Clifford W. J. Chang

Electronic spectra of substituted naphthoquinones

Abstract Echinoderms elaborate many closely related structural pigments (spinochromes) based on a naphthoquinone skeleton. As an aid to structural elucidation of these compounds the electronic spectra of a large number of substituted naphthoquinones were examined. The bands in the 240–600 mμ region of the electronic spectra of 1,4-naphthoquinone, juglone, and naphthazarin have been assigned to either benzenoid or quinoid electronic excitations and the effect of substitution on the position of these bands has been systematically studied. As a result, a number of empirical correlations have been derived that are useful in the structure determination of unknown pigments.

Polyhydroxynaphthoquinones : Preparation and hydrolysis of methoxyl derivatives☆

Abstract The conditions for selective methylation and hydrolysis were studied for a large number of polyhydroxynaphthoquinones. As a result it has become possible to predict the course of these reactions and therefore utilize these derivatives for readier separation and identification of naturally occurring echinoderm pigments.

Nitration of 2,3-dimethoxynaphthalene

Nitration of 2,3-dimethoxynaphthalene leads to three mononitro-products, one dinitro-product, and one 1,2-naphthaquinone. Structural assignments, based largely on spectral data, differ in part from those in the literature.