Method for measuring chiral distribution of chemical root retarder

Abstract

The invention discloses a method for measuring chiral distribution of a chemical root retarder. The invention relates to a method for measuring chiral distribution of a chemical root retarder, which comprises the following steps: carrying out saponification reaction on the chemical root retarder, and converting active substances in the chemical root retarder into 2-methyl-4-chlorophenoxypropionic acid; purifying the 2-methyl-4-chlorophenoxypropionic acid by using an eluent, and dissolving the purified 2-methyl-4-chlorophenoxypropionic acid in a solvent to obtain a refined 2-methyl-4-chlorophenoxypropionic acid solution; relation data between the optical rotation and the optical purity of multiple sample solutions are obtained, a standard curve is obtained through fitting of the relation data, and the multiple sample solutions comprise the sample solutions with the optical purity being 95% and the sample solutions with the optical purity being 0%; the optical rotation of the refined 2-methyl-4-chlorophenoxypropionic acid solution is measured, and the measured optical rotation is obtained; and determining the chiral distribution of the chemical root retarder according to the measured optical rotation and the standard curve. According to the embodiment of the invention, the chiral distribution of the chemical root retarder can be rapidly and accurately measured at low cost.

Description

Technical Field

[0001] The present application belongs to the field of asphalt coil additives, and in particular to a method for measuring the chiral distribution of a chemical root inhibitor. Background Art

[0002] The commonly used chiral distribution test is to use a high performance liquid chromatography (HPLC) chiral column to separate different configurations and then calculate the distribution. Among them, it can be divided into chiral derivatization method, chiral mobile phase method and chiral stationary phase method.

[0003] Although this test method is relatively mature, due to the wide variety of root inhibitors, especially polymer root inhibitors, which have complex structures, it is difficult to directly use chiral columns for chiral separation. There are also problems such as high testing costs and long testing time. Summary of the invention

[0004] The embodiment of the present application provides a method for measuring the chiral distribution of a chemical root inhibitor, which can measure the chiral distribution of a chemical root inhibitor quickly and accurately at low cost.

[0005] The embodiment of the present application provides a method for measuring the chiral distribution of a chemical root inhibitor, comprising: performing a saponification reaction on the chemical root inhibitor to convert the active substance in the chemical root inhibitor into 2-methyl-4-chlorophenoxypropionic acid; purifying the 2-methyl-4-chlorophenoxypropionic acid using an eluent and dissolving it in a solvent to obtain a refined 2-methyl-4-chlorophenoxypropionic acid solution; obtaining relationship data between the optical rotation and optical purity of multiple sample liquids, and fitting the relationship data to obtain a standard curve, wherein the multiple sample liquids include sample liquids with optical purities of 95% and 0%; measuring the optical rotation of the refined 2-methyl-4-chlorophenoxypropionic acid solution to obtain a measured optical rotation; measuring the optical purity of the refined 2-methyl-4-chlorophenoxypropionic acid solution according to the measured optical rotation and the standard curve to determine the chiral distribution of the chemical root inhibitor.

[0006] In any embodiment of the present application, the step of saponifying the chemical root inhibitor includes: mixing materials containing the chemical root inhibitor, an organic solvent and an alkali solution under preset conditions to obtain a mixed solution; subjecting the mixed solution to rotary evaporation to remove the organic solvent to obtain an aqueous solution; adding an extractant to the aqueous solution to obtain an upper aqueous phase; adjusting the pH of the upper aqueous phase to 5.8-6.2, and then adding an extractant to obtain a lower organic phase, and subjecting the mixture to rotary evaporation and drying to obtain 2-methyl-4-chlorophenoxypropionic acid.

[0007] In any embodiment of the present application, in the step of mixing materials containing chemical root inhibitor, organic solvent and alkali solution under preset conditions, the ratio of the mass of the chemical root inhibitor to the volume of the organic solvent and the volume of the alkali solution is 1:15~25:15~25.

