Hydrofluoric acid synthesis

[Mick]

has anyone got any info on the synthesis of HF?

seem like a pretty interesting chemical as far as bio-warfare goes.

[Rhadon]

Basically there is no problem: H2SO4 and CaF2(*) yields HF... but there are practical problems: What kind of material can be used when leading the resulting HF into water? I'd like to perform this synthesis myself, but I cannot imagine another container which lets a stopper fit tight than an erlenmeyer flask or a test tube (and these are made of glass) when looking at my avaibale apparatuses. And I don't aim to stand in a cloud of HF.

(*) CaF2 isn't poisonous and thus easy to get. If I remember correctly the reason is that the toxicity of fluorides is based on their ability to bind whith calcium.

[rikkitikkitavi]

classical lab-method :

heating CaF2, fluorite with H2SO4.
CaF2 isnt poisonus because its almost insoluble in water. Soluble fluorides are very toxic.

Beware, it reacts with glass (SiO2 + 4HF => SiF4(g) + H2O)

(seems like someone was quicker than me, phone rang.. :)

anyway, materials of construction:
absolutely dry HF doesnt react with ordinary steel. Weak acid can be kept in plastic containers. Monell metal(a nickel alloy) is resistant to both HF and HF in solution.

/rickard

<small>[ June 28, 2002, 06:32 PM: Message edited by: rikkitikkitavi ]</small>

[MrSamosa]

I have an Ammonium Bifluoride (NH4FHF) Solution used for cleaning automobile tires. It's easy to make Hydrogen Fluoride from this; all you do is add another strong mineral acid. I use Hydrochloric Acid. The yields aren't anything spectacular since it's only about a 5% solution, but it makes Hydrogen Fluoride fumes. I'm sure you can figure out a way to bubble the fumes through water to make Hydrofluoric Acid. You know, you can BUY Hydrofluoric Acid as a hubcap cleaner. A friend of mine knows people who use it to clean tractor-trailers. It's a common chemical, just not common concentrated.

If you're considering its use as a Chemical Weapon, then the binary components can easily be combined on-sight for use. No, it won't be nearly as effective as ready made Hydrogen Fluoride, but it should get the job done. It's not like you're going to have to worry about impurities giving it an irritating effect, as is the case with Sarin or other Nerve Agents. HF is one of the most acidic gasses already; so with or without impurities, you will know you're being gassed.

<small>[ June 28, 2002, 09:02 PM: Message edited by: MrSamosa ]</small>

[Flake2m]

I would be very careful when synthesising HF.

As rikkitikkitavi said:
</font><blockquote><font size="1" face="Verdana, Arial, Helvetica">quote:</font><hr /><font size="2" face="Verdana, Arial, Helvetica"> Beware, it reacts with glass (SiO2 + 4HF =&gt; SiF4(g) + H2O)</font><hr /></blockquote><font size="2" face="Verdana, Arial, Helvetica">My chemistry also teacher told me:
If you spill conc H2SO4 on you the burn will eventually heal, however
if you get HF on you then you will probaly die :( because the HF creates a bio-chemical reaction with your body.

so this would make it a very good chemical weapon :D

Remember that flourine is the most reactive element in the universe (correct me on this). Most compounds that store flourine are often contain flourine themselves. So something like PVF should be able store flourine without any problems.

[nbk2000]

HF production isn't a topic for discussion in the BC section since it isn't itself a proper CW agent. It is, however, used in the synthesis of several CW agents such as sarin and octylfluoride and poisons like 1080, so that puts it back here.

Lead is inert to HF, wet or dry, since it forms a passivating layer. Or you can use readily available teflon tubing and such to conduct the gas.

To concentrate OTC HF acid (like Wink rust remover) you add baking soda to it till nuetralized. Then dry. Mix the crystals with concentrated H2SO4 and heat.. The anhydrous HF is unreactive to pyrex glass, and is used for preparing sarin. Conduct the fumes through a small amount of water to get the fuming acid

An HF solution of under 60% won't cause any immediate burning sensation on contact with the skin, but when over 30% concentration, it will be absorbed through the skin where it will bind with the calcium in the body, causing heart attack and bone disintegration.

So just make it about 40-50% and proceed to spray your victim down with a supersoaker full of the stuff. Also, as far as I know, it's not immediately corrosive to rubber, which may open up water ballons as a weapon.

[vulture]

HF is so dangerous because it penetrates through the skin easily and starts breaking down bone material and in the process it sets free poisonous fluorides.

Well, you are half correct when you say fluorine is the most reactive compound. <img border="0" title="" alt="[Wink]" src="wink.gif" /> Fluorine is the strongest oxidant known, together with Francium or Caesium it's one of the most reactive compounds.
Because it's so reactive, do not attempt to make it by reacting F2 and H2, the mixture autoignites into a violent explosion even at -200C.

[megalomania]

I had a chemistry professor once tell me that there are very very few chemists who do any research with fluorine, and those that do are rather crazy. A HF burn is rather painful I hear, and it does not really even heal. The flesh may come back but the pain remains deep inside you for years to come, hence the reason few deal with fluorine compounds. They also tend to be highly explosive when they react. The original developer of Teflon expected to be killed or injured by his 'discovery' because that's what fluorine usually does.

[MrSamosa]

I believe one of the Geneva Protocols listed acid vapors as Chemical Weapons and banned them. So HF is technically a chemical weapon.

I think Sodium or Potassium Fluoride would be better when it comes to making Sarin though. When Hydrofluoric Acid reacts with DC (DimethylPhosphonyl Chloride), it yields the desired DF (DimethylPhosphonyl Fluoride) and Hydrochloric Acid. If I know my chemistry properly, and if this will react at all, the Sodium/Potassium Fluoride creates Sodium/Potassium Chloride. Simply put, it's less acids to deal with. In addition to that, the glass equipment should be sufficient to carry out these reactions, opposed to the less common materials needed for Hydrofluoric Acid.

