Bisphosphonic acid and salt compound thereof, and preparation method and application thereof

Abstract

The invention discloses diphosphonic acid and a salt compound thereof, a preparation method and application. The structural formula of the bisphosphonic acid and the salt compound thereof is shown as a formula (I). According to the preparation method, methyl (3-oxopropyl) phosphinic acid is taken as an initial raw material, a target product [1-hydroxy-3-(methylphosphonyl) propyl]-methylphosphinic acid is prepared through condensation and hydrolysis two-step reaction, and the target product reacts with an alkaline substance to obtain corresponding salt. The obtained target product has a bisphosphonic acid skeleton, and the bisphosphonic acid herbicide lead compound with a novel structure is beneficial to improving the weed removal effect; meanwhile, the target product is salified to obtain a salt compound, the salt compound is used for preparing herbicides for preventing and controlling green bristlegrass, amaranthus retroflexus, chenopodium album and other weeds, the obvious weeding effect is achieved, the water solubility, hygroscopicity, stability and the like of the compound can be changed by preparing the salt compound into the salt, and therefore different preparation requirements are met.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of bisphosphonic acid and its salt compound, its preparation method and the application in the preparation of herbicide. BACKGROUND

[0002] In modern agricultural production, weeds are one of the key factors affecting the growth, development, yield and quality of crops. Traditional weeding methods such as manual weeding and mechanical weeding not only consume a lot of manpower, material resources and time, but also are difficult to implement completely and inefficient in large-scale agricultural production. Chemical weeding gradually becomes the main means of modern agricultural weeding due to its high efficiency, convenience and economy. Phosphorus-containing compounds have a unique position in the field of herbicides. Phosphorus can participate in various physiological metabolic processes of organisms. Herbicides based on phosphorus-containing structure design often have unique action targets and mechanisms. Some varieties of phosphorus-containing herbicides have been widely used in agricultural production, and they show good activity and selectivity in controlling specific weed species. However, with the increasing requirements of agricultural production and the increasing problem of weed resistance, it is of great significance to develop new types of phosphorus-containing herbicides with novel structure and mechanism, which are efficient, low-toxic, environmentally friendly and have novel structure and mechanism. The present application provides a novel bisphosphonic acid and its salt compound with herbicidal activity. SUMMARY

[0003] In view of the above problems existing in the prior art, the purpose of the present application is to provide a novel bisphosphonic acid and its salt compound with novel structure, which is efficient, low-toxic, environmentally friendly and has novel structure, its preparation method and its application in the preparation of herbicides.

[0004] The present application defines a bisphosphonic acid and its salt compound, the general structure of which is shown in formula (I): , wherein: X is H, alkali metal, alkaline earth metal, transition metal, organic amine or NH4 + , the alkali metal includes Li, Na, K, the alkaline earth metal includes Be, Ca, Mg, and the transition metal includes Zn, Cu, Fe.

[0005] Further, the present application also defines a preparation method of the bisphosphonic acid and its salt compound, which is specifically: taking methyl (3-oxopropyl) phosphinic acid shown in formula (II) as the starting material, first reacting with methyl phosphite in the presence of trimethylchlorosilane to generate (3- (methylphosphoryl)-1-trimethylsiloxypropyl)-methyl phosphinate ethyl ester shown in formula (III), and then acidolysis of (3- (methylphosphoryl)-1-trimethylsiloxypropyl)-methyl phosphinate ethyl ester under the action of hydrochloric acid to obtain the product [1-hydroxy-3- (methylphosphoryl) propyl]-methyl phosphinic acid, and then reacting the product with an alkaline substance to synthesize the corresponding bisphosphonic acid salt compound, The reaction process is as follows: ,

