4,4'-Biphenol
Chemical compound
From Wikipedia, the free encyclopedia
4,4â²-Biphenol is an organic compound with the formula (C6H4OH)2/ It is one of three symmetrical isomers of biphenol. It is a colourless crystalline solid with a high melting point. It is primarily used in the production of polymers, particularly liquid crystals where it imparts high thermal stability, and PPSU-type polysulfone (also called polyphenylenesulfone, or Radel R).[2]
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| Names | |
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| Preferred IUPAC name
[1,1â²-Biphenyl]-4,4â²-diol | |
| Other names
4,4â²-Dihydroxybiphenyl 4,4â²-Diphenol 4,4â²-Biphenyldiol | |
| Identifiers | |
3D model (JSmol) |
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| ECHA InfoCard | 100.002.001 |
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| KEGG | |
PubChem CID |
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| UNII | |
CompTox Dashboard (EPA) |
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| Properties | |
| C12H10O2 | |
| Molar mass | 186.210 g·molâ1 |
| Appearance | colorless or white solid |
| Melting point | 283 °C (541 °F; 556 K)[1] |
| Boiling point | Sublimes |
| Insoluble in water Soluble in ethanol and ether | |
| Hazards | |
| Flash point | > 93.3 °C (199.9 °F; 366.4 K) |
| Safety data sheet (SDS) | MSDS |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Synthesis
The industrial synthesis of 4,4â²-biphenol was developed in the 1960s by Allan Hay, while working at the historic General Electric Research Laboratory.[3][4] As the direct oxidative coupling of phenol gives a mixture of isomers,[5][6] 4,4â²-biphenol is instead prepared from 2,6-di-tert-butylphenol, where para-coupling is the only possibility.[4] A reaction with oxygen produces phenol-radicals which undergo rapid dimerisation, ultimately forming a diphenoquinone.
This intermediate is reduced to the tetra-butyl-biphenyl derivative by a reaction with two equivalents of 2,6-di-tert-butylphenol, in an oxygen-free environment (with the radicals generated dimerising to form additional tetra-butyl-biphenyl).[3] In the final step, high temperature dealkylation is performed to remove the butyl groups, producing the desired 4,4â²-biphenol product.[4] If groups less bulky that t-butyl are used then polyphenylene ethers such as poly(p-phenylene oxide) can be produced.[7]
Safety
4,4'-Biphenol exhibits estrogenic SAR.[8]