Diphenyl ether

Diphenyl ether

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Names
IUPAC name Diphenyl ether
Other names Diphenyl oxide; 1,1'-Oxybisbenzene; Phenoxybenzene
Identifiers
CAS Number	101-84-8 Y
ChEBI	CHEBI:39258 Y
ChEMBL	ChEMBL38934 Y
ChemSpider	7302 Y
Jmol 3D model	Interactive image
UNII	3O695R5M1U Y
InChI InChI=1S/C12H10O/c1-3-7-11(8-4-1)13-12-9-5-2-6-10-12/h1-10H Y Key: USIUVYZYUHIAEV-UHFFFAOYSA-N Y InChI=1/C12H10O/c1-3-7-11(8-4-1)13-12-9-5-2-6-10-12/h1-10H Key: USIUVYZYUHIAEV-UHFFFAOYAV
SMILES O(c1ccccc1)c2ccccc2
Properties
Chemical formula	C12H10O
Molar mass	170.21 g·mol−1
Appearance	Colorless solid or liquid
Odor	geranium-like
Density	1.08 g/cm3 (20°C)
Melting point	25 to 26 °C (77 to 79 °F; 298 to 299 K)
Boiling point	121 °C (250 °F; 394 K) at 1.34 kPa (10.05 mm Hg), 258 °C at 100 kPa (1 bar)
Solubility in water	Insoluble
Vapor pressure	0.02 mmHg (25°C)
Vapor pressure	{{{value}}}
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Diphenyl ether is the organic compound with the formula O(C₆H₅)₂. The molecule is subject to reactions typical of other phenyl rings, including hydroxylation, nitration, halogenation, sulfonation, and Friedel–Crafts alkylation or acylation. This simple diaryl ether enjoys a variety of niche applications.

Synthesis

Diphenyl ether and many of its properties were first reported as early as 1901. It is synthesized by a modification of the Williamson ether synthesis, here the reaction of phenol and bromobenzene in the presence of base and a catalytic amount of copper:

PhONa + PhBr → PhOPh + NaBr

Involving similar reactions, diphenyl ether is a significant side product in the high-pressure hydrolysis of chlorobenzene in the production of phenol.

Uses

The main application of diphenyl ether is as a eutectic mixture with biphenyl, used as a heat transfer medium. Such a mixture is well-suited for heat transfer applications because of the relatively large temperature range of its liquid state. A eutectic mixture [commercially, Dowtherm A] is 73.5% diphenyl ether (diphenyl oxide) and 26.5% diphenyl (biphenyl).

Diphenyl ether is a starting material in the production of phenoxathiin via the Ferrario reaction. Phenoxathiin is used in polyamide and polyimide production.

Because of its odor reminiscent of scented geranium, as well as its stability and low price, diphenyl ether is used widely in soap perfumes. Diphenyl ether is also used as a processing aid in the production of polyesters.

Several polybrominated diphenyl ethers (PBDEs) are useful flame retardants. Of penta-, octa-, and decaBDE, the three most common PBDEs, only decaBDE is still in widespread use since its ban in the European Union in 2003. DecaBDE, also known as decabromodiphenyl oxide, is a high-volume industrial chemical with over 450,000 kilograms produced annually in the United States. Decabromodiphenyl oxide is sold under the trade name Saytex 102 as a flame retardant in the manufacture of paints and reinforced plastics.

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