[0006] Further, the present application also limits a specific process of the preparation method of the bisphosphonic acid compound, comprising the following steps (1) under the protection of nitrogen, diethyl methylphosphonite is dissolved in trimethylchlorosilane reagent, stirring at 20-30℃ for 10 min, after mixing uniformly, the temperature is raised to 40℃, then slowly adding methyl (3-oxopropyl) phosphinic acid shown in formula (II) into it, after keeping the reaction for 30 min, the temperature is raised to 90-100℃, and the reaction is carried out for 1-2h, after the reaction is completed, cooling to room temperature, and removing the low boiling point substances generated in the reaction by rotary evaporation, to obtain (3- (methylphosphono) -1-trimethylsiloxypropyl) -methylphosphinic acid ethyl ester shown in formula (III); (2) mixing (3- (methylphosphono) -1-trimethylsiloxypropyl) -methylphosphinic acid ethyl ester obtained in step (1) with water, adding concentrated hydrochloric acid, then gradually raising the temperature to 100-110℃, stirring and refluxing for 12-24h, after rotary evaporation and recrystallization, the product [1-hydroxy-3- (methylphosphono) propyl] -methylphosphinic acid is obtained; (3) the [1-hydroxy-3- (methylphosphono) propyl] -methylphosphinic acid obtained in step (2) is reacted with an alkaline substance, and the reaction is completed when the PH is about 7, then cooling to room temperature, and rotary evaporation and drying to obtain the corresponding bisphosphonate compound.

[0007] Further, the present application also limits the molar ratio of diethyl methylphosphonite and methyl (3-oxopropyl) phosphinic acid in step (1) to be 1:1-1.5; the molar ratio of trimethylchlorosilane reagent and diethyl methylphosphonite to be 1:1.

[0008] Further, the present application also limits the solvent for recrystallization in step (2) to be methanol.

[0009] Further, the present application also limits the alkaline substance in step (3) to be Li2CO3, NaOH, KOH, CuCO3, CaCO3, MgCO3, Zn(OH)2, ammonia, dimethylamine, diethylamine or isopropylamine.

[0010] Further, the present application also limits the application of the bisphosphonic acid and its salt compound in preparing herbicides.

[0011] Further, the present application also limits the application of the bisphosphonic acid and its salt compound in preparing herbicides for controlling barnyard grass, crabgrass, dogtail grass, abutilon, amaranthus retroflexus and small amaranth.

[0012] The specific steps of the bisphosphonic acid sodium salt compound (I, X=Na) are as follows: Dissolve [1-hydroxy-3-(methylphosphono)propyl]-methyl phosphinic acid in water, add an appropriate amount of NaOH solution in batches, stop adding when the PH of the reaction is about 7, and then cool to room temperature. Dry by rotary evaporation to obtain [1-hydroxy-3-(methylphosphono)propyl]-methyl phosphinic acid sodium salt, whose structural formula is as follows: .

[0013] The specific steps of the bisphosphonic acid potassium salt compound (I, X=K) are as follows: Dissolve [1-hydroxy-3-(methylphosphono)propyl]-methyl phosphinic acid in water, add an appropriate amount of KOH solution in batches, stop adding when the PH of the reaction is about 7, and then cool to room temperature. Dry by rotary evaporation to obtain [1-hydroxy-3-(methylphosphono)propyl]-methyl phosphinic acid potassium salt, whose structural formula is as follows: .

[0014] The specific steps of the bisphosphonic acid zinc salt compound (I, X=Zn) are as follows: Dissolve [1-hydroxy-3-(methylphosphono)propyl]-methyl phosphinic acid in water, add an appropriate amount of Zn(OH)2 in batches, stop adding when the PH of the reaction is about 7, and then cool to room temperature. Dry by rotary evaporation to obtain [1-hydroxy-3-(methylphosphono)propyl]-methyl phosphinic acid zinc salt, whose structural formula is as follows: .

