Pyrazoline derivatives

A compound of formula I, ##SPC22##

• in which R.sub.1 is halogen or alkyl of 1 to 4 carbon atoms,
• R.sub.2 and R.sub.3, which may be the same or different, are hydrogen, halogen or alkyl of 1 to 4 carbon atoms,
• R.sub.4 is hydrogen or alkyl of 1 to 4 carbon atoms,
• R.sub.5 signifies a hydrogen atom, a halogen atom, an alkyl radical of 1 to 4 carbon atoms or an alkoxy radical of 1 to 4 carbon atoms,
• R.sub.6 is hydrogen or alkyl of 1 to 4 carbon atoms, and
• A is an alkylene chain of 1 to 3 carbon atoms,
• which compound is in free acid or salt form.