The Vespiary

The Hive => Chemistry Discourse => Topic started by: no2meth on October 11, 2004, 03:51:00 PM

Title: toluenesulfonic acid
Post by: no2meth on October 11, 2004, 03:51:00 PM
30mL toluene and 30mL 98% H2SO4 was gently refluxed (with minimal stirring - toluene starts to fiercely boil when shaken) for 50min after which toluene layer disappeared. Cooled to RT - oily syrup, very dark brown, 50mL. After sitting in a flask at RT several hours the entire mass crystallized.

Questions to you bees: is it normal that the results is so dark (opaque, almost black)? Is it normal that everything crystallizes at RT? (I guess yes, this would mean that all toluene and most sulfuric reacted  :) )

How do you propose to separate o- and p- isomers? Thought about dissolving in lots of water, adding finely ground CaCO3 to precipitate CaSO4, filter, evap water to get calcium tosylate (mixture), carefully add H2SO4 to crystallize tosic acid, filter... and? How to separate the isomers? UTFSEd a bit, there seems to be a method involving difference in solubility of the isomers in dilute-concentrated H2SO4. Or the HCl method... I'm stuck. Browsed the net, no solid data on solubility found  :(  Do you have any? Any experience?

Also, is hydrolysis to cresols a significant side reaction under these conditions?

So many questions... Thanks in advance for any suggestions.

yours truly n2m
Title: the only hydrolysis I know of would be back to
Post by: yei on October 12, 2004, 06:58:00 AM
the only hydrolysis I know of would be back to toluene and sulfuric acid. If you want cresols (a worthy goal indeed), you will have to roast the tosic acid with NaOH or KOH at a nice high temperature.

This is feasible, and a good way to obtain DOM precursor.