[0008] In any embodiment of the present application, in the step of mixing the materials containing the chemical root inhibitor, the organic solvent and the alkali solution under preset conditions, the concentration of the alkali solution is 0.1-0.5 g / mL.

[0009] In any embodiment of the present application, the step of adjusting the pH of the upper aqueous phase to 5.8-6.2 includes: adding an acid solution of a preset concentration to the upper aqueous phase to adjust the pH to 5.8-6.2.

[0010] In any embodiment of the present application, the step of adjusting the pH of the upper aqueous phase to 5.8-6.2 includes: subjecting the upper aqueous phase to column separation treatment and adjusting the pH to 5.8-6.2.

[0011] In any embodiment of the present application, in the step of purifying 2-methyl-4-chlorophenoxypropionic acid by using an eluent and dissolving it in a solvent, the eluent includes at least one of dichloromethane and methanol.

[0012] In any embodiment of the present application, in the refined 2-methyl-4-chlorophenoxypropionic acid solution and the plurality of sample solutions, the solvent comprises at least one of dichloromethane, toluene, chloroform and petroleum ether.

[0013] In any embodiment of the present application, the concentrations of the purified 2-methyl-4-chlorophenoxypropionic acid solution and the plurality of sample solutions are all 0.1 to 0.3 g / mL.

[0014] In any embodiment of the present application, the correlation coefficient of the standard curve is 0.99 to 0.999.

[0015] The method for measuring the chiral distribution of the chemical root inhibitor in the embodiment of the present application can solve the problem of difficulty in separating chirality of a chiral column, and can measure the chiral distribution of the chemical root inhibitor quickly and at low cost; at the same time, the purified 2-methyl-4-chlorophenoxypropionic acid can reduce the difference in optical rotation caused by impurities, reduce interference factors, and improve measurement accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solution of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0017] Figure 1 This is the standard curve in Example 1 of the present application. DETAILED DESCRIPTION

[0018] In order to more clearly understand the above-mentioned purposes, features and advantages of the present application, the scheme of the present application will be further described below. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0019] In the following description, many specific details are set forth to facilitate a full understanding of the present disclosure, but the present application may also be implemented in other ways different from those described herein; it is obvious that the embodiments in the specification are only part of the embodiments of the present application, rather than all of the embodiments.

[0020] "Scope" disclosed in the present application is limited in the form of lower limit and upper limit, and a given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a special range. The scope limited in this way can be including end values ​​or not including end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a scope. For example, if the scope of 60-120 and 80-110 is listed for a specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following scope can be all expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise specified, the numerical range "ab" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0021] If not otherwise specified, all embodiments and optional embodiments of the present application may be combined with each other to form new technical solutions, and such technical solutions should be deemed to be included in the disclosure of the present application.

[0022] Unless otherwise specified, all technical features and optional technical features of the present application may be combined with each other to form new technical solutions, and such technical solutions should be deemed to be included in the disclosure of the present application.

[0023] If there is no special explanation, all steps of the present application can be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0024] Unless otherwise specified, the raw materials in the examples of this application were purchased through commercial channels.

[0025] Unless otherwise specified, this application adopts conventional test methods or test methods recommended by the instrument.

[0026] In the present application, the optical rotation test instrument model is WZZ-2S automatic polarimeter.

[0027] Among the common chemical root inhibitors currently used, the active one is 2-methyl-4-chlorophenoxypropionate, and common products include 2-methyl-4-chlorophenoxypropionate isooctyl ester and 2-methyl-4-chlorophenoxypropionate polyethylene glycol ester. After being added to the asphalt roll, in the natural environment, the ester bond in the chemical root inhibitor will slowly break to produce 2-methyl-4-chlorophenoxypropionic acid (MCPP acid) with certain biological toxicity, thereby inhibiting the growth of plant roots. Due to the different chiral configurations, the chemical activity of MCPP acid can differ by more than ten times, so determining the chiral distribution of chemical root inhibitors is very important for the calibration of root inhibitor performance. The more active MCPP acid is the R configuration, and its structural formula is shown below. After investigation, it was found that it has optical rotation.

