Preparation and antioxidant activities of phenolic esters and ethers of L-ascorbic acid
1998
Gan, L. | Seib, P.A.
Esterification of L-ascorbic acid in concentrated sulfuric acid with 0.33 moles of gallic acid gave a 90% yield of a 2:5 mixture of L-ascorbyl 5- and 6-gallate esters. The 6-gallate ester (1) was purified from the 5-gallate ester (2) by fractional crystallization in 40% yield. Three other aromatic derivatives of L-ascorbic acid also were prepared. The order of antioxidant activities of the L-ascorbyl derivatives determined by thiobarbituric acid number in methyl linolenate at 37 degrees C was as follows: 6-gallate (1)>6-(3',4'-dihydroxy)benzoate (3) approximately equal to 6-(4'-hydroxy)phenyl ether (4)>6-(4'methoxy)phenyl ether (5).
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