5,8-dihydroxy naphthalene-1,4-dione derivative and a hair dye composition containing the same

摘要

A naphthalene derivative having the general formula: <IMAGE> (I) wherein R represents hydrogen, an alkyl group having 1 to 8 carbon atoms, an R1O (CH2)n group, or a benzyl group, R1 represents hydrogen or a lower alkyl group, and n represents an integer of 2 or 3. This compound in the leuco state can be stably isolated and can produce a strong and fast color upon oxidation under moderate conditions. This compound can be advantageously included in a hair dye composition, which is capable of stably and safely dyeing hair with a good and stable color under moderate conditions.