Deo
Harmless
Posts: 29
Registered: 2-12-2024
Member Is Offline
|
|
Removal of Alkanes from Toluene
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
Hazard to Others
Posts: 110
Registered: 2-6-2024
Member Is Offline
|
|
Maybe azeotropic distillation with water could help
|
|
|
DraconicAcid
International Hazard
Posts: 4504
Registered: 1-2-2013
Location: The tiniest college campus ever....
Member Is Offline
Mood: Semi-victorious.
|
|
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.
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
|
|
|
j_sum1
Administrator
Posts: 6472
Registered: 4-10-2014
Location: Limbo
Member Is Offline
Mood: Just got through yet another "take this job and shove it" moment.
|
|
My first thought was to oxidise to benzoic acid.
I like the azeotropic distillation idea better.
|
|
|
DraconicAcid
International Hazard
Posts: 4504
Registered: 1-2-2013
Location: The tiniest college campus ever....
Member Is Offline
Mood: Semi-victorious.
|
|
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.
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
|
|
|
j_sum1
Administrator
Posts: 6472
Registered: 4-10-2014
Location: Limbo
Member Is Offline
Mood: Just got through yet another "take this job and shove it" moment.
|
|
Like I said. That was my first thought. And I knew it wasn't a great one. 
|
|
|
macckone
Dispenser of practical lab wisdom
Posts: 2211
Registered: 1-3-2013
Location: Over a mile high
Member Is Offline
Mood: Electrical
|
|
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.
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
