METHOD FOR PREPARING 1-PHENYLPYRRAZOLIN-3-CARBOXYLIC ACID DERIVATIVES

There is described a process for the preparation of 1-phenylpyrazoline-3-carboxylic acid derivatives of the formula III by means of base-catalyzed reaction of hydrazones of the formula I with olefins of the formula II where Ph, R1, R2, R3, X and Y have the following meanings: Ph is optionally substituted phenyl, R1 is hydrogen or alkyl, R2 and R3 independently of one another are hydrogen, halogen, cyano, an optionally substituted organic radical, or R2 and R3 together with the carbon atom to which they are attached form a saturated or partially saturated ring having 5 or 6 atoms, x is amino, hydroxyl, alkoxy, cycloalkoxy, alkylamino, dialkylamino, alkyloxyalkyloxy, trialkylsilyloxy or trialkylsilylmethyloxy and Y is chlorine or bromine. The reaction is carried out in a two-phase system composed of an organic and an aqueous phase using a sterically hindered amine and, if appropriate, a further base. These 1-phenylpyrazoline-3-carboxylic acid derivatives are employed as so-called safeners, i.e. agents which protect the useful plants in agricultural and silvicultural crops from undesired damage associated with the effect of herbicides.