[Polverone]

It's interesting to note that certain fluorine compounds - such as NaF and KF - are regulated under the chemical warfare conventions because of their utility as precursors in chemical weapon manufacture. I'm pretty sure nobody tracks lab-sized quantities of these salts, though. If you have a choice between KF and NaF, definitely get the KF. It is far more soluble than NaF. Likewise, react your Whink with potassium carbonate/hydroxide instead of the sodium salt.

Back in Ye Olde Times (before plastics), hydrofluoric acid was stored in wax bottles. I imagine that, for low-temperature reactions, a wax-coated glass or metal container could temporarily serve without degradation.

I've once made HF from CaF2 and H2SO4. I didn't have any suitably resistant containers. I just did it in a glass test tube and observed the destruction of the glass. I have plenty of CaF2 left. I'm just not eager to die a horrible death attempting to make HF in bulk.

[inferno]

I thought Pyrex glass was pretty much 100% corrosion (by acids at least) proof? Maybe that was just for H&lt;sub&gt;2&lt;/sub&gt;SO&lt;sub&gt;4&lt;/sub&gt;, but as it's just the H+ that corrodes it, should Pyrex be fine? A Pyrex Erlenmeyer flask should do fine, with a rubber stopper and hose bubbled into a Pyrex beaker/flask.

I also don't intend on making this, but it should work fine with Pyrex.

[vulture]

No, every glass, even pyrex, consists of at least 80% SiO2 which is attacked by the fluorine ion because it has a much greater electronegativity than oxygen. Normally the H+ ion attacks, but if the rest of the acid is more reactive, then that will be the attacking ion.
If you had bothered to read the above posts you would have seen the following reaction:

SiO2 + 4HF -&gt; SiF4 + 2H2O

[Flake2m]

I short:
Do not go near pure flourine or HF it is very x 10^23 nasty shit.

Flourine is SO reactive that is has been found to react with the noble gas Xenon <img border="0" title="" alt="[Eek!]" src="eek.gif" /> .
Compounds such as XeF6 has been discovered because of these crazy scientists working with Flourine.

[Fl4PP4W0k]

NBK...
May I ask why one would be interested in making Sarin :p

And about filling water ballons with Hydrofluoric acid... uh... that sounds like theyd be AWFUL hard to tie...

"Slippery..son of a... goddamn.. get in the.."
*POP*
"Oh...Fuck Me"

You'd hope to be wearing damn thick gloves... But that makes those little bastards even HARDER!!! to tie :(

Also... There was a report a few years back of a geologist who was working in his shed with hydrofluoric acid, when he spilt a beaker on his pants (duh). Apparently he wigged out, jumped into the pool and later on died in hospital from blood poisoning.
I cant remember the details... but thats gotta hurt.

[MrSamosa]

I remember that story... It was 60% HF he was working with. He knocked over a container of HF, which spilled in his lap (ahh, the poor guy). He did not have any Calcium Gluconate gel, so the best he could do was call an ambulance and jump into the pool to try to relieve the pain. When the ambulance came, he was passed out in the pool, as I recall. He died from a lack of Calcium, which caused a heart-attack...if I know my Biology/Pathology properly. As mentioned before, the H+ in HF isn't what causes the bulk of the injury. It is the F- that penetrates down to the bones, depleting Calcium, which in turn stops your heart (heart needs Calcium in order to beat).

[VX]

I thought that the F- ion reacts with the Ca2+ in the bone to form CaF2, which, being extremely insoluble in water exists as a precipitate in the blood. This precipitate is what causes the heart to fail as it collects in the heart, and blocks it. Also it's worth mentioning that HF is classed as a weak acid (less that 50% of the molecules are dissociated in water) I am not sure of it's exatct value though.

[Purple Fire]

A friend of my fathers had a pretty close call with some fluorine gas. He owns a company that does something with ceramics (cant remember what). A company that did teflon coatings (I think) went bust, and he bought a small furnace from them that they use for melting the teflon with. They set up this furnace and fired it up, then realised that the temperatures they were using it at were significantly higher than those it had been used for with the teflon. The layer of teflon that had biult up around the sides and floor of the furnace broke down and started giving off fluorine gas. The workshop started filling with the gas and the guy noticed that the windows of his office had started to be attacked and were going cloudy. He got everyone out and no one was hurt, but still...

I remember reading somewhere that if you get HF on your skin it starts burning its way down through the skin, and that the only way you can stop it is to inject a really strong alkali solution underneath, so it attacks its way down to there and then is neutralised. Is that true?

Even so, I wouldnt go near hydrofluoric acid if you fucken PAID me!

[Ctrl_C]

just a side note: XeF6 is used in microprocessor etching. Part of the technique makes XeF4 which has been found to be extremely explosive.

<small>[ July 03, 2002, 09:10 PM: Message edited by: Ctrl_C ]</small>

[MrSamosa]

The burns by Hydrofluoric Acid are not really the problem. No, it won't burn and burn and burn. You'd probably get a worse burn from Hydrochloric Acid...but this burn would heal a lot faster. The real threat is from the Fluoride Ion which reeks havoc on the Calcium in your bones. To treat HF burns, they use Calcium Gluconate gel. I don't think I'd want to inject any strong alkali solutios into my body anyway, I don't care what the problem is :) .

[VX]

Injecting an alkali would do no use whatsoever anyway. This is because the alkali would react with the HF to form a fluorine salt. This salt would probably be very soluble (depends on alkali). Then instead of having a low concentration of F- ions in your body (In the acid most of them remain covalantly bonded to the H+ ion, and so stable and safe), you suddenly have all them released into the body. Which will attack you much faster.

