Preparation
in return conditions (or slightly belt pressure), in naoh aqueous solution will be (E)-2-(2-sulfo-4-nitrostyryl)-5-nitrobenzenesulfonic acid with Sodium 4-aminobenzenesulfonate diazotization and Naphthalen-1-amine coupling product heating together, then its product (C.I. Direct Red 111) into dicyclohexyl amine salt.
