hellman (Soothsayer)
06-28-03 01:26
No 443006
      p-TOLUENESULPHONIC ACID  Bookmark   

Sulphonation of Aromatic Hydrocarbons- Hellman Style

There has been a lot of struggle with the syntheses of P-Toluenesulponic Acid, so as a matter of benevelovancy
I thought that this might bee of interest to you all,.

Aside from the basic mechanics of the reactions which are
RC6H5 +SO3------------->RC6H4SO3H + H+(positive)
there was the purificaion of commercial toluene, which I thought I would add in to eliminate unwanted messes in the final product,.
So all in all, welcome bees to your new method to "Knock theTop off" your peracid Procedures,.

What yo will need:

2 Litre RBF
Buchner Flask,Funnel & Papers
1 Litre Toluene ( commercial is Fine)
H2SO4 (concenttrated)
HCL (concentrated)
Cacl2 (or Sodium Wire if you have this lying around)
Sodium Carbonate

Purification of Commercial Toluene
Toluene comes a little wet, and a little contaminated with Methyl thiophens (bp 112-113)
These can NOT be removed by diillation, as Toluene's Boiling point is 110.5@760mm.
The easiest way to remove these is as follows,.

Insert 1000ml of your toluene ( well technically it is not yours, ownership really is an illusion based on greed)
into your 2 Litre RBF,.
Make sure you are wearing rubber gloves, and have a bronze ring placed on both index fingers,.*
Gently and smoothly add 100ml of Conc. Sulphuric Acid, and antagonise the solution(Stir) for about 30 mintues,.
Making sure throughout this proceddure that you don't let the reaction go above 30c.
The lower acid layer is then dumped, with compassion & sympathy, and this stage is repeated twice,.
Pure H20 is then added (100ml) and shaken for 5 minutes, les if you masturbate more than 4 times a week( I am serious)-
-Muscle tensioning and endurance,.-
After the water wash add 10% Sodium carbonate solution, and the dry with Cacl2,
Filter and that is all,.
I agree that it is a tedious process, but you will thank me for it,.
When purity is essential, this is essential,.

p-Toluenesulphonic Acid
Direct sulphonation of the aromatic nucleus is an electrophilic substitution brought about by either sulphur trioxide or its protonated form:

In your 2 litre RBF fitted with a reflux condensor place toluene 150ml and Conc sulphuric acid 60ml.
Boil sweetly(gently) for 5 minutes, with frequent shaking to mix intimately the layers,.
Cool solution in an ice water bath, and remove the upper layer which you will find is mostly toluene,.
Now here's the tricky part,.
Slowly but with no real risk of imminent danger, add 120ml conc HCL, and heat gently until solution goes clear,
and then cool yet again,.
You will see a solid form and seperate, which is mainly the goods( P-acid) but it is also apparantly contaminated with the o-isomer, but to remove this just repeat the crystallization, to obtain a pure sample with a mp of 105c.
You should have roughly 30g of the p-acid,.

*I was only joking about the bronze rings, they can be any metal, really- smile

Joke- What's the worst thing about "going out" with a 12 Year Old?
Ans- Going to bed at 6:30,.
Ref P268,.
Vogels Elemantary Practical Organic Chenistry !
Preperations - Third Edition

IQ is the rate of logic, as Wisdom increases logic, fear & compromise decrease to reveal objectivity