The only way to combat HF is to react the F- ion into a stable, non toxic molecule using Calcium Gluconate gel.

[vulture]

Let me get something straight here, Teflon = PTFE = PolyTetraFluorEthylene right?
Now, what kind of gas would heated PTFE produce?

[Machiavelli]

The most interesting pyrolisis product is PFIB, perfluoroisobutylene. It's been discussed a bit in the improvised chemical weapons thread.

[VX]

Just a small thing, but PTFE actualy stands for polytetraflouroethene. <img border="0" title="" alt="[Wink]" src="wink.gif" />

[vulture]

I'm very sorry VX, but according to my chemistry encyclopedia and according to DIN 7728-1:1988-08 (confuse the enemy with facts, a classic american court strategy <img border="0" title="" alt="[Wink]" src="wink.gif" /> )
PTFE stands for Polytetrafluorethylene .
No hard feelings.... <img border="0" title="" alt="[Wink]" src="wink.gif" />

[kingspaz]

vx and vulture, you are both right. it stands for both. according to my chemsitry book its poly(tetrafluorethene) the part in brackets shows the monomer from which the polymer is formed. ethylene is the american/industrial/old way of writing enthene. in a similar way to acetic acid being the same as ethanoic acid or methyl alcohol being the same as methanol.

[vulture]

Sorry kingspaz, but I still have to disagree. Ethyl stands for 2 carbon atoms which are single bonded and can accept in total six other bonds, four for the flourine and the two other for making the link. Ethene are two carbon atoms double bonded leaving only four possible bonds which would be taken by the fluorine and then it couldn't connect to the other molecules anymore.

I think what you are trying to say is that one of the production intermediates is tetrafluorethene, which than moves the double bond under influence of a polymerisation catalyst to connect with two molecules on it's sides.

[VX]

PTFE is fully saturated, i.e. it has no double bonds. Ethene C2H4 has a C=C bond, and potential to form another two covalent bonds when the double bond opens up, which is what happens when C2F4 polimerises.
Ethyne C2H2 has a triple bond and therefore potential to form an extra four bonds. Once fully saturated both molecules will have 6 bonds, excluding the covalent bond joining the two Carbons.

Edit: According to the the IUPAC naming system the proper modern name is as I said. The same as simple Poly(ethene) AKA polythene. p.s. I do hope to God I understand this correctly as this did come up on my Chem A level paper a the other week!

<small>[ July 05, 2002, 06:27 PM: Message edited by: VX ]</small>

[VX]

OK, I've thought about this for a while and I think I know where the misunderstanding is coming from.

Vulture, if I am right it seems that you think that tetraflouroethene is formed by saturating a molecule of ethyne (acetylene) with flourine across the triple bond. I.e. C2H2+2F2---&gt; CHF2CHF2,This may be the case. (I don’t know for sure, but it seems feasible) but I do know that their is a double bond in the monomer and the monomer is C2F4.

Is this the reaction pathway ? Ethyne (C2H2) gets fully saturated with F, and then the molecule gets oxidised by removing the remaining two H atoms to reform the double bond? (There are no H atoms in PTFE)

Either way according to modern IUPAC naming rules, it does not matter what the starting material is for a compound, only in this case what the actual monomer unit is for the polymer. i.e. If it is made from ethyne is irrelevant. The monomer is tetraflouroethene, and so the polymer is called poly(tetraflouroethene). If the monomer itself was tetreflouroethyne, then PTFE would be poly(tetrafoluroethyne)

By the way this is NOT a flame in any way. I just wanted to clear things up, which I hope I have now done?

-------
you missed an 'e' on poly(tetrafluoroethene) - kingspaz

<small>[ July 06, 2002, 08:21 AM: Message edited by: kingspaz ]</small>

[kingspaz]

VX i agree with all you have said but i'd like to add these pics.
<img src="http://www.boomspeed.com/kingspaz/PTFE.JPG" alt=" - " />
Vulture, trust me, i'm a doctor <img border="0" title="" alt="[Wink]" src="wink.gif" />

<small>[ July 06, 2002, 08:42 AM: Message edited by: kingspaz ]</small>

[vulture]

You guys didn't understood me, what I said is exactly what those pictures show. Keep in mind that ethene is not the same as ethylene. Anyways, were getting way off topic here.

[pyromaniac_guy]

a note on working with f and hf. when we had an excimer laser insalled in my shop the service tech STRONGLY suggested that we do away with stainless gas lines and used copper as it had much better passivation properties. I belive that NBK suggested lead as well. If copper works, and so deos lead, well then you ahve yourself something to make labware with, as well as solder joints...

[Sparky]

I just thought I'd add my two cents: As other people noted, HF reacts with glass. So, if you wanted a source for it, it is sold to etch (frost) glass with.

[Boob Raider]

Sorry but I have to clarify this ...
Alkane(Ethane, C2H6), Alkyl group(Ethyl, C2H5-), Alkene(Ethene aka Ethylene, C2H4) , Alkyne(Ethyne aka Acetylene, C2H2). So both of you were correct. <img border="0" title="" alt="[Wink]" src="wink.gif" />
Back to HF.... How would one get the F from HF ? I am suspecting
electrolysis (some oxidizer might kick it out too). Once the H and F are seperated one could make a really powerful fuel cell :D . So would Pt react with F or HF.
Just thinking of another application besides CW agent or a precursor for one. :p What about NaFO3 and KFO3 and NF3 ? Anybody know anything about them ?

[MrSamosa]

You should look in the Fluoroacetates thread, it has some information about Hydrofluoric Acid. No oxidizer will expel the Fluorine, because Fluorine has the highest electronegativity and is thus the strongest oxidizer. Electrolysis would be the only way. Fluorine reacts with anything, so yes it will react with Pt.

