Anhydrous HCl in IPA preparation idea

[Bandil]

Inspired by

Post 510698

(Novice: "Try this.", Methods Discourse), I thought of the idea of making anhydrous HCl in IPA using, the following scheme.

Make a suspension of eqimolar amounts of NaCl and CaO in IPA, and drip in equimolar amounts of conc. sulfuric acid. Wouldn't this release HCl in situ into the IPA over time, leaving Ca(OH)₂ and NaHSO₄ as a sludge to be filtered off?

Any ideas, comments?

Thanks, regards
Bandil

[starlight]

Hmmm.

Although the solubility of calcium hydroxide in alcohol is low, won't the HCl react with the Ca(OH)2 forming CaCl2 which will then react with the IPA?

[Pimpo]

Starlight might be right. Furthermore I wonder if not finally Ca 2+ would react with SO4 2- to form highly insoluble gypsum. Compare the caustification of soda solutions with Ca(OH)2 which leads to the stronger base NaOH being formed. NaHSO4 might react similar to Na2CO3. NaOH would definately kill the HCl. Of course things in IPA solution might be a lot different from aqueous solution. Just guessing. Why not try the thing on a test tube scale?

[Nicodem]

Bandil, could you explain what is the purpouse of CaO in your propousal?
Obviously, a sulphuric acid solution in IPA reacts with CaO to yield CaSO4×H2O. It might be worth trying without it and it might just work. H2SO4 is about ten thousants time stronger acid than HCl so it is quite possible that it would drive the HCl in the IPA solution and leave only the NaHSO4 solid. The NaCl should bee finely grinded and in excess to H2SO4 in order to consume as much of it or it as possible. Otherwise it would leave you with too much H2SO4 in the HCl/IPA after decantation.

[Novice]

This sounds like a great idea. For me, HCl in ether is of more use, and I wonder if this method could be applied on ether instad of IPA. As I see it, ether should work even better, as most inorganic salts are insoluble in it.

I don't know anything about the solubility of sulphuric acid in ether, however I assume it's not too great, but I don't see why this would be a problem.

[Bandil]

Well the problem with simply mixing sulfuric acid and NaCl in IPA, is that a mole of water is formed for each mole of HCl generated. This water has to be removed somehow. Don't know if the formed NaHSO₄ will soak it up sufficiently?

Otherwise, an alternative approach would be to do the reaction above, and dry the IPA over a proper amount of 3A molecular sieves.

Say for 1 L of 5N IPA, the following would be required:

1 L IPA
5 moles NaCl
5 moles H₂SO₄

Let it react, and decant the IPA, rinsing the sludge with a little more fresh IPA, to get a total volume of 1 L.

5 moles of water should be present here. This would require(assuming 20% wt% capacity of the sieves):

18g/mole * 5mole = 90 / 0.2 = 450 g's sieves (500 g's to be sure).

Sure is a lot of sieves to use, but the can of course be reused over and over to generate unlimited supplies of cheap dry HCl / IPA...

Comments?

Regards
Bandil

[Novice]

Bandil, no water is formed in this reaction, so there's no need to dry it - which makes it even more simple :-)

H₂SO₄ + NaCl -> NaHSO₄ + HCl

[Bandil]

As the subject line says - sorry about that...

Hmmm... sounds like its worth a try  

Regards
Bandil

[Barium]

How about using calcium chloride instead?

CaCl₂ + H₂SO₄ --> CaSO₄(s) + 2HCl

[Antoncho]

Filtering's gonna bee a bitch.

OTOH, NaCl is too poorly soluble in IPA to provide for a complete conversion of H2SO4. IMO.

Yet another objection - NaHSO4 is much more alcohol-soluble, and it will also act as an excellent acid in terms of amines' acidification, won't it?

Maybee, better use straight NaHSO4 in IPA?


P.S. After all this using CaCl2 beegins to seem like the best option

[Bond_DoubleBond]

cacl2 doesn't work with alcohols

[hest]

If I was old and grumpy I would say that the usual way by just gassing is much more easy  

[Bandil]

Bond_DoubleBond>

Found the

chart

(https://www.thevespiary.org/rhodium/Rhodium/chemistry/equipment/dryingagent.html) on rhodium's side, that states that they are not compatible. But isn't this simply if they contain amines, which will be complexed?

