MXPA99007904A - Improved procedure for the production of an n-acid derivative of fosforoamidotioato de o, -dialqu - Google Patents

Abstract

The present invention relates to an improved process for the preparation of an acyl derivative of 0, S-dialkyl phosphoramidothioate by reaction of an O, S-dialkyl phosphoroamidothioate with an acylating agent in the presence of an acid, where the improvement lies in adding a C4 to C8 aliphatic alcohol, after completion of the acylation reaction, to the mixture of O, S-dialkyl phosphoroamidothioate, the acylating agent and talc acid. In one embodiment of the present invention, the acylation reaction is carried out in the absence of solvent. The aliphatic alcohol is easily recovered and can be reused in a subsequent acylation reaction

Description

IMPROVED PROCEDURE FOR THE PRODUCTION OF AN N-ACID DERIVATIVE OF O-FOSFOROAMIDOTIOATE. S-DIALOUILO TECHNICAL FIELD OF THE INVENTION The field of the present invention is the preparation of an acyl derivative of 0, S-dialkyl phosphorone idothioate. More specifically, the present invention relates to an improved process for the preparation of the acyl derivative of 0, S-dimethyl phosphoramidothioate known as Orteno. The Orteno is produced by the reaction of an O, S-dialkyl phosphoramidothioate with an acylating agent in the presence of an acid, where the improvement consists in the addition of a C4 aliphatic alcohol to Ce, after the acylation reaction is completed, to isolate and recover the Orteno. BACKGROUND OF THE INVENTION The acyl derivative of 0, S-dimethyl phosphoramidothioate is known as Orteno. Orteno is typically produced by reaction of 0, S-dimethyl phosphoramidothioate with conventional acylating agents, such as acid anhydrides. Acetic acid anhydride is a preferred acylating agent. The acylation reaction is typically carried out at temperatures of 0 ° C to 60 ° C in the presence of a catalytic amount of an acid and in the presence of a solvent. Such solvents include methylene chloride, chloroform, tetrahydrofuran and benzene (see, for example, US Patents 3,716,600 and 3,732,344). The solvents used in the process are suspected carcinogens. Moreover, tetrahydrofuran tends to form a dangerous peroxide when stored. Therefore, methylene chloride, chloroform, tetrahydrofuran and benzene are not commercially viable solvents. It would be desirable to develop a process for producing Orteno that does not require the use of a volatile toxic solvent. BRIEF SUMMARY OF THE INVENTION It is an object of the present invention to provide an improved process for the preparation of an acyl derivative of 0, S-dialkyl phosphoramidothioate, consisting of the reaction of a 0, S-dialkyl phosphoramidothioate with an acylating agent in presence of an acid, where the improvement resides in the addition of a C4 to C8 aliphatic alcohol to the reaction mixture after completion of the acylation reaction, to isolate and recover the Orteno. It is also an object of the present invention to provide a process for producing an acyl derivative of 0, S-dialkyl phosphoroamidothioate in the absence of a volatile toxic solvent. These and other objects, which will be apparent to those skilled in the art, are achieved by the addition of a C4 to C8 aliphatic alcohol to the acylating mixture, upon completion of the acylation reaction, to isolate and recover the acyl derivative of O-phosphoramidothioate. , S-dialkyl. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION The present invention is directed to an improved process for the preparation of an acyl derivative of 0, S-dialkyl phosphoramidothioate by reaction of an O, S-dialkyl phosphoramidothioate with an agent acylating in the presence of an acid, where the improvement resides in the addition of a C to C8 aliphatic alcohol as a solvent to isolate and recover the acyl derivative of O, S-dimethyl phosphoramidothioate. The C to C8 aliphatic alcohol is added to the mixture of the O, S-dialkyl phosphoroamidothioate, the acylating agent and the acid after completion of the acylation reaction. In one embodiment of the present invention, the acylation reaction is carried out in the absence of solvent. The aliphatic alcohol is easily recovered and can be reused in a subsequent process to isolate and recover the phosphoramidothioate of O, S-dialkyl. In a preferred embodiment, the 0, S-dialkyl phosphoroamidothioate, the acylating agent and the acid are added to a reactor and heated for a period of from about 0.5 hours to about 8 hours, preferably from about 1 hour to about 3 hours , at a temperature of about 20 ° C to about 80 ° C and, preferably, from about 40 ° C to about 60 C. Any excess of acylating agent is removed under vacuum. The mixture is cooled to a temperature of about 0 ° C to about 10 ° C and neutralized to a pH of about 7.0 to about 7.2 by the addition of a base. Such bases include ammonium hydroxide, sodium hydroxide, potassium hydroxide, sodium carbonate or potassium carbonate. Water is added in an amount of about 10% to about 50% by weight (based on the combined weight of the reagents) and an aliphatic alcohol to the mixture after completion of the acylation reaction. The two resulting phases are separated (an organic / alcoholic phase and an aqueous phase) and the aqueous phase is extracted with alcohol. The alcohol phases are combined and concentrated, the mixture is cooled to a temperature of about 0 ° C to about 10 ° C and filtered to recover the desired acyl derivative. The filtrate is distilled to recover the aliphatic alcohol. The O, S-dialkyl phosphoratnidothioates, as well as the manufacturing methods thereof, are known in the art and are described in US Pat. 3,309,266, the description of which is hereby incorporated by reference. Said O, S-dialkyl phosphoramidothioates include O-methyl-S-methyl phosphoroamidothioate, O-methyl-S-ethyl phosphorus amide, O-ethyl-S-methyl phosphoroamidothioate, O-methyl-S-phosphoramidothioate. -ethyl, O-ethyl-S-propyl phosphoramidothioate and the like. A preferred O, S-dialkyl phosphoramidothioate is O-methyl-S-methyl phosphoramidothioate. Acylating agents are also known in the art and include acyl halides, ketenes and acid anhydrides. Preferred acylating agents are acetic anhydride and acetyl chloride. Acid catalysts are known and include phosphoric acid, sulfuric acid, methanesulfonic acid, nitric acid, hydrochloric acid, perchloric acid and acidic ion exchange resins (such as Amberlyst N15). A preferred acid catalyst is sulfuric acid. The acylation reaction is typically carried out at temperatures from about 0 ° C to about 80 ° C. The pressure is not critical in the reaction. For reasons of convenience, atmospheric pressure is generally used. Under usual conditions, stoichiometric proportions or a slight excess of acylating agent are used. The amount of acid catalyst can vary over a wide range and is typically from about 0.5% to about 50% by weight and, preferably, from about 1% to about 3% by weight, based on combined weight of the O, S-dialkyl phosphoroamidothioate and the acylating agent. The improved process of the present invention includes the addition of a C4 to C8 aliphatic alcohol, upon completion of the acylation reaction, to isolate and recover the acyl derivative of 0, S-dimethyl phosphoramidothioate. Said aliphatic alcohols include n-butyl alcohol, pentanol and its various isomers; 4-methyl-2-pentanol, t-butanol, isobutyl alcohol, 2-methyl-1-butanol, hexanol and its various isomers; heptanol and its various isomers, and octanol and its various isomers. Preferred alcohols are n-butyl alcohol, n-pentanol and 4-methyl-2-pentanol. The amount of alcohol can vary over a wide range and is typically from about 100% to about 500% by weight and, preferably, from about 200% to about 400% by weight, based on the combined weight of the phosphoramidothioate of O, S-dialkyl and the acylating agent. A preferred embodiment includes the addition of water to the mixture after completion of the acylation reaction. The amount of water can vary over a wide range and is typically from about 10% to about 5 ~ 0% by weight, based on the combined weight of the O, S-dialkyl phosphoroamidothioate and the acylating agent. The invention is still illustrated, but without intending to limit it, by the following examples, where all parts and percentages are by weight, unless otherwise indicated.

