| Abstract: | It has been shown that under the action of UV light on solid preparations of lignin the generation of electron paramagnetic centers (EPCs) takes place, their concentration rising with a fall in the wavelength of the exciting light. In a dark stage there is a slow  death of EPCs with time. The reactivities of individual model compounds of lignin in radical reactions in solutions were followed with the aid of a stable nitrogen radical used as a spin label. The results show that the efficiency of quenching differs considerably for individual chromophores and decreases in the sequence benzoquinone, vanillin, quinone methide, Björkman lignin, and soda lignin. The change in the concentration of EPCs of the stable radical with time is described by a first-order equation.Siberian Pulp and Paper Scientific-Research Institute, Bratsk. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 236–239, March–April, 1980. |
