2,6-Diaminopyridine → 5,7-Bis(pentafluoroethyl)-1,8-naphthyridin-2-amine

A mixture of 2,6-diamino pyridine (5.2 g., 4.76 mmole), 1,1,1,2,2,6,6,7,7,7-decafluoroheptan-3,5-dione (14.5 g., 4.80 mmole) and 85% phosphoric acid (50 ml.) is stirred at 90°-95° C. for 6 hours. When cool, the reaction mixture is poured into ice-water and neutralized with ammonium hydroxide to pH 7. The solid is collected, washed with water, dried, and can be purified by recrystallization from benzene.