Fotoutlenianie

Fotoutlenianie, commonly translated as photochemical oxidation, is the chemical process in which light energy promotes the oxidation of a substrate, typically through reactive oxygen species generated during irradiation. In irradiation events, molecules can reach excited electronic states that react with molecular oxygen or other oxidants, leading to formation of radicals, hydroperoxides, carbonyls and other oxidized products. Mechanisms include direct photooxidation by excited species, energy transfer to oxygen that produces singlet oxygen, and photosensitized oxidation in which a sensitizer mediates electron transfer or hydrogen abstraction.

The process plays a major role in several fields. In materials science, fotoutlenianie contributes to the aging and degradation of polymers and coatings exposed to sunlight, causing changes such as chain scission, embrittlement, and formation of oxidative functional groups. In environmental chemistry, photochemical oxidation drives the degradation of organic pollutants in surface waters and soils, often transforming compounds into more polar or mineralized products. In biology, light-induced oxidative stress can occur when photosensitive processes generate reactive oxygen species in cells.

Factors that influence the rate and outcome of fotoutlenianie include light intensity and spectrum (especially UV and visible wavelengths), exposure duration, temperature, and the presence of oxygen. The chemical structure of the substrate and the availability of photosensitizers or catalysts also play important roles. Stabilizers such as UV absorbers and antioxidants can slow photooxidation in materials, while environmental conditions and pollutant properties determine degradation pathways.

Studying fotoutlenianie typically involves monitoring changes in oxidation state (for example, carbonyl formation by infrared spectroscopy), tracing oxygen consumption, detecting radical and reactive intermediates (e.g., by EPR), and identifying oxidation products by chromatography and mass spectrometry.