Picric acid question

[F1reman]

I was wondering if you could use Sodium bisulphate instead of Sulphuric acid in the synthesis of picric acid. In one chemistry book I have, it says you can use NaHSO4 instead of H2SO4 in reactions.

[nbk2000]

I find it highly doubtful.

[c.Tech]

That’s because sodium bisulfate (easily brought in pool shops) breaks down to sulfuric acid and sodium sulfate.

In some situations this happens such as in ethanol, I've tried with no success, maybe heat would work?

As the synthesis of picric acid uses 98% sulphuric acid, it may be hard to get that concentration from your sodium bisulfate. But the real question would 98% be needed?

Does anybody know how to break down sodium bisulfate to sodium sulfate and sulfuric acid easily?

[akinrog]

Does anybody know how to break down sodium bisulfate to sodium sulfate and sulfuric acid easily?

When you heat sodium bisulfate it first gives off water then SO3, which can be collected and used to make oleum. HTH.

[c.Tech]

I did some more research into the preparation of sulfuric acid and found the following information.

If you were going to make sulfuric acid with heat you need sulfuric acid, which defeats the purpose of trying to make it in the first place.

http://www.sciencemadness.org/member_publications/SO3_and_oleum.pdf
EDIT: This process uses sodium persulfate, but as the sodium persulfate is turned into sodium pyrosulfate, sodium bisulfate can be substituted for it does the same.

http://en.wikipedia.org/wiki/Sodium_bisulfate
Solutions of sodium bisulfate are acid, with a 1M solution having pH of 1.4. In some applications, such solutions can be used instead of sulfuric acid solution. For example, from a solution of sodium bisulfate and sodium acetate it is possible to distill acetic acid. Sodium bisulfate solutions will also liberate CO2 from most carbonates.

The anhydrous form is hygroscopic. Its melting point is poorly defined because it begins to decompose into sodium pyrosulfate and water before it reaches its melting points.

Sodium bisulfate behaves, to some degree, as if it were a complex of sodium sulfate with sulfuric acid. This is evident if either the anhydrous form or the monohydrate come in contact with ethanol, which causes them to separate into those two components. [1]

I'm going to try the ethanol synthesis again, would the acid separate from the ethanol leaving 2 distinct layers?

EDIT: I just tested the ethanol process to sulfuric acid. There were no visible layers present.

First I added some sodium bisulfate to ethanol (95%) and stirred. I then added a piece of aluminium from an old beer can, nothing changed no hydrogen forming or corrosion of the Al.

When I added water and stirred lots of tiny bubbles formed, could it have been the acid dehydrating the ethanol to ethene? As if stirred more these bubbles disappeared and over half of the substance dissolved.

At this point the Al was out, I added a small piece of magnesium that reacted forming bubbles that I’m assuming are hydrogen.

I then thought that the aluminium didn’t react because the can could be different from pure aluminium.

I sawed a tiny bit off a piece of aluminium I have that seems to be more pure and dropped it in. No instant effect but it is sitting outside and I will check it shortly.

[F1reman]

Thanks akinrog, I will try make some oleum the way you suggested.

[akinrog]

When I added water and stirred lots of tiny bubbles formed, could it have been the acid dehydrating the ethanol to ethene?

Even with sulfuric acid, it takes too much heat to convert ethanol to ethene (ethylene). So I don't think it's an option.

I saw that setup (i.e. SO3 from Bisulfate) on the Rhodium's site when it was online. However, the site stated that Potassium bisulfate is better for such a job.

In ancient times, people were using Iron Sulfate to make SO3 from Sulfuric acid. When Iron (III) Sulfate is heated it decomposes into Iron (II) sulfate, releasing SO3, which can be adsorbed into sulfuric acid, to make it more concentrated. For that reason it was called Oil of Vitriol before the modern times. HTH

[c.Tech]

Now from the past ethanol and bisulfate experiment the white bisulfate has disappeared and formed fine clear crystals, I’m assuming it's sodium sulfate.

The aluminium did nothing.


I saw that setup (i.e. SO3 from Bisulfate) on the Rhodium's site when it was online.
A while ago I uploaded rhodium’s drug chemistry archive to Rapidshare, take a look if you can find it in my copy.

http://rapidshare.de/files/31798088/Rhodium_s_Drug_Chemistry_Archive.zip


In ancient times, people were using Iron Sulfate to make SO3 from Sulfuric acid. When Iron (III) Sulfate is heated it decomposes into Iron (II) sulfate
Anhydrous copper sulfate can also be used. More on sulfuric acid and SO3 synthesis can be found in this thread (http://www.roguesci.org/theforum/chemistry-related/793-sulphuric-acid-synthesis.html), or here. (http://species8472.dyndns.org/so3/so3.html)

EDIT: If a small amount of alcohol (enough to cover) was added to sodium bisulfate and covered, over time it would decompose to sulfuric acid and sodium sulfate. The later could be filtered out and the sulfuric acid/alcohol gently heated to drive off all the alcohol.

This would probably work, right? Because the sodium sulfate would gradually come in contact with the ethanol and decompose, the process would be slow but inevitable.

I will try this on the weekend.