Has anyone heard of Silicon Fluoride (SiF4)? Usually, it's the result of doing something wrong in the lab, and therefore not somethign you'd like to have around. I can't find any toxicological information on it, although I know it is quite toxic. It is made by putting Silica in Hydrofluoric Acid.

I was at Home Depot the other day, and in the plumbing section I saw some Teflon Glue. Would it work to line some glassware with this glue so that it would be resistant to etching by HF?

[vulture]

NF3 is highly unstable and explosive, like all nitrogen halogens. Fluorates don't exist, because fluorine has a higher electronegativity than oxygen. When you look at other halogenates like ClO3, you'll see that the halogen always has a lower electronegativity than oxygen.

SiF4 is a colorless and toxic gas with acidic smell. With water it reacts to H2SiF6.

Normally teflon glue should make the glass resistant to HF if it's well covered. Teflon glue tends to be very expensive though.

[THe_rEaL_dEaL]

Plain and Simple if you dont have LOTS of Calcium Gluconate then dont even consider messing with HF in high concentrations.

That is unless you have long white hair and have a death wish <img border="0" title="" alt="[Wink]" src="wink.gif" />

<small>[ January 22, 2003, 11:52 PM: Message edited by: THe_rEaL_dEaL ]</small>

[Marvin]

HF is a very weak acid, becuase the more electronegative the halogen, the stronger the HF bond, and so the more energy required to dissociate.

Fluorates and perfluorates dont exist, but the reason generally taught is that fluorine is too small to be able to expand its octet. The point about electronegativity is interesting and could well be valid, but I'm not sure if it holds water on its own, classical oxidation states often bear little resemblence to whats actually going on.

Ignoring complexing agent effects, or polymerisation, the nitrogen halides trend look like this.
NI3 is endothermic,
NBr3 is less endothermic,
NCl3 is even less,
NF3 continues the trend by being exothermic, and therefore not explosive.

Unfortunatly I dont have reliable numbers for this easily to hand. Think of it as the increasing stability of the N-Hal bond over the largest energy producer, N triple bond N which stays the same.

Just in case anyone is in any doubt. Poly Tetra Fluoro Ethene/Ethylene are equally as valid.

Rather dissapointing for my 100th post, but maybe I'll post something useful later instead. Not here though, I abhor chemical warfare. Fritz Haber should have been aborted for the good of the planet.

[nbk2000]

HF is used in "superacid" systems, usually with antimony pentafluoride. I believe the same with Silicon trifluoride.

Unfortunately, not much info on the actually preparation of superacids is to be found on the net. This sort of info is still "analog" (books) for the most part, so would have to be scanned in from there.

Superacids have various uses, the most obvious being destroying things. Almost nothing can hold them, not even wax or teflon. That's why they have to be made in situ when they're needed. The main use is in the petrochemical industry for cracking hydrocarbons.

In our field, we'd be interested in using them for destroying things. The military is researching their use to dissolve and destroy tanks, trucks, and anything else! <img border="0" title="" alt="[Eek!]" src="eek.gif" />

In the PDF "Safe Cracking" by Wayne Yeager (FTP), he mentions how euro thieves use acids to dissolve their way into safes. Surely some sort of superacid system is being used. Though I have to wonder at the time it might take, and the danger of destroying the contents.

[Sarevok]

Posted by VX:
</font><blockquote><font size="1" face="Verdana, Arial, Helvetica">quote:</font><hr /><font size="2" face="Verdana, Arial, Helvetica">"I thought that the F- ion reacts with the Ca2+ in the bone to form CaF2, which, being extremely insoluble in water exists as a precipitate in the blood. This precipitate is what causes the heart to fail as it collects in the heart, and blocks it. Also it's worth mentioning that HF is classed as a weak acid (less that 50% of the molecules are dissociated in water) I am not sure of it's exatct value though."</font><hr /></blockquote><font size="2" face="Verdana, Arial, Helvetica">HF: 8%

Since NBK mentioned "super acids" I got a link about it.
<a href="http://www.psc.edu/science/Klein2000/getting_jump_on_superacids.pdf" target="_blank">http://www.psc.edu/science/Klein2000/getting_jump_on_superacids.pdf</a>

<small>[ February 15, 2003, 11:05 AM: Message edited by: Sarevok ]</small>

[Polverone]

</font><blockquote><font size="1" face="Verdana, Arial, Helvetica">quote:</font><hr /><font size="2" face="Verdana, Arial, Helvetica">An advice to anyone trying to do HF: don't do it. It is far more dangerous than any explosive.</font><hr /></blockquote><font size="2" face="Verdana, Arial, Helvetica">Ah, truly you have spoken as one without experience. I don't mean to flame you, so I will rant instead. People almost always assume that the devil they don't know is worse than the devil they do. The other day in lab a biochemistry professor was regaling us with anecdotes about explosives. She said that when old jars of picric acid become dried out, they could explode just if you opened them, so the bomb squad often gets called to dispose of them. Now I know that bomb squads do get called to dispose of old picric acid, but personal experience and every explosives reference I've seen lead me to believe that picric acid isn't nearly as sensitive as that tale would suggest. She thinks that dry TNP is horrendously dangerous.

I've been cruising around some of the lower class mayhem/chemistry forums on the net trying to spread the gospel of the homemade cyanide. I can almost always find one or even several posts/threads from people who would like to make this substance, probably because they've seen too many episodes of Murder, She Wrote. Interesting item number one is that no matter how many people have previously seemed interested in cyanides, few seem to notice my meticulously detailed and personally verified procedure for making NaCN when I post it. Maybe I should just say "mix household ammonia and weed killer and YUO HAVE MADE TEH CYANIDE!!1!." Interesting item number two is that when the discussion does turn to cyanides, I hear all the time things like "if you make it at home you will die" and "I would never want to make something so dangerous!" The irony, of course, is that this is coming from kids who set off pipes full of matchheads and crank out acetone peroxide like they're baking cookies. They fear what they don't know when death lurks much closer.

