Process for producing hydrazone derivatives of pyridinaldehydes

Claim 1

A process for producing a compound of the formula I ##STR17## wherein Z is ##STR18## Q 1 is hydrogen or alkyl having 1-4 C atoms, and Q 2 is phenyl which can be substituted by halogen, alkyl or alkoxy each having 1-4 C atoms, or is naphthyl, which comprises the steps of: reacting in an inert organic solvent an at least stoichiometric amount of an aminomethylpyridine and of a compound of the formula II ##STR19## wherein R 1 is hydrogen or alkyl having 1-8 C atoms, R 2 is alkyl having 1-8 C atoms, or R 1 or R 2 together are alkylene having 4-8 C atoms, to produce a compound of the formula ##STR20## wherein R 1 and R 2 are as defined for formula II, isomerizing said compound III in said solvent at a temperature from 0° to 80° C., in the presence of at least 0.1 mole %, relative to the amount of said compound III, of a catalyst of the formula IV (X).sup.n⊕ (OY).sub.n.sup.⊖ (IV) wherein X is an alkali metal ion or alkaline earth metal ion, or the ammonium group ##STR21## wherein R 3 to R 6 each independently of the other, are unsubstituted straight-chain or branched-chain alkyl having 1-20 C atoms or alkyl having 1-20 C atoms substituted by phenyl or naphthyl, Y is hydrogen or alkyl having 1-12 C atoms, and n is the charge of the alkali metal ion or alkaline-earth metal ion, to produce a compound of formula V ##STR22## wherein R 1 and R 2 are as defined in formula II, and, finally converting said compound V, in the presence of at least a stoichiometric amount of an inorganic acid and in an aqueous medium or in in the presence of a catalytic amount of an organic acid and in an inert organic solvent, and in the presence of a compound of the formula VI ##STR23## wherein Q 2 is as defined for formula I, Q 1 ' is hydrogen, alkyl having 1-4 C atoms or --SO 3 .sup.⊕ M.sup.⊖, Q 3 is hydrogen or --SO 3 .sup.⊕ M.sup.⊖, and M.sup.⊕ is an alkali metal cation, into a compound of the formula I.