Benzoquinone

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1,4-Benzoquinone
Benzoquinone Crystals.jpg
Names
IUPAC name
Cyclohexa-2,5-diene-1,4-dione
Other names
Benzoquinone
para-Benzoquinone
Bara-quinone
Properties
C6H4O2
Molar mass 108.10 g/mol
Appearance Yellow solid
Odor Acrid, chlorine-like
Density 1.318 g/cm3 (at 20 °C)
Melting point 115 °C (239 °F; 388 K)
Boiling point Sublimes
1.1 g/100 ml (18 °C)
Solubility Soluble in acetone
Slightly soluble in benzene, diethyl ether, ethanol, petroleum ether
Vapor pressure 0.1 mmHg at 25 °C
Hazards
Safety data sheet Sigma-Aldrich
Lethal dose or concentration (LD, LC):
130 mg/kg (rat, oral)
25 mg/kg (mouse, oral)
Related compounds
Related compounds
Hydroquinone
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

1,4-Benzoquinone, commonly known as para-quinone, is a chemical compound with the formula C6H4O2. In a pure state, it forms bright-yellow crystals with a characteristic irritating odor. This six-membered ring compound is the oxidized derivative of hydroquinone. The molecule is multifunctional: it exhibits properties of a ketone, forming an oxime; an oxidant, forming the dihydroxy derivative; and an alkene, undergoing addition reactions, especially those typical for α,β-unsaturated ketones. 1,4-Benzoquinone is sensitive toward both strong mineral acids and alkali, which cause condensation and decomposition of the compound.

It is an isomer of 1,2-benzoquinone.

Properties

Chemical

An acidic potassium iodide solution reduces a solution of benzoquinone to hydroquinone, which can be reoxidized back to the quinone with a solution of silver nitrate.

Physical

Benzoquinone readily undergoes sublimation, even at room temperature.

Benzoquinone forms bright yellow needle-like crystals.

Availability

1,4-Benzoquinone is sold by chemical suppliers.

Preparation

Benzoquinone can be prepared by oxidation of hydroquinone.

Projects

  • Make hydroquinone
  • Make hydroxyquinol triacetate

Handling

Safety

Benzoquinone vapours are very irritating to the eyes and to the respiratory system. Handle in a well ventilated area, ideally in a fume cupboard.

Skin contact can result in brown staining, and apparently even localised tissue necrosis in severe cases. Benzoquinone is potentially a skin sensitiser.

Benzoquinone is probably carcinogenic.

Storage

In tightly-closed glass bottles. Stains/degrades polyethylene containers.

Disposal

Can be destroyed by oxidizing it with an oxidizing mixture, though due to its strong odor, this must be done outside or in a fumehood.

References

Relevant Sciencemadness threads