[0015] The specific steps of the bisphosphonic acid copper salt compound (I, X=Cu) are as follows: Dissolve [1-hydroxy-3-(methylphosphono)propyl]-methyl phosphinic acid in water, add an appropriate amount of basic copper carbonate in batches, stop adding when the PH of the reaction is about 7, and then cool to room temperature. Dry by rotary evaporation to obtain [1-hydroxy-3-(methylphosphono)propyl]-methyl phosphinic acid copper salt, whose structural formula is as follows: .

[0016] The specific steps of the bisphosphonic acid ammonium salt compound (I, X=NH4) are as follows: Dissolve [1-hydroxy-3-(methylphosphono)propyl]-methyl phosphinic acid in water, add an appropriate amount of ammonia in batches, stop adding when the PH of the reaction is about 7, and then cool to room temperature. Dry by rotary evaporation to obtain [1-hydroxy-3-(methylphosphono)propyl]-methyl phosphinic acid ammonium salt, whose structural formula is as follows: .

[0017] By adopting the above-mentioned technology, compared with the prior art, the present application has the following beneficial effects: 1) The both ends of the propane chain are connected with two phosphinic acid groups, and one end is provided with a hydroxyl group, so that the obtained [1-hydroxy-3-(methyl phosphinyl) propyl]-methyl phosphinic acid has a bisphosphonic acid skeleton, and the novel bisphosphonic acid herbicide lead compound with the structure is beneficial to improve the weed removal effect; 2) In the preparation process of the present application, trimethylchlorosilane is used as a key reagent to promote the condensation reaction of methyl (3-oxopropyl) phosphinic acid and diethyl methyl phosphite, which is the key to build the core carbon-carbon bond and form the specific functional group (trimethylsiloxy), and only two steps are needed from the starting material to the final core acid compound, the reaction condition is mild, the post-treatment is convenient, and it is beneficial to popularization and application; 3) The present application obtains several different salt compounds, which can change the water solubility, hygroscopicity, stability and the like of the compounds, so as to adapt to different formulation requirements (such as water agent, soluble granule and the like), and the metal salts such as zinc and copper may have bactericidal or nutritional functions, may bring the synergistic effect of weeding, bactericidal and / or nutrition, and through salification, the toxicity and environmental behavior of the product can be adjusted. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is the hydrogen spectrum (400 MHz, D2O) diagram of the product of embodiment 4 of the present application; Figure 2 is the carbon spectrum (400 MHz, D2O) diagram of the product of embodiment 4 of the present application; Figure 3 is the phosphorus spectrum (400 MHz, D2O) diagram of the product of embodiment 4 of the present application; Figure 4 is the mass spectrum diagram of the product of embodiment 4 of the present application; Figure 5 is the mass spectrum diagram of (3-(methyl phosphinyl)-1-trimethylsiloxy propyl)-methyl phosphinic acid ethyl ester (III) of embodiment 1 of the present application. DETAILED DESCRIPTION

[0019] The present application will be further specifically described below by combining with the accompanying drawings of the specification.

[0020] Example 1: Synthesis of (3-(methyl phosphinyl)-1-trimethylsiloxy propyl)-methyl phosphinic acid ethyl ester (III) To a round bottom flask, methyl phosphonous diethyl ester 1.36 g and trimethylchlorosilane 1.08 g were added under nitrogen atmosphere, stirred for 10 min at 20 °C, then warmed to 40 °C, methyl (3-oxopropyl) phosphinic acid 1.64 g was added dropwise slowly, stirred for 30 min, then warmed to 90 °C, reacted for 1 h, after reaction, the low boiling point substance was removed by rotary evaporation, (3-(methylphosphono)-1- trimethylsilyloxypropyl)-methylphosphinic acid ethyl ester 1.2 g was obtained.

[0021] The mass spectrum of the compound is shown in Figure 5 The high resolution mass spectrum m / z 245.0700 [M+H] + (C7H 18 O5P2 theoretical value, 244.1540), the oxysilane group was broken into hydroxyl group in the reaction.

