834 



X. THE VITAMIN K GROUP 



Another indication of the quinone nature of this vitamin can be de- 

 duced by reductive acetylation, which yields a crystaUine diacetate 

 (IV). ^^ The vitamin can be recovered by means of a Grignard reaction, 

 after which the product is oxidized in the air. The color of the quinone 

 produced is yellow; this indicates that the oxj'-gens are in the 1,4 position 

 in the vitamin. If the oxygen had been present in the 1,2 position, the re- 

 sulting compound would have been red. 



I 



GRISNARD'S REAGENT 

 + 0, 



H OCCH, 

 HC C CCH, 



OH, 



CH.. 



CM^ 



OH, 

 I 



HC. C ^C— CHjCH^CCHjCHjCHjCHCHiCHjCHjCHCHsCHjCHiCHCH, 



H I 



OCCK 



Reversible Reaction of Vitamin K, in the Formation of a Diacetate Hydroquinone 



or a Quinone 



Additional proof of the nature of the cyclic portion of the molecule can be 

 obtained by investigation of the products of chromic acid oxidation. When 

 an excess of chromic acid is employed, phthalic acid (V) originates.^" If 

 the original ring structure is a 1 ,4-naphthoquinone, substitution can be 



H 

 HC CC-OH 



CrOj 



(SMALL AMOUNTI 



H 9 



HC C CCHoC-GH 



HC^ fiC-OH 

 H 



HC. G CCH, 



H II 







Oxidation Products on Strenuous or Mild Oxidation of Vitamin Ki with Chromic Acid 



" D. W. MacCorquodale, S. B. Binkley, S. A. Thayer, and E. A. Doisy, J. Am. Chem. 

 Soc, 61, 1928-1929 (1939). 



