The separation and identification of the products transformed from indole itself by the action of sunlight were studied. The following results were obtained.
(1) Exposure to sunlight resulted in the decomposition of indole accompanied with brown precipitates, but in case of dark ex-periment no change was observed.
(2) A crystalline material of yellow plates, m. p. 245°, was obtained, it was identical to 2, 2-diindyl-
φ-indoxyl.
(3) Among other products, anthranilic acid was identified by paper chromatography, ul-traviolet spectra or counter-current distribu-tion procedure.
(4) Therefore, a possible mechanism for the transformation of indole was proposed as shown in the scheme.
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