Sciencemadness Discussion Board

Getting the Last of the Toluene out of the Product

JJay - 9-2-2018 at 13:25

What is the best way to get toluene out of anhydrous oxalic acid? Ideally, I'd like to just stick it in my vacuum desiccator, but I have no idea what desiccant would absorb toluene, and it's kind of hard on the pump to run it for hours to pump off the toluene vapor.

Cryolite. - 9-2-2018 at 14:34

Maybe try washing out the toluene in something that doesn't dissolve oxalic acid (DCM maybe) and then evap off the volatile wash? Kind of wasteful though.


Texium - 9-2-2018 at 14:39

Pull a direct vacuum on it in a flask while gently heating with a heat gun or hot plate. Use a cold trap in between the flask and the pump.

j_sum1 - 9-2-2018 at 14:42

My inclination would be to crush it up and leave it in thae hot Australian sun for a while. Maybe double the time for the smell to be indiscernable. But, I confess I have no practical experience of this particular problem.

You are welcome to pop over and borrow some sun. It looks like we will have too much over the next few days.

UC235 - 9-2-2018 at 14:49

I believe shredded parrafin wax is the recommended "dessicant" for nonpolar hydrocarbon solvents.

JJay - 9-2-2018 at 15:07

Quote: Originally posted by UC235  
I believe shredded parrafin wax is the recommended "dessicant" for nonpolar hydrocarbon solvents.


Oh, thank you! I was considering shredded rubber, but I wasn't sure if that would work and didn't have any immediately available. Shredded wax sounds like an excellent idea!

AvBaeyer - 9-2-2018 at 19:03

UC235 is correct. Shredded paraffin in a desiccator is very efficient for removing residual volatile hydrocarbons. I use this quite frequently for hexane and toluene. It does not really require a vacuum, just a bit of time.

AvB

[Edited on 10-2-2018 by AvBaeyer]