The invention concerns novel compounds of the formula I STR1 wherein: Z is selected from oxygen and the group --YAn wherein Y is selected from C1 to C6 alkyl and benzyl and An is an anion; k is zero or the integer 1; n is an integer selected from 3 and 4; X is selected from halogen, nitro, cyano, alkyl, substituted alkyl, hydroxy, alkoxy, substituted alkoxy, alkenyl, alkenyloxy, alkynyl, alkynyloxy, acyloxy, alkoxycarbonyl, alkylthio, alkylsulfinyl, alkylsulfonyl, sulfamoyl, substituted sulfamoyl, alkanoyloxy, benzyloxy, substituted benzyloxy, amino, substituted amino and the groups formyl and alkanoyl and the oxime, imine and Schiff base derivatives thereof; R1 is selected from hydrogen, alkyl, alkenyl, alkynyl, substituted alkyl, alkylsulfonyl, arylsulfonyl, acyl and an inorganic or organic cation; R2 is selected from alkyl, substituted alkyl, alkenyl, haloalkenyl, alkynyl and haloalkynyl; R3 is selected from alkyl, fluoroalkyl, alkenyl, alkynyl, and phenyl; and R4 is selected from hydrogen, halogen, alkyl, cyano and alkoxycarbonyl. The compounds of the invention show herbicidal properties and plant growth regulating properties and in further embodiments the invention provides processes for the preparation of compounds of formula I, intermediates useful in the preparation of the compounds of formula I, compositions containing as active ingredient a compound of formula I, and herbicidal and plant growth regulating processes utilizing compounds of formula I.