Heterocyclic-alkylene quinoxalinyloxyphenoxypropanoate herbicides

A compound having the formula:

• ##STR30## wherein:
• n is 0, 1, 2 or 3;
• R.sup.1 and R.sup.2 are each independently selected from the group consisting of halogen, hydrogen, C.sub.1 -C.sub.3 alkoxy, C.sub.1 -C.sub.3 haloalkoxy, monohalomethyl, dihalomethyl, trihalomethyl, cyanato and nitro;
• and
• R.sup.3 is a 4-, 5- or 6-membered saturated, unsaturated or partially unsaturated ring containing 1 or 2 oxygen atoms, or a 5- or 6-membered saturated, unsaturated or partially unsaturated heterocyclic ring containing 1 or 2 sulfur atoms or one sulfur atom and one oxygen atom;
• said ring having no nitrogen atoms and optionally being substituted with between 1 and 3 substituents each independently selected from the group consisting of oxo, C.sub.1 -C.sub.3 alkyl and C.sub.1 -C.sub.3 alkoxy;
• with the proviso that when R.sup.1 or R.sup.2 is hydrogen or 6-chloro and n is 1, then R.sup.3 is either the 5- or 6-membered saturated, unsaturated or partially unsaturated ring containing 1 or 2 oxygen atoms or the 5- or 6-membered saturated, unsaturated or partially unsaturated heterocyclic ring containing 1 or 2 sulfur atoms or one sulfur atom and one oxygen atom, but not furanyl, tetrahydrofuranyl or tetrahydropyranyl.