CS266142B1 - Method of 0,0-dimethyl-s-phthalimidomethyldithiophosphate preparation - Google Patents

Abstract

The solution relates to the method of preparation of 0.0- -dimethyl-S-phthalimidomethyldithiophosphate by reacting a suspension of N-hydroxymethylphthalimide in an inert organic solvent with hydrogen chloride and / or an aqueous acid solution hydrochloric acid followed by reaction of a solution of N-chloromethylphthalimide 0,0-dimethyldithiophosphoric sodium salt acid to give a solution of 0,0-dimethyl- -S-phthalimidomethyldithiophosphate in inert an organic solvent from which it is washed with sodium hydroxide solution and water in a known manner, technical 0,0-dimethyl- -S-phthalimidomethyldithiophosphate in high extract and purity.

Description

The present invention relates to a process for the preparation of 0,0-dimethyl-S-phthalimidomethyldithiophosphate (phosmet) from phthalimide as a starting material. Fosmet is the active ingredient in several insecticidal and acaricidal preparations.

It is generally known that phosmet can be prepared by reacting N-halomethylphthalimide with an alkaline resp. ammonium salt of 0,0-dimethyldithiophosphoric acid according to the reaction scheme

N-CH ₂ -X + Me-S - P (OCH ₃ ) ₂ ll s ^ N-CH ₂ -SP (OCH ₃ ) ₂ +

MeX wherein X is chlorine or bromine and Me is hydrogen, potassium or NH4.

In the preparation of phosmet, N-bromomethylphthalimide (DE 930 446) and N-chloromethylphthalimide (U.S. Pat. No. 2,767,194) are generally mentioned as starting materials. Since the production of these starting materials follows the preparation of N-hydroxymethylphthalimide (DRP 104 624, Buc SR: J. Am. Chem. SOc. 69, 245 (1947)), the possibility of simplifying the multistage synthesis of phosmet was sought. (12020) that the reaction of N-hydroxymethylphthalimide with hydrogen chloride can be carried out in the presence of such an inert solvent which will serve as a reaction medium in the subsequent reaction step.

In another process for the production of phosmet (CS 162 692), the starting anhydrous N-hydroxymethylphthalimide suspended in toluene, first catalyzed by pyridine, is converted to N-chloromethylphthalimide with thionyl chloride, which is filtered off after crystallization, washed with cold water and wet water. state, with stirring, it is added to the prepared toluene-in-water emulsion containing β, β-dimethyldithiophosphoric acid sodium salt, whereby the reaction is completed within 1.5 hours at a temperature of 55 to 60 ° C. After phase separation, impurities (phthalimide, sulfur, etc.) are removed from the toluene layer by filtration, and after distilling off the toluene under reduced pressure, a technical phosmet melt is obtained.

The patent literature (SU 652 897, GB 1 487 038) describes a process in which the starting N-hydroxymethylphthalimide in the form of a wet filter cake is suspended in benzene, reacted with N-chloromethylphthalimide with 35 to 40% hydrochloric acid and hydrogen chloride. , which then in the form of a benzene solution with an aqueous solution of the sodium salt of β, β-dimethyldithiophosphoric acid gives a benzene solution of phosmet, which, after washing with 10% sodium hydroxide solution and water, gives technical phosmet after evaporation of the solvent.

Of the above methods, the process of CS 162 692 has the disadvantage that the starting material is anhydrous N-hydroxymethylphthalimide, which upon reaction with thionyl chloride gives N-chloromethylphthalamide, which must be filtered off, washed twice with cold water and used after thorough suction to react with sodium chloride. β, β-dimethyldithiophosphoric acid salt in the presence of toluene and 0,0,5-trimethyldithiophosphate. After the reaction, the toluene layer is freed of impurities by further filtration and only then is the expected product isolated. Nowhere is it mentioned how the technical product gets rid of 0,0,5-trimethyldithiophosphate. The process uses thionyl chloride to produce N-chloromethylphthalimide, which is associated with the development of a mixture of sulfur dioxide and hydrogen chloride, which must either be complicated to separate or, after neutralization, oxidized to sulfite to sulfate. The handling of N-chloromethylphthalimide is also extremely difficult.

