A quinone. The molecular formula is C6H4O2. There are two kinds of benzoquinone: p-benzoquinone and p-benzoquinone. P-benzoquinone is more important, and benzoquinone usually refers to p-benzoquinone. P-benzoquinone is a gold prism; Melting point115 ~17℃, density 1.3 18 g/cm (20℃), which can be distilled by steam sublimation; Soluble in hot water, ethanol and ether. O-benzoquinone is red flake or prism; Decompose at 60-70 DEG C; Soluble in ether, acetone and benzene. Benzoquinone has a strong tendency to return to benzene ring structure and has oxidation effect. It can absorb iodine from the acidic solution of potassium iodide and reduce itself to hydroquinone. P-benzoquinone can be prepared by oxidizing hydroquinone with sodium chlorate and sulfuric acid. It can be prepared by oxidation of aniline or phenol in industry; Benzoquinone can also be prepared by direct electrolytic oxidation of benzene. Benzoquinone can be prepared by oxidizing catechol with silver oxide. Benzoquinone is a raw material for organic synthesis industry, and its reduction product hydroquinone is a reducing agent, which can be used as a developer and polymerization inhibitor for negative films. Benzoquinone vapor can stimulate cornea and mucosa.