Syntheses of Negative Anthraquinone Type Dichroic Dyes for Liquid Crystal Colour Display

Seventeen negative dichroic dyes of p-alkoxy-benzoylaminoanthraquinone type were prepared with 1 -aminoanthraquinoe, 1, 4-diaminoanthraquinone, 1,5-diaminoanthraquinone, 1,5-diamino-4, 8-dihydroxyanthraquinone and p-Alkoxybenzoylchloride. Three negative dichroic dyes of alkylaminoanthraquinone type were obtained in that 1,5-dichloroanthraquinone, 1,4,5,8-tetrachloroanthraquinone reacted with n-octylamine and n-nonylamine. 14 among them are new compounds. The order parameter (S) of dye molecules in liquid crystal were determined, and the characteristics of negative dichroic dyes structure were discussed.