Date of Award
Master of Arts
Dr. Donald R. Schreiber
Dr. James Howell
Dr. Donald C. Berndt
Masters Thesis-Open Access
The nonenzymatic autoxidation of the phenolic compounds chlorogenic acid in aqueous solution was studied. The study demonstrated that the oxidation rate of chlorogenic acid was strongly dependent on pH. The higher the pH, the faster the rate of oxidation. The involvement of phenolate ions and radicals in oxidation reactions are two possible reasons for the pH dependency. The presence of a trace amounts of reducible transition metal ions, such as copper(II), dramatically increases the oxidation rate of chlorogenic acid. Light also increases the oxidation rate of chlorogenic acid. However, the photochemical reaction was a much slower process.
The TLC and HPLC results show that the oxidation of chlorogenic acid produces a mixture. The percentage of the various components in the mixture was affected by oxidation time.
The NMR results indicate that under strong alkaline conditions, some chlorogenic acids were initially hydrolyzed into caffeic acid and quinic acid. The study also showed that the oxidation of caffeic acid was pH dependent. The oxidation rate of caffeic acid was much faster than that of chlorogenic acid under acidic and neutral conditions.
Both NMR and UV /VIS results demonstrated that the conjugated double bond on the side chain of chlorogenic acid was involved in the oxidation reaction.
Jiang, "An Investigation on Nonenzymatic Autoxidation of Phenolic Compounds in Natural Waters" (1996). Master's Theses. 4357.