492 THE TOCOPHEROLS 



C. PHYSICAL PROPERTIES J 



The absorption maxima, in the ultraviolet, of a-, /3-, and 7-tocopherol 

 are given as 292, 297, and 298 mju, respectively;^^ those of the synthetic 

 compounds are the same except for the 7, which was at 300 m/x; the ex- 

 tinction coef!icients2«' '^' ^^ are 70 to 73.7, 86 to 87, and 90 to 93. 



Infrared spectra of some natural and synthetic tocopherols, their esters, 

 tocopherylquinone, and hydroquinone were obtained by Rosenkrantz;^'*- ^^ 

 bands near 8.6 /x and 10.9 m are characteristic of tocopherols. Much may 

 be expected from the application of spectrophotometric methods in the 

 elucidation of structure of the tocopherols, their oxidation products, and 

 derivatives. 



The specific rotations of the a, /3, and 7 compounds in ethyl alcohol are 

 +0.32, +2.9, and +2.2, respectively; in benzene those of the a and 7 are 

 -3.0 and -2.4.^3 



D. PRODUCTS OF OXIDATION 



Tocopherylquinone, the first stable oxidation product of tocopherol, is a 

 yellow compound and is obtained by the action of ferric chloride or silver 



HsC 



CH3 OH 



I o 



/CH, 



C16H3 



CHs/^ 

 a-Tocopherylquinone 



nitrate. It was identified by John^^ and is quite without activity for the 

 rat.^^' ^^'^^ The same quinone was produced by Karrer et at. with various 

 agents;^"'' with gold chloride a potentiometric titration was made the basis 

 of a quantitative determination. 1°^ This quinone can be reduced to tocoph- 

 erylhydroquinone by the use of palladium in alcohol or of zinc in glacial 

 acetic acid and is unstable unless acetylated. In strong acid solution with 



8' J. G. Baxter, C. D. Robeson, J. D. Taylor, and R. W. Lehman, J . Avi. Chem. Soc. 



65, 918 (1943). 

 9*H. Rosenkrantz, /. Biol. Chem. 173, 439 (1948). 

 85 H. Rosenkrantz and A. T. Milhorat, /. Biol. Chem. 187, 83 (1950); /. Am. Chem. 



Soc. 72, 3304 (1950). 

 9« P. Karrer and A. Geiger, Helv. Chim. Acta 23, 455 (1940). 

 9^ C. Golumbic and H. A. Mattill, J. Biol. Chem. 134, 535 (1940). 



98 M. D. Wright and J. C. Drummond, Biochem. J. 34, 32 (1940). , 



99 R. R. Ridgeway, J. C. Drummond, and M. D. Wright, Biochem. J. 34, 1569 (1940). 

 ""> P. Kerrer, R. Escher, H. Fritzsche, H. Keller, B. II. Ringier, and H. Salomon, [ 



Helv. Chim. Acta 21, 939 (1938). 

 "1 P. Karrer and H. Keller, Helv. Chim. Acta 21, 1161 (1938); 22, 253, 617 (1939). 