And now we have the not-so-wise words that HF is more dangerous than any explosive. Hypothetical situation: would you rather work with 50 grams of 70% HF or one of

-50 grams silver fulminate
-50 grams nitrogen tri(iodide, bromide, chloride)
-50 grams methyl perchlorate
-50 grams dimeric acetone peroxide
-50 grams Armstong's mixture
-50 grams manganese heptoxide ?

HF has hazards that explosives don't and vice-versa. Skin contact with explosives, while generally not advised, isn't the disaster that it is with HF. On the other hand, static electricity near HF is never going to cause a disastrous explosion. HF is nasty stuff but it was regularly used by chemists for many years before we had modern safety equipment, OSHA, and all the rest. Some of those chemists even lived to be very old. Safety warnings are well advised when we're talking about such a potentially dangerous chemical, but dismiss it outright as too dangerous for any amateur? Hogwash. The hydrogen fluoride is just as afraid of you as you are of it :p

[a_bab]

You're right. People are afraid of the things they don't know. And the tendency is always to exagerate the facts. As pyranha fish for instance. There were several death cases among some chemists who were trying to isolate fluorine from HF, but this was due to the lack of equipment, of care and so on. For god sake, the gas mask wasn't invented then! There were no latex gloves, no googles, no protection at all. Bunsen himself when studied golden fulminate was injured because of an explosion, as expected. He wasn't able to see almost a year !
But now we have plenty of protective measures. Still the legend remains. What I can say from my experience is that HF is indeed a hazardous chemical, but once properly manipulated, it won't bite you. I once got a HF burn; I spilled some on my finger with one ocassion. Well, it wasn't enough to disolve my bones aka Harry Potter <img border="0" title="" alt="[Wink]" src="wink.gif" /> . The danger with HF is rather in intoxication than in burning. The side effects are drastical; the teeth loosing is one of the mildest.
What is true about the HF is that once it gets near the nail, it'll be sucked by the tissue under the nail and the imediate effect it'll be loosing of the affected nail. That's why it's written that HF causes the nail to fall. Well, I saw by myself which is the mecanism. And it hearts alot. I didn't lost the nail, but the healing is a slow process.

[Sarevok]

Have a look:

<img src="http://www.emedicine.com/emerg/images/161EME0804-01.jpg" alt=" - " />
Grade 1 hydrofluoric acid (HF) burns of the fingertips. The patient has severe pain (maximum middle digit) with only minimal redness of the nail beds.

<img src="http://www.emedicine.com/emerg/images/279EME0804-02.jpg" alt=" - " />
Grade 3 hydrofluoric acid (HF) burns of the fingertips. Note how the nailbed and tip of the fingers have severely been injured, but the nails show no damage.

Some info:

<a href="http://www.hfacid.com/pdf/hfmedbook.pdf" target="_blank">Medical Treatment</a>
<a href="http://www.hfacid.com/pdf/hfgraphs.pdf" target="_blank">Properties and Graphs</a>
<a href="http://www.nicnas.gov.au/publications/CAR/PEC/PEC19/PEC19.pdf" target="_blank">Public Report</a>

Synthesis:

CaF₂ + H₂SO₄ —(200°C)—&gt; CaSO₄ + 2HF

CaF₂ can be bought with no problems (at least in Brazil). You can easily achieve 200°C at your kitchen. HF destroys most containers, but not all.

Posted by nbk2000:

</font><blockquote><font size="1" face="Verdana, Arial, Helvetica">quote:</font><hr /><font size="2" face="Verdana, Arial, Helvetica">The anhydrous HF is unreactive to pyrex glass, and is used for preparing sarin.Conduct the fumes through a small amount of water to get the fuming acid.</font><hr /></blockquote><font size="2" face="Verdana, Arial, Helvetica">

<small>[ February 18, 2003, 02:53 AM: Message edited by: Sarevok ]</small>

[a_bab]

My wound wasn't close to these, but it was very painfull. The nailbed actually absorbes the HF like a toilet paper, hence these horrible wounds. I was burned with 33% HF.

[vulture]

HF will dissolve all types of glass including quartz. Normal glass is mostly SiO₂ which is only dissolved by HF, that's why glass is used as a reaction vessel. However, normal glass suffers from severe erosion in contact with alkalimetalhydroxides. Pyrex glass has improved resistance to this because it contains B₂O₃, MgO, Na₂O,...

However, all of these oxides dissolve in HF, so pyrex glass is NOT resistant to HF.

[Sarevok]

Posted by vulture:
</font><blockquote><font size="1" face="Verdana, Arial, Helvetica">quote:</font><hr /><font size="2" face="Verdana, Arial, Helvetica">HF will dissolve all types of glass including quartz. Normal glass is mostly SiO2 which is only dissolved by HF, that's why glass is used as a reaction vessel. However, normal glass suffers from severe erosion in contact with alkalimetalhydroxides. Pyrex glass has improved resistance to this because it contains B2O3, MgO, Na2O,...

However, all of these oxides dissolve in HF, so pyrex glass is NOT resistant to HF.</font><hr /></blockquote><font size="2" face="Verdana, Arial, Helvetica">NBK said pyrex can be used. You are disagreeing? <img border="0" title="" alt="[Eek!]" src="eek.gif" /> Sinner! :p

Ok, no pyrex, but what type of containers can be used? Teflon or Lead will work to condut HF gas to water and store it? This is important, the synthesis is useless without knowledge about the proper equipment.

