N,N-Dihydrocarbylaminocarboxylic acids and methods for their preparation and use

Abstract

This application provides an N,N-dihydrocarbylaminocarboxylic acid and its preparation and use. The N,N-dihydrocarbylaminocarboxylic acid can be used as an extractant to enrich rare earth elements from low-concentration rare earth materials, separate and purify yttrium from mixed rare earth materials, and separate elements such as aluminum, iron, radioactive thorium, radioactive uranium, and actinium from mixed rare earth materials. This compound is easy to synthesize, inexpensive, and has good chemical stability as an extractant, being resistant to strong acids and bases without decomposition.

Description

[Technical field]

[0001] This application relates to the field of organic compound synthesis and to N,N-dihydrocarbylamino carboxylic acids and methods for their preparation and use. [Background technology]

[0002] Rare earth elements refer to 17 metallic elements in total, including the 15 lanthanide elements with atomic numbers 57-71 in the periodic table, as well as the 21st element scandium and the 39th element yttrium, which have similar chemical properties. Rare earth elements have special magnetic, optical and electrical properties, and are known as "industrial vitamins". They are widely used in metallurgy, petrochemistry, glass ceramics, energy materials, military industry and other fields, and are important basic raw materials for the development of human society. At present, the mining of rare earth ores in nature is first performed by leaching rare earth ions with leaching agents to obtain rare earth leaching solution, and then sequentially extracting and separating rare earth ions by solvent extraction. The development of extractants is the most core technology in the solvent extraction process, and the industrial application of rare earth metal extractants requires consideration of multiple factors, such as extraction selectivity, extraction rate, extraction capacity, compound stability, solubility, stripping performance, safety, synthesis method and raw materials, etc. Excellent extractants are rare, but good extractants can simplify the production process, improve separation efficiency, reduce production costs and reduce pollutant emissions. In the art, the known commercially available extractant products mainly include organic phosphine extractants, carboxylic acid extractants and amine extractants, typical organic phosphine extractants include mono(2-ethylhexyl) 2-ethylhexylphosphonic acid (P507), bis(2-ethylhexyl)phosphonic acid (P204), bis(2,4,4-trimethylpentyl)phosphinic acid (C272), tributyl phosphonate (TBP) and the like, amine extractants include tri-n-octylamine (N235), secondary carbon primary amine (N1923), methyltrioctyl ammonium chloride (N263) and the like, and carboxylic acid extractants include naphthenic acid, neodecanoic acid, sec-octylphenoxyacetic acid (CA-12). Commercially available extractants have some shortcomings. For example, P507 is the most commonly used extractant in the rare earth separation industry, but it has a low separation factor for adjacent rare earth elements, such as only 1.4 for praseodymium and neodymium, making it difficult to separate praseodymium and neodymium. Naphthenic acid is mainly used to separate and refine yttrium oxide, but naphthenic acid, a by-product of the petrochemical industry, has a complex composition and requires high pH conditions to extract rare earth elements. Its composition is prone to change with long-term use, resulting in a decrease in the concentration of the organic phase and affecting the stability of the separation process. CA-12 extractant has been tried as a substitute for naphthenic acid. This extractant can effectively separate yttrium and all lanthanides in the extraction and separation process of rare earth elements, and can overcome the problem of low organic phase concentration in the extraction and separation of yttrium using naphthenic acid. However, in this extraction system, the separation coefficient of heavy rare earth elements and yttrium is low, making it difficult to separate heavy rare earth elements and yttrium. In order to achieve the separation effect, it is necessary to set up multiple extraction tanks. In order to separate rare earth elements more effectively, it is necessary to develop a new extractant that has a higher separation factor than the conventional techniques and overcomes the shortcomings of the conventional techniques, and an extraction and separation method using this extractant. Summary of the Invention