[0022] Example 2: Synthesis of (3-(methylphosphono)-1-trimethylsilyloxypropyl)- methylphosphinic acid ethyl ester (III) To a round bottom flask, methyl phosphonous diethyl ester 1.36 g and trimethylchlorosilane 1.08 g were added under nitrogen atmosphere, stirred for 10 min at 30 °C, then warmed to 40 °C, methyl (3-oxopropyl) phosphinic acid 1.64 g was added dropwise slowly, stirred for 30 min, then warmed to 100 °C, reacted for 1.5 h, after reaction, the low boiling point substance was removed by rotary evaporation, 1.3 g of the compound shown in formula (III) was obtained.

[0023] Example 3: Synthesis of (3-(methylphosphono)-1-trimethylsilyloxypropyl)- methylphosphinic acid ethyl ester (III) To a round bottom flask, methyl phosphonous diethyl ester 1.63 g and trimethylchlorosilane 1.29 g were added under nitrogen atmosphere, stirred for 10 min at 30 °C, then warmed to 40 °C, methyl (3-oxopropyl) phosphinic acid 1.64 g was added dropwise slowly, stirred for 30 min, then warmed to 90 °C, reacted for 2 h, after reaction, the low boiling point substance was removed by rotary evaporation, 1.5 g of the compound shown in formula (III) was obtained.

[0024] Example 4: Synthesis of [1-hydroxy-3-(methylphosphono)propyl]-methylphosphinic acid (I, X=H) In a round bottom flask, add (3-(methylphosphono)-1-trimethylsiloxylpropyl)- methylphosphinic acid ethyl ester 1.5 g of formula (III), add concentrated hydrochloric acid 10 mL, reflux at 100°C for 12 hours, after the reaction is completed, spin dry and add 5 mL of methanol solution, crystallize to obtain the target compound [1-hydroxy-3- (methylphosphono) propyl] methylphosphinic acid 1.2 g.

[0025] Example 5: Synthesis of [1-hydroxy-3-(methylphosphono)propyl]-methylphosphinic acid (I, X = H) In a round bottom flask, add (3-(methylphosphono)-1-trimethylsiloxylpropyl)- methylphosphinic acid ethyl ester 1.5 g of formula (III), add concentrated hydrochloric acid 10 mL, reflux at 110°C for 24 hours, after the reaction is completed, spin dry and add 5 mL of methanol solution, crystallize to obtain the target compound [1-hydroxy-3- (methylphosphono) propyl] methylphosphinic acid 1.1 g.

[0026] Example 6: Synthesis of [1-hydroxy-3-(methylphosphono)propyl]-methylphosphinic acid (I, X = H) In a round bottom flask, add (3-(methylphosphono)-1-trimethylsiloxylpropyl)- methylphosphinic acid ethyl ester 1.5 g of formula (III), add concentrated hydrochloric acid 10 mL, reflux at 110°C for 18 hours, after the reaction is completed, spin dry and add 5 mL of methanol solution, crystallize to obtain the target compound [1-hydroxy-3- (methylphosphono) propyl] methylphosphinic acid 1.1 g.

[0027] The structure of the target product [1-hydroxy-3-(methylphosphono)propyl]- methylphosphinic acid of the present application is determined by nuclear magnetic resonance and mass spectrometry, and the spectral data of the compound are as follows: As shown in Figures 1-4 , the structure of the target product of the present application is confirmed, and its high resolution mass spectrum m / z 215.0226 [M-H] - (C5H 14 O5P2 theoretical value, 216.102); 1 H NMR (400 MHz, D2O) δ 3.63 (m, J = 10.1, 3.4Hz, 1H), 1.98 -1.77 (m, 2H), 1.76 -1.54 (m, 2H), 1.38 - 1.27 (m, 6H). 13C NMR (101 MHz, D20) δ 156.21, 69.13, 68.97, 68.00, 67.84, 25.87, 25.75, 24.95, 24.83, 21.98, 21.94, 21.90, 13.43, 12.51, 10.34, 9.45. 31 P NMR (162 MHz, D20) δ 56.64 (d, J = 5.8 Hz), 52.19 (d, J = 6.0 Hz).

