Abstract: A stetic capillary mcthcd of ESR has been used to investigate the chemical reactions of gentisic acid in different alkaline solutions. The ESR spectra of chemical reactions of gentisic acid in sodium alkoxide-alcohol were different from those in sodium hydroxide aqueous solution. The difference was given as follows:
1. The chemical reactions of gentisic acid in sodium alkoxide-alcohol solution were autcoxidation. Three new free radicals in the chemical reactions were found and their structural models were given.
2. The chemical rearlions of gentistic acid in sodium hydroxide aqueous solution were first autooxidation and then substitution. A new free radical in the autooxidation step was found and its structural model was given^[1]. In the substicittiea step the hydrogen(H) on the benzene ring of the gentisic acid was substisated by the hydroxyl group (OH) in the solution.

Key words: Gentisic acid, Free radical, Alkaline solution