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Author: Subject: Toluenesulfonic acid and Sulfonic acids in genera
markgollum
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[*] posted on 30-12-2004 at 19:51
Toluenesulfonic acid and Sulfonic acids in genera


Over the past couple of days I have been reading about sulfonic acids and have attempted to make toluenesulfonic acid.
While searching the forum, I realized that it dosent have a thread in which sulfonic acids are discussed in any detail so I thought to make one.

My attempt at toluenesulfonic acid was as follows:

(1) 180 mL of crappy (black) drain cleaner sulfuric acid, and 20mL of toluene were added to a 300mL erlinmeyer flask.

(2) A 40cm liebig condensor was attached to the flask, and two lines were drawn on the flask. One where the toluene floating on top met the acid below, the other where the meniscus (sp?) was.
Then, I refluxed the contents for approx 1hour. The phases finished mixing in the last 10 min (toluenesulfonic acid is soluble in H2SO4), during which I left the setup un-attended. When I came back, all the toluene had been used up and the flask was starting to smoke, I quickly cooled the flask by adding 3 ml of toluene to the top of the liebig so it would drip down to the flask, vapourise, condense in the liebig, and drip down again.
After the flask had cooled down, another 40mL of toluene was added and refluxing was resumed for another 45min, after which it was apparent that the toluene was no longer reacting (the volume of toluene stayed constant approx 37mL).(total volume of flask contents approx 240mL).

(3) I attempted to extract the sulfonic acid with DCM, but because my DCM had water and methanol in it the heat of hydration caused some of the DCM to violently boil.
And, to my surprise, the different phases mixed(I am fairly sure that DCM is not soluble in H2SO4). So, after only adding 10mL of DCM, I decided to try the extraction with toluene the next day.

(4) Next Day.

Flask contents were mixed with 50mL of toluene, stirred vigourously, then carefully decanted. This was repeated 12 times to give approx 600mL of slightly pink and cloudy solution.
This pink solution was distilled until only 50mL of black liquid was left in the flask (the temp of the toluene+something azotrope vapours was 106degC)(looks exactly like the drain opener :().
This 50mL of shit was put in a 100mL beaker
and boiled until only 20mL remained which was put in a 50mL beaker and boiled until 10mL of black crap remained. (I was hoping to get some crystal formation)

This experiment wasn't a complete failure, after all, the toluene I first refluxed disolved into the SA, an indication that the sulfonic acid had formed it was very disapointing.


I have searched the net and all I have found concerning the solubility of toluenesulfonic acid is that it is soluble in alcohol and water.
(I hoped it would be soluble in DCM and toluene)

How are sulfonic acids usually seperated from the sulfuric acid they are made in?.

Has anyone here sulfonated something, not using oleum?
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S.C. Wack
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[*] posted on 30-12-2004 at 20:13


One isolates them as their salts, or uses excess toluene and a Dean-Stark in the reflux to get all of the H2SO4 to sulfonate.
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acx01b
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[*] posted on 9-11-2005 at 06:15


very insteresting isolate as a salt....

how you would do that ???

and how to get ptsa xtals then ????
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[*] posted on 10-11-2005 at 01:59


Take a look in Vogels or most any organic practical book for reliable proven protocols for pTSA and separation of the isomers.

No need to reinvent the wheel here!

If anyone has what they consider to be the "best' procedure for the pAcid by the azeotropic water removal method I would appreciate if someone could either post it or point in the right direction. Seems benzene would be preferable to keep the temp down for primarily pAcid production.
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garage chemist
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[*] posted on 10-11-2005 at 05:57


@markgollum:
The method in Gattermann- Wieland uses 40ml sulfuric acid and 200ml toluene. All H2SO4 reacts, because of the equilibrium shift when the water is being constantly removed.
You are using waaaaay too much H2SO4!

A Dean-Stark water trap is used to remove the water as azeotrope with toluene.
The reaction is stopped when no more water is collecting.
PTSA is isolated by adding water to the mix, filtering the resulting crystals, dissolving in water and bubbling in HCl gas (decreases the solubility of PTSA), filtering and washing with conc. HCl. Then drying in exsiccator over KOH (removes the HCl as well as the water).

The entire process is more involved than my short summary. Download "Practical methods of organic chemistry" by Gattermann and follow the detailed description.

And using benzene is nonsense, it would get sulfonated too and you would get a mix of toluene- and benzenesulfonic acid.

[Edited on 10-11-2005 by garage chemist]
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[*] posted on 10-11-2005 at 12:20


In my experience, conc H2SO4 is miscible with DCM, so that's why your extraction failed.



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[*] posted on 11-11-2005 at 14:06


is it illegal to download ebooks ??

there you can get it:

http://www.chimicando.it/pagine/e-book.htm
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[*] posted on 16-11-2005 at 10:40


Amidosulfonic acid (hope thats correct) is available OTC as descaler and can replace toluenesulfonic acid in many reactions.

/ORG




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[*] posted on 16-11-2005 at 17:44


As a leaving group in SN2 reactions, is there much(if any) difference between o, m, p toluenesulphonic acids in their abilities as a good leaving group?