[0028] Example 7: Synthesis of [1-hydroxy-3-(methylphosphono)propyl]-methylphosphinic acid sodium salt (I, X=Na): 1 g of [1-hydroxy-3-(methylphosphono)propyl]-methylphosphinic acid was added into 2 ml of water, stirred and dissolved, and an appropriate amount of NaOH aqueous solution was added in batches while stirring. When the PH was measured to be about 7, the addition was stopped. After the addition was completed, the reaction was carried out at 40°C for 0.5 h. After cooling to room temperature, rotary evaporation was carried out to obtain a crude product of [1-hydroxy-3-(methylphosphono)propyl]-methylphosphinic acid sodium salt. The crude product was dried to obtain [1-hydroxy-3-(methylphosphono)propyl]-methylphosphinic acid sodium salt. The drying temperature was 100°C, and the drying time was 1 hour.

[0029] Example 8: Synthesis of [1-hydroxy-3-(methylphosphono)propyl]-methylphosphinic acid copper salt (I, X=Cu): 1 g of [1-hydroxy-3-(methylphosphono)propyl]-methylphosphinic acid was added into 2 ml of water, stirred and dissolved, and an appropriate amount of basic CuCO3 was added in batches while stirring. When the PH was measured to be about 7, the addition was stopped. After the addition was completed, the reaction was carried out at 90°C for 1 h. After cooling to room temperature, rotary evaporation was carried out to obtain a crude product of [1-hydroxy-3-(methylphosphono)propyl]-methylphosphinic acid copper salt. The crude product was dried to obtain [1-hydroxy-3-(methylphosphono)propyl]-methylphosphinic acid copper salt. The drying temperature was 100°C, and the drying time was 1 hour.

[0030] Example 9: Synthesis of [1-hydroxy-3-(methylphosphono)propyl]-methylphosphinic acid zinc salt (I, X=Zn): 1 g of [1-hydroxy-3-(methylphosphono)propyl]-methylphosphonic acid was added to 2 ml of water and stirred to dissolve. A suitable amount of Zn(OH)2 powder was added in batches while stirring. Addition was stopped when the pH reached approximately 7. After the addition was complete, the mixture was reacted at 40 °C for 0.5 h. After cooling to room temperature, rotary evaporation was performed to obtain crude zinc salt of [1-hydroxy-3-(methylphosphono)propyl]-methylphosphonic acid. The crude product was dried at 100 °C for 1 hour to obtain zinc salt of [1-hydroxy-3-(methylphosphono)propyl]-methylphosphonic acid.

[0031] Example 10: Synthesis of potassium salt of [1-hydroxy-3-(methylphosphono)propyl]-methylphosphinic acid (I, X=K): 1 g of [1-hydroxy-3-(methylphosphono)propyl]-methylphosphonic acid was added to 2 ml of water and stirred to dissolve. A suitable amount of KOH solution was added in batches while stirring. Addition was stopped when the pH reached approximately 7. After the addition was complete, the mixture was reacted at 40 °C for 0.5 h. After cooling to room temperature, rotary evaporation was performed to obtain crude potassium [1-hydroxy-3-(methylphosphono)propyl]-methylphosphonic acid. The crude product was dried at 100 °C for 1 hour to obtain potassium [1-hydroxy-3-(methylphosphono)propyl]-methylphosphonic acid.

[0032] Example 11: Synthesis of [1-hydroxy-3-(methylphosphono)propyl]-methylphosphinic acid ammonium salt (I, X=NH4): 1 g of [1-hydroxy-3-(methylphosphono)propyl]-methylphosphonic acid was added to 2 ml of water and stirred to dissolve. A suitable amount of ammonia was added in batches while stirring. Addition was stopped when the pH reached approximately 7. After the addition was complete, the mixture was reacted at 40 °C for 0.5 h. After cooling to room temperature, rotary evaporation was performed to obtain crude [1-hydroxy-3-(methylphosphono)propyl]-methylphosphonic acid ammonium salt. This crude product was dried at 100 °C for 1 hour to obtain [1-hydroxy-3-(methylphosphono)propyl]-methylphosphonic acid ammonium salt.

