Does Pyrocatechin go bad?

A friend has a bottle of unopened Pyrocatechin from 1988, and it is "about Zone VII" in his words. Does this stuff go bad?

If you are referring to the pure solid then no. It has the same stability as hydroquinone. Keep it in a well sealed jar, preferably glass, protected from light and moisture. Unlike hydroquinone it does have a measureable vapor pressure at room temperature. Therefore the jar must be well sealed to prevent loss. The rate is quite small but noticeable over a long period.