GB1024032A - New dithiophosphoric acid esters and pesticidal compositions containing them - Google Patents

Abstract

The invention comprises organo-phosphorus compounds of formula <FORM:1024032/C2/1> wherein R1 and R2 are the same or different C1 to C3 alkyl groups, X and Y are either both oxygen, both sulphur, or X is oxygen and Y is sulphur. The compounds are prepared:-(A) when X and Y are both oxygen or both sulphur, by reaction of an N-2-haloethyl-substituted oxalidinone or thiazolidonone with an O,O-dialkyl phosphorodithioate, or (B) when X is O and Y is S, by partial oxidation of the corresponding thiazolidinthione. In reaction (A), the dithioate is that of a monovalent cation such as ammonium or alkali metal, or the free acid, and the reaction may be performed in an organic solvent (e.g. benzene, tetrahydrofuran, lower alkanol), at elevated temperature; when the acid is used, zinc chloride may be used as a catalyst. Reaction (B) is suitably performed at about 25 DEG C. using, as oxidizing agent, H2O2 in glacial acetic acid. Examples are given for the preparation of: (1) (i) N-2-hydroxy-ethyl-2-thiazolidinthione from diethanolamine and CS2 in aqueous alkali; (ii) chlorination of the said product of (i) with thionyl chloride; (iii) reaction of the chlorinated product with O,O-diethyl-dithio phosphoric acid ammonium salt to give O,O-diethyl-S-b -(thiazolid-2-thione-3-yl) - ethyl phosphorodithioate; (2) the corresponding preparation of the dimethyl analogue of (1) (iii), using O,O-dimethyl phosphorodithioate ammonium salt; (3) preparation of N-2-hydroxyethyl-2-oxazolidonone from diethanolamine and ethyl trichloroacetate, followed by reactions analogous to (1) (ii) and (1) (iii) to give O,O - diethyl - S - b - (oxazolid - 2 - one - 3 - yl) - ethyl phosphorodithioate; and (4) partial oxidation of O,O-diethyl-S-b -(thiazolid-2-thione-3-yl)-ethyl phosphorodithioate to give O,O-diethyl - S - b (thiazolid - 2 - one - 3 - yl) ethyl phosphorodithioate, using H2O2 and glacial acetic acid. The compounds are useful as pesticides (see Division A5).ALSO:Pesticidal compositions comprise compounds of formula <FORM:1024032/A5-A6/1> wherein R1 and R2 are the same or different C1 to C3 alkyl groups, X and Y are either both oxygen, both sulphur, or X is oxygen and Y is sulphur (see Division C2), together with an acceptable carrier. Other ingredients which may be present are dispersing, wetting or surface active agents, stickers, thickening agents, and emulsifying agents. Forms taken by the compositions include granules, dust (suitably in a wettable or dispersible powder form), spray or drench in water, or water/oil emulsion, or together with a thermoplastic or thermosetting resin. Examples are given for (1) a miscible oil composition, of O, O-diethyl-S-b -(thiazolid-2-thione-3-yl)-ethyl phosphorodithioate, with methyl naphthalenes, and, as emulsifier, a mixture of an alkylaryl-polyethylene oxide condensate and a calcium alkylaryl sulphonate; (2) a dispersible powder, comprising the same active ingredient as (1), with a kieselguhr absorbent and disodium methylene dinaphthalene sulphonic acid as a surface active agent.