Diphenyl ether is the

organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. T ...

with the formula ( C₆ H₅)₂ O. It is a colorless solid. This, the simplest diaryl

ether In organic chemistry, ethers are a class of compounds that contain an ether group—an oxygen atom connected to two alkyl or aryl groups. They have the general formula , where R and R′ represent the alkyl or aryl groups. Ethers can again be ...

, has a variety of niche applications.

Synthesis and reactions

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 The Williamson ether synthesis is an organic reaction, forming an ether from an organohalide and a deprotonated alcohol (alkoxide). This reaction was developed by Alexander Williamson in 1850. Typically it involves the reaction of an alkoxide io ...

, here the reaction of

phenol Phenol (also called carbolic acid) is an aromatic organic compound with the molecular formula . It is a white crystalline solid that is volatile. The molecule consists of a phenyl group () bonded to a hydroxy group (). Mildly acidic, it ...

and

bromobenzene Bromobenzene is an aryl halide, C6H5Br. It is a colourless liquid although older samples can appear yellow. It is a reagent in organic synthesis. Synthesis and reactions Bromobenzene is prepared by the action of bromine on benzene in the presenc ...

in the presence of base and a

catalytic Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recyc ...

amount of

copper Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkis ...

: :PhONa + PhBr → PhOPh + NaBr Involving similar reactions, diphenyl ether is a significant side product in the high-pressure

hydrolysis Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution, elimination, and solvation reactions in which water is the nucleophile. Biological hydrolys ...

chlorobenzene Chlorobenzene is an aromatic organic compound with the chemical formula C6H5Cl. This colorless, flammable liquid is a common solvent and a widely used intermediate in the manufacture of other chemicals. Uses Historical The major use of chlorob ...

in the production of phenol. Related compounds are prepared by

Ullmann reaction The Ullmann reaction or Ullmann coupling is a coupling reaction between aryl halides. Traditionally this reaction is effected by copper, but palladium and nickel are also effective catalysts. The reaction is named after Fritz Ullmann. Mechanism ...

s. The compound undergoes reactions typical of other

phenyl In organic chemistry, the phenyl group, or phenyl ring, is a cyclic group of atoms with the formula C6 H5, and is often represented by the symbol Ph. Phenyl group is closely related to benzene and can be viewed as a benzene ring, minus a hydrogen ...

rings, including hydroxylation,

nitration In organic chemistry, nitration is a general class of chemical processes for the introduction of a nitro group into an organic compound. The term also is applied incorrectly to the different process of forming nitrate esters between alcohols an ...

, halogenation,

sulfonation Aromatic sulfonation is an organic reaction in which a hydrogen atom on an arene is replaced by a sulfonic acid functional group in an electrophilic aromatic substitution. Aryl sulfonic acids are used as detergents, dye, and drugs. Stoichiometry a ...

, and Friedel–Crafts alkylation or acylation.

Uses

The main application of diphenyl ether is as a eutectic mixture with

biphenyl Biphenyl (also known as diphenyl, phenylbenzene, 1,1′-biphenyl, lemonene or BP) is an organic compound that forms colorless crystals. Particularly in older literature, compounds containing the functional group consisting of biphenyl less one ...

, used as a

heat transfer fluid In fluid thermodynamics, a heat transfer fluid is a gas or liquid that takes part in heat transfer by serving as an intermediary in cooling on one side of a process, transporting and storing thermal energy, and heating on another side of a proc ...

. Such a mixture is well-suited for heat transfer applications because of the relatively large temperature range of its liquid state. A eutectic mixture ommercially, Dowtherm Ais 73.5% diphenyl ether (diphenyl oxide) and 26.5% biphenyl (diphenyl). Diphenyl ether is a starting material in the production of

phenoxathiin Phenoxathiin (dibenzooxathiane) C12H8OS is a heterocyclic compound of molecular weight 200.25632 g/mol with the CAS Registry Number 262-20-4. Diphenyl ether is a starting material in the production of phenoxathiin via the Ferrario reaction. Phen ...

via the

Ferrario reaction Ferrario is an Italian surname. Notable people with the surname include: * Bill Ferrario (born 1928), American footballer * Carlo Ferrario (born 1986), Italian footballer * Joseph Anthony Ferrario (1926–2003), American Roman Catholic bishop ...

. Phenoxathiin is used in

polyamide A polyamide is a polymer with repeating units linked by amide bonds. Polyamides occur both naturally and artificially. Examples of naturally occurring polyamides are proteins, such as wool and silk. Artificially made polyamides can be made through ...

and polyimide production. Because of its odor reminiscent of

scented geranium ''Pelargonium'' () is a genus of flowering plants that includes about 280 species of perennials, succulents, and shrubs, commonly called geraniums, pelargoniums, or storksbills. '' Geranium'' is also the botanical name and common name of a sep ...

, 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.

Related compounds

It is a component of important

hormone A hormone (from the Greek participle , "setting in motion") is a class of signaling molecules in multicellular organisms that are sent to distant organs by complex biological processes to regulate physiology and behavior. Hormones are require ...

T3 or

Triiodothyronine Triiodothyronine, also known as T3, is a thyroid hormone. It affects almost every physiological process in the body, including growth and development, metabolism, body temperature, and heart rate. Production of T3 and its prohormone thyroxine ...

. Several

polybrominated diphenyl ethers Polybrominated diphenyl ethers or PBDEs, are a class of organobromine compounds that are used as flame retardants. Like other brominated flame retardants, PBDEs have been used in a wide array of products, including building materials, electronics, ...

(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.DIRECTIVE 2003/11/EC of the European Parliament and of the Council
/ref> 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. Decabromodiphenyl ether

References

{{DEFAULTSORT:Diphenyl ether Symmetrical ethers Sweet-smelling chemicals