I recently got some BF3*Et2O because I had the one-time chance to buy it.
However, I don't know too much uses for it. I know that it can be used as a water- scavenging agent in some reactions and also as a catalyst. It
is a strong lewis-acid.
Can you tell me some applications? What would you do if you had it?sparkgap - 10-6-2005 at 07:21
Rather interesting link on BF<sub>3</sub>:
http://64.177.90.157/science/html/bf3.html
Usage, usage... as you have mentioned, it's a Lewis acid. It's useful as a catalyst in certain organic syntheses and polymerizations, and is
sometimes partnered with alumina, as Hive bees can attest. (maybe they'd bugger you for some if they find out )
BF3 is an important catalyst if you want to make RDX from acetic anhydride and paraformaldehyde.
I'm rather interested in how you EVER obtained it...garage chemist - 13-6-2005 at 11:57
It was from a sale of some old chemicals- no renewable source.
I read up on BF3 in a chemistry book and the listed uses were mainly organic reactions where it is needed as a catalyst.
The book also described its synthesis, the raw materials for which are easy to get.
Calcium fluoride (fluorspar) is heated with boron trioxide (produced by dehydrating boric acid at red heat) and an excess of conc. sulfuric acid.
HF is first formed:
CaF2 + H2SO4 ---> CaSO4 + 2 HF
This doesn't escape, but reacts with the B2O3:
B2O3 + 6 HF ---> 2 BF3 + 3 H2O
The formed H2O must be removed to prevent hydrolysis of the BF3, hence the excess of H2SO4.
So mixing 3 mol CaF2, 1 mol B2O3 and 6 mol conc. H2SO4 and heating the resulting mixture will yield gaseous BF3.
BF3 doesn't attack glass, so only the boiling flask would need to be made of a resistant substance (I think steel would work, since conc. H2SO4
and anhydrous HF don't attack it).
The BF3 could be led into diethyl ether, the etherate boils at 124°C (IIRC), so separation
from excess ether would be very simple.12AX7 - 13-6-2005 at 13:46
Quote:
Originally posted by garage chemist(I think steel would work, since conc. H2SO4 and anhydrous HF don't attack it).
If I'm not mistaken, doesn't the reaction dilute the sulfuric acid in the process?
Lead would be a good candidate. Easy to cast as well
)