[Polverone]

Glasses will resist HF if it is absolutely anhydrous. But it is hard to prepare absolutely anhydrous HF from the beginning. Even CaF2 + conc. H2SO4 won't produce a perfectly dry acid.

I think, in one of the Making of America books converted to PDF by a_bab, that lead was the traditional material used for HF production/distillation. Of course it's a little harder to find lead pipes nowadays, but you could probably fashion something out of sheet lead and copper. I would think Teflon-coated vessels would be even better but I would also think they'd be more expensive.

[Dathai]

Hello.

Heres almost everything I know about HF.

Appereance:colourless liquid.
Melting Point:-35c
Boiling Point:108c.

Stability:Stable.Do not store in glass containers.Light sensitive.Incompatible with strong bases,metals,glass,leather,water,alkalies,concreat e,silica,sulphides, cyanides,carbonates.

Toxicology:
Extremely Toxic!.May be fatal if inhaled or ingested.Causes serious burns.

Personal Protection:
Rubber gloves,face mask or safety glasses,apron and good ventalation.Do not work without calcium gluconate gel available to treat burns,Do not work this alone!!

I would have put in more but it wasnt really relative.

[Machiavelli]

Hmm, while I don't know how good your chemical knowledge is, at least you know how to use google :)
But what does "it wasnt really relative" mean?

[kingspaz]

think he means relavent :)

[Sarevok]

Posted by Polverone:
</font><blockquote><font size="1" face="Verdana, Arial, Helvetica">quote:</font><hr /><font size="2" face="Verdana, Arial, Helvetica">I think, in one of the Making of America books converted to PDF by a_bab, that lead was the traditional material used for HF production/distillation. Of course it's a little harder to find lead pipes nowadays, but you could probably fashion something out of sheet lead and copper. I would think Teflon-coated vessels would be even better but I would also think they'd be more expensive.</font><hr /></blockquote><font size="2" face="Verdana, Arial, Helvetica">Lead tubing, Sulfuric Acid, CaF₂... well, at least it's possible. It's very useful - can be used to make Sarin and other chemical weapons as said before, or as a "superacid". Anyone knows something about how Antimony Pentafluoride can be obtained?

[Dathai]

Machiavelli your right my chemical knowledge isnt as good as most of the people on this site but Ive got enough to get me by and know what your talking about.Oh and I didnt use Google I used <a href="http://www.eircom.net" target="_blank">Eircom</a> it has tonnes of information about basics,medium and advanced chemistry

[Nihilist]

you can get small lead tubes from some dry cell batteries, although it is a bit dangerous to get them out. If you break off the top of a fairly large dry cell there should be 4 or 6 big tubes made of lead( though i'm not sure of the purity of the lead obtained this way or how easy it would be to make these into containers for HF).

[Tuatara]

You can buy lead sheet from a plumbing or roofing supply shop - its used as a flashing for covering joins in iron roofing. It comes on a roll, about a foot wide, so you should be able to get a nice long piece. Then just wrap it around a mandrel, fold the edges over to form a nice seam, then beat the crap out of it to seal it.

[Sarevok]

Posted by Tuatara:
</font><blockquote><font size="1" face="Verdana, Arial, Helvetica">quote:</font><hr /><font size="2" face="Verdana, Arial, Helvetica">You can buy lead sheet from a plumbing or roofing supply shop - its used as a flashing for covering joins in iron roofing. It comes on a roll, about a foot wide, so you should be able to get a nice long piece. Then just wrap it around a mandrel, fold the edges over to form a nice seam, then beat the crap out of it to seal it.</font><hr /></blockquote><font size="2" face="Verdana, Arial, Helvetica">Wonderful. :cool: But how much it costs?

[Aaron-V2.0]

Of course now it's Lead! Dont forget that you can melt lead with one of those butane crack pipe lighters. A complete seal would be much better than hammering it.

[Chade]

First let me say, bugger. I'd just finish typing this whole darn post, and you can see how long it it, then I dropped the keyboard, and it landed on the ESC button. Wiped the whole thing. Well fuck it, I'm typing the whole thing again.

Ok, So, Hydrofluoric acid. I managed to pick up a trilogy of science books published in 1891 for just £20 from a charity shop. They consist of articles (5-10 pages roughly) on a variety of science topics. Several are of interest to this forum. Most notable are the three articles 'Firing a shot', which details ballistics, and such wonders as how to find muzzle velocity using 1891 equipment, 'A Cannon shot' Which gives an excellent digest of black powder theory, and 'Modern explosives', which, considering when this was written, gives a very nice overview of nitrated explosives at the time.
For the purposes of this topic though, the two of interest are 'A chemical laboratory', and the uninspiringly titled 'flint'. The second gives the best info for our purposes. I've got it scanned, it's 4.15 Mb. It's all in greyscale with diagrams. I've got OCR software, but it took me two hours just to do the frst two pages with all the reformatting needed, so stuff it. I also can't access the FTP, so if anyone wants to read it to verify it's not already there, and then upload it, that's fine with me. (No copyright worries! 1891 remember!)

Anyway, here's the highlights of the relevant article. Flint starts by looking at an ordinary bit of flint, then looking a bit closer. It's SiO2, mostly, same as glass and quartz (and a whole host of other stuff). Now HF reacts with SiO2 so even partially fluorinated compounds will be gradually eroded. Lead or platinum are resistant. Now I'm sure a few folk won't be able to afford a platinum alembic, so for those of us in the cheap seats, we need lead. (most of the locals here seem to get theirs off nearby rooves!) As described, beat or melt it into shape. It's really malleable, and you can cut lead sheet with tin snips or even strong scissors. I'd fold the edges together twice over to provide a stronger join. What you'd want is a base plate with a lip around the edge for the top half of your apparatus to sit on. The top half of the apparatus is essentially a big lid which sits in the lip. The idea is to have a sort of moat with a dry area in the middle. The moat is filled with sulphuric acid (I'm suddenly getting interesting ideas of toy soldiers) and the lid sits in it to make an air tight seal, and the HF won't react with H2SO4. (although the lead will, so freshen it each time you do the experiment. A lead pipe leads into a container of water to make a saturated HF solution.

