Nephlite - 19-5-2004 at 10:47
I made one reactions in two ways and the resaults were different.
The reaction is between NaOH and CH20
When I mixed water solutions(concentrated) of them the reasault was onl warming up.
But when I mixed water solution of CH2O (concentrated) and NaOH ( solid) the reasult was not only warming up.The mixture became orange-brown.
Does anybody knows the reason?
chemoleo - 19-5-2004 at 12:06
Yes, it turns brown due to polymerisation I believe. It is not paraformaldehyde, but a high chain length polymer. I dont know if there's some
interchain crosslinking going on, but probably there is, because methanol will be produced too (see below). This produces the equivalent of acetals,
presumably (The latter is guesswork)
I.e.
the smallest unit in the polymer is [H2C-O]n.
In the other case, at low conc. of each, you presumably have the Cannizzaro reaction taking place.
I.e.
2 CH2O --> HCOO- + CH3OH,
a reaction that only occurs in the presence of a base, OH-.
vulture - 20-5-2004 at 06:01
Bakelite (one of the first synthetic polymers) was made by NaOH + formaldehyde. The reaction is very exothermic and should be monitored carefully.
Now that I think of it, you need resorcinol too to make bakelite.
chemoleo - 20-5-2004 at 08:21
I thought bakelite was made with phenol and formaldehyde??? This was my excuse for obtaining 1 l of phenol from a pharmacy, to make bakelite!
Bakelite
markgollum - 20-5-2004 at 20:56
Bakelite, is a phenol-formaldehyde resin, it is synthesised by first reacting phenol and formaldehyde together in a condensation reaction, forming
mono-, di-, and tri- hydroxymethyl phenols, this first reaction is both base and acid catalysed.
Then, acid catalyses further condensation to bakelite but before it finishes polymerizing it is placed in a mould and heated.
"At a low degree of polymerization the fluid material is poured into a mold.
the final cure to produce an infinite network is accomplished by heating, which causes further phenol alkylation with loss of water"
Formaldehyde reacts with phenol because it is converted by the acid to its powerfully electrophilic conjugate acid (H2COH+ I think).
The hydroxymethyl phenols interlink because "Since the products are benzyl alcohols, they are readily converted to carbonium ions, which may
alkylate another nucleus"
As far as why the first reaction is base catalysed, I dont know.
All my quotes are from the book
Organic Chemistry by
James B. Hendrickson, Donald J. Cram, and George S. Hammond.
The_Davster - 21-5-2004 at 18:22
I have made bakelite once. It was on an IB field trip in highschool to the university. It was made by dissolving 2g of resorcinol in about 5 mL of
formaldehyde(forgot the concentration) and then KOH(30%) was added as a catalyst. The bakelite solidifies quick after a short time and the object was
to drop a penny in at exactly the right time causing the penny to be stuck suspended in the newly formed bakelite.
Adas - 28-12-2011 at 05:52
I am sorry to bring up an old topic, but I want to ask what happens, if anhydrous CH2O and NaOH react. Would it form sodium methoxide? Or am I just
insane? 
Dr.Bob - 28-12-2011 at 06:28
You are just insane, NaOH and CH2O will not form methoxide. I don't think they would form anything useful at all.
AndersHoveland - 28-12-2011 at 11:24
Under alkaline conditions, formaldehyde can undergo a canizarro reaction, disproportionating into formic acid and methanol.