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Author: Subject: p-toluene sulphonic acid synthesis
acx01b
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[*] posted on 4-11-2005 at 15:12
p-toluene sulphonic acid synthesis


hi,

i dont think this is already posted:

if i try making para toluene sulphonic acid by refluxing
toluene and 90% h2so4 (2mol h2so4 for 1mol h2o)

C6H5CH3 + 2H2SO4 + H2O will i get CH3C6H5HSO3.H2O + H3OHSO4
or will the yield be poor ????

this suggesting that in the reaction, the H3OHSO4 in my 90% sulphuric acid would act as a spectator...

ty

[Edited on 5-11-2005 by chemoleo]
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hydrargirum
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[*] posted on 4-11-2005 at 20:13


Preparation p-toluenesulphonic acid: it is necessary to operate to temperature
on 100ºC (around 170ºC), it must have an excess of toluene to avoid disulphonation, in addition it must bubble a slow airflow to mix well both phases while the reflux of the mixture is made.
To temperatures under 100ºC is obtained o- and m- isomers (to 0ºC up to 45% of o-)
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acx01b
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[*] posted on 6-11-2005 at 03:50


this doesn't answer at all because my question was more about the sulphonation power of a non 100% sulphuric acid.... but ty
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[*] posted on 7-11-2005 at 01:49


If water is azeotropically removed during the sulphonation less than concentrated acid will work satisfactorily.

Just how dilute the sulfuric may be I can't say. Benzene is used as entrainer if the temp needs to be kept below PhMe boiling point.

Seems there is a thread on this subject in the forum IIRC.
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