[0033] Example 12 Bioactivity Test: This invention tests the herbicidal bioactivity of the products of Examples 7-11 according to the "NY / T 1155.4-2006 Guidelines for Indoor Bioassays of Pesticides - Herbicides - Part 4: Activity Assay Test - Foliar Spray Method".

[0034] The specific process of using the novel agricultural antibiotic herbicide of this invention for weed control is as follows: Preparation of reagent: Weigh a certain mass of the product of Examples 7-11, dissolve it in water to prepare a 10% mother liquor, and then dilute it with 0.1% Tween-80 water to a concentration of 600 gai / ha for later use.

[0035] Weed targets: barnyard grass, crabgrass, foxtail grass, velvetleaf, amaranth, and lambsquarters.

[0036] Crop targets: soybeans, corn, rapeseed, rice, wheat, sorghum.

[0037] Planting method: Sow several groups of target seeds in plastic pots with a diameter of 8.0cm. After sowing, cover with 0.2-0.5cm of soil, add water to the bottom, and then place in a greenhouse for cultivation. The greenhouse temperature is about 26±2℃.

[0038] Application method: At the 3-4 leaf stage of the target, half of the targets were treated with foliar spray of the product of Examples 7-11 at a concentration of 600 gai / ha, and the other half was the control group. The amount of pesticide was applied quantitatively, and the plants were allowed to stand indoors until the pesticide was absorbed by the leaves. Then the plants were moved into the greenhouse for cultivation and trial harvesting under normal management. The weed control effect was visually assessed 14 days after the application.

[0039] Investigation methods: After the application of the herbicide, the growth of the target plants and the symptoms of poisoning were observed regularly. 14 days after the application, the weed control efficacy and crop safety were visually assessed. The visual assessment method was: experienced testers directly assessed the target plant population in the field to estimate the aboveground coverage or degree of damage. For example, a weed control efficiency of 60% means that the growth of weeds (coverage, growth, etc.) was reduced by about 60% compared with the control group. The weed control activity is shown in Table 1, and the crop safety results are shown in Table 2.

[0040] Table 1. Visually observed control efficacy of the products from Examples 7-11 against six weeds.

[0041] The bisphosphonic acid [1-hydroxy-3-(methylphosphonoyl)propyl]-methylphosphonic acid prepared in this invention contains multiple acidic hydroxyl groups and is highly polar. This may make it difficult for it to penetrate the waxy layer and lipid bilayer cell membrane on plant leaves or cell walls, thus failing to reach the target site and having no herbicidal activity against weeds. However, when it is made into a salt compound, it becomes an ionic compound with excellent water solubility. It can be absorbed by plants in the form of aqueous solution and transported and distributed in the plant through the vascular bundle system, eventually reaching the site of action. As can be seen from Table 1, the salt compounds of Examples 7-11 have certain efficacy against barnyard grass, crabgrass, foxtail grass, velvetleaf, amaranth, and lambsquarters. Among them, the copper and zinc salts of Examples 8-9 have a 100% control efficacy against foxtail grass, and the sodium, copper, and zinc salts of Examples 7-9 have a 100% control efficacy against lambsquarters.

[0042] Table 2. Safety results of the products from Examples 7-11 on six crops.

[0043] Experiments showed that, 14 days after application, the salt compounds in Examples 7-11 exhibited good growth in crops such as soybeans, corn, rapeseed, rice, wheat, and sorghum, with no signs of poisoning. Therefore, the drug is safe for crops.