[0003] The present application aims to provide an N,N-dihydrocarbylaminocarboxylic acid and its preparation method and use. The N,N-dihydrocarbylaminocarboxylic acid is used as an extractant to separate and purify a specific rare earth element from a mixed rare earth raw material solution, particularly yttrium from a mixture of rare earth elements. To achieve this objective, the present application employs the following invention. In a first aspect, the present application provides an N,N-dihydrocarbyl amino carboxylic acid, the N,N-dihydrocarbyl amino carboxylic acid having the structure shown in Formula I: [ka] wherein R1 and R2 are independently a C6 or higher (e.g., C7, C8, C9, C10, C11, C12, C13, C14, C15, C16, C17, C18, C19, C20, C22, C24, C26, C28, C30, C35, C40, etc.) linear or branched, saturated or unsaturated, substituted or unsubstituted hydrocarbyl group; R3 is a linear or branched, saturated or unsaturated, substituted or unsubstituted hydrocarbyl group; X is H or OH; n is a natural number from 1 to 10 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, etc.). The present application provides an aminocarboxylic acid compound having the structure shown in formula I as an aminocarboxylic acid type extractant for separating rare earth metals, and a method for extracting and separating the same, but does not disclose the use of such a compound as an extractant for rare earth metals. As an extractant for metals, such a compound has a high separation factor for rare earth elements, is particularly efficient in separating heavy rare earth elements and yttrium, and overcomes the disadvantages of naphthenic acid when separating yttrium. Preferably, the hydrocarbyl group of the present application is any one selected from a substituted alkyl group, a substituted alkenyl group, and a substituted alkynyl group, and the substituents of the alkyl group, alkynyl group, and alkenyl group are each independently any one or a combination of at least two or more selected from the group consisting of halogen, hydroxyl, carboxyl, acyl, ester, ether, alkoxy, phenyl, phenoxy, amino, amido, nitro, cyano, mercapto, sulfonyl, thiol, imino, sulfoacyl, and sulfanyl, and preferably the substituents are halogen. Preferably, R1 and R2 are independently a C7-C30 linear or branched, saturated or unsaturated, substituted or unsubstituted hydrocarbyl group, preferably a C7-C18 linear or branched, saturated or unsaturated, substituted or unsubstituted hydrocarbyl group. Preferably, R1 and R2 are independently a C7 or higher linear or branched, saturated or unsaturated, unsubstituted hydrocarbyl group, such as a (C7, C8, C9, C10, C11, C12, C13, C14, C15, C16, C17, C18, C19, C20, C22, C24, C26, C28, C30, C35, C40, etc.) linear or branched and unsubstituted alkyl group, alkynyl group, or alkenyl group, preferably a C7-C30 branched, saturated or unsaturated, unsubstituted hydrocarbyl group, and more preferably a C7-C12 branched, saturated or unsaturated, unsubstituted hydrocarbyl group. Preferably, R1 and R2 are independently a C7-C30 linear or branched, unsubstituted alkyl group, preferably a C7-C18 linear or branched, unsubstituted alkyl group, preferably a C7-C10 linear or branched, unsubstituted alkyl group. Preferably, X is H, and more preferably, n is a natural number from 1 to 6. Preferably, R1 and R2 are independently: [ka] [ka] Preferably, R3 is selected from the group consisting of C6 or higher (e.g., C6, C7, C8, C9, C10, C11, C12, C13, C14, C15, C16, C17, C18, C19, C20, C30, C40, etc.) linear or branched, saturated or unsaturated, substituted or unsubstituted hydrocarbyl groups, preferably C6-C30 linear or branched, saturated or unsaturated, substituted or unsubstituted hydrocarbyl groups. Preferably, R3 is selected from the group consisting of C6 or higher (which may be, for example, C6, C7, C8, C9, C10, C11, C12, C13, C14, C15, C16, C17, C18, C19, C20, C30, C40, etc.) linear or branched, saturated or unsaturated, unsubstituted hydrocarbyl groups, preferably C10 or higher linear alkenyl groups, preferably C10-C18 linear alkenyl groups. Preferably, R3 is any one of the following groups: [ka] In a second aspect, the present application provides a method for preparing an N,N-dihydrocarbylamino carboxylic acid of the first aspect, the method comprising: The N,N-dihydrocarbyl secondary amine shown in formula II and the dicarboxylic anhydride compound shown in formula III are mixed and reacted to obtain the N,N-dihydrocarbyl amide carboxylic acid shown in formula IV, which is reduced with a reducing agent to obtain the N,N-dihydrocarbyl amide carboxylic acid shown in formula I, the reaction formula is as follows: [ka] wherein R1, R2, R3 are the groups defined in the first aspect, n is a natural number from 1 to 10, and X is H or OH. Preferably, the molar ratio of the N,N-dihydrocarbyl secondary amine of formula II to the dicarboxylic anhydride compound of formula III is 1:(0.8-1.2), such as 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, etc. Preferably, the temperature when the N,N-dihydrocarbyl secondary amine represented by formula II and the dicarboxylic anhydride compound represented by formula III are mixed and reacted is 0-125°C, for example, 0°C, 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, etc., and the time for mixing and reacting is 0.5-4h, for example, 0.5h, 0.6h, 0.8h, 1h, 1.2h, 1.4h, 1.6h, 1.8h, 2h, 2.2h, 2.4h, 2.6h, 2.8h, 3h, 3.2h, 3.4h, 3.6h, 3.8h, 4h, etc. Preferably, the N,N-dihydrocarbyl secondary amine represented by formula II and the dicarboxylic anhydride compound represented by formula III are mixed and reacted under solvent-free conditions, or are reacted in a solvent, the solvent being an inert solvent. In the present invention, the reaction can be carried out without a solvent, by directly mixing and reacting the compound represented by formula II and the compound represented by formula III. Preferably, the inert solvent is any one or a combination of at least two selected from the group consisting of hexane, dichloromethane, petroleum ether, toluene, xylene, and kerosene. In a third aspect, the present application provides the use of the N,N-dihydrocarbylaminocarboxylic acid of the first aspect in the preparation of an extractant for separating rare earth elements. Preferably, separating the rare earth elements specifically extracts and separates yttrium from the rare earth mixture. Compared with the prior art, the present application has at least the following advantageous effects: (1) The aminocarboxylic acids provided by the present application are used for concentrating rare earth elements from low-concentration rare earth raw materials, separating and purifying yttrium from mixed rare earth raw materials, removing elements such as aluminum, iron, radioactive thorium, radioactive uranium, and actinium from mixed rare earth raw materials, and in other fields. (2) The aminocarboxylic acids provided by the present application have good chemical stability and can withstand strong acids and strong bases without decomposition. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0004] The present invention will be further described in the following specific embodiments. Those skilled in the art will appreciate that the specific embodiments are merely for ease of understanding of the present invention, and are not intended to limit the present invention.