Besides that the CaCl₂, will be converted to CaSO₄ the instant the sulfuric acid is added.

On the other hand, one could premix the acid and alcohol, and then add the finely powdered CaCl₂ carefully, to ensure complete conversion.

Hest> Gassing is cool in a real lab with fumehood etc. Gassing is not fun when confined to less fancy locations    So there: You are and old grumpy gassing man  

Enjoy

Regards
Bandil

[Rhodium]

Calcium chloride forms "alcohols of crystallization" just like it forms hydrates. Anything with a lone pair will complex with Ca²⁺

[Bandil]

Rhodium>
Does this mean that the Calcium salts will be soluble in alcohol (IPA in this case)? Or will it simply imply that some of the alcohol will be trapped in the CaSO₄? In that case a little extra IPA should take care of the problem.

So, what salt would you suggest dr. chief? And please don't suggest gassing, as its the whole point to avoid this  

There has to be an easy easy way of getting HCl / IPA without "Camp Auswitch" with your own health  

Regards
Bandil

[Rhodium]

Does this mean that the Calcium salts will be soluble in alcohol (IPA in this case)? Or will it simply imply that some of the alcohol will be trapped in the CaSO4?

Mainly the latter, but a slight solubility of some calcium isopropylate chlorides cannot be ruled out.

What you need is a desiccant which is neutral or acidic and which does not react with or dissolve in alcohols. I don't know if anything besides molecular sieves would fit that description.

[xxxxx]

i would like to suggest the following procedure. take a 500 ml jar of 34% hcl and a 500 ml jar of ipa and place them together in a 4000 ml jar with a lid. after a day or two the hcl vapor should go into the ipa.

[Rhodium]

Most definitely not. Water has a considerable higher affinity for hydrogen chloride than any alcohol has.

[Barium]

One very convinient way of preparing alcoholic solutions of HCl is to add e.g. acetyl chloride to IPA. This gives of course a mixture of IPA and isopropyl acetate if excess IPA is used, but the ester will not interfere with the formation of most hydrochlorides. In most cases it will even aid the crystallisation.

[hest]

Why not use ether ? mixing dry ether (or THF) with HCl(aq) and then dry out the wather ?. I'v done it with H2O2 and it works fine. Actual ill give it a try now.

[hest]

100mL THF and 50mL HCl was mixed (exoterm) for 1 min, then 50-70g MgSO4 was added (more exoterm), and the mixture filtered.
Titration of the THF indikated an 2.4M HCl in THF solution.
Iff you don't have a fumehood cool with ice :-)
Ill give ether a shot later on.

[Bandil]

Kisses for you Hest  

Seems like a very easy procedure. Do you know how much HCl ether can hold?

Regards
Bandil

[hest]

When I gass ether I'll usual end up with an 5-6M so Iguess that's the limit.

[hest]

100mL diethylether was stirred with 50mL 12MHCl (exoterm) for 1 min, the ether was seprated from the HCl(aq), dryed with Mgso4. The MgSO4 was filtereed off and 10 mL of the ether was mixed with wather and titrated. yeald was an 0,22M HCl in ether solution.
Guess this could bee repeated to increase the ether-consentration (cooling and longer reacton-time might help too)

[Nicodem]

Adding some anhydrous CaCl2 into the HCl(aq)/Ether mixture would force much more HCl into the ether phase. Considerably more as the water phase would get way oversaturated with HCl. Don't exagerate on the amount of CaCl2 though, or you will gas the whole lab with HCl fumes. Just a sugestion to improve the otherwise nice and practical idea.

[hest]

The ether from the post above was treated with 12M HCl for 12H, seperated, dryet and titrated, still 0.22M.
So if we have 15g(71mmol) mescaline disolved into 100mL ether we have to add 322mL 0,22M hcl in ether to make the hydrochloride. Thats not good enough.