Syntheses of the 1-, 2-, and 4-thiosemicarbazones and the 1- and 4-amidinohydrazones of 2-hydroxy-1,4-naphthoquinone (I) are described. The position of condensation of the quinone (I) with thiosemicarbazide is pH dependent in contrast to condensation with aminoguanidine which is independent of pH. A possible explanation for this difference is presented. Chemical and spectral evidence is presented to support the structural assignments for the products.
Thiosemicarbazone and Amidinohydrazone Derivatives of Some 1,4-Naphthoquinones
Carroll, F., Miller, H. W., & Meck, R. (1970). Thiosemicarbazone and Amidinohydrazone Derivatives of Some 1,4-Naphthoquinones. Journal of the Chemical Society C: Organic Chemistry, 1993, 1993-1996. https://doi.org/10.1039/J39700001993