rot - 28-1-2006 at 01:11
I know it's possible to convert sodium chlorate to potassium chlorate by a double replacement reaction with KCl, but can you also convert potassium
chlorate to sodium chlorate? I need some for TACC synthesis.
mantis - 28-1-2006 at 01:47
Maybe you can convert KClO3 to NaClO3 in another solvement, but in water it is impossible.
12AX7 - 28-1-2006 at 07:09
The usual way is to displace the anion with a strong acid and neutralize with the required base.
2KClO3(aq) + H2SO4(aq) > K2SO4(aq) + 2HClO3(g)
HClO3 is distilled off.
HClO3(aq) + Na2CO3 (or NaOH, etc.) > NaClO3(aq)
Note: 2HClO3 <---> H2O + 2ClO2 (+ O2?). ClO2 is a yellow gas that in small amounts is quite stinky and poisonous, and in larger amounts tends
to spontaneously explode. Making HClO3 is a baaad idea...
If you added sodium perchlorate or sodium hexanitricobaltate (I think?) it might precipitate the potassium, leaving sodium in solution. KClO3 is
pretty insoluble, but those two are at least less soluble. Of course, you have to obtain them too. 
Tim
woelen - 28-1-2006 at 08:49
Never attempt to distill off HClO3 if you value your limbs and your life. HClO3 is unstable and only can exist in low to moderate concentration in
aqueous solution. At higher concentration it disproporionates to ClO2 and HClO4. This is what you observe H2SO4 to solid KClO3. An orange liquid is
obtained and a deep yellow gas. The orange liquid is ClO2 dissolved at high concentration in H2SO4 and the deep yellow gas is ClO2. Exceedingly
dangerous to do. I once did and while I was watching the fascinating reaction (I also had little flashes of light every few seconds, when a dust
particle entered the liquid) it suddenly did BANG. Fortunately I only used a single large drop of H2SO4 and a small spatula full of KClO3, but it
nicely demonstrates the dangers of mixing KClO3 with H2SO4.
I'm afraid that in practice, you'll not be able to convert KClO3 to NaClO3, because of the low solubility of KClO3. You can make NaClO3 from NaCl
though, by electrolysis. There are threads on that subject here as well. It requires a good PSU and a good anode.
[Edited on 28-1-06 by woelen]
TACC
MadHatter - 28-1-2006 at 10:33
Rot, I assume you're starting out with CuSO4 in your synthesis. If available, you could
produce Ca(ClO3)2 by thermal decomposition of Ca(OCl)2 usually available as bleaching
powder or pool shock. The metathesis reaction with CuSO4 would cause the relatively
insoluble CaSO4 to precipitate out of solution. Filter this out and dry the solution to solid
copper chlorate. From there, dissolve in ethanol and bubble the ammonia gas through it.
Marvin - 28-1-2006 at 12:08
Madhatters method has the germ of a good idea, but it has problems.
The problem is that copper chlorate made in aq solution keeps moisture like an SOB. I failed to make it anhydrous without decomposing it, ammonia gas
just made a sludgy mess, ended up giving up on TACC alltogether.
If you need to make sodium chlorate, try the following method. Calcium chloride and potassium chlorate should precipitate KCl in boiling solution.
(I say, 'should' some guesswork is involved, it certainly works for sodium chlorate/calcium chloride, but the difference is that potassium chlorate is
less soluable than the sodium version, particually cold). After removal of the chloride you then have calcium chlorate.
Add sodium sulphate, or carbonate to the calcium chlorate and you get sodium chlorate. Method will need a lot of washing/filtering preciptate and
fractional crystalisation I suspect, but workable for a 'backwards' metathesis.