2-Naphthylamine-1-sulfonic acid [81-16-3-A] C10H9O3S
Caution! 2-Naphthylamine and 1,1,2,2-tetrachloroethane are very toxic substances. Work must be carried out in a well-ventilated fume hood.
Procedure: In a 250-ml two-neck round-bottom flask equipped with a KPG stirrer and Dimroth condenser, dissolve 28.6 g of 2-naphthylamine in 90 ml of 1,1,2,2-tetrachloroethane. After dissolution, add 13.4 ml of chlorosulfonic acid. Stir this mixture at 20 °C for 6 hours and then heat it to reflux in an oil bath for 3 hours. After this time, remove all the apparatus and equip the flask with a distillation bridge and a gas inlet tube. Distill off the solvent and some excess 2-naphthylamine with steam. The solvent can be reused for new preparations after separating the water in a separatory funnel. Disposal should be avoided if possible. Precipitate the 2-naphthylamine-1-sulfonic acid from the residue with concentrated hydrochloric acid, filter, wash with ice-cold water, and dry in a drying oven at 80 °C.
Description: 2-Naphthylamine-1-sulfonic acid forms weakly beige, sparingly soluble in cold water, easily soluble in hot water, dimorphic flakes. The acid is used for the production of insoluble azo dyes, which are important as pigments in the paint industry.
Source: DE 392460 • Fortschr. Teerfarbenfabr. Verw. Industriezweige; DE; GE; 14; 405;
Delivered by: Mephisto
Last updated: 29/09/2006
Other names: 2-Amino-1-naphtholsulfonic acid; NSC 5523; 1-Sulfo-2-naphthylamine; Tobias acid