Blarglesworth
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Silver perchlorate incompatibilities
I recently obtained some AgClO4 at a very low price on eBay. I'm wondering what compounds it forms sensitive explosives with, so that I can avoid
them. I've never had an unintentional explosion before and would rather not start now.
I've looked up MSDS and other safety information but as usual it's pretty useless, not telling me which incompatibilities can maybe result in
explosions under unusual conditions and which will certainly precipitate something as sensitive as silver fulminate.
In particular, I'm wondering about its compatibility with ethanol. I'm hoping it's useful for detecting halide ions in EtOH without being as dangerous
as silver nitrate. I'm a lab tech at an ethanol distillery, and it would be nice to have something quick and dirty to back up the ICs when measuring
chloride levels.
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clearly_not_atara
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Silver trifluoroacetate, methanesulfonate, or lactate might be easier to work with.
Google does not show any incompatibilities between AgClO4 and EtOH, but if there are ethyl halides present you could accidentally make ethyl
perchlorate. Likewise the presence of acids should be avoided, particularly acids whose counterions precipitate with Ag+. Anhydrous perchloric acid in
ethanol is almost certainly a bad thing.
Silver fulminate will definitely not form because there is no nitrogen with which to form it.
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unionised
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Quote: Originally posted by clearly_not_atara  | Silver trifluoroacetate, methanesulfonate, or lactate might be easier to work with.
Google does not show any incompatibilities between AgClO4 and EtOH, but if there are ethyl halides present you could accidentally make ethyl
perchlorate. Likewise the presence of acids should be avoided, particularly acids whose counterions precipitate with Ag+. Anhydrous perchloric acid in
ethanol is almost certainly a bad thing.
Silver fulminate will definitely not form because there is no nitrogen with which to form it. |
"Silver trifluoroacetate, methanesulfonate, or lactate might be easier to work with. "
Yes, but those are not what he got on eBay, so they are utterly irrelevant.
"Google does not show any incompatibilities between AgClO4 and EtOH,"
Yes and no
There's no shortage of data suggesting that any fuel- like alcohol mixed with any strong oxidant- like perchlorate- is a potential problem.
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Blarglesworth
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| Quote: Originally posted by clearly_not_atara | Silver trifluoroacetate, methanesulfonate, or lactate might be easier to work with.
Google does not show any incompatibilities between AgClO4 and EtOH, but if there are ethyl halides present you could accidentally make ethyl
perchlorate. Likewise the presence of acids should be avoided, particularly acids whose counterions precipitate with Ag+. Anhydrous perchloric acid in
ethanol is almost certainly a bad thing.
Silver fulminate will definitely not form because there is no nitrogen with which to form it. |
Silver lactate - interesting idea. How would I make it? I have silver nitrate along with the perchlorate.
I've made the acetate from silver nitrate and an excess of sodium acetate, precipitating silver acetate by metathesis. The lactate seems considerably
more soluble in water, though - I found a site that says 77 g/L. Still considerably less than AgNO3, though, so it could work with some loss of
product.
I'd like to find something with at least a little bit of ethanol solubility for the halide detection. The acetate didn't appear soluble at all a
precipitate would form whenever it was introduced to EtOH whether there was a halide there or not. All I've found so far is "slightly soluble", but
nothing quantitative.
I know silver fulminate won't form for that reason, but some silver compounds and perchlorates both seem to have strong tendencies to blow up. I don't
think ethyl halides should be much of a concern, though, as long as I don't try refluxing the EtOH with HCl or something.
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chemister2015
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Bretherick’s Handbook (vol.1):
-----------------
1. Anon., Angew. Chem. (Nachr.), 1962, 10, 2
It melts without decomposition although the enthalpy of conversion to silver chloride
and oxygen appears to be about 0.5 kJ/g. An explosion while grinding the
salt (which had not been in contact with organic materials) has been reported [1].
A powerful oxidant.
Acetic acid MRH 2.80/22
Mellor, 1956, Vol. 2, Suppl.1, 616
The salt solvated with acetic acid is impact sensitive.
See Aromatic compounds, below
Alkynes, Mercury
Comyns, A. E. et al., J. Amer. Chem. Soc., 1957, 79, 4324
Concentrated solutions of the perchlorate in 2-pentyne or 3-hexyne (complexes are
formed) explode on contact with mercury.
