Molecules: You'd better learn to live with them.
Formaldehyde's funny stuff. It's naturally a gas. If you put too much of it in solution, it will polymerize and form a polyacetal, "paraformaldehyde," which is just -O-CH2- repeating over and over.
Because of this tendency towards polymerization, formaldehyde of commerce is sold with a little methanol added to keep it in solution. Interestingly, formaldehyde polymer is used as a plastic - and it's food approved! In some ways, it stands to reason - the stuff won't dissolve in much of anything so it's pretty chemically resistant. On the other hand, you can actually "crack" paraformaldehyde just by heating it (releasing formaldehyde gas), which makes it a little scary to think of it being in your kid's Hot Wheels.
Comments
Not only that, but you can accelerate breakdown of the crosslinkage with a few drops of NaOH.
Posted by: Evil Monkey | August 28, 2007 9:04 PM
Somehow I can't think about formaldehyde without mentioning Bakelite.
Posted by: justawriter | August 28, 2007 10:21 PM
It's a lot more scary thinking of it in my food packaging.
Posted by: Richard Gay | August 28, 2007 10:41 PM
Maybe you could help me understand something.
In our lab we have a variety of different fixatives. Formalin, formaldehyde (with methanol stabilizer), paraformaldehyde etc.
Now, from what I understand they all are essentially formaldehyde and crosslink based on the same mechanism of action, but what, other than absence of methanol or other stabilizers, is the difference between the different fixatives?
I've always just used paraformaldehyde, it works, is easy to make, etc., but is there any difference in their fixative ability?
Posted by: MarkH | August 29, 2007 1:50 AM
(CH2O) n, a white powder - The dust may form an explosive mixture with air.
Posted by: Mikael Franzen | August 29, 2007 8:57 AM
Delrin like Teflon is all about endcapping. With endcaps the polymers are tough as nails. Without endcaps they thermally unzip.
Posted by: Uncle Al | August 29, 2007 10:30 AM
Where I work we use measured amounts of paraformaldehyde in 'fry-daddys' and turn them on to fumigate our labs (of course, I wouldn't recommend this at home without proper air-handling).
Posted by: Scotty B | August 29, 2007 12:58 PM
They used paraformaldehyde to kill the Ebola-ridden monkeys in Reston, VA
Posted by: Wavefunction | September 1, 2007 5:58 PM