Pyrazole carboxylic acid derivs. prepn. - by reacting azo-carboxylic acid cpd. with an enol-ether and aromatising

摘要

Pyrazole carboxylic acid derivs. of formula (I) are prepd. by reacting the azo cpd (II) with enolethers of formula CH2C(R2)OR5 (III), and aromatising the prod. of formula (IV). In formulae, R1 = independently 1-4C haloalkyl or halogen; R2 = 1-6C alkyl or 2-4C alkinyl; R3 = 1lkali(ne earth) metal, H, 1-6C alkyl or (1-4C) alkoxy-(1-4C)alkyl; R5 = 1-6C alkyl; Z = Cl or Br; and n = 1 or 2. The reaction of II and III is carried out at (10-100 deg.C at pH 7-10 in a two-phase system (aq./organic) in the presence of an inorganic base. IV is aromatised in the two-phase system without isolation, by acidification. Pref. the inorganic base is Na2CO3, NaHCO3, K2CO3 or KHCO3; IV is aromatised at pH 0-3 under reflux. Pref. (I) is 1-(2,4-dichlorophenyl) -5-isopropylpyrazole -3-carboxylate ethyl ester.