See METAL ACETYLIDES
Aromatic compounds MRH Aniline 3.47/11, toluene 3.51/9
1. Sidgwick, 1950, 1234
2. Brinkley, S. R., J. Amer. Chem. Soc., 1940, 62, 3524
3. Peone, J. et al., Inorg. Synth., 1974, 15, 69
4. Stull, 1977, 22
Silver perchlorate forms solid complexes with aniline, pyridine, toluene, benzene
and many other aromatic hydrocarbons [1]. A sample of the benzene complex
exploded violently on crushing in a mortar. The ethanol complex also exploded
similarly, and unspecified perchlorates dissolved in organic solvents were observed
to explode [2]. Solutions of the perchlorate in benzene are said to be dangerously
explosive [3], but this may be in error for the solid benzene complex. The energy
released on decomposition of the benzene complex has been calculated as 3.4 kJ/g,
some 75% of that for TNT [4].
Carbon tetrachloride, Hydrochloric acid
491M, 1975, 368
Silver perchlorate and carbon tetrachloride in presence of a little hydrochloric acid
produce trichloromethyl perchlorate, which explodes at 40°C.
See Trichloromethyl perchlorate
1,2-Diaminoethane
491M, 1975, 368
Dropwise addition of the amine to the salt led to an explosion (possibly initiated
by heat liberated by complex formation).
Diethyl ether
1. Heim, F., Angew. Chem., 1957, 69, 274
After crystallisation from ether, the material exploded violently on crushing in a
mortar. It had been considered stable previously, since it melts without decomposition
[1].
Dimethyl sulfoxide
Ahrland, S. et al., Acta. Chem. Scand. A, 1974, 28, 825
The crystalline complex solvated with 2DMSO explodes with extreme violence if
rubbed or scratched.
See Dimethyl sulfoxide: Metal oxosalts
Ethanol MRH 3.30/13
See Aromatic compounds, above
Other reactants
Yoshida, 1980, 81
MRH values for 20 combinations with oxidisable materials are given.
1,4-Oxathiane
Barnes, J. C. et al., J. Chem. Soc. Pak., 1982, 4, 103–113
The perchlorate forms complexes with 2, 3 or 4 mols of oxathiane which explode
on heating.
Tetrachlorosilane, or Tetrabromosilane, or Titanium tetrachloride, and Diethyl ether
Schmeisser, M., Angew. Chem., 1955, 67, 499
Reaction gives explosive volatile organic perchlorates, probably ethyl perchlorate.
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Blarglesworth
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Thanks for digging up all of that info! It seems that AgClO4 plus basically any organic solvent leads to explosive complexes. That's disappointing but
not too surprising.
I have added a few drops of AgClO4 in aqueous solution (5.5 g/25 mL) to c. 20 mL of ethanol without incident, but I'm not going to try any more than
that. I definitely don't want the ethanol complex to precipitate out.
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woelen
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Please do not worry about explosions in your specific use-case. You add a single drop of indicator solution (which contains a little AgClO4) to your
alcohol to be tested. What concentration of silver(I) or perchlorate do you think you will get? 0.1%? 0.05% ?? Do you really think that such low
concentrations can lead to explosions?
And even if you evaporated all of it to dryness, how much solid residue would remain? 1 mg? 5 mg? And even if that amount exploded, what would happen?
You would hear a little pang, something like the pangs from a kid's toy gun. But I do not even expect these little pangs. The way you use it is safe,
no chance of explosion.
The risks, described above, are about syntheses, in which AgClO4 is used in combination with organics. In such syntheses, the amounts used are much
larger, and you may have much higher concentrations.
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Blarglesworth
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Oh sure, I'm not worried about anything particularly dangerous happening in that case, and I'm continuing to use it as such. I'm mostly worried about
people overreacting if I brought it into work, it formed an insoluble complex or got left out where it evaporated, the tube got bumped, and this
created a little bang around people who might freak out about such things. I want to continue being able to do little experiments without anyone
noticing or caring is all.
I also did want to see if I could safely use it for other purposes including as a reagent for synthesis at home, which I know now is not a good idea.
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woelen
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23-5-2019 at 11:43 |
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