206 



ASCORBIC ACID 



ously, there is formed an isomeric monomethyl ether 1 -methyl heteroascor- 

 bic acid (LXIX) characterized by the red color it gives with ferric chlo- 

 ride/^' *'^ The identification of these two monomethyl ethers shows the 

 facility with which ascorbic acid can pass into its tautomeric modifications. 



LXXII 



LXXIII 



LXXIV 



LXXV 



CH.OH 

 LXXVI 



The monomethyl heteroascorbic acid (LXIX) has been shown to possess 

 high antiscorbutic activity,'^^ no doubt because it readily reverts to L-as- 

 corbic acid. There seems to be some difference of opinion as to how active 

 the 3-methyl-L-ascorbic acid is/^^- '*" but according to the most recent work 

 it prol)ably has about one-fiftieth the activity of L-ascorbic acid.'^'' The 



"9 B. S. Gould, II. M. Goldman, and J. T. Clarke, Arch. Biochem. 23, 205 (1949); 



H. M. Goldman and B. S. Gould, ./. Nutrition 43, 19,3 (1951). 

 '" C. S. Vestling and M. C. Rebstock, J. Biol. Chem. 164, 631 (1946). 



