Phenylpyrazole herbicides

A compound of formula I ##STR238## wherein R.sub.2 is C.sub.1 -C.sub.2 alkyl;

• n is 0, 1 or 2;
• R.sub.3 is C.sub.1 -C.sub.4 alkyl;
• R.sub.4 is hydrogen, fluorine, or chlorine;
• R.sub.5 is halogen, methyl or cyano;
• R.sub.6 is
• (i) hydrogen,
• (ii) OR.sub.20 in which
• R.sub.20 is hydrogen, C.sub.1 -C.sub.8 alkyl, C.sub.3 -C.sub.8 alkenyl, C.sub.3 -C.sub.8 alkynly, C.sub.1 -C.sub.8 haloalkyl, C.sub.3 -C.sub.6 cycloalkyl, C.sub.1 -C.sub.4 alkoxy-C.sub.1 -C.sub.4 alkyl, C.sub.1 -C.sub.4 alkylthio-C.sub.1 -C.sub.4 alkyl, C.sub.1 -C.sub.8 alkyl-COXR.sub.21, phenyl, benzyl, those aromatic rings being unsubstituted or mono- to tri-substituted by C.sub.1 -C.sub.4 alkyl, C.sub.1 -C.sub.4 haloalkyl or by halogen, in which;
• X is oxygen, sulfur or NR.sub.22 ;
• R.sub.21 is hydrogen, C.sub.1 -C.sub.8 alkyl, C.sub.3 -C.sub.8 alkenyl, C.sub.3 -C.sub.8 alkynyl, C.sub.1 -C.sub.8 haloalkyl, C.sub.3 -C.sub.6 cycloalkyl, C.sub.1 -C.sub.4 alkoxy-C.sub.1 -C.sub.4 alkyl, C.sub.1 -C.sub.4 alkylthio-C.sub.1 -C.sub.4 alkyl, phenyl, phenyl mono- to tri-substituted by C.sub.1 -C.sub.4 alkyl, C.sub.1 -C.sub.4 haloalkyl or by halogen, benzyl, or benzyl mono- to tri-substituted by C.sub.1 -C.sub.4 alkyl or by halogen;
• and
• R.sub.22 is hydrogen, C.sub.1 -C.sub.8 alkyl or C.sub.3 -C.sub.8 alkenyl;
• (iii) COYR.sub.50 in which
• Y is oxygen, sulfur, NR.sub.51 or NOR.sub.54, and
• R.sub.50 is hydrogen, C.sub.1 -C.sub.8 alkyl, C.sub.3 -C.sub.8 alkenyl, C.sub.3 -C.sub.8 alkynyl, C.sub.1 -C.sub.8 haloalkyl, C.sub.3 -C.sub.6 cycloalkyl, C.sub.1 -C.sub.4 alkoxy-C.sub.1 -C.sub.4 alkyl, C.sub.1 -C.sub.4 alkylthio-C.sub.1 -C.sub.4 alkyl, phenyl, phenyl mono- to tri-substituted by C.sub.1 -C.sub.4 alkyl, C.sub.1 -C.sub.4 haloalkyl or by halogen, benzyl, benzyl mono-to tri-substituted by C.sub.1 -C.sub.4 alkyl, C.sub.1 -C.sub.4 haloalkyl or by halogen, C.sub.1 -C.sub.4 alkyl-COZR.sub.52, in which
• Z is oxygen, sulfur, NR.sub.53 or NOR.sub.56 ;
• R.sub.52 is hydrogen, C.sub.1 -C.sub.8 alkyl, C.sub.3 -C.sub.8 alkenyl, C.sub.3 -C.sub.8 alkynyl, C.sub.1 -C.sub.8 haloalkyl, C.sub.3 -C.sub.6 cycloalkyl, C.sub.1 -C.sub.4 alkoxy-C.sub.1 -C.sub.4 alkyl, C.sub.1 -C.sub.4 alkylthio-C.sub.1 -C.sub.4 alkyl, phenyl, phenyl mono- to tri-substituted by C.sub.1 -C.sub.4 alkyl, C.sub.1 -C.sub.4 haloalkyl or by halogen;
• R.sub.51 and R.sub.53 are each independently of the other C.sub.1 -C.sub.8 alkyl, C.sub.3 -C.sub.8 alkenyl, C.sub.3 -C.sub.8 alkynyl, C.sub.1 -C.sub.8 haloalkyl, C.sub.1 -C.sub.4 alkylcarbonyl, C.sub.1 -C.sub.4 haloalkylcarbonyl, C.sub.1 -C.sub.4 alkylsulfonyl, C.sub.1 -C.sub.4 haloalkylsulfonyl, benzoyl, benzoyl mono-to tri-substituted by C.sub.1 -C.sub.4 alkyl, C.sub.1 -C.sub.4 haloalkyl or by halogen, benzyl, or benzyl mono- to tri-substituted by C.sub.1 -C.sub.4 alkyl,
• C.sub.1 -C.sub.4 haloalkyl or by halogen;
• and
• R.sub.54 and R.sub.55 are each independently of the other C.sub.1 -C.sub.4 alkyl;
• or
• (iv) C.sub.1 -C.sub.4 alkyl-COZR.sub.52, C.sub.1 -C.sub.4 haloalkyl-COZR.sub.52, C.sub.2 -C.sub.4 alkenyl-COZR.sub.52, C.sub.3 -C.sub.8 alkynyl-COZR.sub.52, or the salts or stereoisomers thereof.