[0005] [Example 1] This example provides compound I-1 as shown in formula I, and the structural formula of compound I-1 is as follows: [ka] The synthetic route of compound I-1 is as follows. [ka] The synthesis method is as follows. (1) N,N-diheptyl secondary amine (21.4 g, 0.10 mol) represented by formula II-1 was dissolved in toluene (20 mL) to obtain solution I, and octenyl glutaric anhydride compound (22.5 g, 0.10 mol) represented by formula III-1 was dissolved in toluene (30 mL) to obtain solution II. (2) Solution 1 was added to solution 2, the solution was stirred, and the temperature was raised to 80°C. This reaction temperature was maintained for 2 hours. After the reaction was completed, the mixture was concentrated in vacuum to remove toluene, and compound IV-1 was obtained. (3) Compound IV-1 was reduced in a tetrahydrofuran solution containing sodium borohydride (NaBH4) and ZnCl2 to give compound I-1. The present application analyzed compound I-1 by NMR. 1 HNMR(500MHz,CDCl3),δ12.01(1H),5.42(1H),5.34(1H),2.46(2H),2.40(4H),2.33(2H),2.03(1H),1.94(2H),1.54(2H ),1.45(4H),1.33(2H),1.31(4H),1.31(2H),1.31(2H),1.29(2H),1.25(4H),1.19(4H),0.93(6H),0.88(3H),0.88(6H). 13 CNMR(500MHz,CDCl3),δ178.4,134.9,129.3,64.6,64.4(2C),34.8(2C),31.9,31.6,31.3 (2C),31.2,29.9,29.4,29.0(2C),28.0,27.5,23.0(2C),22.7,18.7(2C),14.1,14.1(2C).

[0006] [Example 2] This example provides compound I-2 as shown in formula I, and the structural formula of compound I-2 is: [ka] The synthetic route of compound I-2 is as follows. [ka] The synthesis method is as follows. (1) N,N-diisooctyl secondary amine (24.1 g, 0.10 mol) shown in formula II-2 was dissolved in toluene (20 mL) to obtain solution I, and decenyl glutaric anhydride compound (25.2 g, 0.10 mol) shown in formula III-2 was dissolved in toluene (30 mL) to obtain solution II. (2) Solution 1 was added to solution 2, the solution was stirred, and the temperature was raised to 80°C. This reaction temperature was maintained for 1 h. After the reaction was completed, the mixture was concentrated in vacuum to remove toluene, and compound IV-2 was obtained. (3) Compound IV-2 was reduced in a tetrahydrofuran solution containing sodium borohydride (NaBH4) and ZnCl2 to give compound I-2. The present application analyzed compound I-2 by NMR. 1HNMR(500MHz,CDCl3),δ12.01(1H),5.42(1H),5.34(1H),2.46(2H),2.40(4H),2.33(2H),2.03(1H),1.94(2H),1.55(2H),1.54(2H),1.3 3(2H),1.31(4H),1.30(2H),1.29(2H),1.26(2H),1.26(2H),1.26(2H),1.25(2H),1.25(4H),1.19(4H),0.99(6H),0.88(3H),0.88(6H). 13 CNMR(500MHz,CDCl3),δ178.4,134.9,129.3,64.6,63.1(2C),38.0(2C),32.3(2C),31.9,31. 6,31.2,29.9,29.7,29.3,29.3(2C),28.0,27.5,26.3(2C),22.7,14.1,14.1(2C),11.6(2C).