The process in which the starting material is a wet N-hydroxymethylphthalimide filter cake (SU 652 897, GB 1 487 038) had to be preceded by its preparation and the very inconvenient filtration of N-hydroxymethylphthalimide from formaldehyde-containing mother liquors.

The process for preparing 0,0-dimethyl-S-phthalimidomethyldithiophosphate by reacting phthalimide with formaldehyde to remove excess formaldehyde, methanol and water overcomes these shortcomings.

EN 266 142 B1 by azeotropic distillation with an inert organic solvent, reaction of N-hydroxymethylphthalimide with hydrogen chloride and subsequent reaction of the formed N-chloromethylphthalimide with the sodium salt of 0,0-dimethyldithiophosphoric acid according to the invention. The invention is based on the reaction of a suspension of N-hydroxymethylphthalimide in an inert organic solvent with hydrogen chloride and / or aqueous hydrochloric acid at 20 DEG C. to 80 DEG C., and the resulting N-chloromethylphthalimide solution is reacted with the sodium salt Ο, Ο. -dimethyldithiophosphoric acid at 40 ° C to 70 ° C to give a solution of 0,0-dimethyl-S-phthalimidomethyldithiophosphate in an inert organic solvent, from which it is washed with 0.5 to 8% sodium hydroxide solution with water and removed. The technical isolates O, O-dimethyl-S-phthalimidomethyldithiophosphate of the solvent in a known manner in high yield and high purity. As the inert organic solvent, especially aromatic hydrocarbons such as benzene, toluene, xylene and mixtures thereof can be used, but 1,2-dichloroethane, carbon tetrachloride and the like can also be used. The process according to the invention gives a high-purity technical phosmet containing more than 97% of O, O-dimethyl-S-phthalimethylmethyl dithiophosphate in a yield of more than 80%, calculated on the starting phthalimide.

The process starting from anhydrous N-hydroxymethylphthalimide (CS 162 692) gives an yield of up to 95.2% of active compound, calculated on hydroxymethylphthalamide. However, the stated melting points of the product (69 ° C, 70 ° C) do not correspond to the stated purities (98.5%), since pure phosmet has a m.p. t. 74 ° C. In the case of starting from a wet filter cake of N-hydroxymethyl-phthalimide (SU 652 897, GB 1 487 038), a yield of 73% of technical phosphate of 95% purity is reported.

The advantages of the method according to the invention are the following:

N-hydroxymethylphthalimide does not need to be obtained in the form of a wet filter cake (CS 201 536) or in the form of a solid anhydrous product (CS 162 692).

The N-chloromethylphthalimide preparation step does not require separate isolation and washing (CS 162 692).

In the stage of preparation of techn. phosmet, the reaction of a solution of N-chloromethylphthalimide with the sodium salt of Ο, Ο-dimethyldithiophosphoric acid can also be carried out using the principle of a two-stage excess of reactants (CS 253 920).

Despite the fact that the basic starting material is phthalimide, that neither N-chloromethylphthalimide (CS 162 652) nor N-hydroxymethylphthalimide (SU 615 897 GB 1 487 038) is specifically isolated, by combining all three processes, techn. phosmet in such high purity that its further crystallization is unnecessary.

The following examples illustrate but do not limit the scope of the invention.

Example 1

To 147.2 parts of phthalimide was added 101.2 parts of a 35.6% aqueous formaldehyde solution, and the mixture was heated to reflux, which remained for 1 hour after the reaction mixture became clear. Then, the hot solution of N-hydroxymethylphthalimide was poured into 900 parts by volume of toluene, and the resulting suspension of N-hydroxymethylphthalimide was again heated to reflux, with stirring and constant separation of the aqueous phase, the reaction mixture was heated until the temperature of the reaction mixture reached 95 ° C. Dilute to 68 volumes of aqueous phase containing water, methanol and formaldehyde. After cooling the reaction mixture to 70 ° C, 348 parts of 32.4% hydrochloric acid was added thereto. The temperature of the reaction mixture was then adjusted to 34 ° C, and 104 parts of hydrogen chloride were introduced into the mixture over a period of 50 minutes. The reaction mixture was then slowly heated to 55 ° C to 60 ° C, at which temperature the mixture was maintained with stirring for 1 h, which was sufficient to sharply separate the upper organic layer containing N-chloromethylphthalimide from the lower acid layer. To a separate 970 part of a toluene solution of N-chloromethylphthalimide was added 439 parts of a 39.0% solution of β, β-dimethyldithiophosphoric acid sodium salt, temperature