This being an old book, before the days of fluorinated plastics and teflon, they also use gutta percha for piping and containers to hold the saturated acid solution. This is a naturally occuring plastic. Obviously Fluor spar works too, but if you fancy getting enough to carve into usable apparatus, best hope your chisel doesn't slip.

So, that's the apparatus, but what goes inside? The fluorine compound back then was fluor spar (also known as fluorospar). This stuff's everywhere as the following attests:

"Fluor-spar is a mineral of very wide distribution. Some of the finest crystals occur in the lead-veins of the Carboniferous Limestone series in the north of England, especially at Weardalè, Allendale and Alston Moor. It is also found in the lead and copper-mines of Cornwall and S. Devon, notably near L-iskeard, where fine crystals have been found, with faces of the six-faced octahedron replacing the corners of the cube. In Cornwall fluorspar is known to the miners as “cann.” Fine yellow fluor-spar occurs in some of the Saxon mines, and beautiful rose-red octahedra are found in the Alps, near GOschenen. Many localities in the United States yield fluor-spar, and it is worked commercially in a few places, notably at Rosiclare in southern Illinois."
-http://89.1911encyclopedia.org/F/FL/FLUOR_SPAR.htm

So that's UK and US guys happy. If you can't find a spot where you can walk by and pick it off the floor, most rock and mineral shops sell it. It's cheaper to get an uglier rock than a polished stone though.

Now the easy part, take a dish and boil up fluor spar in Sulphuric acid. Set it going somewhere you aren't and with a bit of glass suspended above it. When it's done, you'll come back and find that the glass polish is gone and it's pitted. (unless you've done too much, and your glass is gone!) Try painting wax on the surface and you can make your own frosted glass patterns.
Boil this mix of H2SO4 and fluor spar in your alembic on a low heat sand bath and make HF solution. Crude, but it works.

If, for some reason you need to break down glass, NaOH works also, as does KOH. One method describes boiling Sodium hydroxide in a glass bowl with ground glass. The ground glass is reacted before the container, although that is still attacked. Words of warning for those who keep their caustic soda in glass containers. It will probably survive, but you may contaminate your alkali with Na2SiO2. Reminds me of the other day I kept some 1 molar NaOH on an old pop bottle. Some must have precipitated in a clump at the bottom then re-dissolved. The heat melted the plastic and NaOH solution started leaking all over the place. Irritating stuff in every sense.

I'm eventually planning on making HF, as its action on glass is an intermediate for making silicon.

Now, health issues. Latest news is that Calcium gluconate is not used, and even if it was, it seems to be getting the same press as cardiac defibrilators. Both are treated as a panacea by the uninformed, but they only work in about 10% of cases. First thing to do with a burn is to irrigate with water for five minutes. (or do what that guy did, and jump in the pool) Then gently rub in the calcium gel. if' you're stuck by yourself, you'll probably be too busy screaming in pain unless it's a minor burn, so make sure you've got someone who can give you first aid. They'll be the ones saving your life, so explain things carefully in advance. Fluorine and HF are unforgiving at best. if something has gone wrong with homemade equipment, most times a pot of calcium chloride gel on the workbench won't be much help.

Now, even though it's more toxic if it gets in your bloodstream (calcium gluconate can be given in an IV) what is now recommended in the emergency rooms is use of a lab staple, Calcium chloride, as it's got much more calcium by weight. If you don't have some, you can get it as a room dehydrator refill, and purify it. It's pretty pure (over 99%) to start with, but it's likely to get into your bloodstream, so get rid of anything that's not CaCl2. Mix it with KY jelly (which is water soluble) to make the calcium gel.

Some emergency doctors recommend drinking 1-5% CaCl2 solution as it binds the fluorine, but in a pinch, and you can bet you'll be in a pinch here, any calcium rich compound or antacid will do. Milk, calcium carbonate solution, or milk of magnesia are good substitutes. You can make HF without having this stuff ready, but it's no problem to have around.
In the extreme cases, like you just dunked your hand in a saturated HF solution, I'd seriously considering hacking off the hand before that fluorine gets into you bloodstream. I've not seen the effect with very high doses, but I'd rather lose the hand than risk my life that much.

Emergency treatment of HF acid burns:
http://www.emedicine.com/emerg/topic181.htm

Finally, Fluorine and HF victims:

Humphrey Davy of England: poisoned, recovered.
George and Thomas Knox of Ireland: both poisoned, one bedridden 3 years, recovered.
P. Louyet of Belgium: poisoned, died.
Jerome Nickels of Nancy, France: poisoned, died.
George Gore of England: fluorine / hydrogen explosion, narrowly escaped injury.
Henri Moissan of France: poisoned several times, success, but shortened lifespan.

Humphrey Davy is one smart son of a bitch. If it can get him, I for one am taking extreme care when I get around to making it.

Lots more Fluorine info here:

http://www.lateralscience.co.uk/Fluorine/Fluorine.html

[pyromaniac_guy]

Originally posted by nbk2000
*snip*
An HF solution of under 60% won't cause any immediate burning sensation on contact with the skin, but when over 30% concentration, it will be absorbed through the skin where it will bind with the calcium in the body, causing heart attack and bone disintegration.

So just make it about 40-50% and proceed to spray your victim down with a supersoaker full of the stuff. Also, as far as I know, it's not immediately corrosive to rubber, which may open up water ballons as a weapon.

i have never worked with HF, but I KNOW that flourine gas certainly has a destinctive smell in even minute quantities... does 50% HF not ahve any distinctive smell to it? In other words, just because your victem's skin isnt immedialty melting off, would they not be suspicious of getting hozed with the funky smelling water?

