Dialkyl-1-H-3-(2,4-dimethylphenyl)-pyrrolidine-2,4-diones, their preparation and their use

A dialkyl-1-H-3-(2,4-dimethylphenyl)-pyrrolidine-2,4-dione, in which

• A represents straight-chain or branched C.sub.1 -C.sub.10 -alkyl which is optionally substituted by halogen,
• B represents straight-chain or branched C.sub.2 -C.sub.10 -alkyl,
• A, B and the carbon atom to which they are bonded preferably represent an unsubstituted C.sub.3 -C.sub.12 -spiro cycle,
• G represents the groups ##STR275## in which R.sup.1 represents in each case optionally halogen-substituted C.sub.1 -C.sub.20 -alkyl, C.sub.2 -C.sub.20 -alkenyl, C.sub.1 -C.sub.8 -alkoxy-C.sub.1 -C.sub.8 -alkyl, C.sub.1 -C.sub.8 -alkylthio-C.sub.1 -C.sub.8 -alkyl, C.sub.1 -C.sub.8 -polyalkoxy-C.sub.1 -C.sub.8 -alkyl or cycloalkyl having 3 to 8 ring atoms, wherein said cycloalkyl is optionally interrupted by oxygen and/or sulphur atoms,
• or represents phenyl which is optionally substituted by halogen, nitro, C.sub.1 -C.sub.6 -alkyl, C.sub.1-C.sub.6 -alkoxy, C.sub.1 -C.sub.6 -halogenoalkyl, C.sub.1 -C.sub.6 -halogenoalkoxy, C.sub.1 -C.sub.6 -alkylthio or C.sub.1 -C.sub.6 -alkylsulphonyl,
• or represents phenyl-C.sub.1 -C.sub.6 -alkyl which is optionally substituted by halogen, C.sub.1 -C.sub.6 -alkyl, C.sub.1 -C.sub.6 -alkoxy, C.sub.1 -C.sub.6 -halogenoalkyl or C.sub.1 -C.sub.6 -halogenoalkyoxy,
• or represents hetaryl which is optionally substituted by halogen and/or C.sub.1 -C.sub.6 -alkyl,
• or represents phenoxy-C.sub.1 -C.sub.6 -alkyl which is optionally substituted by halogen and/or C.sub.1 -C.sub.6 -alkyl,
• or represents hetaryloxy-C.sub.1 -C.sub.6 -alkyl which is optionally substituted by halogen, amino and/or C.sub.1 -C.sub.6 -alkyl,
• R.sup.2 represents C.sub.1 -C.sub.20 -alkyl, C.sub.3 -C.sub.20 -alkenyl, C.sub.1 -C.sub.8 -alkoxy-C.sub.2 -C.sub.8 -alkyl or C.sub.1 -C.sub.8 -polyalkoxy-C.sub.2 -C.sub.8 -alkyl, each of which is optionally substituted by halogen,
• or represents cycloalkyl, phenyl or benzyl, each of which is optionally substituted by halogen, nitro, C.sub.1 -C.sub.6 -alkyl, C.sub.1 -C.sub.6 -alkoxy or C.sub.1 -C.sub.6 -halogenoalkyl,
• R.sup.4 and R.sup.5 independently of one another represent C.sub.1 -C.sub.8 -alkyl, C.sub.1 -C.sub.8 -alkoxy, C.sub.2 -C.sub.7 -cycloalkyloxy, C.sub.1 -C.sub.8 -alkylamino, di-(C.sub.1 -C.sub.8)-alkylamino, C.sub.1 -C.sub.8 -alkylthio, C.sub.3 -C.sub.8 -alkenylthio or C.sub.3 -C.sub.7 -cycloalkylthio, each of which is optionally substituted by halogen, or represent phenyl, phenoxy, benzyloxy or phenylthio, each of which is optionally substituted by halogen, nitro, cyano, C.sub.1 -C.sub.4 -alkoxy, C.sub.1 -C.sub.4 -halogenoalkoxy, C.sub.1 -C.sub.4 -alkylthio, C.sub.1 -C.sub.4 -halogenoalkylthio, C.sub.1 -C.sub.4 -alkyl or C.sub.1 -C.sub.4 -halogenoalkyl,
• R.sup.6 and R.sup.7 independently of one another represent hydrogen or represent C.sub.1 -C.sub.8 -alkyl, C.sub.3 -C.sub.8 -cycloalkyl, C.sub.1 -C.sub.8 -alkoxy, C.sub.3 -C.sub.8 -alkenyl or C.sub.1 -C.sub.8 -alkoxy-C.sub.2 -C.sub.8 -alkyl, each of which is optionally substituted by halogen, or represent phenyl which is optionally substituted by halogen, C.sub.1 -C.sub.8 -halogenoalkyl, C.sub.1 -C.sub.8 -alkyl or C.sub.1 -C.sub.8 -alkoxy, or represent benzyl which is optionally substituted by halogen, C.sub.1 -C.sub.8 -alkyl, C.sub.1 -C.sub.8 -halogenoalkyl or C.sub.1 -C.sub.8 -alkoxy, or together with the N-atom to which they are bound represent a ring having 3-6 C-atoms which is optionally interrupted by oxygen or sulphur.