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Author: Subject: How hazardous is fluorine chemistry?
dicyanin
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[*] posted on 20-2-2024 at 07:52


Quote: Originally posted by Sulaiman  
Quote: Originally posted by unionised  
Quote: Originally posted by clearly_not_atara  



I have considered the preparation of certain 2-fluoroethyl compounds with AgF.

There's a plant which makes 2 fluoroethyl compounds.
https://en.wikipedia.org/wiki/Dichapetalum_cymosum

"commonly known as gifblaar from Afrikaans, "
"gifblaar " means "poison leaf.

So this stuff- which is toxic enough for a plant to be named after it- is one of the less dangerous fluorine compounds...
Thanks, good to know,
Where can I get some?


Africa Seeds carries it, but it's really expensive for what is essentially a native weed, $35 for 8 seeds. Monofluoroacetate is toxic to humans, but other mammals are much more sensitive to it. Attached paper discusses its properties and the preparation of some derivatives.
They also prepare monofluoroacetic acid by refluxing methyl monoiodoacetate with silver fluoride at 170°C in a platinum apparatus:D, followed by saponification of the ester. Apparently when a platinum refluxing apparatus is not available, the authors note a lead one can be used.

gifblaar.png - 509kB

Attachment: MONOFLUOROACETIC ACID the toxic principle of Gifblaar (Dichapetalum cymosum) _marais1944_20_1.pdf (664kB)
This file has been downloaded 96 times




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[*] posted on 20-2-2024 at 11:52


After reading this thread, I'm in no hurry to do so, but if I wanted to extract fluorine compounds from gifblaar, does anyone know of a reasonably safe way to do it? I ask because here (southern Africa) I have an almost unlimited supply of that plant available.
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[*] posted on 20-2-2024 at 13:18


I found the previous paper published by the author of the one above. I wasn't able to access the full text, but fortunately the relevant portion was available:
Quote:
Extract 10 kg. dried and finely ground plant material with 96% EtOH for 36-48 hrs., distil the alc. under reduced pressure, dissolve the sirupy mass in 4 l. water, add 500 cc. 10% H2SO4 and let stand for 1-2 days to allow precipitated material to settle. Filter the solution by suction, extract the filtrate repeatedly with Et2O, neutralize the combined extracts to phenolphthalein with N KOH and sep. the aqueous solution which contains the K cymonate. Evaporate the solution to about 300 cc. on the water bath, liberate the free acid by adding the equivalent amount of dilute H2SO4, and repeatedly extract the solution with Et2O until practically all the acid is removed. Decolorize the Et2O extract with activated charcoal, dry overnight with anhydrous Na2SO4, filter and distil the Et2O at low temperature Transfer the concentrate to a small distillation flask, collect the distillate in fractions of 10° up to 160°, carefully neutralize (N KOH and phenolphthalein) the individual fractions, as well as the initial Et2O distillate, and evaporate the K salt solutions separately to dryness on a water bath. Wash the residues with acetone, dry at 100° and crystallize from 96% EtOH. The best yields of the K salt are obtained from the 110-160°, fractions. After repeated recrystallization from 96% alc. the salt melts at 213° with decomposition; insoluble in anhydrous organic solvents except MeOH.
J. S. C. Marais, Onderstepoort Journal of Veterinary Research, Volume 18, Pages 203-206, 1943

Apparently before they figured out it was monofluoroacetate, they called the mystery anion "cymonate."




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[*] posted on 21-2-2024 at 02:11


This is molten NH4F inside my DIY home fume hood.
And I am still alive. So, the answer: it depends ...

When I did planning to start playing with F I've selected boron trifluoride and BF4 anion as an entry level but still very interesting F compound.

qqq.jpg - 200kB
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ItalianChemist
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[*] posted on 21-2-2024 at 03:58


BF4 anion is very interesting in coordination chemistry since it forms many compounds that can be easily crystallized from water.
Also I don't think it is very dangerous unless it is heated. (It will release some amounts of HF I suppose)
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[*] posted on 21-2-2024 at 06:01


NH4BF4 is quite volatile. I kept it in an open container for drying and it covered inside walls of my cabinet.
I plan to use it for generate BF3 which have many interesting applications in inorganic as well as in organic chemistry. Also it's very potent drying agent.

