| 摘要 |
PURPOSE:To cause slow development into a clear blue or bluish purple color and enhance light fastness of developed color images by using a specified compound for a pressure sensitive copying paper, a thermal recording paper or the like, and bringing the compound into intimate contact with a color developer. CONSTITUTION:An indolylmethane compound of formula I (wherein each of R<1> and R<2> is hydrogen or a 1-5C alkyl, and ring A is phenyl having one to three methyl, ethyl or 1-5C alkoxyl groups) gives a clear hue with high light fastness upon making intimate contact with a color developer. The compound can be obtained by bringing a diphenylamine derivative and a 3-formyl-2- phenylindole derivative into dehydration condensation in a solventless manner or in an organic solvent such as methanol, ethanol, benzene and toluene in the present of an acid catalyst such as hydrochloric acid, sulfuric acid, phosphor oxychloride and p-toluenesulfonic acid. |
