- The Photochemical Discolouration of Methoxy-p-benzoquinone in Solution
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Irradiation of a dimethoxyethane solution of methoxy-p-benzoquinone with sun-light lamps results in discolouration of the solution and the rapid disappearance of the starting material.A strongly coloured red dibenzofuran derivative, 8-hydroxy-3,7-dimethoxybenzofuran-1,4-quinone, was isolated from the reaction mixture and identified by comparison with the synthesized compound.The photochemical reactions of the possible intermediates, the dimer quinones 5-methoxy-2-(2,5-dihydroxy-4-methoxyphenyl)1,4-benzoquinone and 4,4'-dimethoxybiphenyl-2,5,2',5'-bis-quinone, were also studied by visible light spectroscopy and significant changes in the spectra were observed.It is concluded that these dimer quinones and their rearrangement products play a significant role in the production of colour in old methoxy-p-benzoquinone solutions and other solutions in which this quinone participates as an intermediate.In alkaline aqueous solution the isolated dibenzofuran derivative rapidly disappears via radical reactions.
- Forsskahl, Ingegerg,Gustafsson, Jean,Nybergh, Anna
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p. 389 - 394
(2007/10/02)
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