Certain glyoxyl-cyclohexendiones as herbicides

A compound of the general formula I ##STR81## wherein X represents a group OH, OR.sup.7, NH.sub.2, NHR.sup.7, NR.sup.7 R.sup.8, NOH, NOR.sup.7, OCOR.sup.7, OCONHR.sup.7, OCONHCOR.sup.7, OCONHSO.sub.2 R.sup.7, NHCONHCOR.sup.7, OCOSR.sup.7, NHCOSR.sup.7, SCOR.sup.7, SR.sup.7, SCONHR.sup.7, SCONHCOR.sup.7, SCONHSO.sub.2 R.sup.7 or SCOSR.sup.7 ;

• R.sup.1 to R.sup.4 each independently represents a hydrogen atom or a straight-chain or branched-chain C.sub.1-6 alkyl, C.sub.2-6 alkenyl or C.sub.2-6 alkynyl group which is optionally substituted by one or more of the same or different substituents selected from halogen atoms and CN, OH, R.sup.6, OR.sup.6, COOR.sup.6, NO.sub.2, NH.sub.2, NR.sup.6.sub.2, SO.sub.3 H, SO.sub.2 R.sup.6 and SR.sup.6 groups;
• R.sup.1 and R.sup.2 and/or R.sup.3 and R.sup.4 together form a straight-chain or branched-chain, saturated or unsaturated, C.sub.2-6 -methylene bridge, optionally substituted by one or more of the same or different substituents selected from halogen atoms and CN, OH, R.sup.6, OR.sup.6, COOR.sup.6, NO.sub.2, NH.sub.2, NR.sup.6.sub.2, SO.sub.3 H, SO.sub.2 R.sup.6 and SR.sup.6 groups;
• R.sup.5 is a straight-chain or branched-chain C.sub.1-20 alkyl, C.sub.2-20 alkenyl or C.sub.2-20 alkynyl group, a C.sub.3-20 cycloalkyl, phenyl, naphthyl or thienyl group, each of which is optionally substituted by one or more of the same or different substituents selected from halogen atoms and CN, OH, R.sup.6, OR.sup.6, COOR.sup.6, NO.sub.2, NH.sub.2, NR.sup.6.sub.2, SO.sub.3 H, SO.sub.2 R.sup.6 and SR.sup.6 groups;
• R.sup.6 is a straight-chain or branched-chain C.sub.1-20 alkyl group, a C.sub.3-20 cycloalkyl, phenyl or naphthyl group, each of which is optionally substituted by one or more of the same or different substituents selected from halogen atoms and CN, OH, COOH, NO.sub.2, NH.sub.2, SO.sub.3 H and SH groups;
• and
• R.sup.7 and R.sup.8 each independently has the same meaning as R.sup.5.