2-(Poly-substituted aryl)-6-amino-5-halo-4-pyrimidinecarboxylic acids and their use as herbicides

A compound of the formula I

• wherein
• Q represents a halogen;
• R1 and R2 independently represent H, C1-C6 alkyl, C3-C6 alkenyl, C3-C6 alkynyl, hydroxy, C1-C6 alkoxy, amino, C1-C6 acyl, C1-C6 carboalkoxy, C1-C6 alkylcarbamyl, C1-C6 alkylsulfonyl, C1-C6 trialkylsilyl or C1-C6 dialkyl phosphonyl or R1 and R2 taken together with N represent a 5- or 6-membered saturated ring;
• and
• Ar represents a polysubstituted aryl group selected from the group consisting of
• a)
• wherein
• W1 represents F or Cl;
• X1 represents C1-C4 alkyl, C1-C4 alkoxy, C1-C4 alkylthio, C1-C4 haloalkyl, C1-C4 haloalkoxy, C1-C4 haloalkylthio or —NR3R4;
• Y1 represents halogen or C1-C4 haloalkyl or, when X1 and Y1 are taken together, represents —O(CH2)nO— wherein n=1 or 2;
• and
• R3 and R4 independently represent H or C1-C4 alkyl;
• b)
• wherein
• W2 represents F or Cl;
• X2 represents C1-C4 alkyl, C1-C4 alkoxy, C1-C4 alkylthio, C1-C4 haloalkyl, C1-C4 haloalkoxy, C1-C4 haloalkylthio or —NRO3R4;
• Y2 represents halogen or C1-C4 haloalkyl or, when X2 and Y2 are taken together, represents —O(CH2)nO— wherein n=1 or 2;
• and
• R3 and R4 independently represent H or C1-C4 alkyl;
• and
• c)
• wherein
• Y3 represents halogen or C1-C4 haloalkyl or, when Y3 and Z3 are taken together, represents —O(CH2)nO— wherein n=1 or 2;
• Z3 represents C1-C4 alkyl, C1-C4 alkoxy, C1-C4 alkylthio, C1-C4 haloalkyl, C1-C4 haloalkoxy, C1-C4 haloalkylthio or —NR3R4;
• and
• R3 and R4 independently represent H or C1-C4 alkyl;
• and agriculturally acceptable derivatives of the carboxylic acid group.