Summary 1. Thiaxanthenol-5-dioxide and several of its derivatives have been prepared and characterized. 2. The existence of a mobile, two-step oxidation-reduction equilibrium between thiaxanthenol-5-dioxide and thiaxanthone-5-dioxide in alkaline solution has been established. By optical, chemical and electrochemical means it was shown that the colored entity in this equilibrium is a semiquinone.
[Brumfield, Martha A.; Quillen, Suzanne L.; Yoon, Ung Chan; Mariano, Patrick S. Journal of the American Chemical Society, 1984 , vol. 106, # 22 p. 6855 - 6856]