[0007] [Example 3] This example provides compound I-3 as shown in formula I, and the structural formula of compound I-3 is as follows: [ka] The synthetic route of compound I-3 is as follows. [ka] The synthesis method is as follows. (1) N,N-diisodecyl secondary amine (29.8 g, 0.10 mol) shown in formula II-3 was dissolved in toluene (20 mL) to obtain solution I, and dodecenyl pimelic anhydride compound (32.2 g, 0.10 mol) shown in formula III-3 was dissolved in toluene (30 mL) to obtain solution II. (2) Solution 1 was added to solution 2, the solution was stirred, and the temperature was raised to 80°C. This reaction temperature was maintained for 1 h. After the reaction was completed, the mixture was concentrated in vacuum to remove toluene, and compound IV-3 was obtained. (3) Compound IV-3 was reduced in a tetrahydrofuran solution containing sodium borohydride (NaBH4) and to give compound I-3. The present application analyzed compound I-3 by NMR. 1 HNMR(500MHz,CDCl3),δ11.87(1H),5.42(1H),5.34(1H),5.31(1H),4.66(1H),2.40(4H), 2.21(2H),2.03(1H),1.94(2H),1.55(4H),1.54(2H),1.33(2H),1.30(2H),1.30(2H),1.2 9(2H),1.26(2H),1.26(2H),1.26(2H),1.26(2H),1.26(4H),1.26(4H),1.25(2H),1.25(2 H),1.25(2H),1.25(2H),1.25(4H),1.25(4H),1.19(4H),0.99(6H),0.88(3H),0.88(6H). 13 CNMR(500MHz,CDCl3),δ178.4,133.5,132.4,55.7(2C),29.6,95.0,38.3(2C),37.5,34.0,32.6(2C),31.8(2C),31.9,29.9,29 .6(2C),29.7,29.7,29.6,29.4,29.3,28.0,27.2,27.1(2C),27.0,26.3(2C),24.7,22.7(2C),22.7,14.1(2C),14.1,11.6(2C).

[0008] [Example 4] This example provides compound I-4 as shown in formula I, and the structural formula of compound I-4 is as follows: [ka] The synthetic route of compound I-4 is as follows. [ka] The synthesis method is as follows. (1) N,N-dioctadecyl secondary amine (52.1 g, 0.10 mol) shown in formula II-4 was dissolved in toluene (20 mL) to obtain solution I, and hexadecenylazelaic anhydride compound (37.8 g, 0.10 mol) shown in formula III-4 was dissolved in toluene (30 mL) to obtain solution II. (2) Solution 1 was added to solution 2, the solution was stirred, and the temperature was raised to 80°C. This reaction temperature was maintained for 1 h. After the reaction was completed, the mixture was concentrated in vacuum to remove toluene, and compound IV-4 was obtained. (3) Compound IV-4 was reduced in a tetrahydrofuran solution containing sodium borohydride (NaBH4) and ZnCl2 to give compound I-4. The present application analyzed compound I-4 by NMR. 1 HNMR(500MHz,CDCl3),δ11.87(1H),5.42(1H),5.34(1H),2.46(2H),2.43( 4H),2.21(2H),2.03(1H),1.94(2H),1.54(2H),1.36(4H),1.33(2H),1.33 (2H),1.30(2H),1.30(2H),1.29(2H),1.29(4H),1.27(4H),1.26(48H),1. 26(4H), 1.26(16H), 1.25(2H), 1.25(2H), 1.25(2H), 0.88(3H), 0.88(6H). 13 CNMR(500MHz,CDCl3),δ178.4,133.5,132.4,64.3,57.6(2C),34.0,33.2,32.2,31.9,31.9(2C),29.9,29.7,29.7,29.7,29. 6(6C),29.6(20C),29.3,29.3(2C),29.3(2C),29.0,28.3(2C),28.0,27.3(2C),27.2,24.7,22.7,22.7(2C),14.1,14.1(2C).