[0044] The specific embodiments described in this invention are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains can make various modifications or additions to the described specific embodiments or use similar methods to replace them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

[0045] Although the present invention has been described in detail and specific embodiments have been cited, it will be apparent to those skilled in the art that various changes or modifications can be made without departing from the spirit and scope of the invention.

Claims

1. A bisphosphonic acid and its salt compounds, characterized in that... Its general structural formula is shown in formula (I): ， Where: X is H, alkali metal, alkaline earth metal, transition metal, organic amine, or NH4. + The alkali metals include Li, Na, and K; the alkaline earth metals include Be, Ca, and Mg; and the transition metals include Zn, Cu, and Fe.

2. A method for preparing bisphosphonic acid and its salt compounds as described in claim 1, characterized in that... Starting with methyl(3-oxopropyl)phosphonic acid as shown in formula (II), it is first reacted with diethyl methylphosphonite in the presence of trimethylchlorosilane to generate ethyl (3-(methylphosphono)-1-trimethylsiloxypropyl)-methylphosphonic acid as shown in formula (III). The ethyl (3-(methylphosphono)-1-trimethylsiloxypropyl)-methylphosphonic acid is then acidified in the presence of hydrochloric acid to obtain the product [1-hydroxy-3-(methylphosphono)propyl]-methylphosphonic acid. The product is then reacted with an alkaline substance to synthesize the corresponding bisphosphonate compounds. The reaction process is as follows: 。 3. The method for preparing bisphosphonic acid and its salt compounds according to claim 2, characterized in that... Includes the following steps: (1) Under nitrogen protection, diethyl methylphosphonite was dissolved in trimethylchlorosilane reagent and stirred at 20℃-30℃ for 10 min. After mixing evenly, the temperature was raised to 40℃, and methyl (3-oxopropyl)phosphonic acid of formula (II) was slowly added. After reacting at this temperature for 30 min, the temperature was raised to 90℃-100℃ and reacted for 1-2 h. After the reaction was completed, the temperature was cooled to room temperature, and the low-boiling-point substances generated by the reaction were removed by rotary evaporation to obtain ethyl (3-(methylphosphono)-1-trimethylsiloxypropyl)-methylphosphonic acid of formula (III). (2) The ethyl 3-(methylphosphono)-1-trimethylsiloxypropyl)-methylphosphino acid obtained in step (1) was mixed with water, concentrated hydrochloric acid was added, and then the temperature was gradually raised to 100-110℃ and stirred under reflux for 12-24 h. After rotary evaporation and recrystallization, the product [1-hydroxy-3-(methylphosphono)propyl]-methylphosphino acid was obtained. (3) The [1-hydroxy-3-(methylphosphono)propyl]-methylphosphonic acid obtained in step (2) reacts with an alkaline substance. The reaction is completed when the pH is approximately 7. Then, the mixture is cooled to room temperature and dried by rotary evaporation to obtain the corresponding bisphosphonate compound.

4. The method for preparing bisphosphonic acid and its salt compounds according to claim 3, characterized in that... In step (1), the molar ratio of diethyl methyl phosphite to methyl (3-oxopropyl)phosphonic acid is 1:1 to 1.5; the molar ratio of trimethylchlorosilane to diethyl methyl phosphite is 1:

1.

5. The method for preparing bisphosphonic acid and its salt compounds according to claim 3, characterized in that... The solvent used for recrystallization in step (2) is methanol.

6. The method for preparing bisphosphonic acid and its salt compounds according to claim 3, characterized in that... The alkaline substances in step (3) are Li2CO3, NaOH, KOH, CuCO3, CaCO3, MgCO3, Zn(OH)2, ammonia, dimethylamine, diethylamine or isopropylamine.

7. The use of bisphosphonic acid and its salt compounds as described in claim 1 in the preparation of herbicides.

8. The application of bisphosphonic acid and its salt compounds as described in claim 1 in the preparation of a herbicide, said herbicide being used to control one or more of barnyard grass, crabgrass, foxtail grass, velvetleaf, amaranth, and lambsquarters.

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