STRUCTURE OF THE K VITAMINS 



833 



methyl-3-phytyl-l,4-naphthoqiiinone (I), largely as a result of the experi- 

 mental work of the Doisy group. 



HC'6 





"t 3C-CH, 



; zC-CHjCH^C CH^CHjCHjCHCHjCH^CHjCHCHjCHjCH^CHCHj 

 \j CHj CHj CHj CH3 



A number of circumstances indicate that vitamin Ki contains a naphtho- 

 quinone residue. In the first place, the redox potential is found to be 

 similar to that of many known 1 ,4-quinones*^ such as the anthraquinone- 

 hydroanthraquinone system. ^'^■■'^ Second, the ultraviolet absorption spec- 

 trum corresponds closely to that given by 2,3-disubstituted-l,4-naphtho- 

 quinones.^^ Still another circumstance which points to the quinone struc- 

 ture is the instability of the vitamin toward light and alkali. Furthermore, 

 McKee et al. ^^ found that vitamin Ki absorbs 8 atoms of hydrogen to form 

 a colorless compound (II) on catalytic hydrogenation ; in the light this re- 

 oxidizes to give a yellow compound (III) similar in color to that of the 

 original vitamin. The quinone, after reduction, may be oxidized as shown. 



I 



4H, 



HjC 



H^ OH 

 C CCH, 



Cn« CH-. CHt CH« 



I I I I I 



Hf C C-CH^CHjCHCHjCHjCHjCHCH^CHjCH^CHCHjCHjCH^CHCH, 



C C 



H, 



OH 



H 



Ha ^ 

 HX C CCHj CH, 



CH, 



CH, 



CH, 



HjC h C-CH^CHjCHCHjCHjCHjCHCH^CHjCH^CHCH^CH^CH^CHCHj 



C C' 



H 'I 



n 



Autoxidation of Octah^^drovitamin Ki in Light 



« S. B. Binklev, D. W. MacCorquodale, L. C. Cheney, S. A. Thayer, R. W. McKee, 

 and E. A. Doisy, /. Am. Chem. Soc, 61, 1612-1613 (1939). 



