A compound of the formula:where X is phenyl substituted at the 3, 4 and 5 positions with R1, R2 or R3 which are selected from hydrogen, chloro, lower alkyl of 1 to 5 carbons, phenoxy, phenyl, naphthyl, or phenyl (lower) alkyl where the lower alkyl group has 1-5 carbon atoms and m is 0 or 1； Y is —CONH— or —NHCONH— where the nitrogen atoms are unsubstituted or substituted with other phenoxyisobutyric acid derivatives, or the residue of a phenoxyisobutyric acid and n is 0 or 1； Z is unsubstituted phenyl when m is 1 and n is 1； when Y is 0, X is 0； Z is also substituted.