[Anthony]

I've not noticed any smell when working with 48% HF, it was in a fume cupboard and I wasn't getting too close, but under the same circumstances you do notice smelly chems (ammonium hydroxide, acetic acid etc).

[simply RED]

You can make an effective HF granade.
The key is NH4F. Ammonium fluoride.

http://physchem.ox.ac.uk/MSDS/AM/ammonium_fluoride.html

Ammonium fluoride burns with strong nonmetal conatining oxidizers to give HF.

5NH4F + 3NH4ClO4 = 5HF + 4N2 + 3HCl + 12H2O

It gives off a good cocktail of HF and HCl. For good burning - add charcoal powder.

[MrSamosa]

If I recall correctly from Material Safety Data Sheets, HF has an Acrid odor... I have never smelled it, though. I have a bottle of 2-3 % HF from rust remover, and I have never even opened it. However, I have smelled Ammonium Bifluoride solution. It is not a very strong odor, like Ammonia or Chlorine or such, but it is noticeable- kind of like a "light" Ammonia smell, but non-stingy. If some of it were spilled, you should be able to smell it (Unless you are in a fume hood, because as I said, it's not a very strong odor).

Hmm, never thought about burning NH4F, but this will be something I have to try now. Something new to play around with. A HCl/HF combination would be best though, if you are considering it solely on a basis of cost. Sadly though, I have no Chlorates or non-metal containing oxidizers (my Oxidizers are Sodium/Calcium Hypochlorite and Potassium Permangante only :( ).

[Anthony]

BTW, 40% HF will dissolve its way through a pyrex flask easily overnight.

You'd think that someone with a degree in chemical engineering (not me!) would have realised that...

[teshilo]

Maybe used Pyrex coating inside PTFE (teflon) tape.HF non eat it,and PTFE resistance high temperature.

[pyromaniac_guy]

Originally posted by teshilo
Maybe used Pyrex coating inside PTFE (teflon) tape.HF non eat it,and PTFE resistance high temperature.

how do you propose to coat the inside of a flask with ptfe tape? i would think it would be much easier to just use ptfe labware

[teshilo]

Why flask,pyrex tube very avaiable and coat inside tube PTFE very simple.

[Chade]

I'd have thought it'd be a bit of a nightmare trying to cover the whole interior surface of a flask with that tape. It's never that good at sticking to itself, and it will hardly stick to glass at all. Add to that the fact that you only need the tinyest gap for the acid to leak through and attack the glass, and when you pour the acid in, it'll just swirl the tape around in there and it'll hardly contact the flask walls at all.
I guess you'd be coating the neck of the flask as well as the stopper given that the fumes are also corrosive and pure HF has a boiling point around 20 degrees C, which would make it almost impossible, and you'd have to get the rest of the tape through that gap to apply it to the inside. The whole exercise sounds more difficult than making a ship in a bottle.

Maybe you were thinking of a wide necked jar, or something, with some other sort of PTFE tape. Maybe the type you use has an adhesive backing? Well, not that I've ever seen anything like that, it wouldn't work anyway, as the acid would seep under and destroy the adhesive coating. Rather like trying to use sellotape on something that's going to go underwater.

Perhaps there's some theoretical way to get this to work, but i dont think it's remotely feasible, and a bit daft when other HF resistant materials are easily acquired (flourinated glass, plastics, lead)

I happened across this story while looking up HF stuff:

Years back, one of our operators where I worked (not the current company) got
HF contact. Since it was late on a Friday, she didn't want to spend her own
time getting treatment, so she waited until Monday so she could get treatment
on company time. I gather she paid dearly for her weekend--IIRC, she returned
to work, with a much greater respect for HF burns.

What kind of idiot gets HF burns then waits two days for treatment? I hear that dilute solutions are not even noticable on your skin until about 12 hours later, then the deep tissue damage hurts like nothing on earth.
Interesting fact, HF isn't tecnically a strong acid, but a weak one. Doesn't seem to make it any less dangerous.

Some info on getting calicum gluconate. Very useful stuff for this kind of work.
http://www.biotech.ufl.edu/EM/data/hydroflouricacid.html
You can make it from NaOH and HF, or
Glucose (aq) + Cu2+ +NaOH -> Sodium Gluconate + Cu2O(red) (not balanced)

I have to confess, I don't know the chemical formula for gluconates, so I can't see if these methods look feasible.

[Nevermore]

Today i met a worker that described me his adventure with HF.
He was working at Montedison (a famous italian company) with 40% HF, when he had a accident:
he broke his protective gloves (probably eat up by HF) and touched the acid with his middle fingertip of the right hand.
He didn't notice the contact until 2-3 minutes later when felt a burning stinging pain, then he realised what happened, and washed his hands..
unfortunately the HF was already making his way to the bone, the man told me in around 4 hours his finger tip became progressively gray white, then the nail started to discolour too and the finger started to swell, at this point he started to feel a bumping pain.
After the supervisor saw what happened he sent him promptly to the hospital with a paper describing what happened, at the hospital his fingertip was quite swollen and very white, they promptly made 4 injection on the fingertip, applied a cream, then made a big injection on the shoulder.
On the next day the finger was not swollen anymore, he told me took around 3 months to regain the sensitivity, and almost the same time till the burning was completely repaired, he lost the nail but it grow back after some months.
He suffered of pain on the fingertip for a couple of years after the accident, but at now, 20 years later, he doesn't feel anything particular..
Note that i didn't ask him about that, we were just chatting about Hg melting gold, then switched to H2SO4 and HNO3 melting gold, then i said that Hf is the most dangerous..and he told me everything..