Patent GB-807598-A (GB)
Title: Method for the manufacture of o-aryl o-lower alkyl phosphorochloridothioates
IPC: C07F9/20
Filed: 1957-03-19
Abstract: An O-aryl O-lower alkyl-phosphorochloridothioate wherein the lower alkyl group contains 1 to 3 carbon atoms is obtained by reacting from 1 to 7 molecular proportions of a C1-C3 alkanol with one molecular proportion of an O-aryl phosphorodichloridothioate at a temperature at which hydrogen chloride is formed as a product of reaction while continuously withdrawing the hydrogen chloride in the gaseous state from the reaction mixture as formed, the said temperature being at least 15 DEG  C. below the boiling-point at 760 millimetres pressure of the alkanol employed.  The term "aryl" is defined as an aromatic hydrocarbon radical which may be unsubstituted or substituted by one or more substituents such as chlorine, bromine, alkyl, alkoxy, nitro, cyclohexyl, benzyl and phenyl.  The hydrogen chloride may be continuously withdrawn from the reaction mixture by carrying out the reaction under reduced pressure, or while passing an inert gaseous entraining agent through the mixture, or by effecting the reaction in the presence of an inert solvent having a low solvent power for hydrogen chloride.  Suitable gaseous entraining agents include nitrogen, methyl chloride, carbon dioxide or air, while suitable solvents include the hydrocarbon and halohydrocarbon solvents boiling at temperatures not exceeding 165 DEG  C., e.g. methylene dichloride (or dibromide), ethylene dichloride, chloroform, carbon tetrachloride, benzene, chlorobenzene and toluene.  The reaction may be carried out under such conditions that the reaction mixture boils, e.g. by using a suitable inert solvent, provided the boiling temperature is within the defined temperature range.  When the formation of hydrogen chloride is substantially complete the reaction mixture may be distilled under reduced pressure at temperatures up to 15 DEG  C. below the boiling-point at 760 millimetres pressure of the employed alkanol to separate excess alkanol and then at temperatures up to 90 DEG  C. to separate low-boiling constituents such as inert solvent and obtain the desired product as a liquid or crystalline residue. Examples are given for the production of O-aryl O-lower alkyl phosphorochloridothioates in which the lower alkyl radical is methyl and the aryl radical is 2,4,6-trichlorophenyl, 2,4,5-trichlorophenyl, 2-chloro-4-nitrophenyl, 2,5-dichlorophenyl, 4 - chlorophenyl, and 2,4 - dichlorophenyl, respectively, and in which the lower alkyl radical is ethyl and the aryl radical is 2,4,5-trichlorophenyl and 2,4-dichlorophenyl, respectively.  Other products which are stated to have been prepared are those in which the lower alkyl radical is methyl and the aryl radical is phenyl, 3-ethylphenyl, 4-nonylphenyl, 4 - secondary - butylphenyl, 4 - tertiary - butylphenyl, 4-methylphenyl, 3,4-dimethylphenyl, 2,5 - dimethylphenyl, 4 - tertiarybutyl - 2 - methylphenyl, 2 - bromo - 4 - tertiary - butylphenyl, 2 - chloro - 4 - tertiary - butylphenyl, 3,5 - dimethylphenyl, 4 - chloro - 2 - cyclohexylphenyl, 2-cyclohexylphenyl, 3-phenylphenyl, and 2-phenylphenyl respectively. The products are stated to be useful as pesticides and as preservatives for paper, paint and wood.  O - (2,4,6 - trichlorophenyl) O - methyl - phosphoroamidothioate is obtained by reacting the corresponding phosphorochloridothioate with excess ammonia in chlorobenzene at 5 DEG  to 15 DEG  C.  O - (2,4,5 - trichlorophenyl) O - ethyl - phosphoroamidothioate and the corresponding -N-ethyl phosphoramidothioate are obtained by reacting the corresponding phosphorochloridothioate with excess ammonia and excess ethylamine respectively in benzene at 10 DEG  C. O-(2-chloro - 4 - nitrophenyl) O - methyl-, O - (2,5 - dichlorophenyl) O - methyl -, and O - (4 - chlorophenyl) O - methyl - phosphoroamidothioates are also obtained by reacting the corresponding phosphorochloridothioate with excess ammonia.  O-aryl phosphorodichloridothioates are obtained by reacting at least two mols. of thio phosphoryl chloride with one mol. of an alkali metal salt of a phenol or suitably substituted phenol.