814 



IX. THE VITAMIN E GROUP 



The tocopherols exhibit characteristic absorption spectra in the infrared 

 spectrum. Absorption bands occur in the neighborhood of 3.0, 6.3, and 

 8.0 ij.; additional unassigned absorption bands near 8.6 and 10.9 /x are 

 characteristic of the tocopherol structure. ^"^ The maximum which occurs 

 at 2.9 to 3.0 /x is due to the effect of the hydroxyl group, while the intense 



2100 2300 2500 2700 2900 3100 



^^ IN ANGSTROM UNITS 

 Fig. 4. Absorption spectrum of a-tocopiieroi in iso-octane.^^ 



absorption at 8.0 m is probably to be traced to the C — O vibration of the 

 phenolic hydroxyl. The conjugated C=C system of the benzene portion of 

 the molecule accounts for the strong band in the 6.15 to 6.35 n region. 

 Phenol itself has a strong absorption maximum at 6.27 m-^"^ Some absorp- 

 tion also originates near 3.25 n from the C — H groups of benzene, while the 



ics H. Rosenkrantz, J. Biol. Chem., 173, 439-447 (1948). 



i<" R. B. Barnes, R. C. Gore, U. Liddel, and V. Z. Williams, Infrared Spectroscopy. 

 Industrial Applications and Bibliography, Reinhold, New York, 1944. 



