Patent GB-809653-A (GB)
Title: A process for the deodorization of s-(1,2-dicarbethoxyethyl) o, o-dimethyl-dithiophosphate
IPC: C07F9/02
Filed: 1955-08-08
Abstract: S - (1,2 - dicarbethoxyethyl) - O, O - dimethyl dithiophosphate is deodorized by submitting it to the oxidizing action of an aqueous solution of a metal hypochlorite, preferably sodium hypochlorite, the treatment being carried out by agitating the dithiophosphate in a vessel while gradually adding thereto said hypochlorite solution, continuing the agitation for at least half an hour at a temperature not exceeing 50 DEG  C., allowing the mixture to cool down to room temperature, removing the oxidized hypochlorite solution from the mixture by vacuum filtration, decantation or centrifugal action after allowing the mixture to settle, and finally removing residual moisture from the deodorized product.  Preferably for 100 parts by volume dithiophosphate there are employed 50 parts by volume of a 4.7 to 5 per cent aqueous sodium hypochlorite solution.  During the oxidizing action a current of air free from water but saturated with a mixture of nitrobenzene and amyl acetate may be passed through the mixture and the deodorized product after separation thereof from the oxidizing solution may be further treated by passing said saturated current of air therethrough to remove residual vapours and moisture. In a preferred embodiment 100 parts by volume of the dithiophosphate to be deodorized are subjected in a vessel for at least 2 hours and at a temperature not exceeding 50 DEG  C. to the action of 50 parts by volume of a 4.7 to 5 per cent aqueous sodium hypochlorite solution which is poured over it gradually and continuously whilst said saturated current of air is passed through the liquid, air and vapour being allowed to escape from the vessel, and after allowing the mixture to cool to room temperature the deodorized product, after separation thereof from the decomposed hypochlorite and of amorphous matter in suspension, is again treated with said saturated current of air for about 4 hours in a dry clean vessel, preferably with a vitrified or enamelled bottom, the air being admitted under pressure at the bottom of the vessel.  Examples are given.  The deodorized product may be used as an insecticide (see Group VI).  Specification 699,522 is referred to.ALSO:A pesticidal composition comprises an inert carrier material and the compound S-(1,2-dicarbethoxyethyl) O,O-dimethyl dithiophosphate which has been deodorized by submitting it to the oxidizing action of an aqueous solution of a metal hypochlorite, preferably sodium hypochlorite, the treatment being carried out (see Group IV (b)) by agitating the dithiophosphate in a vessel while gradually adding thereto said hypochlorite solution, continuing the agitation for at least half an hour at a temperature not exceeding 50 DEG  C., then allowing the mixture to cool to room temperature, removing the decomposed hypochlorite solution from the mixture by vacuum filtration, decantation, or centrifugal action after allowing the mixture to settle and finally removing residual moisture from the deodorized product. During the oxidizing action a current of air free from water but saturated with a mixture of nitrobenzene and amyl acetate may be passed through the mixture and the deodorized product after separation thereof from the oxidizing solution may be further treated by again passing therethrough said saturated current of air to remove residual vapours and moisture. The deodorized product may also be dissolved in water to form a pesticidal composition.  Specification 699,522 is referred to.