2,6-Di-tert-butylphenol

2,6-Di-tert-butylphenol is an organic compound with the structural formula 2,6-((CH₃)₃C)₂C₆H₃OH. This colorless solid alkylated phenol and its derivatives are used industrially as UV stabilizers and antioxidants for hydrocarbon-based products ranging from petrochemicals to plastics.^[1] Illustrative of its usefulness, it prevents gumming in aviation fuels.

2,6-Di-tert-butylphenol

Names
Preferred IUPAC name 2,6-Di-tert-butylphenol
Other names 2,6-Bis(1,1-dimethylethyl)phenol Dibutylphenol 2,6-Bis(tert-butyl)phenol 2,6-Di(1,1-dimethylethyl)phenol 2,6-DTBP Ethanox 701 Ethyl 701 Ethyl AN 701 Irganox L 140 Isonox 103 TK 12891
Identifiers
CAS Number	128-39-2 Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:131421 N
ChEMBL	ChEMBL281071 Y
ChemSpider	29135 Y
ECHA InfoCard	100.004.441
EC Number	204-884-0
PubChem CID	31405
RTECS number	SK8265000
UNII	21294V58PF
UN number	2430, 3077
CompTox Dashboard (EPA)	DTXSID6027052
InChI InChI=1S/C14H22O/c1-13(2,3)10-8-7-9-11(12(10)15)14(4,5)6/h7-9,15H,1-6H3 Y Key: DKCPKDPYUFEZCP-UHFFFAOYSA-N Y InChI=1/C14H22O/c1-13(2,3)10-8-7-9-11(12(10)15)14(4,5)6/h7-9,15H,1-6H3 Key: DKCPKDPYUFEZCP-UHFFFAOYAK
SMILES Oc1c(cccc1C(C)(C)C)C(C)(C)C
Properties
Chemical formula	C14H22O
Molar mass	206.329 g·mol−1
Appearance	Low-melting colourless solid
Melting point	34 to 37 °C (93 to 99 °F; 307 to 310 K)
Boiling point	253 °C (487 °F; 526 K)
Hazards
GHS labelling:
Pictograms
Signal word	Warning
Hazard statements	H315, H319, H410
Precautionary statements	P264, P273, P280, P302+P352, P305+P351+P338, P321, P332+P313, P337+P313, P362, P391, P501
Flash point	118 °C (244 °F; 391 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

Production

2,6-Di-tert-butylphenol is prepared industrially via the Friedel–Crafts alkylation of phenol with isobutene catalyzed by aluminium phenoxide:

C₆H₅OH + 2 CH₂=C(CH₃)₂ → ((CH₃)₃C)₂C₆H₃OH

In this way, approximately 2.5M kg/y are produced.^[2] Alkylation of phenol usually favours the para-position, and a strong lewis acid such as the Al³⁺ ion is necessary to give selective ortho‑alkylation.^[3][4] If a conventional brønsted acid is used then 2,4-di-tert-butylphenol will be produced instead.

Applications

Its dominant use is as an antioxidant.

2,6-di-tert-butylphenol is a precursor to more complex compounds used as antioxidants and light-protection agents for the stabilization for polymers. Of particular note is methyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate (CAS# 6386-38-5), which is formed by the Michael addition of methyl acrylate. This compound is used as a feedstock in the synthesis of more complex antioxidants such as Irganox 1098. 2,6-Di-tert-butylphenol is also used in the synthesis of CGP-7930, probucol, and nicanartine.

Safety and regulation

The LD₅₀ is 9200 mg/kg, indicating a low toxicity.^[2]

2,6-Di-tert-butylphenol is covered by the U.S. Department of Transportation Code of Federal Regulations 49 CFR 172.101, Appendix B (20 Dec 2004). This substance is designated by the U.S. Department of Transportation (DOT) as a marine pollutant.

See also

• Butylated hydroxytoluene
• 2,4-di-tert-butylphenol
• 2,4-Dimethyl-6-tert-butylphenol
• Para tertiary butyl phenol

References

1. Peter P. Klemchuk (2005). "Antioxidants". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a03_091. ISBN 978-3527306732.
2. Helmut Fiege; Heinz-Werner Voges; Toshikazu Hamamoto; Sumio Umemura; Tadao Iwata; Hisaya Miki; Yasuhiro Fujita; Hans-Josef Buysch; Dorothea Garbe; Wilfried Paulus (2002). "Phenol Derivatives". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a19_313. ISBN 978-3527306732.
3. Kolka, Alfred J.; Napolitano, John P.; Filbey, Allen H.; Ecke, George G. (June 1957). "The ortho-Alkylation of Phenols 1". The Journal of Organic Chemistry. 22 (6): 642–646. doi:10.1021/jo01357a014.
4. Küpper, Friedrich-Wilhelm (June 2004). "A new mechanism — key for an improved synthesis of 2,6-di-tert-butylphenol". Applied Catalysis A: General. 264 (2): 253–262. doi:10.1016/j.apcata.2003.12.043.