[0009] [Example 5] This example provides compound I-5 as shown in formula I, and the structural formula of compound I-5 is as follows: [ka] The synthetic route of compound I-5 is as follows. [ka] The synthesis method is as follows. (1) N,N-dieicosanyl secondary amine (57.8 g, 0.10 mol) shown in formula II-5 was dissolved in toluene (20 mL) to obtain solution I, and dodecenyl adipic anhydride compound (29.4 g, 0.10 mol) shown in formula III-5 was dissolved in toluene (30 mL) to obtain solution II. (2) Solution 1 was added to solution 2, the solution was stirred, and the temperature was raised to 80°C. This reaction temperature was maintained for 1 h. After the reaction was completed, the mixture was concentrated in vacuum to remove toluene, and compound IV-5 was obtained. (3) Compound IV-5 was reduced in a tetrahydrofuran solution containing sodium borohydride (NaBH4) and to give compound I-5. The present application analyzed compound I-5 by NMR. 1 HNMR(500MHz,CDCl3),δ11.87(1H),5.42(1H),5.34(1H),5.31(1H),4.66(1H),2.43(4H),2.33(2H),2.03(2H),1.94(2H),1.54(2H),1.3 7(4H),1.33(2H),1.30(2H),1.30(2H),1.29(2H),1.29(4H),1.27(4H),1.26(4H),1.26(8H),1.26(56H),1.25(2H),0.88(3H),0.88(6H). 13 CNMR(500MHz,CDCl3),δ178.4,133.5,132.4,94.4,51.4(2C),37.2,34.4,31.9,31.9(2C),29.9,29.7,29.7,29.6,2 9.6,29.6(24C),29.3,29.3(2C),29.3(2C),28.6(2C),28.0,27.3(2C),26.4,25.5,22.7,22.7(2C),14.1(2C),14.1.

[0010] [Example 6] This example provides compound I-6 as shown in formula I, and the structural formula of compound I-6 is as follows: [ka] The synthetic route of compound I-6 is as follows. [ka] The synthesis method is as follows. (1) N,N-diisooctenyl secondary amine (23.8 g, 0.10 mol) shown in formula II-6 was dissolved in toluene (20 mL) to obtain solution I, and decenylazelaic anhydride compound (30.8 g, 0.10 mol) shown in formula III-6 was dissolved in toluene (30 mL) to obtain solution II. (2) Solution 1 was added to solution 2, the solution was stirred, and the temperature was raised to 80°C. This reaction temperature was maintained for 1 h. After the reaction was completed, the mixture was concentrated in vacuum to remove toluene, and compound IV-6 was obtained. (3) Compound IV-6 was reduced in a tetrahydrofuran solution containing sodium borohydride (NaBH4) and ZnCl2 to give compound I-6. The present application analyzed compound I-6 by NMR. 1 HNMR(500MHz,CDCl3),δ11.87(1H),5.92(1H),5.42(1H),5.34(1H),3.23(2 H),2.21(2H),2.18(4H),2.03(1H),2.00(4H),1.94(2H),1.54(2H),1.38(4H ),1.33(2H),1.33(2H),1.30(2H),1.29(2H),1.29(4H),1.26(2H),1.26(2H) ,1.26(2H),1.25(2H),1.25(2H),1.25(2H),0.93(6H),0.88(3H),0.85(6H). 13 CNMR(500MHz, CDCl3),δ178.4,133.5,132.4,124.6(2C),116.6(2C),62.0,34.0,33.4,32.4,31.9,29.9,29.7,29. 7,29.7,29.6(2C),29.3,29.0,28.3(2C),28.0,28.0(2C),27.2,24.7,23.1(2C),22.7,11.8(2C),14.1,14.1(2C).

[0011] [Example 7] This example provides compound I-7 as shown in formula I, and the structural formula of compound I-7 is: [ka] The synthetic route of compound I-7 is as follows. [ka] The synthesis method is as follows. (1) N,N-diisodecenyl secondary amine (29.3 g, 0.10 mol) shown in formula II-7 was dissolved in toluene (20 mL) to obtain solution I, and octadecenyl tridecane dianhydride compound (47.6 g, 0.10 mol) shown in formula III-7 was dissolved in toluene (30 mL) to obtain solution II. (2) Solution 1 was added to solution 2, the solution was stirred, and the temperature was raised to 80°C. This reaction temperature was maintained for 1 h. After the reaction was completed, the mixture was concentrated in vacuum to remove toluene, and compound IV-7 was obtained. (3) Compound IV-7 was reduced in a tetrahydrofuran solution containing sodium borohydride (NaBH4) and ZnCl2 to give compound I-7. The present application analyzed compound I-7 by NMR. 1 HNMR(500MHz,CDCl3),δ11.87(1H),5.92(2H),5.42(1H),5.34(1H),3.23(2H),2.21(2H), 2.18(4H),2.03(1H),2.00(4H),1.94(2H),1.54(2H),1.33(2H),1.33(2H),1.33(4H),1.3 1(4H),1.31(4H),1.30(2H),1.30(2H),1.30(2H),1.29(2H),1.29(4H),1.26(2H),1.26(2 H),1.26(2H),1.26(20H),1.25(2H),1.25(2H),1.25(2H),0.88(3H),0.88(6H),0.85(6H). 13CNMR(500MHz,CDCl3),δ178.4,133.5,132.4,124.6(2C),116.6(2C),62.0,34.0,33.4,32.4,31.9,31.9(2C),30.0,29.9,29.7,29.7,29.6(8C ),29.6,29.6,29.6,29.7(2C),29.3,29.3,29.0,28.6(2C),28.6(2C),2 8.0,28.0(2C),27.2,24.7,22.7,22.7(2C),14.1,14.1(2C),11.8(2C).

