α-Tocopherol
Names | |
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Preferred IUPAC name
(2R)-2,5,7,8-Tetramethyl-2-[(4R,8R)-4,8,12-trimethyltridecyl]-3,4-dihydro-2H-1-benzopyran-6-ol | |
Identifiers | |
3D model (
JSmol ) |
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ChEBI | |
ChEMBL | |
ChemSpider | |
DrugBank | |
ECHA InfoCard
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100.000.375 |
EC Number |
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E number | E307a (antioxidants, ...) |
PubChem CID
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UNII | |
CompTox Dashboard (EPA)
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Properties | |
C29H50O2 | |
Molar mass | 430.71 g/mol |
Appearance | yellow-brown viscous liquid |
Density | 0.950 g/cm3 |
Melting point | 2.5 to 3.5 °C (36.5 to 38.3 °F; 275.6 to 276.6 K) |
Boiling point | 200 to 220 °C (392 to 428 °F; 473 to 493 K) at 0.1 mmHg |
insoluble | |
Solubility | soluble in alcohol, ether, acetone, oils |
Pharmacology | |
A11HA03 (WHO) | |
Hazards | |
NFPA 704 (fire diamond) | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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α-Tocopherol (alpha-tocopherol) is a type of vitamin E. Its E number is "E307". Vitamin E exists in eight different forms, four tocopherols and four tocotrienols. All feature a chromane ring, with a hydroxyl group that can donate a hydrogen atom to reduce free radicals and a hydrophobic side chain which allows for penetration into biological membranes. Compared to the others, α-tocopherol is preferentially absorbed and accumulated in humans.
Stereoisomers
α-Tocopherol has three stereocenters, so it is a chiral molecule.[4] The eight stereoisomers of α-tocopherol differ in the configuration of these stereocenters. RRR-α-tocopherol is the natural one.[5] The older name of RRR-α-tocopherol is d-α-tocopherol, but this d/l naming should no longer be used, because whether l-α-tocopherol should mean SSS enantiomer or the SRR diastereomer is not clear, from historical reasons. The SRR may be named 2-epi-α-tocopherol, the diastereomeric mixture of RRR-α-tocopherol and 2-epi-α-tocopherol may be called 2-ambo-α-tocopherol (formerly named dl-α-tocopherol). The mixture of all eight diastereomers is called all-rac-α-tocopherol.[6]
One IU of tocopherol is defined as 2⁄3 milligram of RRR-α-tocopherol (formerly named d-α-tocopherol). 1 IU is also defined as 0.9 mg of an equal mix of the eight stereoisomers, which is a
References
- ^ Merck Index, 11th Edition, 9931.
- PMID 17320165.
- PMID 30936625.
- PMID 17628178.
- S2CID 7031925.
- ^ IUPAC Nomenclature of Tocopherols and Related Compounds, from https://www.degruyter.com/document/doi/10.1351/pac198254081507/pdf
- USDA. February 2008. Archived from the original(PDF) on 2012-02-19.
- ^ "Unit Conversions". National Institutes of Health. Retrieved 2018-11-21.