Hydrochloric Acid → Ethyl 3-aminopyridazine-4-carboxylate

Reaction equation

[NH2:1][C:2]1[N:3]=[N:4][CH:5]=[CH:6][C:7]=1[C:8]([OH:10])=[O:9].Cl.[C:12]1(C)C=CC(S(Cl)(=O)=O)=C[CH:13]=1>C(O)C>[CH2:12]([O:9][C:8]([C:7]1[CH:6]=[CH:5][N:4]=[N:3][C:2]=1[NH2:1])=[O:10])[CH3:13]

Participants

Procedure

3-Aminopyridazine-4-carboxylic acid (1.68 g, prepared as in JOC, (1985), 50, 346) was refluxed in ethanol (170 ml) with concentrated hydrochloric acid (2 ml) and p-toluene-sulphonyl chloride (0.1 g) for 55 hours. The solvent was evaporated and ice water added to the residue, which was then neutralised with solid sodium bicarbonate. The mixture was extracted with chloroform, insoluble material filtered, the organic extract dried over magnesium sulphate and evaporated to give 3-aminopyridazine-4-carboxylic acid ethyl ester (1.02 g) as a white solid.