[0012] [Example 8] This example provides compound I-8 as shown in formula I, and the structural formula of compound I-8 is as follows: [ka] The synthetic route of compound I-8 is as follows. [ka] The synthesis method is as follows. (1) N,N-didequinyl secondary amine (28.9 g, 0.10 mol) shown in formula II-8 was dissolved in toluene (20 mL) to obtain solution I, and eicosanyl azelaic anhydride compound (45.0 g, 0.10 mol) shown in formula III-8 was dissolved in toluene (30 mL) to obtain solution II. (2) Solution 1 was added to solution 2, the solution was stirred, and the temperature was raised to 80°C. This reaction temperature was maintained for 1 h. After the reaction was completed, the mixture was concentrated in vacuum to remove toluene, and compound IV-8 was obtained. (3) Compound IV-8 was reduced in a tetrahydrofuran solution containing sodium borohydride (NaBH4) and ZnCl2 to give compound I-8. The present application analyzed compound I-8 by NMR. 1HNMR(500MHz,CDCl3),δ11.87(1H),2.69(2H),2.46(4H),2.21(2H),1.55 (2H),1.54(2H),1.44(4H),1.33(2H),1.29(4H),1.26(4H),1.26(4H),1.2 6(4H),1.26(4H),1.26(26H),1.25(2H),1.25(2H),1.25(2H),1.25(2H),1 .19(2H),1.19(2H),1.15(1H),1.10(1H),0.99(3H),0.88(3H),0.88(6H). 13 CNMR(500MHz, CDCl3),δ178.4,83.3(2C),81.9(2C),56.6,34.9,37.3,34.0,31.9,31.9(2C),29.9,29.6,29.6(10C),29.3,29.3( 2C),29.0,28.9,28.7(2C),28.7(2C),28.4(2C),28.3,27.7,27.4,24.7,23.5,22.7,22.7(2C),15.9(2C),12.2,14.1,14.1(2C).

[0013] [Example 9] This example provides compound I-9 as shown in formula I, and the structural formula of compound I-9 is: [ka] The synthetic route of compound I-9 is as follows. [ka] The synthesis method can be carried out in a solvent or in solvent-free conditions, and the synthesis method in a solvent is described below. (1) N,N-dihexadecanyl secondary amine (45.8 g, 0.10 mol) shown in formula II-9 was dissolved in toluene (20 mL) to obtain solution I, and triaconyl azelaic anhydride compound (52.0 g, 0.10 mol) shown in formula III-9 was dissolved in toluene (30 mL) to obtain solution II. (2) Solution 1 was added to solution 2, the solution was stirred, and the temperature was raised to 80°C. This reaction temperature was maintained for 1 h. After the reaction was completed, the mixture was concentrated in vacuum to remove toluene, and compound IV-9 was obtained. (3) Compound IV-9 was reduced in a tetrahydrofuran solution containing sodium borohydride (NaBH4) and ZnCl2 to give compound I-9. The present application analyzed compound I-9 by NMR. 1 HNMR(500MHz,CDCl3),δ11.87(1H),2.69(2H),2.46(4H),2.21(2H),1.54(2H), 1.44(4H),1.33(2H),1.30(1H),1.29(4H),1.26(40H),1.26(16H),1.26(22H),1 .25(2H),1.25(2H),1.25(2H),1.25(2H),1.25(2H),1.25(2H),1.19(2H),1.19( 2H), 1.19(2H), 1.15(1H), 1.00(1H), 0.88(3H), 0.88(3H), 0.88(3H), 0.88(6H). 13 CNMR(500MHz,CDCl3),δ178.4,83.3(2C),81.9(2C),56.9,43.9,35.5,35.1,34. 0,32.7,31.9,31.9,31.9(2C),29.9,29.9,29.6,29.6(5C),29.6(8C),29.6(12C ),29.3,29.3,29.3(2C),29.2,29.0,28.7(2C),28.7(2C),28.4(2C),28.0,27.4 ,27.4,26.1,24.7,22.7,22.7,22.7(2C),19.1,15.9(2C),14.1,14.1,14.1(2C).

