| abstract |
A process for the purification of esters of phosphorus thioacids having the formula: <IMAGE> wherein R is an organic radical which is attached via a carbon atom thereof to X; R1 and R2 are optionally substituted hydrocarbon radicals which may be the same or different, and X is O or S, and which contains as an impurity a thiolo isomer having the formula: <IMAGE> in which R, R1, R2 and X have the previously defined meanings, which comprises washing the ester with an aqueous solution of an acid or an acid salt. Particularly applicable to esters in which R is a substituted pyrimidinyl, phenyl or benzyl radical and R1 and R2 are alkyl radicals containing from 1 to 4 carbon atoms, especially methyl or ethyl radicals, which are useful as insecticides. |