The reaction mixture was adjusted to 50 ° C to 55 ° C and stirred vigorously at this temperature for 3.5 h. The stirring was then stopped, the lower aqueous layer containing the salts was separated, and the upper toluene layer was washed with 400 parts by volume of 2% sodium hydroxide solution and 300 parts of water after cooling to 25 ° C to 30 ° C. The toluene layer was then freed of solvent on a vacuum rotary evaporator, finally at a pressure of 2.6 kPa and a bath temperature of 80 ° C. 294.3 parts of melt techn. product, which, after solidification, crushing and drying in a stream of nitrogen, at 50 DEG C., gave 264.9 parts of product containing 99.2% of 0,0-dimethyl-S-phthalimidomethyldithiophosphate, which corresponds to 82.81% of yield, calculated on the starting phthalimide.

Example 2

To 73.6 parts of phthalimide was added 50.0 parts of a 36% aqueous formaldehyde solution, and the mixture was heated to reflux for 1 hour. The resulting solution of N-hydroxymethylphthalimide was then poured into 400 volumes with stirring. parts of benzene and azeotropic distillation to remove 32 vol. parts of the aqueous phase. The mixture was then cooled to 25 ° C, 240 parts of 41.5% hydrochloric acid were added and heated to 60 ° C over 1 hour and stirred at this temperature for a further 1 hour, the lower acid layer was separated and the remaining 444.0 parts of a benzene solution of N-chloromethylphthalimide was added 227.0 parts of a 38.5% solution of O, O-dimethyldithiophosphoric acid sodium salt, and the mixture was then stirred at 50 ° C to 55 ° C for 3 hours. Then, the reaction mixture was cooled to 25 ° C, the lower aqueous layer and the benzene solution were separated. phosmet was washed with 200 vol. parts of 3% sodium hydroxide solution and 300 vol. parts of water. The washed solution was freed of solvent by distillation on a vacuum rotary evaporator, in a stream of nitrogen, finally at a pressure of 1.3 kPa and a bath temperature of 80 ° C, whereby after cooling and crystalline solidification 130.5 parts of product were obtained which contained 99.3%. O-dimethyl-S-phthalimide methyldithiophosphate, corresponding to an 81.7% yield calculated on phthalimide.

Example 3

To 147.2 parts of phthalimide was added 110.5 parts of a 32.6% formaldehyde solution, the mixture was heated to reflux for 1.5 hours, then 31 vol. parts of a mixture of water, formaldehyde and methanol and a concentrated solution of N-hydroxymethylphthalimide were poured with stirring into 900 parts by volume of toluene and, after heating to reflux, a further 40 parts of aqueous phase were separated from the reaction mixture. Then, the reaction mixture was cooled to 40 ° C, 350 parts of a separated acid layer from the preparation of the N-chloromethylphthalimide solution from Experiment 1 containing 32.6% hydrochloric acid was added thereto, and at 40 ° C to 55 ° C was added to stirred 105 parts of hydrogen chloride were introduced into the reaction mixture over a period of 1 hour. The reaction mixture was then heated to 60 ° C to 65 ° C and held at this temperature for 1 h. This was followed by separation of the lower acid layer from the toluene layer containing N-chloromethylphthalimide, to which was then added 462.0 parts of a 39.0% aqueous solution of O, O-dimethyldithiophosphoric acid sodium salt, and the temperature of the reaction mixture was adjusted to 50 ° C. to 55 ° C and at this temperature the reaction mixture was stirred for 3 h. After stirring was stopped, the lower aqueous layer containing the excess sodium salt of O, O-dimethyldithiophosphoric acid was separated from the toluene layer containing phosmet. The toluene layer was then washed with 400 parts of 2.5% sodium hydroxide solution and then with 400 parts of water. The toluene solution was then freed of solvent on a vacuum rotary evaporator, finally at a pressure of 2.0 kPa and a bath temperature of 80 ° C, to give 288.5 g of a melt containing 8% of toluene and 91.4% of 0,0-dimethyl-S -phthalimidomethyldithiophosphate, corresponding to an 83.05% yield calculated on phthalimide. The product can be used directly for the production of emulsion concentrates.