[0014] [Example 10] This example provides compound I-10 as shown in formula I, and the structural formula of compound I-10 is as follows: [ka] The synthetic route of compound I-10 is as follows. [ka] The synthesis method can be carried out in a solvent or in solvent-free conditions, and the synthesis method in a solvent is described below. (1) N,N-dichlorohexadecyl secondary amine (47.9 g, 0.10 mol) shown in formula II-10 was dissolved in toluene (20 mL) to obtain solution I, and decenyl glutaric anhydride compound (32.2 g, 0.10 mol) shown in formula III-10 was dissolved in toluene (30 mL) to obtain solution II. (2) Solution 1 was added to solution 2, the solution was stirred, and the temperature was raised to 80°C. This reaction temperature was maintained for 2 h. After the reaction was completed, the mixture was concentrated in vacuum to remove toluene, and compound IV-10 was obtained. (3) Compound IV-10 was reduced in a tetrahydrofuran solution containing sodium borohydride (NaBH4) and ZnCl2 to give compound I-10. The present application analyzed compound I-10 by NMR. 1 HNMR(500MHz,CDCl3),δ12.01(1H),5.48(1H),5.43(1H),3.60(2H),3.60(2H),2.46(2H),2.43(1H), 2.33(1H),2.33(2H),2.03(1H),1.94(2H),1.77(2H),1.77(2H),1.54(2H),1.49(2H),1.49(2H),1.4 6(2H),1.35(1H),1.33(2H),1.31(2H),1.31(2H),1.30(2H),1.29(2H),1.26(2H),1.26(2H),1.26(2 H),1.26(6H),1.26(10H),1.25(2H),1.25(2H),1.25(2H),1.25(2H),0.88(3H),0.88(3H),0.87(3H). 13CNMR(500MHz, CDCl3),δ178.4,134.9,129.3,77.0,75.5,59.9,44.7,44.7,40.1,38.2,34.0,32.3,31.9,31.3,31.3,31.1,31.2,29.9,29.7,2 9.7,29.6,29.6,29.6,29.6,29.6,29.6,29.6,29.6,29.3,28.8,28.8, 27.6,27.5,27.3,26.7,26.3,26.2,22.7,18.5,16.7,14.1,11.6,11.0.

[0015] [Example 11] This example provides compound I-11 as shown in formula I, and the structural formula of compound I-11 is as follows: [ka] The synthetic route of compound I-11 is as follows. [ka] The synthesis method is as follows. (1) N,N-dichlorotetradecyl secondary amine (47.9 g, 0.10 mol) shown in formula II-11 was dissolved in toluene (20 mL) to obtain solution I, and decenyl glutaric anhydride compound (32.2 g, 0.10 mol) shown in formula III-11 was dissolved in toluene (30 mL) to obtain solution II. (2) Solution 1 was added to solution 2, the solution was stirred, and the temperature was raised to 80°C. This reaction temperature was maintained for 2 h. After the reaction was completed, the mixture was concentrated in vacuum to remove toluene, and compound IV-11 was obtained. (3) Compound IV-11 was reduced in a tetrahydrofuran solution containing sodium borohydride (NaBH4) and ZnCl2 to give compound I-11. The present application analyzed compound I-11 by NMR. 1HNMR(500MHz,CDCl3),δ12.01(1H),5.48(1H),5.43(1H),3.60(4H),2.46 (2H),2.43(2H),2.33(2H),2.03(1H),1.94(2H),1.77(4H),1.54(2H),1.4 9(4H),1.46(4H),1.33(2H),1.31(4H),1.30(2H),1.29(2H),1.26(2H),1. 26(2H), 1.26(2H), 1.26(20H), 1.25(4H), 1.25(4H), 0.88(3H), 0.87(6H). 13 CNMR(500MHz,CDCl3),δ178.4,134.9,129.3,75.2(2C),59.6,44.7(2C),38.2,34.0,32.3(2C),31.9,31.2,31.1 (2C),29.9,29.7,29.7,29.6(10C),29.3,28.8(2C),27.5,27.3(2C),26.7(2C),26.2(2C),22.7,14.1,11.0(2C).