[0028]

[0029] The present application converts 2-methyl-4-chlorophenoxypropionate in the test object into MCPP acid by saponification reaction, and then measures the optical rotation of MCPP acid by polarimeter, and then substitutes its optical rotation into the standard curve about optical rotation and optical purity, so as to obtain the optical purity of MCPP acid obtained by conversion of 2-methyl-4-chlorophenoxypropionate in the test object, and then obtain the chiral distribution of the test object (chemical root inhibitor), wherein the standard curve about optical rotation and optical purity is established by several groups of MCPP acid with known optical purity and optical rotation. Especially for polymer root inhibitors with more complex composition, the problem of difficulty in chiral separation of chiral column can be solved. And the test method has the advantages of fast, strong versatility, low test cost and short test time. At the same time, the present application can reduce the difference in optical rotation caused by impurities and reduce interference factors by purifying MCPP acid, so that the measurement result is more accurate. The test method provided in the present application has lower requirements on instruments and operators, and also has lower requirements on solvents. Different solvents such as dichloromethane, toluene, methanol, ethanol, DMF, etc. can be used. A visual polarimeter can be equipped in the factory to conduct on-site testing using analytically pure or industrial-grade solvents. After the numerical values ​​are obtained, the corresponding tables can be filled in to obtain the results, and the chiral distribution of MCPP acid and chemical root inhibitors can be obtained quickly at a low cost.

[0030]

Measurement method

[0031] The embodiment of the present application provides a method for measuring the chiral distribution of a chemical root inhibitor, comprising: performing a saponification reaction on the chemical root inhibitor to convert the active substance in the chemical root inhibitor into 2-methyl-4-chlorophenoxypropionic acid; purifying the 2-methyl-4-chlorophenoxypropionic acid using an eluent and dissolving it in a solvent to obtain a refined 2-methyl-4-chlorophenoxypropionic acid solution; obtaining relationship data between the optical rotation and optical purity of multiple sample liquids, and fitting the relationship data to obtain a standard curve, wherein the multiple sample liquids include sample liquids with optical purities of 95% and 0%; measuring the optical rotation of the refined 2-methyl-4-chlorophenoxypropionic acid solution to obtain a measured optical rotation; measuring the optical purity of the refined 2-methyl-4-chlorophenoxypropionic acid solution according to the measured optical rotation and the standard curve to determine the chiral distribution of the chemical root inhibitor.

[0032] A standard curve is a curve composed of the values ​​of a certain physical and chemical property obtained by measuring a series of standard substances of known components. The standard curve is the functional relationship between the physical / chemical properties of the standard substance and the instrument response. This belongs to the empirical coefficient method to represent the matrix effect of one element on another element. Even without mathematical proof, it can be intuitively understood that there is a single-valued functional relationship between the spectral line intensity of element i in the matrix and the content of other coexisting elements. Through several groups of standard samples with the same matrix composition (elements or element oxides, but different contents) and known contents of each component, this single-valued functional relationship is obtained by solving the matrix through simultaneous equations (calculated by a computer program). Optical purity is also called optical purity. The optical purity of a compound is the percentage of its specific optical rotation to the pure product. The present application converts 2-methyl-4-chlorophenoxypropionate in a chemical root inhibitor into MCPP acid through a saponification reaction, measures the optical rotation of the MCPP acid using a polarimeter, and then obtains the optical purity corresponding to the MCPP acid through the functional relationship between the optical rotation and the optical purity revealed by a standard curve established by a standard substance (sample), thereby obtaining the optical purity of the chemical root inhibitor.

