HALOGENATED ANTHRAQUINONE AND THEIR USE AS NEAR INFRARED RAYS ABSORBING OPTICAL FILTERS

摘要

High-purity 1,4,5,8-tetraanilidoanthraquinones which are substituted at the p-position of at least one of four anilido benzene rings by a halogen atom are good near infrared rays absorbing filters and are prepared from high purity 1,4,5,8-tetrachloroanthraquinone by reaction with a correspondingly substituted aniline or mixture of anilines in the presence of a salt of an aliphatic carboxylic acid, a benzyl alcohol derivative and copper ions as reaction catalyst.