Kuraishi, Tsukasa published the artcile< 4,5-Substituted pyridazines. I>, Recommanded Product: Pyridazin-4-amine, the main research area is PYRIMIDINES.
4,5-Substituted pyridazines were desired as intermediates in the preparation of 4-aminopyridazine (I) (C.A. 51, 5085h), and were easily prepared from 4,5-dichloro-3-pyridazone (II) according to Grundmann (C.A. 43, 176g). N2H4.H2SO4 (3.1 g.) and 3 g. AcONa added with stirring to a concentrated aqueous solution of 3.9 g. HO2CCCl:CClCHO at 80-100° yielded 3.5 g. II, prisms, m. 199-200°. II (20 g.) refluxed 5 hrs. with 150 cc. POCl3 in an oil bath, excess POCl3 removed, and the residue poured into ice H2O and extracted with ether yielded 20 g. 3,4,5-trichloropyridazine (III), b14-15 117-18°, m. 61° (from dilute Me2CO). III (8 g.) heated 5 hrs. in a sealed tube in an oil bath at 120-30° with absolute EtOH saturated with NH3, the solvent removed, the residue refluxed 20 min. on an H2O bath with 20 cc. CHCl3 and kept several hrs. at room temperature, and the undissolved residue crystallized from H2O yielded 2.8 g. (probably) 4-amino-3,5-dichloropyridazine (IV), prisms, m. 176-8°, and from the mother liquor 2 g. (probably) 5-amino-3,4-dichloropyridazine (V), thin needles, m. 150-1°. V (2 g.) in 30 cc. EtOH containing 0.98 g. NaOH catalytically hydrogenated (10% Pd-C) yielded 0.5 g. I, m. 128-9° (from AcOEt), formed also (0.4 g.) by the catalytic hydrogenation (8% Pd-C) of 2 g. IV in 25 cc. MeOH containing 5 cc. concentrated NH4OH. I (1 g.) acetylated with 20 cc. Ac2O in the usual way yielded 1.1 g. 4-acetamidopyridazine, m. 259-60° (from EtOH). Ultraviolet absorption curves were shown for I, IV, V, and 5-amino-3,6-dichloropyridazine.
Pharmaceutical Bulletin published new progress about UV and visible spectra. 20744-39-2 belongs to class pyridazine, and the molecular formula is C4H5N3, Recommanded Product: Pyridazin-4-amine.
Referemce:
Pyridazine – Wikipedia,
Pyridazine | C4H4N2 – PubChem