Anthrone, used as intermediate for benzoanthrone dyes - prepd. by heating (1,4,4a,9a-tetra)-hydro-anthra-quinone in inert gas atmos.

摘要

is heated at >200 degrees C in an atmos. free of oxygen, to prepare anthrone. This process is novel, simple without using large amounts of mineral acid, solvent and expensive catalyst required by conventional methods. Anthrone is a useful compound as the intermediate for dyes of benzoanthrone derivatives and as a starting material for organic synthesis. 1,4,4a,9a-tetrahydroanthraquinone (I) is easily obtained by Diels-Alder reaction between 1,4-naphthoquinone and butadiene. (I) is heated in a nitrogen atmos. at >200 degrees C pref. ca. 300 degrees C for ca. 3 hours. The reaction mixture usually contains anthrone, anthraquinone, anthracene, unreacted (I) etc. Anthrone is extracted with solvent, which dissolves anthrone only.