[Edited on 21-2-2024 by teodor]
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EF2000
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[*] posted on 21-2-2024 at 06:44


Quote: Originally posted by Texium  
I found the previous paper published by the author of the one above. I wasn't able to access the full text, but fortunately the relevant portion was available:
J. S. C. Marais, Onderstepoort Journal of Veterinary Research, Volume 18, Pages 203-206, 1943

Apparently before they figured out it was monofluoroacetate, they called the mystery anion "cymonate."

Here's the paper, found it in open access on the University of Pretoria website: https://repository.up.ac.za/handle/2263/59331

Attachment: 19marais1943_18.pdf (279kB)
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mr_bovinejony
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[*] posted on 25-2-2024 at 06:12


Quote: Originally posted by teodor  
NH4BF4 is quite volatile. I kept it in an open container for drying and it covered inside walls of my cabinet.
I plan to use it for generate BF3 which have many interesting applications in inorganic as well as in organic chemistry. Also it's very potent drying agent.

[Edited on 21-2-2024 by teodor]


Sodium tetrafluoroborate can be used as well for this, does NH4BF4 work better? I'd like to make trifluoroacetic acid but I have found no other way than to use antimony fluoride compounds.
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[*] posted on 26-2-2024 at 07:50


Quote: Originally posted by dicyanin  


Africa Seeds carries it, but it's really expensive for what is essentially a native weed, $35 for 8 seeds.

Gastrolobium calycinum is ~5 AU dollars for packet from Australian Seed: https://www.australianseed.com/shop/item/gastrolobium-calyci...
Gastrolobium bilobum is 6.5 USD for 10 seeds from rarepalmseeds.com, even though it's not rare and not a palm. And $14 for 1,000 seeds, meaning that for the price of 8 giftblaar seeds one can get ~2,500 poison brush seeds and plant an entire garden with it. Very toxic garden.

I also found a little instruction how to pre-treat seeds and sow them.

Attachment: Gastrolobium species.pdf (339kB)
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[*] posted on 27-2-2024 at 08:20


Side note, he is some dude spraying cold fluorine gas onto a fire brick (time index 11:12)
https://youtu.be/KX-0Xw6kkrc?t=672




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[*] posted on 26-3-2024 at 11:14


I did work in a fluorochemical synthesis lab for a few years with my old friend Ed, who was much more jaded about working with fluorine than most people are today, having worked with it for 50+ years. But only long after working there did I realize how many things he had there were incredibly toxic, like cylinders of F2, HF, SF4, and many others, plus some other things like monofluoroacetic acid and related compounds. But he was somehow lucky, and I think the F2 just made him inert to all other chemicals, as he lived to be about 98.

But even Ed had Calcium Gluconate kits and other safety gear, plus some very large scrubbers which most of the gas streams went out through. Mostly I worked with Freons, which are quite safe to handle, but the process of fluorinating hydrocarbons is quite exciting, and involves some very specialized equipment.

I have also used anhydrous liquid HF for cleaving and deprotecting peptides, which is mostly not done any more now (mostly used for tBoc type peptide chemisty, which is rarer now). That was almost as crazy, but done in special hood with special equipment, and 2 thick gloves, special aprons, face mask, etc. That was just as nuts, and done in big pharma lab. I would not do it for fun or much else now. But I have done other fluorine type chemistry that is safer and many fluoro groups are fine, like many, but not all, -CF3 type reagents. So the safety is quite dependent on the exact type of chemistry, the equipment, and the real need to do it. Like making some fluorophosphates, minor changes can make drastic differences in toxicity.

So I would say that some fluorine chemistry is quite safe, some is dangerous, and some is nuts. Even Ed tried to use ClF3 a few times and decided that it was not able to be used safely for anything, depsite being a very powerful fluorinating agent.

[Edited on 26-3-2024 by Dr.Bob]
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[*] posted on 26-3-2024 at 14:23


Had a very nasty experience with SF4 at one point Dr.Bob, always interesting to see people mention it since it tends to fly under the radar of most chemistry.




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