496 THE TOCOPHEROLS 



are a, 7, and 5 forms, and those in wheat germ oil are a- and |8-tocopherols.^"^ 

 Consequently, concentrates made from any of these oils represent a prepa- 

 ration of the particular predominant tocopherol or tocopherols of the origi- 

 nal oil. The tocopherols in the commercial concentrates of mixed tocopherols 

 are standardized to contain 50% a-tocopherol and the remainder 7- plus 

 6-, with only negligible amounts of /3-tocopherol. 



The preparation of concentrates of the a form of tocopherol is of prime 

 interest, since this form possesses the highest physiological activity. How- 

 ever, concentrates of the individual (8-, 7-, and 5-tocopherols can be pre- 

 pared. ^"^ 



2. Synthetic Tocopherols 



Trimethylhydroquinone and phytol or phytyl chloride are most often 

 mentioned as source chemicals for the preparation of synthetic, racemic 

 a-tocopherol. However, the synthesis can be carried out with a variety of 

 other starting materials,^- ^ but apparently with considerably more diffi- 

 culty and less efficiency. 



Synthetic /3- and 7-tocopherols, A\'ith two methyl groups, and synthetic 

 5-tocopherol, with only one methyl group, on the chroman ring, can be 

 prepared from the properly constituted dimethyl- and monomethylhydro- 

 quinones, respectively, and phytol. 



B. PROCEDURES 



Details of commercial operations in the vitamin E field have not been 

 published. However, the following references cover procedures which should 

 be usable. 



1. Natural Tocopherols 



Saponification, with subsequent extraction and concentration of tocoph- 

 erols in the non-saponifiable fraction, is a feasible method for preparing 

 low potency preparations. It is used, for example, to make about an eight- 

 fold concentration of the tocopherols of wheat germ oil (Table I). Similarly, 

 direct, hot ethanol extraction of wheat germ, followed by low-temperature 



1 E. L. Hove and Z. Hove, J. Biol. Chem. 156, 601 (1944). 

 2M. L. Quaife, /. Biol. Chem. 175, 605 (1948). 

 3 F. Brown, Biochem. J. 51, 2.37 (1952). 

 * F. Brown, Biochem. J. 52, 52.3 (1952). 



6.1. G. Baxter, C. D. Robeson, J. D. Taylor, and R. W. Lehman, /. Am. Chem. 

 Soc. 65, 918 (1943). 



6 C. D. Robeson, /. Am. Chem. Soc. 65, 1660 (1943). 



7 M. H. Stern, C. D. Rol)eson, L. Weisler, and J. G. Baxter, /. Am. Chem. Sor. 69, 

 869 (1947). 



8 L. I. Smith, Chem. Revs. 27, 287 (1940). 



9 W. John and H. Pini, Z. physiol. Chem. 273, 225 (1942). 



I 



