Abstract: Herbicidal compounds of formula (I) and salts thereof, where A is --N.dbd. or --CH.dbd.; X is --OH, --OR.sup.10, --SH, --SR.sup.10, --SCN, NH.sub.2, --NHacyl, --CH.sub.2 OH, --CH.sub.2 OR.sup.9 or --CN; R.sup.1 and R.sup.2, which may be the same or different, each represent alkyl, alkoxy, haloalkyl, haloalkoxy, halo, alkylamino or dialkylamino; R.sup.3 is --CN, --COOR.sup.5, --CONR.sup.6 R.sup.7, --CSNH.sub.2, --CHO, --CH.dbd.Z, --CH(Oalkyl).sub.2, --CH.sub.2 OH, --CH.sub.2 OR.sup.9, --COSR.sup.4a, --CS.sub.2 R.sup.4a, or a substituted or unsubstituted 5- or 6-membered heterocyclic group linked via a ring carbon atom which is between two ring heteroatoms; R.sup.4 and R.sup.4a, which may be the same or different, are each H, or a substituted or unsubstituted alkyl, alkenyl, alkynyl, cycloalkyl, aryl, aralkyl or heteroaryl group; R.sup.

Abstract: Novel herbicidal thiadiazoles of the formula: ##STR1## (wherein: R.sup.1 represents a group R.sup.a, --S(O)nR.sup.a or --SO.sub.2 NR.sup.a R.sup.b, where R.sup.a and R.sup.b, which may be the same or different, each represent hydrogen, cycloalkyl of 3 to 7 carbon atoms, alkenyl or alkynyl of 2 to 6 carbon atoms, phenyl, phenylalkyl of 7 to 10 carbon atoms, or alkyl of 1 to 10 carbon atoms, any phenyl or alkyl group present being optionally substituted by one or more halogen atoms, cyano groups, alkoxy or alkylthio groups of 1 to 4 carbon atoms, or phenoxy groups, or R.sup.a and R.sup.b together form an alkylene chain of 2 to 6 carbon atoms, and n represents 0, 1 or 2;X represents oxygen or sulphur;Z represents a group --NR.sup.c R.sup.d ; andY represents a group --NR.sup.e R.sup.f or a group --N.dbd.CR.sup.e R.sup.f ; where R.sup.c, R.sup.d, R.sup.e and R.sup.f, which may be the same or different, each represent a group as defined for R.sup.