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.
A process for the purification of esters of phosphorus thioacids having the formula: ##STR8## wherein R is an organic radical which is attached via a carbon atom thereof to X; R 1 and R 2 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: ##STR9## in which R, R 1 , R 2 and X have the previously defined meanings, which comprises washing the ester with 1 to 5% by weight aqueous sulfuric acid whereby the content of thiolo impurity in the ester is reduced to a level at which the subsequently stabilized ester does not develop objectionable odors on storage.
Claim 2
Dependent Claim
122 words
A process for the purification of esters of phosphorus thioacids having the formula: ##STR8## wherein R is an organic radical which is attached via a carbon atom thereof to X; R 1 and R 2 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: ##STR9## in which R, R 1 , R 2 and X have the previously defined meanings, which comprises washing the ester with 1 to 5% by weight aqueous sulfuric acid whereby the content of thiolo impurity in the ester is reduced to a level at which the subsequently stabilized ester does not develop objectionable odors on storage.
Claim 3
Dependent Claim
21 words
A process as claimed in claim 1 wherein the ester is given up to four washes with said aqueous sulfuric acid.
Claim 4
Dependent Claim
45 words
A process as claimed in claim 1 wherein the ester, in the form of a solution in a water-immiscible inert organic solvent, is washed with said aqueous sulfuric acid in amount of from one half to one third of the volume of solution being washed.
Claim 5
Dependent Claim
24 words
A process as claimed in claim 1 wherein the amount of thiolo isomer remaining in the purified ester does not exceed 0.3% by weight.
Claim 6
Dependent Claim
24 words
A process as claimed in claim 1 wherein the amount of thiolo isomer remaining in the purified ester does not exceed 0.1% by weight.