in plastic pails, about 25 litres. The top of the pails was simply snapped on, so it’s no surprise that when he was involved in a minor collision and the pail fell over, it burst open.

What was a surprise was that the Fire and Rescue people promptly treated the thing as a serious hazard and our van was parked up with tape all around it for several hours until they declared it safe. The driver had to leave the windows open wide for a few days as the smell made him nauseous. The liver that was in the pail was, of course, past its sell-by date and had to be incinerated.

am77494, what’s the “M” in those equations? An arbitrary metal?

The M is for an inert molecule that doesn’t react with the reactants, but is still required somehow.


The ‘M’ here is a molecule that absorbs excess energy from the products, to stabilize them. Otherwise, in their excited states, they may recombine into Formaldehyde.

Edit: From my view at least, I seem to have posted the reply 41 minutes before the question was asked. Is that a record?

It’s a minor byproduct of incomplete combustion. Burn it oxygen and you’ll primarily get CO[sub]2[/sub] and water. Pyrolyze it and you’ll primarily get CO and H[sub]2[/sub]

You must have had the window open overnight (i.e., from before midnight to after it) before replying. When the page was loaded, my post was timestamped “Today, 07:11 PM” (or whatever is appropriate for your timezone). When you used the quick reply, it didn’t change anything else on the page, but showed your post as “Today, 06:30 AM”. So in other words, you weren’t 41 minutes before me, but 12 hours, 41 minutes before me… but it’s just because it didn’t change my timestamp from “Today” to “Yesterday” when the day rolled over.

Your mention of a “hot coil” suggests your question is related to ecigs. If you’re looking for the straight dope this article may lead you to the right answer.
New CDC study officially debunks ‘vaping and formaldehyde’ myth