Example 4

Of the 147.2 parts of phthalimide, 110.5 parts of a 32.6% formaldehyde solution, 900 vol.

parts of toluene, 351 parts of the acid layer from Experiment 3, which contained 31.9% of hydrogen chloride and 106 cl of hydrogen chloride gas, a toluene solution was prepared according to the procedure of Example 3.

CS 266 142 Bl

N-chloromethylphthalimide, to which was then added a separate aqueous layer containing the sodium salt of 0,0-dimethyldithiophosphoric acid from Experiment 3, and after stirring at 50 ° C to 55 ° C for 1 h, stirring was stopped, and the aqueous layer of salts was added. it already contained only 0.8% of the sodium salt of Ο, Ο-dimethyldithiophosphoric acid. To a toluene solution of 0,0-dimethyldithiophosphoric acid sodium salt, the temperature of the reaction mixture was adjusted to 50 ° C to 55 ° C, and the reaction mixture was stirred at this temperature for 3 h. The reaction mixture was then allowed to separate and, after separation, the upper toluene layer of the techn. phosmetu washed with 500 parts of water. The washed toluene solution was then freed of solvent on a vacuum rotary evaporator, finally under a pressure of 1.1 kPa, in a stream of nitrogen and a bath temperature of 80 ° C, whereby after cooling and solidification 262.7 parts of 99.3% product were obtained, which corresponds to an 82.2% yield of theoretical 317.3 parts.

Example 5

To 147.2 parts of phthalimide were added 103 parts of a 35% formaldehyde solution, the mixture was heated to reflux for 1 hour, then 32 parts of the aqueous phase were distilled off from the mixture, 900 vol. parts of toluene and azeotropically distilled off all the aqueous phase, which distilled to a reaction mixture temperature of 95 ° C to 98 ° C. The N-hydroxymethylphthalimide suspension was then cooled to 40 DEG C., 350 parts of 32% hydrochloric acid were added and 109 parts of hydrogen chloride gas were introduced with stirring, slowly heated to 60 DEG C. to 65 DEG C. and then After heating at this temperature for 1 h, the lower acid layer was separated from the upper toluene layer containing N-chloromethylphthalimide. To the toluene layer was added 430.0 parts of a 39.8% aqueous solution of β, β-dimethyldithiophosphoric acid sodium salt, the temperature of the mixture was adjusted to 50 ° C to 55 ° C, and the reaction mixture was stirred at this temperature for 3 hours. It was then cooled below 30 [deg.] C., 23.8 parts of 42% sodium hydroxide solution were added and, after brief stirring, the lower aqueous layer was separated from the toluene layer, which was finally washed with a further 300 parts of water. The washed toluene layer was then freed of solvent on a vacuum rotary evaporator finally at a pressure of 2.7 kPa and a bath temperature of 75 ° C. 296.2 parts of melt techn. product to which 200 vol. parts of methanol and, after dissolving and cooling to 7 DEG C., 258.3 parts of crystalline 99.7% product were obtained, corresponding to an 81.2% yield calculated on phthalimide.

Example6

Starting from the same amounts of raw materials and in the same manner as in Example 1 (toluene was used instead of benzene only), a toluene solution of N-chloromethylphthalimide was prepared, to which 216.2 parts of a 38.6% ammonium salt solution Ο, Ο were added. -dimethyldithiophosphoric acid and the mixture was then stirred at 50 ° C to 55 ° C for 3 h. Then the lower aqueous layer and the toluene solution were separated. phosmet was washed with 200 vol. parts of 5% sodium hydroxide solution and then 250 parts of water. The washed solution was freed of solvent by distillation at a pressure of 1.5 kPa and a bath temperature of 80 DEG C., after cooling and crystalline solidification, 131.6 parts of product were obtained, which contained 99.2% of 0,0-dimethyl-S-phthalimidomethyldithiophosphate, which corresponds to a yield of 82.3% based on the starting phthalimide.

