PROCESS FOR PRODUCING /2,6-DIALKOXY-PHENYL/-ALKYL-KETONE-, 2,6-DIALKOXY-BENZOIC ACID- AND -BENZYL-ALKOHOL DERIVATIVES, AND HERBICIDE COMPOSITIONS CONTAINING THEM AS ACTIVE COMPONENTS

2,6-Dialkoxyphenyl herbicides of formula: in which: R1 is a group C(=O)-R9 X is O or S; R9 being an optionally substituted hydrocarbyl radical; CROHR9 or CHR9OR14, R9 having one of the meanings of R9, R14 being an optionally substituted hydrocarbyl radical or CHR9OC(=O)R15, R15 being an optionally substituted hydrocarbyl radical; C(=O)R16, R16 being OR13 or SR13, R13 being an optionally substituted hydrocarbyl radical. R2 and R5, which are identical or different, are optionally substituted hydrocarbyl radicals. R3 and R4, which are identical or different, are a hydrogen atom or optionally substituted C1-C6 alkyl radicals or one of the radicals R3 or R4 may be the nitro or amino radical, R6, R7 and R8, which are identical or different, are C1-C6 alkyl or C3-C7 cycloalkyl radicals which are optionally substituted, and agriculturally acceptable salts of these compounds.