FrozenFiremint
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Chlorosulfuric acid preparation
Hello everybody,
btw., this is my first topic in this forum and I'm really excited about this, because I've always been the 'silent reader' in this forum. Finally
created an account  Please excuse any form of bad grammar and/or spelling, since
this is not my native language.
So yesterday I tried the preparation of chlorosulfuric acid ClSO3H by adding thionyl chloride (136 mL, 1.876 Mol, 1.64 g/ml, 99%) to sulfuric acid
(100 mL, 1.867 Mol, 1.84 g/mL, 96-98%, technical grade) in a 1:1 molar ratio. It didn't react very exothermic, maybe +5 K, but I assumed this was
because of the leftover water in the sulfuric acid. It did evolve SO2 and HCl, but very slowly and temperature dependant. Trying to avoid the
formation of SO2Cl2 by not exceeding the equimolar ratio. After 1 1/2 h reaction time at RT I eventually obtained a clear liquid, which did fume in
moist air and reacted more vigorously in water than SOCl2 or H2SO4 alone.
So the question is - since I couldn't find any reference for this reaction to work - has anybody tried it oder could bring arguments why this should
or shouldn't work?
Thanks in advance,
FrozenFiremint
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Magpie
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Hello and welcome to the forum.
I have made chlorosulfonic acid (aka chlorosulfuric acid) using SO3 and HCl, documented elsewhere on this forum.
Your precursors are H2SO4 and SOCl2. So, speculating:
H2SO4 + SOCl2 ---> ClSO3H + HCl
This does seem a little strange, and I could not find a reference for this either although I did not search very hard for one.
Why don't you distill your product, carefully noting the boiling point. If you get the right boiling point(151-152°C) that would be a very strong
indication that you have chlorosulfonic acid.
The single most important condition for a successful synthesis is good mixing - Nicodem
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FrozenFiremint
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Hello Magpie,
thank you for your detailed answer. Determination with the boiling pount seems like a good idea Well I tried to avoid the 'classic' route via dry HCl and SO3, because you've got to have really dry HCl and SO3 isn't
the most easy compound to handle either...so I thought workung with these two substances in the liquid state makes it more suitable for maybe hobby
chemists. Like a 'proof of concept' If some time's left at the end of the
labday, I'll do some IR and compare the spektrum to commercially available chlorosulfuric acid. Would be much more convenient if this reaction does
actually work!
FrozenFiremint
[Edited on 12-4-2017 by FrozenFiremint]
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Aqua-regia
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Hi Frozen
I cooked a couple years before over one liter of this. I Boiled homemade POCl3 with 96% H2SO4. The yield was almost theoretically. (except the water
of H2So4 consumed POCL3) The procedure also OK with PCl5, SOCl2, SO2Cl2 too. (I tested those just in microscale, no registered the yields)
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