p-Benzoquinone

p-Benzoquinone is a yellowish-colored crystalline solid with a pungent, irritating odor. Poisonous by ingestion or inhalation of vapors. May severely damage skin, eyes and mucous membranes. Used to make dyes and as a photographic chemical. p-Benzoquinone is also called 1, 4-benzoquinone or cyclohexadienedione. Quinones are oxidized derivatives of aromatic compounds and are often readily made from reactive aromatic compounds with electron-donating substituents such as phenols and catechols, which increase the nucleophilicity of the ring and contributes to the large redox potential needed to break aromaticity. Derivatives of quinones are common constituents of biologically relevant molecules. Some serve as electron acceptors in electron transport chains such as those in photosynthesis (plastoquinone, phylloquinone), and aerobic respiration (ubiquinone). Quinone is a common constituent of biologically relevant molecules (e. g. Vitamin K1 is phylloquinone). A natural example of quinones as oxidizing agents is the spray of bombardier beetles. Hydroquinone is reacted with hydrogen peroxide to produce a fiery blast of steam, a strong deterent in the animal world.