Diphenyl ether

Diphenyl ether is an organic compound with the formula (C6H5)2O. It is a colorless, low-melting solid that is the simplest diaryl ether[1]. The compound has a variety of niche applications, including as a eutectic mixture with biphenyl, which is used as a heat transfer fluid due to its large temperature range of its liquid state. Diphenyl ether is also used as a starting material in the production of phenoxathiin, which is used in polyamide and polyimide production. Additionally, it is used in soap perfumes due to its odor reminiscent of scented geranium, as well as its stability and low price. It is also used as a processing aid in the production of polyesters.

Diphenyl ether is synthesized by a modification of the Williamson ether synthesis, involving the reaction of phenol and bromobenzene in the presence of base and a catalytic amount of copper. It undergoes reactions typical of other phenyl rings, including hydroxylation, nitration, halogenation, sulfonation, and Friedel–Crafts alkylation or acylation.

The compound has a molecular weight of 170.2072 and is also known by other names such as benzene, 1,1'-oxybis-; phenyl ether; benzene, phenoxy-; biphenyl oxide; diphenyl oxide; phenoxybenzene; phenyl oxide; ether, diphenyl-; oxydiphenyl; and geranium crystals[2]. It is commercially available with a purity of ≥99% and has a melting point of 259 °C[3][4].

Diphenyl ether is a component of important hormone T3 or triiodothyronine. Several polybrominated diphenyl ethers (PBDEs) are useful flame retardants, with decaBDE being a high-volume industrial chemical used in the manufacture of paints and reinforced plastics.

In terms of safety, diphenyl ether has a flash point of 115 °C and is classified as a combustible solid[3][4]. It is also considered hazardous to aquatic life and may cause eye irritation[3][4]. The NIOSH Pocket Guide to Chemical Hazards recommends preventing skin contact and eye contact, and provides guidance on respiratory protection and first aid measures in case of exposure[5].

Citations:

[1] https://en.wikipedia.org/wiki/Diphenyl_ether

[2] https://webbook.nist.gov/cgi/cbook.cgi?ID=101-84-8

[3] https://www.sigmaaldrich.com/US/en/product/aldrich/240834

[4] https://www.sigmaaldrich.com/US/en/product/mm/820978

[5] https://www.cdc.gov/niosh/npg/npgd0496.html