Picolinic acid derivative and herbicidal composition

A picolinic acid derivative of the formula:

• ##STR204## wherein each of R.sup.1 and R.sup.2 is an alkoxy group;
• X.sup.1 is a group of the formula ##STR205## wherein R.sup.3 is a hydrogen atom, an alkyl group, a haloalkyl group, an alkoxyalkyl group, an alkenyl group, an alkynyl group, an alkylcarbonyl group, a benzyloxycarbonyl group or a phenylsulfonyl group;
• and
• R.sup.4 is a haloalkyl group, an alkoxyalkyl group, an alkoxyalkyloxyalkyl group, an alkoxycarbonylalkyl group, a benzyloxyalkyl group, an alkyloxyoxyalkyl group, a phenoxyalkyl group, a dialkylaminoalkyl group, a cyanoalkyl group, an alkoxy group, a cycloalkyl group, an alkenyl group (which may be substituted at one or more positions by a halogen atom or a cyano group), an alkynyl group, a phenylalkyl group (which may be the same or different, and substituted at one or more positions by a halogen atom, an alkyl group, an alkoxy group, a nitro group or a cyano group), a cycloalkylcarbonyl group, a haloalkylcarbonyl group, an alkoxyalkylcarbonyl group, a cyanoalkylcarbonyl group, a phenoxyalkylcarbonyl group, a phenylalkylcarbonyl group, a halophenylalkylcarbonyl group, a benzoyl group (which is substituted by an alkyl group, a haloalkyl group, a halogen atom, an alkoxy group, a cyano group or a nitro group), a furylcarbonyl group, a pyridylcarbonyl group, a pyrrolylcarbonyl group, a thienylcarbonyl group, an alkenylcarbonyl group, a phenylalkenylcarbonyl group, a hydroxycarbonylalkenylcarbonyl group, an alkoxycarbonylalkylcarbonyl group, an alkoxyalkoxycarbonyl group, a monoalkylaminocarbonyl group, a dialkylaminocarbonyl group, a phenylaminocarbonyl group, a benzylaminocarbonyl group, a halobenzylaminocarbonyl group, an alkoxycarbonyl group, a haloalkoxycarbonyl group, a benzyloxycarbonyl group, an alkenyloxycarbonyl group, an alkynyloxycarbonyl group, an alkylsulfonyl group, a haloalkylsulfonyl group, a benzylsulfonyl group which may be substituted by an alkoxycarbonyl group, a phenylsulfonyl group which may be substituted by an alkoxycarbonyl group, a halophenylsulfonyl group, an alkyl(thiocarbonyl) group, a haloalkyl(thiocarbonyl) group, a benzyl(thiocarbonyl) group, a halobenzyl(thiocarbonyl) group, an alkenyl(thiocarbonyl) group, an alkynyl(thiocarbonyl) group which may be substituted by a cyano group, an alkylamino(thiocarbonyl) group, a phenylamino(thiocarbonyl) group, a dialkylamino(thiocarbonyl) group, a benzyloxy group or a group of the formula ##STR206## wherein each of R.sup.5 and R.sup.6 which may be the same or different, is a hydrogen atom, an alkyl group or an alkoxycarbonyl group, or R.sup.5 and R.sup.6 form together with the adjacent nitrogen atom a morpholino group;
• or
• R.sup.3 and R.sup.4 form together with the adjacent nitrogen atom, an azido group, an isothiocyanate group, a phthalimide group, a maleimide group, a succinimido group, a pyrrolidinyl group, a piperidino group, a pyrrolyl group, a morpholino group, a group of the formula ##STR207## wherein n is 0 or 1, and m is 1 or 2, or X.sup.1 is a group of the formula ##STR208## wherein each of R.sup.7 and R.sup.8 which may be the same or different, is a hydrogen atom, an alkyl group, a dialkylamino group, an amino group, an alkylthio group, a phenyl group or a benzyl group;
• and
• R.sup.9 is a hydrogen atom, an alkyl group, an alkenyl group, a benzyl group, an alkali metal atom, an alkaline earth metal atom or an organic amine cation;
• or a salt thereof, wherein said alkyl and alkoxy groups are C.sub.1-5 linear or branched alkyl and alkoxy groups, said alkenyl and alkynyl groups are C.sub.2-6 alkenyl and alkynyl groups, said cycloalkyl groups are C.sub.3-6 cycloalkyl groups, said alkylideneamino groups are C.sub.3-12 alkylideneamino groups, and said cycloalkylideneamino groups are C.sub.3-8 cycloalkylideneamino groups.