Example: To a mixture of 0, S-dimethyl phosphoramidothioate (1.0 mole, 183.2 g of 77% purity) and concentrated H2SO4 (0.05 mole, 5.1 g of 96% purity) acetic anhydride (1.30 mol, 132.6 g) was added slowly over 45 minutes at a temperature of 40 ° C to 50 ° C. The mixture was then baked for 1 hour at 1.5 hours at a temperature of 50 ° C to 55 ° C. The resulting acetic acid thus formed, together with the excess acetic anhydride, was removed at 75 ° C / 10 mm using a rotary evaporator. The melt containing phosphoramidothioate of N-acetyl-O, S-dimethyl was mixed with 100 ml of water (new or recycled from the previous batch) and 750 ml of 4-methyl-2-pentanol (the aliphatic alcohol). This mixture was then cooled to a temperature of 5 ° C and neutralized with a 30% aqueous solution of ammonium hydroxide at a pH of about 6.8 to about 7.2. Control of the temperature and pH of the mixture was important to avoid hydrolysis of the N-acetyl derivative of O, S-dimethyl phosphoramidothioate. The aqueous phase was separated and extracted with 2 x 200 ml of fresh 4-methyl-2-pentanol (the aliphatic aleo-hol). The organic (alcoholic) phases were combined and concentrated to 400 ml. The concentrated organic phase was cooled to 10 ° C and the N-acetyl-O, S-dimethyl phosphoramidothioate was collected by filtration. The filter cake was washed with cold 4-methyl-2-pentanol (5 ° C to 10 ° C) twice (50 ml each). The Orteno crystals collected were refined as follows: The mother liquor and the washes were combined and 70% of this was recycled as is in the next batch, while the remaining 30% was extracted with 100 ml of water (this Water can be mixed with the melt containing phosphoramidothioate of N-acetyl-0, S-dimethyl as described above). The organic phase was distilled to recover 4-methyl-2-pentanol. The hardened Orteno was mixed with 400 ml of 4-methyl-2-pentanol at 40 ° C for 10 minutes, stirred vigorously, cooled to 10 ° C, filtered and dried. The Orteno thus obtained was 99% pure. The average yield of Orteno in 10 recycled was 84%. Although the invention has been described in detail in the foregoing for purposes of illustration, it is to be understood that said detail has that purpose only and that those skilled in the art can make variations therein without departing from the spirit and scope of the invention, except in what may be limited by the claims.

