Compounds of the formula (I) in which X represents halogen, alkyl, alkenyl, alkynyl, alkoxy, benzyloxy, halogenoalkyl, halogenoalkoxy, cyano or nitro, Z represents hydrogen, amino, halogen, alkyl, alkoxy, halogenoalkyl, halogenoalkoxy, hydroxyl, cyano, nitro or respectively optionally substituted phenoxy, phenylthio, 5- or 6-membered hetaryloxy, 5- or 6-membered hetarylthio, phenylalkyloxy or phenylalkylthio and Het represents one of the groups