Hi Nexus!

I had stored some ethyl acetate in some small 250ml mason jars - jars that have a metal lid and a rubber for sealing. I had checked the EA safety link ( https://www.msdsonline.c...melling-safety-hazard/#:~:text=Ethyl%20acetate%20is%20highly%20flammable,with%20the%20eyes%20or%20skin. ) and read elsewhere that EA is used for rubber "conditioning", so I assumed those jars to be fine.

However, after a couple of weeks, the rubber now had become somewhat light, some changed, and one even broke, see picture.

I now found https://www.marcorubber....tibility/ETHYL%20ACETATE - saying that "When exposed to ethyl acetate, rubber can experience swelling, cracking, and embrittlement."

So, my questions are:

1) What mason jar lids are fine/recommended with EA?

2) What is causing this rubber "change"? Is EA extracting something from the rubber? I'd like to re-use the EA with the sodium carbonate + brine wash method, but I'm not sure if the washed EA would be safe to use. Probably the two washes would not remove a possibly different solvent/plasticiser(?) ? Also, maybe even if it would be no health risk, would the compound extracted from the rubber mess with precipitation of our favourite molecules?

I found myself on a similar situation, the EA came into contact with the red and clear plastics on the lid and started to dissolve them as fas as I could tell.
Personally, I chose to discard the EA given that I dont have the means to make sure its safe to use. I imagine the risk is less if yours has only come into contact in gas form, but still.

For short term storage I put some aluminium foil in between the jar and the lid. For long term you might want to find a suitable container.

The red ring does change (swell/discolor) with time. Not something I personally worry too much about, but each should make their own decision.

For long term storage use polypropylene lids (see image).

Solvent and reagent compatibility with various storage and handling materials can be looked up in any of the various materials compatibility charts available online.

Those seals appear to be natural rubber (and looking here, synthetic rubber would be worse), perhaps a replacement made of silicone is available? That would be far more resistant - about as good as polypropylene according to the charts. Nylon is even more resistant to EA than those two but you'd want to weigh that off against its poorer restance to some other materials. Fairly large washers made from both nylon and polypropylene can be found at hardware stores and plumbers' merchants.

Of course, if the PP lids are available, that is the simplest option but it's still helpful to know some alternatives.

Awesome, thanks so much for all the input!