Claims (23)

1. CLAIMS 1. A process for the preparation of an N-acyl derivative of an O, S-dialkyl phosphoramidothioate by reaction of a 0, S-dialkyl phosphoramidothioate with an acylating agent in the presence of an acid, where the improvement consists in adding a C4 to C8 aliphatic alcohol to the reaction mixture after completion of the acylation reaction, to isolate and recover the N-acyl derivative.
2. 2. The method of Claim 1, wherein the acylation reaction is carried out in the absence of solvent.
3. 3. The process of Claim 1, wherein the reaction mixture is heated to a temperature of about 20 ° C to about 80 ° C.
4. 4. The method of Claim 1, wherein the reaction mixture is heated to a temperature of about 40 ° C to about 60 ° C.
5. 5. The process of Claim 1, wherein the 0, S-dialkyl phosphoramidothioate is selected from the group consisting of 0-methyl-S-methyl phosphoroamidothioate, O-methyl-S-ethyl phosphoroamidothioate, O-phosphoramidothioate. -ethyl-S-methyl, O-methyl-S-ethyl phosphoroamidothioate or O-ethyl-S-propyl phosphoramidothioate.
6. 6. The process of Claim 1, wherein the 0, S-dialkyl phosphoramidothioate is O-methyl-S-methyl phosphoramidothioate.
7. The process of Claim 1, wherein the acylating agent is selected from the group consisting of an acyl halide, ketene or acid anhydride.
8. 8. The process of Claim 7, wherein the acylating agent is acetic acid anhydride or acetyl chloride.
9. 9. The method of Claim 1, wherein the acid catalyst is selected from the group consisting of phosphoric acid, sulfuric acid, methanesulfonic acid, nitric acid, hydrochloric acid, perchloric acid or acidic ion exchange resins.
10. 10. The method of Claim 1, wherein the acid catalyst is sulfuric acid.
11. The process of Claim 1, wherein the acid catalyst is from about 0.5% to about 50% by weight of the combined weight of the O, S-dialkyl phosphoroamidothioate and the acylating agent.
12. 12. The process of Claim 1, wherein the acid catalyst is from about 1% to about 3% by weight of the combined weight of the 0, S-dialkyl phosphoroamidothioate and the acylating agent. The method of Claim 1, wherein the aliphatic alcohol is selected from the group consisting of n-butyl alcohol, pentanol or its various isomers; 4-methyl-2-pentanol, t-butanol, isobutyl alcohol, 2-methyl-1-butanol, hexanol or its various isomers; heptanol or its various isomers; or octanol or its various isomers. The method of Claim 1, wherein the "aliphatic alcohol is selected from the group consisting of n-butyl alcohol, n-pentanol or 4-methyl-2-pentanol 15. The method of Claim 1, wherein the amount of alcohol is from about 100% to about 500% by weight of the combined weight of the phosphoramidothioate of 0, S-dialkyl and the acylating agent 16. The method of Claim 1, wherein the amount of alcohol is about 200 % to about 400% by weight of the combined weight of the O, S-dialkyl phosphoroamidothioate and the acylating agent 17. The method of Claim 1, wherein water is added to the reaction mixture after completion of the acylation reaction. The process of Claim 17, wherein the amount of water is from about 10% to about 50% by weight of the combined weight of 0, S-dialkyl phosphoroamidothioate and the acylating agent. of Claim 1, wherein a base is added to the reaction mixture to neutralize the mixture at a pH of about 7.0 to about 7.2. The method of Claim 19, wherein the base is selected from the group consisting of ammonium hydroxide, sodium hydroxide, potassium hydroxide, sodium carbonate or potassium carbonate. 21. The process of Claim 1, wherein the organic phases resulting from the acylation reaction are separated and an aqueous phase is extracted with an aliphatic alcohol, the resulting alcohol phases are combined, the mixture is cooled to a temperature of about 0 ° C. at about 10 ° C and filtered to recover the N-acyl derivative and the filtrate is then distilled to recover the aliphatic alcohol. The method of Claim 21, wherein the aliphatic alcohol used for the extraction is selected from the group consisting of n-butyl alcohol, pentanol or its various isomers; 4-methyl-2-pentanol, t-butanol, isobutyl alcohol, 2-methyl-1-butanol, hexanol or its various isomers; heptanol or its various isomers; or octanol or its various isomers. The process of Claim 21, wherein the aliphatic alcohol used for the extraction is selected from the group consisting of n-butyl alcohol, n-pentanol or 4-methyl-2-pentanol.