Sciencemadness Discussion Board

Distillation with rubber stoppers

mauricethegangsteroflove - 13-3-2026 at 18:44

I was gifted a box of glassware recently (many flasks, beakers, volumetric cylinders, tubing, and random assorted goodies), and it's of the old fashioned sort that takes rubber stoppers rather than ground glass joints. I am putting together a proper ground glass setup for future use, but in the meantime I'm curious what can safely be used with this.

I'd like to try some small scale distillations of some solvents, like diethyl ether, dioxane, chloroform, etc. I'd also like to attempt to distill a small amount of nitric acid.

How much of this is feasible with rubber stoppers and bent glass tubes? I know nitric acid especially will not be kind to such a setup for repeated use, but I suspect it will work once or twice. the solvents I don't expect to be much of an issue but I may as well ask to be safe.

Everyone I've seen doing this uses ground glass (and I intend to when possible), but can I safely run a distillation with what I have now?

bariumbromate - 13-3-2026 at 21:13

Btw nitric acid sets rubber on fire :D

mauricethegangsteroflove - 13-3-2026 at 21:20

That sounds suboptimal.

I was aware it sets nitrile on fire, but just thought it ate up other kinds of rubber relatively quickly.

just a few thoughts.....

Sulaiman - 14-3-2026 at 01:22

1) rubber bungs and glass tubing may give you the mark of the chemist
https://youtu.be/Wn9qxPKkRDw?si=WQFbsxny1wdw9NA3

2) hot conc. nitric or sulphuric will make a mess of rubber bungs

3) wrapping a rubber bung in domestic cling film can add resistance to solvents
as can smearing with silicone grease
I've not tried but I've read that wrapping a rubber bung in plumbers ptfe tape helps

mauricethegangsteroflove - 15-3-2026 at 13:28

It'll be a moot point in a few weeks when I have the proper ground glass distillation apparatus, so i suppose I'll wait until then. I suspect this could probably be done once before the stopper gave out, particularly in the small quantity I am thinking of, but I'd rather not test that assumption on my first time playing with HNO3.

Thanks for your input

macckone - 17-3-2026 at 19:38

Ptfe plumber's tape protects rubber stoppers from aggressive chemicals

Sulaiman - 18-3-2026 at 14:25

Quote: Originally posted by mauricethegangsteroflove  
.......my first time playing with HNO3...
two things about conc. nitric :
1) it is sneaky stuff..delayed then volcanic reactions with many substances
2) many of its reactions release copious quantities of choking NO2 gas
unlikely to be lethal but an ever present risk.