Radiation Chemistry of Polysaccharides: 2. Free-Radical Mechanisms of Formation of Citric Acid and Dicarboxylic Acids

摘要

Based on experimental data on the buildup of citric acid and dicarboxylic (succinic, malic, fumaric, tartaric, and malonic) acids in native starches, low-temperature ESR measurement results, and reaction rate- or reaction yield-detected magnetic resonance data (room temperature, cellulose), the sequences of elementary events (mechanisms) of transformation of free radicals in the anhydroglucose ring of glucose high polymers up to the formation of these acids were determined. Time ranges for the generation of radicals in reactions, such as dehydration (H_2Oβ-elimination), oxygenation, isomerization involving C–C and C–O bond cleavage, and rearrangement of C–H bonds, were estimated at (3–7) * 10~(-9) to (8–10) * 10~(-8) s.