So, recently I distilled some gasoline for solvents (like toluene, hexanes/heptanes, etc). The alkanes were relatively easy to clean, just added some
sulfuric acid and water washed. Now that I'm processing the toluene fraction, I'm trying to remove any residual alkanes. I don't really know how to
since generally aromatics are more reactive than alkanes and everything that I can think of that would destroy the alkanes would also destroy the
toluene. I'm thinking perhaps an extractive distillation with something a bit more polar since toluene is more polar than most alkanes.jackchem2001 - 15-11-2025 at 14:45
Maybe azeotropic distillation with water could helpDraconicAcid - 17-11-2025 at 11:43
If it were benzene, you could purify it by freezing it- the alkane impurities would stay liquid and pure benzene would crystallize at reasonably low
temperatures. Toluene, however, freezes at -95 C, so that's far less feasible, and it would have to start out as mostly pure for any improvement.j_sum1 - 17-11-2025 at 14:40
My first thought was to oxidise to benzoic acid.
I like the azeotropic distillation idea better.DraconicAcid - 17-11-2025 at 17:08
My first thought was to oxidise to benzoic acid.
I like the azeotropic distillation idea better.
Then it's really hard to reduce the acid back to the toluene.
Sulphonation of the toluene to give TsOH could be possible. That would be easily separated from alkanes, and then hydrolyzed to give the toluene
back, but I've never had any luck with either the sulphonation or the hydrolysis.j_sum1 - 17-11-2025 at 19:04
Like I said. That was my first thought. And I knew it wasn't a great one. macckone - 18-11-2025 at 07:09
Toluene can be separated by steam distillation. It will also add water to double bonds to a lesser extent. Treatment with permanganate to remove
oxidizable compounds is best done after steam distillation. Some toluene will be oxidized as well but it is necessary for a pure product.