[0033] In some embodiments, the step of saponifying the chemical root inhibitor includes: mixing materials containing the chemical root inhibitor, an organic solvent and an alkaline solution under preset conditions to obtain a mixed solution; subjecting the mixed solution to rotary evaporation to remove the organic solvent to obtain an aqueous solution; adding an extractant to the aqueous solution to obtain an upper aqueous phase; adjusting the pH of the upper aqueous phase to 5.8 to 6.2, then adding an extractant to obtain a lower organic phase, and subjecting the upper aqueous phase to rotary evaporation and drying to obtain 2-methyl-4-chlorophenoxypropionic acid. The active substance in the chemical root inhibitor is converted into 2-methyl-4-chlorophenoxypropionic acid through a saponification reaction, thereby facilitating and accurately determining the chiral distribution of the chemical root inhibitor.

[0034] In some embodiments, in the step of mixing the materials containing the chemical root inhibitor, the organic solvent and the alkali solution under preset conditions, the ratio of the mass of the chemical root inhibitor to the volume of the organic solvent and the volume of the alkali solution is 1:15 to 25:15 to 25. Under this ratio, the reaction time can be shortened and the output of 2-methyl-4-chlorophenoxypropionic acid can be increased.

[0035] In some embodiments, in the step of mixing the materials containing the chemical root inhibitor, the organic solvent and the alkali solution under preset conditions, the concentration of the alkali solution is 0.1 to 0.5 g / mL. Within this range, the reaction time can be shortened and the output of 2-methyl-4-chlorophenoxypropionic acid can be increased.

[0036] In some embodiments, the step of adjusting the pH of the upper aqueous phase to 5.8-6.2 includes: adding an acid solution of a preset concentration to the upper aqueous phase to adjust the pH to 5.8-6.2.

[0037] The preset concentration of the strong acid solution is not particularly limited, and those skilled in the art can adjust it as needed. As an example, 125 mmol of concentrated hydrochloric acid can be added to the upper aqueous phase to adjust the pH to 5.8-6.2.

[0038] In some embodiments, the step of adjusting the pH of the upper aqueous phase to 5.8-6.2 includes: subjecting the upper aqueous phase to column separation treatment and adjusting the pH to 5.8-6.2.

[0039] The conditions of column separation are not specifically limited, and those skilled in the art can adjust them as needed. As an example, an ion exchange column can be used. As another example, an adsorption column can be used.

[0040] In some embodiments, in the step of purifying the 2-methyl-4-chlorophenoxypropionic acid with an eluent and dissolving it in a solvent, the eluent includes at least one of dichloromethane and methanol. When purifying the 2-methyl-4-chlorophenoxypropionic acid, the crude product is purified by column chromatography, a 200-mesh silica gel column is selected, and impurities are initially eluted with dichloromethane, and later a mixed solvent of dichloromethane / methanol = 20 / 1 is used to elute the MCPP acid, and the refined MCPP acid is obtained after rotary evaporation and vacuum drying.

[0041] In some embodiments, in the refined 2-methyl-4-chlorophenoxypropionic acid solution and the plurality of sample solutions, the solvent comprises at least one of dichloromethane, toluene, chloroform and petroleum ether.

[0042] In some embodiments, the concentration of the refined 2-methyl-4-chlorophenoxy propionic acid solution and the multiple sample solutions are both 0.1 to 0.15 g / mL. Optionally, the concentration of the refined 2-methyl-4-chlorophenoxy propionic acid solution and the multiple sample solutions are both 0.1 to 0.3 g / mL. Within this range, the accuracy and reliability of the measurement results can be ensured. This is because when the concentration of the test product (refined 2-methyl-4-chlorophenoxy propionic acid solution) and the standard (multiple sample solutions) is higher than the linear range, the signal is saturated and it is difficult to obtain reliable data.

[0043] In some embodiments, the correlation coefficient of the standard curve is 0.99 to 0.999. Alternatively, the correlation coefficient of the standard curve is 0.99 to 0.9999.

