Chemistry of ascorbic acid Haworth and Szent-Györgyi, respectively. Ascorbic acid is a vinylogous carboxylic acid and forms the ascorbate anion when deprotonated on one of the hydroxyls. This property is characteristic of reductones: enediols with a carbonyl group adjacent to the enediol group, namely with the group –C(OH)=C(OH)–C(=O)–. The ascorbate anion is stabilized by electron delocalization that results from resonance between two forms: For this reason, ascorbic acid is much more acidic than would be expected if the compound contained only isolated hydroxyl groups. The ascorbate anion forms salts, such as sodium ascorbate, calcium ascorbate, and potassium ascorbate. Ascorbic acid can also react with
Chemistry of ascorbic acid acid solution. Electrolyzing the solution of potassium iodide produces iodine, which reacts with ascorbic acid. The end of process is determined by potentiometric titration in a manner similar to Karl Fischer titration. The amount of ascorbic acid can be calculated by Faraday's law. Another alternative uses "N"-bromosuccinimide (NBS) as the oxidizing agent, in the presence of potassium iodide and starch. The NBS first oxidizes the ascorbic acid; when the latter is exhausted, the NBS liberates the iodine from the potassium iodide, which then forms the blue-black complex with starch. Chemistry of ascorbic acid Ascorbic acid is an organic compound with