Mabus
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Help separating HCl from n-butanol
I found at a hardware store a paint drying accelerator, with the label indicating the following:
-n-butanol
-7%HCl
Unfortunately I can't find any data about the properties or stability of the n-BuOH-HCl mixture. Since n-butanol has a slightly higher boiling point
than water (117.7 °C) would the two-container technique be enough to remove the HCl from the mixture?
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HgDinis25
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Does that 7%HCl mean a 7%HCl solution in water, added to n-butanol? Or is the HCl actualy dissolved in the n-butanol?
Anyway, if you use the two container technique there will still be water in your butanol (if the HCl is in aquous solution). And you can't simply
distill the water because water and Butanol form an azeotrope. Perhaps it would be easier and faster just to neutralize it with NaOH (or another
neutralizing agent of your choice). You would end up with just water, butanol, and the chloride salt.
I don't know if you would see a salting out effect here or not. Butanol as limited solubility in water (7,3g per 100mL). The Sodium Chloride formed
would increase the ionic strenght of water, forcing the Butanol out. You should end up with two layers, one with the Sodium Chloride solution, the
other with the Butanol. Seperation would be quite easy.
Of course this is mostly speculation. Try it out on a test tube, in small quantities, and see if you get two layers.
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Mabus
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The label doesn't specify if it contains water or not (since is consumer product, I'll assume it does).
Well, I wanted to also recover the HCl, but if it's too complicated to do that, I might just neutralize it.
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HgDinis25
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I really don't understand the HCl content, though. It will acelerate the corrosion of metals, if you use it when painting metals. And if the purpose
is to accelerate drying, why containing water?
You could test for the presence of water using anhydrous Copper Sulfate...
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CuReUS
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if you use NaOH to neutralize the HCl,you would have to use a stoichiometric amount or you will end up with excess NaOH with the tert butanol
you could try freezing the tert-butanol/HCl mixture,I have read about products being separated from one another by freezing.
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dermolotov
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What I would do is 2 or 3 things:
1. Reflux with an efficient column. HCl doesn't reflux so that should drive off most of the vapours.
2. Add copious amounts of Sodium Carbonate until it doesn't JUST stop bubbling but until it stops clumping as well. This means it's neutralised AND
dehydrated.
3. Distil off the alcohol.
If you don't have a reflux setup, you can just forgo it and add copious amounts of sodium carbonate.
If you dont' have sodium carbonate, just bake sodium bicarbonate at 300deg for an hour or so. Until it stops steaming.
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dermolotov
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Quote: Originally posted by Mabus  | The label doesn't specify if it contains water or not (since is consumer product, I'll assume it does).
Well, I wanted to also recover the HCl, but if it's too complicated to do that, I might just neutralize it. |
1. Yupp. Virtually all consumer products contain water. It's too expensive and unecessary to dehydrate things like this.
2. It's too complicated collecting that stuff. 7% HCL is really not worth the hassle in the end...
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HgDinis25
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@CuReUS
It's not tert butanol, it's n-butanol. And I don't see the problem on having excess NaOH, after all he's after the butanol. Anyway, a simple ph
indicator would tell you when to stop.
@dermolotov
I was not refering to regular humidity mostly every product has. I was refering to the 7% HCl. I'm assuming it is a 7% HCl solution (93% water, 7%
HCl), so there is a lot more water in there than just regular humidity. Of course it could also mean that the HCl makes 7% of the product, perhaps
dissolved in the butanol. An anhydrous Copper Sulfate test would clear this out.
I agree with you, 7% HCl is just not worth it. Refluxing is not such a good idea though. If there's a lot of water in it you'll just keep refluxing
the azeotrope (~20% Hydrochloric Acid).
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dermolotov
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| Quote: Originally posted by HgDinis25 | @dermolotov
I was not refering to regular humidity mostly every product has. I was refering to the 7% HCl. I'm assuming it is a 7% HCl solution (93% water, 7%
HCl), so there is a lot more water in there than just regular humidity. Of course it could also mean that the HCl makes 7% of the product, perhaps
dissolved in the butanol. An anhydrous Copper Sulfate test would clear this out.
I agree with you, 7% HCl is just not worth it. Refluxing is not such a good idea though. If there's a lot of water in it you'll just keep refluxing
the azeotrope (~20% Hydrochloric Acid). |
7% seems very ambiguous. Best case scenario is to weigh out 100cc and see what it approximates. You can make a moderately certain guess with that
information.
