Herbicidal 4-perfluoroacetyl-, 4-perfluoromethylthio-, 4-perfluoromethylsulfinyl-, and 4-perfluoromethylsulfonyl-4'-nitrodiphenyl ethers

A compound of the formula:

• ##STR8## wherein W is carbonyl, thio, sulfinyl, or sulfonyl
• X is a hydrogen atom, a halogen atom, a trifluoromethyl group, a (C.sub.1 -C.sub.4) alkyl group, or a cyano group,
• Y is a hydrogen atom, a halogen atom, or a trifluoromethyl group, and
• Z is a hydroxy group, an alkoxy group having up to 6 carbon atoms, an alkyl group having up to 4 carbon atoms, a halogen atom, an amino group, an alkylthio group having up to 4 carbon atoms, a cyano group, a carboxy group, a carbalkoxy group having up to 4 carbon atoms in the alkoxy moiety, a carboxyalkyl group having up to 4 carbon atoms, a carbalkoxyalkyl group having up to 6 carbon atoms, an alkanoyloxy group having up to 4 carbon atoms, or a carbamoyloxy group of the formula --OCONH.sub.2, --OCONHR, or --OCONR.sub.2, wherein R represents and alkyl group having up to 6 carbon atoms and when Z is carboxy an agronomically acceptable salt thereof.