III. INDUSTRIAL PREPARATION 495 



Still another partial oxidation product, a-tocopheroxide, was obtained 

 by Boyor and his associates'-*^ ■ '-' by oxidizing a-tocopherol with two eciiii- 

 valents of ferric iron in the presence of a ,a-dipyridyl. If treated immediately 

 by ascorbic acid, the product could be reduced to a-tocopherol, as shown 

 bv the absorption spectrum, but after some days it was irreversibly con- 

 verted to tocopherylquinone; in the ultraviolet region its peak is at 2370 

 A. ; in the infrared it lacks the characteristic absorption of the OH groups 

 at 30 A. Its chemical properties are those of an epoxy compound, the epoxy 



H3C 



CH3 



^CieHa 



o 



H2 

 H2 



2,5,7,8-Tetramethyl-2(4,8,12-trimeth3'ltridecyl)-9,10-epoxy-6(5H)-chromanone 



group probably being in the 8,9 position. Given intraperitoneally in the 

 rat test, it had about one-ninth the activity of a-tocopherol, by mouth onh' 

 one-thirtieth, perhaps related to its rapid oxidation to the inactive toco- 

 pherylquinone. Tocopheroxide may be the second step in the oxidation of 

 tocopherol to its quinone. 



III. Industrial Preparation 



PHILIP L. HARRIS 



A. SOURCE MATERIALS 

 1. Natural Tocopherols 



Corn, cottonseed, soybean, and wheat germ oils with tocopherol con- 

 tents ranging from about 0.1 % to 0.3% constitute the starting material 

 for practically all natural tocopherol preparations. These oils represent a 

 tremendous potential raw material source but one which challenges the 

 manufacturer in his efforts to increase the tocopherol concentration a hun- 

 dredfold, to at least 30 % and sometimes to 100 %, for use in pharmaceutical 

 products. 



The tocopherols in cfjrn oil are largely 7-tocopherol, those in cottonseed 

 oil are a- and 7-tocopluM()ls in ahout ('([\u\\ amounts, those in soybean oil 



'20 P. D. Boyer, M. Rabinovitz, and E. Liehe, Ann. .\ . Y. Acad. Sci. 52, ISS (1049). 

 '" P. D. Boyer, J. Am. Chem. Soc. 73, 733 (1951). 