IF it is 93% alcohol and 7% acid solution, I think you can just get it out the way I mentioned.
However, if it's something silly like 7% acid with 50:50 solvent, a neutralisation (or even basification) followed by a simple distillation should
take care of that?
I thought HCl does a 36% (12M) Azeotrope?
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HgDinis25
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@ dermolotov
The azeotrope of HCl with water boils at 110ºC and it's 20,24% HCl. If it is indeed 93% alcohol and 7% acid the way you mentioned is the best way to
procede. If it's not, the method I mentioned seems to be the way to go. I didn't understand what you said by "7% acid with 50:50 solvent". And, in
this case, the neutralization will be a basification.
Simple distillation won't cut it. Water and Butanol form an azeotrope. That's why I mentioned the salting out effect. Then, if needed, just drying the
solvent and distilling it would get reasonable pure Butanol.
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dermolotov
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Hmmmmm... Not sure where I got the 36% idea from. Would that be the highest stable percentage of HCl in water?
| Quote: Originally posted by HgDinis25 | | If it is indeed 93% alcohol and 7% acid the way you mentioned is the best way to procede. If it's not, the method I mentioned seems to be the way to
go. I didn't understand what you said by "7% acid with 50:50 solvent". And, in this case, the neutralization will be a basification.
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I guess this discussion is useless without OP seeing what the mixture is. I still go with weighing it.
HCl has a density of 1.1 where n-Butanol has a density of 0.8. Should be able to figure it out with a simple weighing of 100cc.
| Quote: Originally posted by HgDinis25 | | Simple distillation won't cut it. Water and Butanol form an azeotrope. That's why I mentioned the salting out effect. Then, if needed, just drying the
solvent and distilling it would get reasonable pure Butanol. |
The latter thing is what I would do. Was thinking of just dumping a lot of calcium chloride/magnesium sulphate into the already distilled azeotrope
and then re-distil.
Salting out is an interesting and perhaps more efficient method, though 
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Templar
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wash with sodium hydroxide soln.
He who fights with monsters should be careful lest he thereby become a monster. And if thou gaze long into an abyss, the abyss will also gaze into
thee.
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CuReUS
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| Quote: Originally posted by HgDinis25 | @CuReUS
It's not tert butanol, it's n-butanol. And I don't see the problem on having excess NaOH, after all he's after the butanol. Anyway, a simple ph
indicator would tell you when to stop.
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what I meant was that if excess NaOH is used,he would have a new problem of separating the n-butanol from the NaOH
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Pomzazed
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Add excess base cautiously (NaOH, CaO, or so on) and frac dist?
Unlike HCl they arent volatile thus not contaminate your pdt.
Don't stare at me making fumes... I'm just experimenting with some gas...
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Mabus
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@HgDinis25 The paint drying accelerator is for wood, more exactly parquet. So it's not meant for painting metals.
The solution is viscous and clear and it does smell like butanol, but I haven't sensed any acidic smell.
I added some bicarbonate to test for acid and there was little fizzling, I guess I can just go for neutralization, there's very little to worth the
effort.
To test for water, I added a few crystals of anhydrous copper sulfate (I heated CuSO4 crystals until they turned white). The solution turned
green-yellow:
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HgDinis25
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Interesting. The yellow may be the Copper complex with Chloride dissolved in water. Anyway, go ahead with the neutralization and see if you get the
salting out effect. With all the information in this topic you have enough for a successful experiment. Good Luck!
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blogfast25
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By far the easiest here is to carefully neutralise the HCl then fractionate that mixture. Then deal with the azeotrope (n-BuOH/H2O).
'Virgin' n-BuOH is cheap though...
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gsd
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I have some experience of dealing with n-Butanol (NBA) and Hydrochloric Acid (HCl) mixtures.
1) NBA + commercial HCl (i.e. 30% HCl in water) are miscible in all proportions, no phase separation occurs.
2) If you reflux the mixture you will get N-Butyl Chloride (NBC) - yes this reaction does occur without using ZnCl2 or any other catalyst.
The Over Head product separates into 2 phases top layer NBC + NBA and bottom layer NBA + Water (+ unreacted HCl)
Best way to remove 7% HCl is by alkali treatment - NaOH or Na2CO3 and then "Salt-out" the water by addition of excess NaCl.
gsd
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CuReUS
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copper chloride is greenish yellow in colour upon absorbtion of moisture,how is this related to complex formation ?
http://en.wikipedia.org/wiki/Copper%28II%29_chloride
[Edited on 2-1-2015 by CuReUS]
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