I am a fish - 6-8-2003 at 10:57
Is there any practical way of converting CaF2 to NaF? I could dissolve the CaF2 in H2SO4 and then bubble the resulting HF through NaOH solution.
However, sanity prevents me from using this method. Is there any non-suicidal way of producing NaF?
chemoleo - 6-8-2003 at 16:53
try Na2SO4 + CaF2 --> 2 NaF + CaSO4. CaSO4 precipitates, so you can easily test it first if it works 
Mumbles - 6-8-2003 at 19:22
CaF<sub>2</sub> isn't soluble in water. I was trying to come up with something similar earlier. Perhaps try heating together while
dry. Then drowning in water. The Calcium compounds would be precipitated. The sodium sulfate/carbonate/hydroxide/whatever you decide to use and the
sodium flouride will be left dissolved. NaF doesn't have a particularly good solubility in water, so this may be useful in separating the sodium
components.
sirius_cm - 7-8-2003 at 09:26
While back, I posted something about strong NaF solutions in Mouthwash. I've seen it up to 5% NaF solution in mostly water. You could get it from
there.
Mumbles - 7-8-2003 at 10:41
I believe NaF can also be found as an incecticide. This information comes from http://www.dekker.com/servlet/product/DOI/101081EEPM10000196... Its near the bottom of the page, in the table.
http://www.fluoridealert.org/brand-names.htm This page shows a number of NaF containing Brand name insecticides. I was supprised to find such
high percentanges. You may also want to check a brew shop. Its also sold for disinfecting fermentation barrels. I know this doesn't really
answer how to convert CaF<cub>2</sub> to NaF, but that task seems quite difficult. These offer an alternative solution for obtaining the
sought after compound.
ammonium bifluoride?
Polverone - 7-8-2003 at 13:00
I know a number of cleaning products you can find in the US contain ammonium bifluoride. They seem to be targeted at cleaning toilets, enamel, and
aluminum. You should be able to react them with NaOH to get NaF. But maybe such products aren't available in the UK. I remember seeing a
high-temperature, no-HF process for making KF from CaF2 in one of the PDF books a_bab supplied. I can't find it now, though.
DDTea - 7-8-2003 at 15:59
I have tried the method which you speak of Polverone... it works just fine 
.
You see, Ammonium Bifluoride in water is essentially Hydrogen Fluoride. But if you're looking to make NaOH on a large scale, I should warn you
that the side product is Ammonia Gas...so either work in small quantities, or with good ventilation, or with a working gas mask.
However, the problem with the Ammonium Bifluoride solutions is that they are so bloody dilute- somewhere in the area of 2%-5%. Be warned though- it
is just as dangerous as HF, and can cause serious flouride burns...
It's not a regulated chemical, however. In fact, there's a guy on eBay who has plenty of the stuff to go around, and quite pure too!
trilobite - 7-10-2005 at 12:49
I've always thought that it would be nice if alkali fluorides could be made from fluorspar. Then I found the patent US2690430 while reading
Gmelin. The reaction is
2KOH + CaF2 --> 2KF + Ca(OH)2
and it seems to work with NaOH, LiOH, SrOH too. In the case of KF it is possible to extract and purify the product by extraction with MeOH. Otherwise
it sounds very good, but in the example they use a mixture prepared by heating all the way to temperatures needed to dehydrate the Ca(OH)2 to CaO. One
explanation is that it is done to prevent the reverse reaction from spoiling the purity of the product, in case of eg. moisture coming into contact
with the mixture, forming KOH which is also quite well soluble in alcohols. Apparently that won't happen without water around and CaO should make
sure there isn't any. Maybe one could do without such high heats and bubble CO2 through the methanolic extract to neutralize the KOH and filter
to remove the precipitated K2CO3, if it is alkaline to begin with. This could also come in handy in cases where the reaction mixture hasn't been
heated enough to complete the conversion to KF and Ca(OH)2 (>300C).
[Edited on 7-10-2005 by trilobite]
NaF from CaF2
al - 8-10-2005 at 05:18
Use cheap sodium carbonate (Na2CO3),
mix it with powdered Fluorite (CaF2), proportion 2/3 - 1/3 , add a little sand.
Put the mixture in a crucible and heat
to 800 - 900° C
You get Calcium silicate and Sodium fluoride.
Use warm water to extract NaF
To get KF use Potasium carbonate.
kazaa81 - 8-10-2005 at 08:23
Be careful because all water-soluble fluorides are dangerous. They're poisonous because of the F- ion to bind with Ca in bones and blood.
Fused NaOH then adding CaF2 would give NaF?