Uses
2,4-Dichloro-1,3,5-triazine is used as an intermediate in organic synthesis and pharmaceutical intermediates, and it is an intermediate in the preparation of bromhexine impurities.
Preparation
2,4-Dichloro-1,3,5-triazine can be synthesized by halogenation of 1,3,5-Triazine with chlorine.
Synthesis
General procedure for the synthesis of 2,4-dichloro-1,3,5-triazine from sodium dicyandiamide and N,N-dimethylformamide: Sodium dicyandiamide (3.0 g, 33.70 mmol) was dissolved in water (13 ml) and the solution was transferred to a flask containing concentrated hydrochloric acid. Hydrochloric acid (15 ml) was added slowly at -78°C. The reaction mixture was stirred at -78°C for 15 min, followed by warming to -35°C and continued stirring for 15 min. After that, the mixture was cooled to 0 °C and the precipitate was collected by filtration. Another flask containing N,N-dimethylformamide (10 ml) was prepared at room temperature to which phosphorous trichloride (1.84 ml, 19.71 mmol) and N,N-dimethylformamide (1.53 ml, 19.71 mmol) were added dropwise at 0 °C. After brief stirring, the resulting mixture was added to the above precipitate in batches, followed by stirring at room temperature overnight. After completion of the reaction, the reaction was quenched with water and the mixture was extracted with ethyl acetate (30 ml x 3). The residue was purified by silica gel fast column chromatography (eluent: ethyl acetate/hexane=1:4, Rf=0.63) to afford 2,4-dichloro-1,3,5-triazine (0.64 g, yield 13.13%) as a white solid.1H-NMR (300 MHz, CDCl3): δ 8.90 (s, 1H).