[0044] Example 1

[0045] Step 1, saponification reaction:

[0046] 10 g of a chemical root inhibitor sample (purchased from Codow CD17767) was dissolved in 200 mL of ethanol to obtain a solution containing the chemical root inhibitor, 5 g of NaOH was dissolved in 200 mL of water to obtain a NaOH solution, the two were mixed and ultrasonicated at 40° C. for 1 h, and then cooled to room temperature to obtain a mixed solution;

[0047] The mixed solution was rotary evaporated at 40°C for 1 h to remove ethanol and obtain an aqueous solution;

[0048] Add 200 ml of dichloromethane to the above aqueous solution, separate the liquids and take the upper aqueous phase;

[0049] Add 12.3 g of concentrated hydrochloric acid to the aqueous phase to adjust the pH to 6, then add 200 ml of dichloromethane. After separation, take the lower organic phase, spin-dry the solvent at room temperature, and vacuum dry to obtain a white or light yellow solid, which is the crude MCPP acid.

[0050] Step 2: Purification:

[0051] The crude MCPP acid was purified by column chromatography using a 200-mesh silica gel column. Dichloromethane was initially used to elute impurities, and a mixed solvent of dichloromethane / methanol = 20 / 1 was later used to elute the MCPP acid. The refined MCPP acid was obtained after rotary evaporation and vacuum drying.

[0052] Step 3: Draw the standard curve:

[0053] Obtaining chiral and achiral MCPP acid standards, the optical purity (ee value) of which is 95% and 0% respectively; during the measurement, the optical rotation test tube is fixed in position and direction;

[0054] Use a 25mL volumetric flask to prepare a dichloromethane solution with a concentration of 0.1g / mL;

[0055] Weigh 2.5g of the obtained refined MCPP acid in a 50mL beaker, dissolve it in 8mL of dichloromethane, transfer it into a volumetric flask after dissolution, and rinse the residue in the beaker three times with a small amount of dichloromethane, adjust the volume to the scale line, mix evenly to obtain a 0.1g / mL dichloromethane solution containing refined MCPP acid, which is recorded as the experimental group. Use the same method to obtain a MCPP acid standard solution (sample solution) with an optical purity of 95% and a MCPP acid standard solution with an optical purity of 0%; take 4mL of the 0% standard solution and 6mL of the 95% standard solution to obtain a standard solution with an optical purity of 57%; take 6mL of the 0% standard solution and 4mL of the 95% standard solution to obtain a standard solution with an optical purity of 38%.

[0056] Use an automatic polarimeter to measure the optical rotation of the four standard solutions and the experimental group, and take the average value of the four measurements. With the optical rotation of the standard solution as the x-axis and the ee value as the y-axis, the standard curve equation of the optical rotation-ee value is obtained by fitting. The results are shown in Figure 1 As shown, y=0.03308x-0.03878.

[0057] Step 4: Chiral distribution test:

[0058] Substituting the measured optical rotation of the experimental group into the above equation, the corresponding ee value calculated was 93.5%, which is the chiral distribution of the chemical root inhibitor.

[0059] Example 2

[0060] The implementation steps are the same as those of implementation 1, except that only the amount of NaOH in step 1 is changed to 20 g, and the ee value of the obtained chemical root inhibitor is 93.9%.

[0061] Example 3

[0062] The implementation steps are the same as those of implementation 1, except that only the solvent in step 2 is changed to chloroform, and the ee value of the obtained chemical root inhibitor is 92.7%.

[0063] Example 4

[0064] The implementation steps are the same as those of implementation 1, except that only the solvent in step 3 is changed to chloroform, and the ee value of the obtained chemical root inhibitor is 93.1%.

[0065] Comparative Example 1

[0066] The experimental steps were the same as those in implementation 1, except that only step 2 was omitted, and the ee value of the obtained chemical root inhibitor was 95.3%.

[0067] It can be seen from Comparative Example 1 and Example 1 that the purified 2-methyl-4-chlorophenoxypropionic acid can reduce the difference in optical rotation caused by impurities, reduce interference factors, and improve measurement accuracy.

[0068] In addition, compared with the chiral column testing method in the related art, the embodiment of the present application has the advantages of low cost, short testing time and strong broad spectrum.

