vmelkon
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concentrate H2SO4 by making isopropanol
Hello,
This is just a thought. From what I read about making isopropanol (2-propanol), they bubble propylene in some sulfuric acid. The H+ attack the double
bond and stays attached to the alpha carbon. Then a positive charge remains on the beta carbon (the second carbon in propylene). Water attaches to
this second carbon and the charge carries over to one of the hydrogens of the water and the H+ detaches itself.
The net equation is between the propylene and water. The sulfuric acid is just a catalyst.
Now, heat the solution and the isopropanol distills off.
You will now be left with a more concentrated sulfuric acid solution.
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kristofvagyok
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Quote: Originally posted by vmelkon  | | they bubble propylene in some sulfuric acid. The H+ attack the double bond and stays attached to the alpha carbon. |
-they compress the proplyene and place it in a high pressure reactor filled with a solid acidic catalyst where it reacts with the water.
If the propylene is simply bubbled through an acidic solution... Nothing will happen or just traces of the alcohol will form.
Also the H2SO4 couldn't be dehydrated after a point with azeotropic distillation of isopropanol and water, the H2SO4 needs the water much more than
the propanol(:
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bbartlog
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I would expect the reaction to proceed at a reasonable rate (unlike kristof), but I don't see what you gain by it. You can already drive off the water
from dilute H2SO4 by heating it. Gassing it with propylene in order to do the same thing at slightly lower BP is a waste of time. And if you are
thinking that you can somehow break the water/H2SO4 azeotrope by this means (i.e. concentrate H2SO4 past 98%) I think that it won't work well. The
equilibrium is way too far towards propylene at that point and I expect that oxidation of the propylene/isopropanol would be a competing reaction.
The less you bet, the more you lose when you win.
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vmelkon
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It isn't a practical approach if it requires high pressure, but it was just an idea. All I know is that it is a chemical reaction that consumes water
and elimination of the product (isopropanol) would be easy by distillation.
Yes, unfortunately, such reactions tends to reach a certain equilibrium.
Anyone know what concentration of H2SO4 they use in industry?
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AndersHoveland
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I suppose it could potentially concentrate sulfuric acid up to a certain point, but eventually at some concentration the reaction would go backwards.
The reaction of concentrated sulfuric acid and isopropanol actually produces propylene.
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