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[*] posted on 17-11-2005 at 10:46


The leaving group ability roughly correlates with the pKa of the originating acid (resulting anion). So the m-toluenesulphonic acid should be a just slightly better leaving group. But since the pKa difference is negligible so is the difference in the leaving group potential of the 3 possible toluenesulphonic acids, while with o-toluenesulphonic acid steric factors probably influence more than the weak electrondonating properties of the methyl group.



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[*] posted on 18-11-2005 at 04:20


...and the only reason why p-toluenesulfonic acid is most commonly used is that it is a cheap byproduct of saccharin manufacture, IIRC. :)

Now for my question: would removing the amine group from taurine work? (Betting on no since the sulfonic acid group would keep it in zwitterion form anyways...)

sparky (~_~)

P.S. You meant "sulfamic acid", eh Org?

[Edited on 18-11-2005 by sparkgap]




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[*] posted on 18-11-2005 at 10:34


Quote:
Originally posted by sparkgap
Now for my question: would removing the amine group from taurine work? (Betting on no since the sulfonic acid group would keep it in zwitterion form anyways...)


What exactly do you mean by removing? The amine group in taurine can easily be substituted with higher boiling amines, presumably trough elimination of NH3 and addition of the other amine on the resulting vinylsulphonic acid:

H2N-CH2-CH2-SO3H + HNR2 => R2N-CH2-CH2-SO3H + NH3

Perhaps it would work with some other neutral nucleophyles as well. But if you mean't removed in a sense of having it replaced by an hydrogen atom (yielding ethanesulphonic acid) then I can't think of an easy way.




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[*] posted on 18-11-2005 at 15:01


.......And using benzene is nonsense, it would get sulfonated too and you would get a mix of toluene- and benzenesulfonic acid........

You would think so under most circumstances however the PhMe sulfonates much easier and there is a patent which claims pTSA almost exclusively azeotroping at 69deg removing the benzene in the process. I'll see if I can find it in my archives.
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[*] posted on 17-6-2006 at 23:53
Replacing sulfonic acid group


I have found from various books that sulfonic acid group can be replaced by hydroxyl when alkali sulfonate is fused with NaOH or KOH. This is used to make phenols.

Sulfonic acid group can also be replaced with NH2 if NaNH2 (sodamide) is used instead of alkali hydroxide. So aniline can be made from benzenesulfonic acid.

Now i read that aromatic nitriles can be made by distilling mix of sulfonic acid and KCN.

My question is what other groups can (or could) be inserted into aromatic compounds this way?

[Edited on 18-6-2006 by chromium]
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[*] posted on 11-12-2021 at 06:52


Could somebody provide the information about the inorganic chemistry of p-toluenesulfonic acid? I know this acid is a good catalyzer for esterification and I've just made it for this purpose, but the properties of its salts and reactions where the acid acts just as an anion or ligand are also interesting for me, so I plan to explore it a bit.



TsOH.jpg - 171kB

Just some hints. TsOH has properties common for both organic and inorganic acid. For example, its barium salt has quite a good solubility in methanol.

[Edited on 11-12-2021 by teodor]
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[*] posted on 11-12-2021 at 18:04


Just an added question, but does anyone know why it goes pink? This happens to me too, but I've never seen it in any prep for the stuff.



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[*] posted on 12-12-2021 at 17:43


Quote: Originally posted by Triflic Acid  
Just an added question, but does anyone know why it goes pink? This happens to me too, but I've never seen it in any prep for the stuff.

Its normal though, my commercial bought one tends to get grayish first and after a year or so it starts to get that pinkish hue.
And I've seen that in several containers over the years.

Its the monohydrate as well, FYI.
Its still a pretty hygroscopic substance in my experience, that seems very likely to be the reason it turns pink, depending on how much water it has adsorbed from the atmosphere.




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[*] posted on 12-12-2021 at 22:26


Interesting, almost like cobalt salts. Wonder if this would be a good moisture indicator for some purposes, if someone didn't have anhydrous cobalt salts.



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[*] posted on 14-12-2021 at 04:33


Now I try to find a way to get anhydrous TsOH from a hydrated form.
Drying in a desiccator (KOH + CaCl2) leaves a hydrate, this is apparent by the melting point.
It's interesting that the water is tightly bound, so when I dissolve the hydrate in e.g. amyl acetate (the solvent which is practically absolutely immiscible with water) I get this water in a solution, there is no separate layer. So, probably it ionizes all the water or forms a different type of a bond which allows the water to be dissolved in the organic layer.
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[*] posted on 14-12-2021 at 05:50


There is something on erowid, regarding the preparation of anhydrous tosic acid.



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[*] posted on 14-12-2021 at 08:36


teodor - using dean stark trap and toluene would maybe work
I have some commercial ptsa, the formula on the label says it is monohydrate




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[*] posted on 14-12-2021 at 23:11


A Dean Stark with toluene will indeed work. The water is so tightly bound it is like a salt; TsO- and H3O+. When you have an anhydrous solution in toluene and you add a drop of water it immediately crystalizes.

[Edited on 15-12-2021 by Tsjerk]
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