Disclosed are herbicidal compounds of the general formula I; ##STR1## wherein A is O-alkylene of 1 to 5 carbon atoms, O-alkenylene of 3 to 6 carbon atoms in which the unsaturation is non-adjacent the oxygen atom thereof or NH-alkylene in which the alkylene is of 1 to 5 carbon atoms, and --COZR is an acid function or forms certain ester or thioester functions, and the mono- and di-salt forms thereof.