I am considering using xylene to pull, but I am concerned about the choice of cap/stopper/lid of potential reaction vessels. If you google material compatibility, you find xylene attacks every common stopper material such as polyethylene, common rubber, and silicon as indicated in their respective compatibility charts. The small number of materials that have "good" or better compatibility with xylene are polypropylene, PTFE and viton rubber. This severely limits choice of glass vessel, since you need to find one that is available with or fits a cap made of one of these compatible materials. A search for "polypropylene cap" results in polypropylene caps with polyethylene foam liner.

I am thinking of springing for the pyrex 2000 mL erlenmeyer flask with linerless polypropylene screw-on cap but it's expensive and hard to obtain in less than a case.

What do you use to contain your basified soup / xylene mixture when pulling?

I've used corks before with naphtha (where appropriate). Avoid using a synthetic cork if you do try this.

I'll give it a try and report back. I found this patent description for applying a silicon coating to cork for use in wine bottles. Silicon is no good for containing xylene -- they are using xylene here to clean the cork and disperse the silicon into the cork. Safe to assume they tested and found xylene doesn't damage cork.

https://patents.google.com/patent/EP0865388B1/en