Technetters,
OK, let's have another go at this. This is not going the way I had hoped.
1) I didn't say not use ammonium bifluoride, just be careful. The hydrogen
fluoride bonds in the HF2- ion are among the strongest hydrogen bonds known,
to the point that the bonds are best described in terms of 3c-4e- MO
covalent bonding theory, so there is less free fluoride than with other
compounds. It is a good choice, just use caution. No attempt to drive
anyone crazy was intended.
2) HF is definitely more dangerous than HCl.
3) I have just got off the telephone with Dr. Jack Passmore, a world
renowned fluorine chemist, and he tells me if he got an ionic fluoride on
his skin he would not be wasting any time getting to a sink to wash it off.
The label on a bottle of sodium fluoride gives it an exposure value of 2 on
a scale of 1 to 4, so I would never wait even five minutes, let alone 15
before washing.
4) If I am not mistaken the active fluorine-containing ingredient in
toothpaste is "stannous fluoride", which on exposure to air forms stannic
oxyfluoride. This material is polymeric and insoluble. The fluorine atoms
in tin compounds have a high degree of covalent character in their bonds to
the central tin, as opposed to a 100% ionic bond, and there is little
tendency for them to leave the tin. As a result, there is an extremely
small amount of free fluoride. If this were not the case we would all be
running around with mottled teeth.
6) In concentrated HF is it more like (HF)n. There may be some (HF)2, but
certainly it would only be the dominant species at one intermediate
concentration. The degree of "polymerization" (hydrogen bonding) is not the
source of the danger, just the increasing concentration of HF.
5) Tom Hybiske wrote about the subcutaneous injection of a calcium salt for
HF burns. Specifically the salt is calcium gluconate and the treatment is
excrutiatingly painful. Fortunately I cannot tell you this from personal
experience. My whole point in mentioning the bit about the FIRST AID
treatment with the ternary ammonium salt skin exposure antidote was to help
people avoid having to go through the MEDICAL treatment of the injections.
Ever vigilantly yours,
Bev Christian, PhD
Nortel
> ----------
> From: RSedlak[SMTP:[log in to unmask]]
> Sent: Wednesday, May 20, 1998 9:06 AM
> To: [log in to unmask]
> Subject: Re: [TN] fluoride burns
>
> You must have a helluva time finding toothpaste that does not burn
> incredibly......
>
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