Claims (1)

5 N-chloromethylphthalimide to which a separate aqueous layer containing sodium Ο, Ο-dimethyldithiophosphoric acid from experiment 3 was added and stirring was stopped after 1 h of stirring at 50 ° C to 55 ° C, the aqueous layer was separated salt, which contained only 0.8 isodium salt of Ο, Ο-dimethyldithiophosphoric acid. To the toluene solution of 0,0-di-dimethyldithiophosphoric acid sodium salt, the temperature of the reaction mixture was adjusted to 50 ° C to 55 ° C and the reaction mixture was stirred for 3 hours at that temperature. techn. Phosmet with 500 parts of water. The washed toluene solution was then freed from the solvent on a vacuum rotary evaporator, finally at a pressure of 1.1 kPa, under a stream of nitrogen and a bath temperature of 80 ° C, yielding 262.7 parts of 99.3% product after cooling and solidification, corresponding to 82%. A 2% yield of the theoretical 317.3 parts. Example 5 103 parts of 35% formaldehyde solution were added to 147.2 parts of phthalimide, heated to reflux for 1 hour, then 32 parts of the aqueous phase were distilled off, 900 parts by volume of toluene was added and azeotropically all the water phase that distilled to the reaction mixture temperature of 95 ° C to 98 ° C was distilled off. The N-hydroxymethyl-phthalimide suspension was then cooled to 40 ° C, 350 parts of 32% hydrochloric acid were added thereto, and 109 parts of hydrogen chloride gas were introduced with stirring, and 60 ° C to 65 ° C was slowly heated. and after 1 h at this temperature, the lower acid layer was separated from the upper toluene layer containing N-chloromethylphthalimide. To the toluene layer was added 430.0 parts of a 39.8% aqueous solution of sodium os, dim-dimethyldithiophosphoric acid, the temperature of the mixture was adjusted to 50 ° C to 55 ° C and the reaction mixture was stirred for 3 hours. below 30 ° C, 23.8 parts of a 42% sodium hydroxide solution was added, and after brief mixing, the lower aqueous layer was separated from toluene, which was finally rinsed with 300 parts of water. The washed toluene layer was then freed from the solvent in a vacuum evaporator, finally at 2.7 kPa and a bath temperature of 75 ° C. 296.2 parts of melt techn. of the product to which 200 parts by volume of methanol was added and after dissolving and cooling to 7 ° C, 258.3 parts of crystalline 99.7% product was obtained, corresponding to a 81.2% yield calculated on phthalimide. EXAMPLE 6 A toluene solution of N-chloromethylphthalimide was prepared starting from the same amounts of raw materials and in the same manner as in Example 1 (instead of benzene only, using 216.2 parts of a 38.6% ammonium salt solution). the dimethyldithiophosphoric acid and the mixture was then stirred at 50 ° C to 55 ° C for 3 h. Subsequently, the bottom aqueous solution and the toluene solution were separated. The phosmet was washed with 200 parts by volume of a 5% solution of sodium hydroxide and then with 250 parts of water. The washed solution was freed from the solvent by distillation of a pressure of finally 1.5 kPa and a bath temperature of 80 ° C, yielding 131.6 parts of a product containing 99.2% of O, O-dimethyl-S-phthalimidomethyldithiophosphate after cooling and crystallization. A 3% yield calculated on the starting phthalimide. OBJECT OF THE INVENTION A process for preparing 0,0-dimethyl-S-phthalimidomethyldithiophosphate by reacting phthalimide with formaldehyde to remove excess formaldehyde, methanol and water by an azeotropic distillation with an inert organic solvent, reacting the resulting mixture containing N-hydroxymethyl-phthalimide with a hydrogen chloride followed by N- N- Ο, Ο-dimethyldithiophosphoric acid chloromethylphthalimide, characterized in that the suspension of N-hydroxymethyl-phthalimide in an inert organic solvent is reacted with hydrogen chloride and / or aqueous hydrochloric acid solution at 20 ° C to 80 ° C, leaving the resulting N-chloromethylphthalimide solution with Ο, Ο-dimethyldithiophosphoric acid sodium salt at 40 ° C to 70 ° C to form a Ο, Ο-dimethyl-S-phthalimidomethyldithiophosphate solution in an inert organic solvent from which, after washing with 0.5 to 8% sodium hydroxide solution and water and after removal of solvent i technical O, O-dimethyl-S-phthalimidomethyldithiophosphate is isolated.