Hoffmann-LaRoche
Hazard to Self
Posts: 64
Registered: 10-9-2002
Location: mid-europe
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Polymerization of formaldehyde
I recently tried to make paraformaldehyde:
(note: cause i lacked 37% formaldehyde, i had to do this with 20% formaldehyde solution, as anywhere else in crappy western europe...)
1st try) added 20% formaldehyde-solution to a huge excess of conc. sulfuric acid, all in a glass beaker.
-No visible reaction occured.
2nd try) then i made the following discovery: i tried the whole again, but this time i used dark coloured sulfuric acid(it was stored in a plastic
container and the known effect of dehydration of organic compounds to give carbon traces gave the acid a dark colour).
The (amazing) effect of that difference now was, that the formaldehyde got immediately a thick paste, and after solution with cold water, a white,
plastic-like residue was left.
I suppose this was paraformaldehyde, but i`m not really shure, as i know very few about paraformaldehyde`s properties.
My theory about this unexpected polymerization is that the carbon traces acted as some kind of polymerization seed.
What do you all think?
HLR
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Polverone
Now celebrating 21 years of madness
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Registered: 19-5-2002
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I found a reference to the handling of anhydrous formaldehyde, and it indicated that free radicals would initiate polymerization. So maybe the dirty
acid had other compounds in it. Can you try mixing some more formaldehyde solution with a small amount of water-miscible organic peroxide, like a
methyl ethyl ketone peroxide?
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Hoffmann-LaRoche
Hazard to Self
Posts: 64
Registered: 10-9-2002
Location: mid-europe
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I dont have methyl ethyl ketone peroxide, but maybe i could use Et2O as reaction medium and then try this with AP instead.
(paraformaldehyde is soluble in Et2O)
Free radicals? - Wouldnt H2O2 do a good job then?
HLR
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Polverone
Now celebrating 21 years of madness
Posts: 3186
Registered: 19-5-2002
Location: The Sunny Pacific Northwest
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Mood: Waiting for spring
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I am suggesting organic peroxides because they, and not inorganic peroxides, are typically used as free radical sources in the syntheses I've read
that require free radicals. I don't know if this is merely convention or if there are good reasons for preferring the organic compounds.
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