α-Tocopherol[1]
IUPAC name	(2R)-2,5,7,8-Tetramethyl-2-[(4R,8R)-(4,8,12-trimethyltridecyl)]-6-chromanol
Identifiers
CAS number	59-02-9 Y
PubChem	14985
EC number	200-412-2
SMILES	Oc2c(c(c1O[C@](CCc1c2C)(C)CCC[C@H](C)CCC[C@H](C)CCCC(C)C)C)C
InChI	1/C29H50O2/c1-20(2)12-9-13-21(3)14-10-15-22(4)16-11-18-29(8)19-17-26-25(7)27(30)23(5)24(6)28(26)31-29/h20-22,30H,9-19H2,1-8H3/t21-,22-,29-/m1/s1
InChI key	GVJHHUAWPYXKBD-IEOSBIPEBS
ChemSpider ID	14265
Properties
Molecular formula	C29H50O2
Molar mass	430.71 g/mol
Density	0.950 g/cm³
Melting point	2.5-3.5 °C
Boiling point	200-220 °C at 0.1 mmHg
Y (what is this?)  (verify) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

α-Tocopherol is a type of tocopherol with formula C₂₉H₅₀O₂. It has E number "E307".

α-Tocopherol is a form of vitamin E that is preferentially absorbed and accumulated in humans.^[2] The measurement of "vitamin E" activity in international units (IU) was based on fertility enhancement by the prevention of spontaneous abortions in pregnant rats relative to alpha-tocopherol.

There are three stereocenters in alpha-tocopherol, so this is a chiral molecule.^[3] The eight stereoisomers of alpha-tocopherol differ in the arrangement of groups around these stereocenters. In the image of RRR-alpha-tocopherol below, all three stereocenters are in the R form. However, if the middle of the three stereocenters were changed (so the hydrogen was now pointing down and the methyl group pointing up), this would become the structure of RSR-alpha-tocopherol. RSR-alpha-tocopherol and RRR-alpha-tocopherol are diastereomers of each other. These stereoisomers can also be named in an alternative older nomenclature, where the stereocenters are either in the d or l form.^[4]

1 IU of tocopherol is defined as ⅔ milligrams of RRR-alpha-tocopherol (formerly named d-alpha-tocopherol or sometimes ddd-alpha-tocopherol). 1 IU is also defined as 1 milligram of an equal mix of the eight stereoisomers, which is a racemic mixture called all-rac-alpha-tocopheryl acetate. This mix of stereoisomers is often called dl-alpha-tocopheryl acetate, even though it is more precisely dl,dl,dl-alpha-tocopheryl acetate). However, 1 IU of this racemic mixture is not now considered equivalent to 1 IU of natural (RRR) α-tocopherol, and the Institute of Medicine and the USDA now convert IU's of the racemic mixture to milligrams of equivalent RRR using 1 IU racemic mixture = 0.45 "milligrams α-tocopherol".^[5]

[edit] References