14Benzoquinone

1,4-Benzoquinone, commonly called p-benzoquinone, is an organic compound with the formula C6H4O2. It is the para-quinone derivative of benzene, featuring a six-membered, planar, conjugated ring with two carbonyl groups at opposite positions (1 and 4). The molecule is typically described as an electron-poor aromatic diketone and serves as a versatile building block in organic chemistry.

Properties include a yellow to orange-yellow crystalline appearance. It is soluble in many organic solvents such as benzene and dichloromethane, and it is sparingly soluble in water. As a quinone, it acts as an electrophile and a two-electron oxidant, readily undergoing reduction to hydroquinone (p-hydroquinone) and participating in a variety of addition and cycloaddition reactions. In particular, 1,4-benzoquinone functions as a dienophile in Diels–Alder reactions and can participate in 1,4-conjugate additions with nucleophiles.

Production and occurrence: 1,4-benzoquinone is typically prepared by the oxidation of hydroquinone or related precursors. It is not a common naturally occurring compound in large amounts but is an established synthetic intermediate in organic and polymer chemistry.

Industrial and research applications: It is used as an oxidant and versatile intermediate in the synthesis of dyes, polymers, agrochemicals, and pharmaceutical intermediates. It also appears in studies of redox chemistry and can act as a redox mediator in electrochemical systems.

Safety and handling: The compound is toxic and can be an irritant to skin, eyes, and respiratory tract. It should be handled with appropriate PPE in a well-ventilated area, with care to avoid reduction or reaction with incompatible substances.