wanna try to make some p-benzoquinone, and some chloranil (that's tetrachloro-p-benzoquinone, and it's the end result of vigorous active chlorine oxidation of a lot of aromatic precursors)

you can make pH electrodes that exploit the redox couple between quinones and their corresponding hydroquinone, q.v. "quinhydrone electrode". the parent quinhydrone electrode starts degrading in high pHs because hydroquinone is soluble in alkali, but the chloranil counterpart should be better

#chemistry