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SUMMARY The structure/anti‐fungal relationships of a group of 137 sulphur‐containing compounds were studied by observation of their effects on the mycelial growth of six fungi, Pythium ultimum, Sclerotinia fructigena, Verticillium albo‐atrum, Alternaria solani, Botrytis cinerea and Aspergillus niger, and the germination of spores of Botrytis cinevea. These compounds consist of (a) salts and (b) carboxy‐alkyl and ‐alkenyl esters of both alkyl‐ and aryl‐substituted dithiocarbamic and hydroxydithioformic acids, (c) certain cyclic derivatives of (b), and (d) alkyl and aryl isothiocyanates. Short homologous series were selected to assess the importance of physico‐chemical properties in fungitoxicity, whilst certain aryl‐substituents were used on the basis of their contrasting electronic effects. Derivatives of alkoxydithioformic acids showed higher toxicity than those of N‐alkyl‐substituted dithiocarbamic acids, except for a series of β‐(N‐alkylthio‐carbamoylthio)acrylic acids. The fungitoxicity of esters of alkyl‐substituted dithiocarbamic or hydroxydithioformic acids showed little change on increasing the size of the alkyl substituent or ester grouping. The fungitoxicity of compounds derived from N‐aryldithiocarbamic acids varied considerably with the nature of the N‐substituent.

The anti-fungal and anti-bacterial activities and phytotoxicity of pyrrole-and 5-nitropyrrole-2-sulphonamides are compared with furan and thiophen analogues. Certain compounds of the group have appreciable anti-bacterial activity consistent with structure-activity investigations of other anti-bacterials derived from these heterocycles.2.1.1.1. Sodium pyrrole-2-sulphonate Pyrrole (30.0 g), pyridine-sulphur trioxide' (75 g) and 1,2-dichloroethane (250 ml) were refluxed 16 h. The solvent was decanted from the solid which was treated with water and the boiling solution neutralised with sodium carbonate. After evaporation, the residue was extracted with boiling ethanol-water (9 : 1 ; 500 ml) for 1 h; the filtered solution yielded sodium pyrrole-2-sulphonate (17.3 g) on cooling. 43