Hexavalent
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Sodium p-toluenesulfonic acid
I recently had some more success with my synthesis of toluene esulfonic acid; after refluxing 25ml each of concentrated sulfuric acid and toluene for
two hours I had a clear, amber liquid. To prepare the sodium salt, a book I have says to dump the still-warm reaction mix into 100 ml of distilled
water and add 15g of sodium carbonate to partly neutralize the solution. It then specifies adding 40g of sodium chloride and stirring 'until the
granular crystals are replaced with pearly white plates of sodium toluenesulfonate.' I have been stirring for three hours now and all I have is a
brown opaque liquid with fair amounts of the NaCl still suspended. Is my reaction mixture salvageable, to obtain the free acid? I thought of heating
up the mixture, filtering to remove excess salt followed by addition of hydrochloric acid and then re-cooling to obtain the crystals.
Will this work to recover the toluenesulfonic acid?
"Success is going from failure to failure without loss of enthusiasm." Winston Churchill
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Hexavalent
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I think I've sorted it out for the time being, without going back to the free acid - I added more water to dissolve the NaCl which resulted in a
clear, orange solution. I then evaporated off some water slowly to return to the original volume, and some NaCl precipitated out - but less than would
dissolve previously. I took it off the heat and it settled to the bottom of my flask. I allowed it to cool and when I returned the solution had
crystallized into a hard mass of what I can only presume to be sodium p-toluenesulfonate. I scraped it out, but avoided all crystals about 5mm from
the bottom to eliminate scraping up any of the settled NaCl as well. I now have a mass of crystals with a coating of the orange liquid, which look
very different to the granular NaCl, thus making it more likely that they are indeed the sulfonate salt. However, the orange liquid on the crystals
will probably contain some NaCl in solution, so when they dry they may be impure, perhaps of technical grade. I have looked for solvents in which to
recrystallize them and when I tried Vogel's it has a procedure for recrystallizing in water.
Sorry for the rant, but I've kinda answered my own question.
[Edited on 1-9-2012 by Hexavalent]
"Success is going from failure to failure without loss of enthusiasm." Winston Churchill
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Hexavalent
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Location: Wales, UK
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I've spoken to ScienceSquirrel and he has suggested to leave this thread as it is for anyone else who wants to make this compound.
"Success is going from failure to failure without loss of enthusiasm." Winston Churchill
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ScienceSquirrel
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Mood: Dogs are pets but cats are little furry humans with four feet and self determination! 
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Amen to that.
Useful information for those faced with an oil.
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