Alternative way of making anhydr. IPA/HCl

[Bandil]

Hi!

I'd really like some 5-6 N hydrochloride in 2-propanol(or other suitable solvent), and gassing is no fun. I was thinking if it would be possible to simply mix 35% hydrochloric acid with IPA untill, say 50% above, 5-6 N is reached. After than one could dry the IPA with anhydr. sodium sulfate or molecular sieves. Is this possible, or will all of the hydrogenchloride be sucked up as well, rendering the IPA nearly netral?

Regards
Bandil

[Rhodium]

will all of the hydrogenchloride be sucked up as well

I believe much of it will be adsorbed to the drying agent. Gassing is probably the best way to do it.

[Bandil]

Rhodium>

If you look

here

(https://www.thevespiary.org/rhodium/Rhodium/chemistry/equipment/calcium.hcl.generator.html), they are preparing gasseous HCl by almost the same method. They dehydrate the hydrogenchloric acid with calciumchloride, thus liberating the free HCl in it's gas form.

Isn't the method i mentioned actually just an in-situ version of that method? The HCl gas is released, but redissolved immediately in the IPA? If we calculate, that we'll get a 40% yield as they report, dissolved in the IPA; what what would in theory differ from doing it in-situ?

Regards
Bandil

[Rhodium]

In the text they use 1:1 CaCl2/35%HCl which is a lot of drying agent, and CaCl2 binds water more strongly than for example Na2SO4. The resulting mush will also be far from "anhydrous", as the CaCl2 only binds enough water to prevent the solution from dissolving as much HCl as it did before. Also, you cannot use CaCl2/35%HCl in IPA as that will produce 2-chloropropane.

To make anhydrous HCl you also need to bubble it through H2SO4 or something after it exits the generator, as it will still carry over water vapor.

[Bandil]

Thanks Rhodium, i see you'r point!

I suppose, there's no way out of just gassing. *sigh*

While we are at the subject; do you(or anyone else), know what the maxiumum obtainable concentration in IPA or ether is?

Regards
Bandil

[hest]

I's around 5M. Personal I drip HCl(aq) into 96% Sulfuric accid wit a press.equ. adding funel. The the gas escape throug the top (and my stopper) throug a washbottle and over in my cold stirred ether. I them dry the ether with MgSO4. Stabel for years.

[abuse]

Rhodium

  The gassing technique using CaCl₂/35%HCL may not work in IPA, but it works in Xylene/Toluene, right? Also, the ratio of CaCl2 to HCL is 1:1 by weight or volume?

[Rhodium]

abuse: No, it will not work to dump CaCl2/HCl directly into toluene, as it will not be anhydrous anyway. The ratio is by weight, read the *entire* document linked by bandil above.

Hest: What kind of losses are you experiencing by drying the ether over MgSO4 (instead of drying the gas in-line), and how do you determine the strength of the solution?

[abuse]

Rhode
Actually, what I meant was to use the HCL gas liberated from reacting CaCl₂ with %35HCL. There was a post regarding this technique and how is was superior to the H₂SO₄ method, but what do I know...

[hest]

What kind of losses are you experiencing by drying the ether over MgSO4 (instead of drying the gas in-line)[ I find it easyer than drying the gas line, that's all, usual the etherr will contain some % wather.

For the strength part i mix 10mL ether with 100mL wather, stirr well and titrate the mixture with 1M NaOH and phenolphtaline.