Patent GB-781227-A (GB)
Title: Substances having a fungicidal effect and processes for producing such substances
IPC: C07C381/04
Filed: 1955-08-25
Abstract: The invention comprises compounds of the general formula <FORM:0781227/IV (a)/1> and their salts and esters, fungicidal compositions containing them (see Group VI), and the preparation of the said compounds by reacting a monocarboxybenzenesulphinic acid, or a salt or carboxylic ester thereof, with perchloromethyl mercaptan (trichloromethanesulphene chloride), advantageously in an aqueous medium.  When the product contains a free carboxyl group it may be converted into a salt, such as an alkali metal salt or a salt with an organic base such as morpholine or triethanolamine (e.g. by reaction with the calculated amount of base), or may be esterified (e.g. by reaction with diazomethane, preferably in a lower aliphatic ether, or with diethyl or dimethyl sulphate, preferably in alcoholic solution). In examples: (1) an aqueous solution of p-carboxybenzenesulphinic acid is made weakly alkaline with caustic soda and re-acidified with half the equivalent amount of hydrochloric acid, and the resulting solution is stirred with perchloromethyl mercaptan to precipitate trichloromethyl p - carboxybenzenethiolsulphonate; (2) the disodium salt of m-carboxybenzenesulphinic acid is shaken with perchloromethyl mercaptan in aqueous solution, and the product is extracted into ether and acidified with dilute H2SO4 to liberate trichloromethyl m-carboxybenzenethiolsulphonate; (3) o-carboxybenzenesulphinic acid is treated as in (1) to produce trichloromethyl o-carboxybenzenethiolsulphonate.  Starting materials.  p - Carboxybenzenesulphinic acid is prepared by stirring p-carboxybenzenesulphochloride with an aqueous solution of sodium sulphite and caustic soda and then acidifying with conc. H2SO4. m-Carboxybenzenesulphinic acid is prepared similarly from m-carboxychloridebenzenesulphochloride, which is obtained by heating benzoic acid with chlorosulphonic acid and heating the resulting m - carboxybenzenesulphochloride with PCl5.  o-Carboxybenzenesulphinic acid is prepared by chlorinating thiosalicylic acid and hydrolysing the resulting compound of the formula <FORM:0781227/IV (a)/2>ALSO:Fungicidal preparations comprise a compound of the general formula <FORM:0781227/VI/1> or an ester or salt thereof, diluted with a solid or liquid carrier substance.  The preparations may, for example, be in the following forms: (a) mixable oils with 15-20 per cent of active constituents, 15 per cent of non-ionogenic emulsifying agent and the rest solvent (e.g. a ketone such as cyclohexanone); (b) aerosols with solvents (e.g. acetone, methyl ethyl ketone or cyclohexanone) and, as propellant, methyl chloride, dichlorodifluoromethane, trichlorofluoromethane or mixtures thereof; (c) spray powders containing 50-80 per cent of active substance together with flowing agents (e.g. fatty alcohol sulphonates), dispersion agents and/or carriers (e.g. kaolin, chalk or alum earth), and additions to prevent clotting (e.g. colloidal silicic acid); (d) seed protecting agents, e.g. 50 per cent of active substance with kaolin and adhesives (e.g. watchmaker's oil); (e) "coated dust" in which the active substance is applied to an absorbent carrier (e.g. infusorial earth).