How to clean xylene safely with a glass distillator

[MatLag]

Hi everybody!

So I have a few liters of xylene from my previous extraction, and I'm wondering how to distillate it properly to get some clean solvent... I own a small distillation apparatus (1 liter), is there a simple and safe way to perform a distillation with that kind of tool?

Thanks!

 

[downwardsfromzero]

Have you distilled anything before? Have you ever distilled a flammable liquid? Are you aware of the necessary safety precautions?

What does your distillation apparatus look like? Is it a stainless steel air-cooled still or do you have glassware? If the latter, what heat source will you use? If the former, don't use that for distilling xylene because, as far as I'm aware, it has plastic components in the distillation train [EDIT: I re-read the title of your thread - it seems you have glass ]

 

[MatLag]

Hi Downwardsfromzero,

Thanks for your reply. So yes, I have distilled before (water, wine, mead), but nothing flammable. I am aware of the safety precaution and I'm conscious of the risks of explosion. This would be done in a well ventilated area (almost outside but protected from the winds) with all the protections necessary (googles and gloves, fire extinguisher).
I would feel really more confident if someone could tell me the right way to do this, or simply tell me to give it up if this is out of my reach!

Thanks a lot!

 

[MatLag]

I've forgot to answer this: heat source would be my electric hot plate stirrer, although stirring doesn't seem necessary, I'm I right?

 

[downwardsfromzero]

OK, well when you distill wine you are in fact distilling something flammable - the ethanol. Xylene is actually 'less flammable' than ethanol in that it has a higher flash point, although this is largely irrelevant since it will be heated for this distillation of course.

It would be better if you did use stirring as this helps to prevent bumping (where the liquid suddenly boils violently). You will get a purer product that way - bumping projects droplets from the boiling flask into the distillation train and thus impurities can make their way through to the receiver. And only fill your flask up to half full.

I would suggest sealing the glass joints with PTFE tape to minimise vapor leakage. It would also be useful to know what kind of receiver adapter you have that fits between the end of the condenser and the receiver flask.

Use of a thermometer at the still head would be prudent. You might notice an azeotrope of water and xylene distilling over at below 100°C if the xylene is a bit damp.

The other thing is to stop distilling before the boiling flask is dry. Distilling to dryness can be dangerous if, for example, the impurities can form peroxides on contact with air.

It seems you've made sure you have good ventilation and a suitable fire extinguisher. Just as long as you have sufficient time to complete the distillation you should be good to go. It would be good to rehearse setting up the equipment beforehand as well.

As an exercise, describe what you'll be doing step-by-step in your own words.

 

[MatLag]

I thought after my last post that distilling wine is already dealing with something flammable. I just meant I never started a distillation from a highly flammable product, but you got me.

I haven't thought about bumping... So a slight stirring would be enough I guess.

Thank you very much for your informations, I feel now more confident to give this a try.

Cheers!

 

[downwardsfromzero]

a slight stirring would be enough I guess.

Get a nice vortex going, at least. This helps bring the hot liquid from the bottom of the flask up to the top surface to evaporate, as well as increasing the area of air/liquid interface.

 

[MatLag]

Ok, many thanks for sharing with me your knowledges!

 

[downwardsfromzero]

Have you tried this yet? Let us know how it turns out.