[0069] The above is only a specific implementation of the present application. Those skilled in the art can clearly understand that for the convenience and simplicity of description, the specific working processes of the systems, modules and units described above can refer to the corresponding processes in the aforementioned method embodiments, and will not be repeated here. It should be understood that the protection scope of the present application is not limited to this. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed in the present application, and these modifications or replacements should be included in the protection scope of the present application.

Claims

1. A method for measuring the chiral distribution of a chemical root inhibitor, characterized in that: include: The chemical root inhibitor is subjected to saponification reaction to convert the active substance in the chemical root inhibitor into 2-methyl-4-chlorophenoxypropionic acid; Purifying the 2-methyl-4-chlorophenoxypropionic acid with an eluent and dissolving the 2-methyl-4-chlorophenoxypropionic acid in a solvent to obtain a refined 2-methyl-4-chlorophenoxypropionic acid solution; Obtaining relationship data between the optical rotation and the optical purity of a plurality of sample solutions, and fitting the relationship data to obtain a standard curve, wherein the plurality of sample solutions include sample solutions with an optical purity of 95% and 0%; Determining the optical rotation of the refined 2-methyl-4-chlorophenoxypropionic acid solution to obtain a measured optical rotation; The optical purity of the refined 2-methyl-4-chlorophenoxypropionic acid solution is measured according to the measured optical rotation and the standard curve to determine the chiral distribution of the chemical root inhibitor.

2. The measuring method according to claim 1, characterized in that: The step of saponifying the chemical root inhibitor includes: Mixing materials containing a chemical root inhibitor, an organic solvent and an alkali solution under preset conditions to obtain a mixed solution; Performing a rotary evaporation treatment on the mixed solution to remove the organic solvent and obtain an aqueous solution; adding an extractant to the aqueous solution to obtain an upper aqueous phase; After the pH of the upper aqueous phase is adjusted to 5.8-6.2, the extractant is added to obtain a lower organic phase, which is subjected to rotary evaporation and drying to obtain the 2-methyl-4-chlorophenoxypropionic acid.

3. The measuring method according to claim 2, characterized in that: In the step of mixing the materials containing the chemical root inhibitor, the organic solvent and the alkali solution under preset conditions, the ratio of the mass of the chemical root inhibitor to the volume of the organic solvent and the volume of the alkali solution is 1:15-25:15-25.

4. The measuring method according to claim 2, characterized in that: In the step of mixing the materials containing the chemical root inhibitor, the organic solvent and the alkali solution under preset conditions, the concentration of the alkali solution is 0.1-0.5 g / mL.

5. The measuring method according to claim 2, characterized in that: The step of adjusting the pH of the upper aqueous phase to 5.8-6.2 comprises: An acid solution of a preset concentration is added to the upper aqueous phase to adjust the pH to 5.8-6.

2.

6. The measuring method according to claim 2, characterized in that: The step of adjusting the pH of the upper aqueous phase to 5.8-6.2 comprises: The upper aqueous phase is subjected to column separation treatment and the pH is adjusted to 5.8-6.

2.

7. The measuring method according to claim 1, characterized in that: In the step of purifying the 2-methyl-4-chlorophenoxypropionic acid by using an eluent and dissolving the 2-methyl-4-chlorophenoxypropionic acid in a solvent, the eluent includes at least one of dichloromethane and methanol.

8. The measuring method according to claim 1, characterized in that: In the refined 2-methyl-4-chlorophenoxypropionic acid solution and the plurality of sample solutions, the solvent comprises at least one of dichloromethane, toluene, chloroform and petroleum ether.

9. The measuring method according to claim 1, characterized in that: The concentrations of the purified 2-methyl-4-chlorophenoxypropionic acid solution and the plurality of sample solutions are both 0.1 to 0.3 g / mL.

10. The measuring method according to claim 1, characterized in that: The correlation coefficient of the standard curve is 0.99-0.999.

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