Benzoquinone (C 6 H 4 O 2) is a quinone with a single benzene ring. There are 2 (out of 3 hypothetical) benzoquinones: 1,4-Benzoquinone, most commonly, right image (also para-benzoquinone, p-benzoquinone, para-quinone, or just quinone) 1,2-Benzoquinone, less commonly, left image (also ortho-benzoquinone, o-benzoquinone, ortho-quinone)