title: [Photochemical reaction of chlorophyll a and pheophytin a with low concentrations of hydroquinone].
abstract: It has been shown that when illuminating chlorophyll a solution (approximately 10(-5) M) in ethanol containing small concentrations of hydroquinone at pH higher than 7, a markable negative photopotential (-PhP) is initiated. Similar picture is also observed both in the presence of 2 . 10(-5) M parabenzoquinone and when using pheophytin a instead of chlorophyll. The data obtained are in favour of the idea that when illuminating the solutions of these pigments in ethanol containing pure p-benzoquinone at pH higher than the definite value, PhP initiation is conditioned by photochemical reaction of pigments with equilibrium amounts of hydroquinones or semiquinone always present in quinone solutions.
mesh_terms: D055598:Chemical Phenomena; D002621:Chemistry; D002734:Chlorophyll / Q000528:radiation effects*; D006863:Hydrogen-Ion Concentration; D006873:Hydroquinones; D008027:Light; D010674:Pheophytins / Q000528:radiation effects; D010777:Photochemistry
chemical_list: D006873:Hydroquinones; D010674:Pheophytins; D002734:Chlorophyll
vernacular_title: O fotokhimicheskom vzaimodeĭstvii khlorofilla a i feofitina a s malymi kontsentratsiiami gidrokhinona.