[noeyedear]

I've searched the forum and couldn't find an answer.

Q. benzyl alcohol that is stored in a high-density polyethylene (HDPE) bottle is 'sucking in' the sides of the bottle.  It has been stored this way for around 24 months. 

Does this mean the benzyl alcohol is being oxidized into another chemical? 

Would the benzyl alcohol still be considered pure?

[curiouscat]

Just a partial vacuum maybe. Perhaps it used up some of the ullage air for oxidation. Or water vapor condensed and dissolved. etc.

Don't think you can say anything offhand about purity.

[Archer]

If you are worried about purity then run a GC. The oxidation products are benzaldehyde and, ultimately, benzoic acid. It sounds likely that the oxygen has been removed so this is possible.

Chromatography will clean it for small scale, distillation for large scale or washing with NaOH followed by bisulfite for a crude purification.