Compounds of the general formula ##STR1## where R.sup.2 and R.sup.3 together, or R.sup.3 and R.sup.4 together, represent an optionally substituted hydrocarbyloxy chain; the ring is optionally substituted at any or each of the remaining sites R.sup.5, R.sup.6 and R.sup.2 or R.sup.4 : n represents 0 or 1; and X represents a cyano group, a group --COOH or a salt, ester or amido derivative thereof; are biocidal, showing activity against fungi, yeast, bacteria and nematodes. Some such compounds, and intermediates therefore, are novel.

3-carbamoyl-4-hydroxy-couramins for combating parasitic helminths of the formula ##STR1## in which R.sup.1 represents hydrogen, halogen, alkyl, NO.sub.2, CN or alkoxy, X represents O, S, SO or SO.sub.2 R.sup.2 represents alkyl, halogenoalkyl, phenyl, naphthyl or pyridyl, which can optionally be substituted; or the radical -X-R.sup.2, together with the radical R.sup.3 can also form an alkylenedioxy (-O-alk-O), halogenoalkylenedioxy, oxyalkyleneoxyalkylene (-O-Alk-O-Alk-) or oxyhalogenoalkylene-oxyhalogenoalkylene bridge; and R.sup.3 and R.sup.4 independently of one another represent hydrogen, halogen, CN, OH, NO.sub.2, amino, mono- or dialklylamino, alkyl, halogenoalkyl, aralkyl or aryl, which can optionally be substituted, can be used for combating parasitic helminths.

Compounds of the formula The compounds are useful in the treatment of bacterial infections.