[0016] [Example 12] This example provides compound I-12 as shown in formula I, and the structural formula of compound I-12 is: [ka] The synthetic route of compound I-12 is as follows. [ka] The synthesis method is as follows. (1) N,N-dialkyl secondary amine (49.9 g, 0.10 mol) shown in formula II-12 was dissolved in toluene (20 mL) to obtain solution I, and eicosanyl azelaic anhydride compound (30.8 g, 0.10 mol) shown in formula III-12 was dissolved in toluene (30 mL) to obtain solution II. (2) Solution 1 was added to solution 2, the solution was stirred, and the temperature was raised to 80°C. This reaction temperature was maintained for 1 h. After the reaction was completed, the mixture was concentrated in vacuum to remove toluene, and compound IV-12 was obtained. (3) Compound IV-12 was reduced in a tetrahydrofuran solution containing sodium borohydride (NaBH4) and to give compound I-12. The present application analyzed compound I-12 by NMR. 1 HNMR(500MHz,CDCl3),δ11.87(1H),5.31(1H),5.20(1H),4.66(1H),2.65(2H),2.43(2H),2.21(2H),2.03(1H),1.94(2H) ,1.79(3H),1.64(3H),1.43(2H),1.37(2H),1.33(4H),1.30(2H),1.29(4H),1.27(2H),1.26(46H),1.25(10H),0.88(9H). 13 CNMR(500MHz,CDCl3),δ178.4,138.0,128.9,91.7,64.3,52.9,51.2,48.1,41.5,34.0,31.9,31.9,31.8,30.2,29.7,29.7,29.6(6C),2 9.6(8C),29.4,29.4,29.3,29.3,29.3,29.3,29.0,28.6,27.8,27.5,27.3,24.7,24.5,22.7,22.7,22.7,21.7,15.2,14.1,14.1,14.1.

[0017] [Example 13] This example provides compound I-13 as shown in formula I, and the structural formula of compound I-13 is as follows: [ka] The synthetic route of compound I-13 is as follows. [ka] The synthesis method is as follows. (1) N,N-dialkyl secondary amine (35.4 g, 0.10 mol) represented by formula II-13 was dissolved in toluene (20 mL) to obtain solution I, and hexadecyl pimelic anhydride compound (36.7 g, 0.10 mol) represented by formula III-13 was dissolved in toluene (30 mL) to obtain solution II. (2) Solution 1 was added to solution 2, the solution was stirred, and the temperature was raised to 80°C. This reaction temperature was maintained for 1 h. After the reaction was completed, the mixture was concentrated in vacuum to remove toluene, and compound IV-13 was obtained. (3) Compound IV-13 was reduced in a tetrahydrofuran solution containing sodium borohydride-zinc chloride (NaBH4-ZnCl2) to give compound I-13. The present application analyzed compound I-13 by NMR. 1 HNMR(500MHz,CDCl3),δ11.87(1H),2.43(2H),2.40(2H),2.40(2H),2.21(2H),1.54(2H),1.45(1H),1.36(2H),1.29(2H),1.27 (2H),1.26(24H),1.26(24H),1.25(4H),1.25(2H),1.25(1H),1.25(4H),1.19(2H),1.19(2H),1.19(2H),0.93(3H),0.88(9H). 13 CNMR(500MHz,CDCl3),δ178.4,64.0,63.0,57.8,35.8,35.1,34.0,32.9,32.6,31.9,31.9,31.9,31.3,29.9,29.9,29.6(2C) ,29.6(4C),29.6(9C),29.3,29.3,29.3,29.3,28.3,27.3,27.1,26.8,26.5,25.0,22.7,22.7,22.7,18.7,14.1,14.1,14.1.

[0018] [Example 14] This example provides compound I-14 as shown in formula I, and the structural formula of compound I-14 is as follows: [ka] The synthetic route of compound I-14 is as follows. [ka] The synthesis method is as follows. (1) N,N-dialkyl secondary amine (24.1 g, 0.10 mol) shown in formula II-14 was dissolved in toluene (20 mL) to obtain solution I, and decenyl glutaric anhydride compound (25.2 g, 0.10 mol) shown in formula III-14 was dissolved in toluene (30 mL) to obtain solution II. (2) Solution 1 was added to solution 2, the solution was stirred, and the temperature was raised to 80°C. This reaction temperature was maintained for 1 h. After the reaction was completed, the mixture was concentrated in vacuum to remove toluene, and compound IV-14 was obtained. (3) Compound IV-14 was reduced in a tetrahydrofuran solution containing sodium borohydride-zinc chloride (NaBH4-ZnCl2) to give compound I-14. The present application analyzed compound I-14 by NMR. 1 HNMR(500MHz,CDCl3),δ12.01(1H),5.48(1H),5.43(1H),2.46(2H),2.43(4H),2.33(2H),2.03(1H) ,1.94(2H),1.54(2H),1.36(4H),1.33(2H),1.30(2H),1.29(6H),1.27(4H),1.26(18H),0.88(9H). 13 CNMR(500MHz,CDCl3),δ178.4,134.9,129.3,64.0,57.6(2C),37.6,34.0,31.9(2C),31.9,31.2 ,29.9,29.7,29.7,29.3(4C),29.3,28.3(2C),27.5,27.3(2C),22.7(2C),22.7,14.1(2C),14.1.

[0019] [Example 15] This example provides compound I-15 as shown in formula I, and the structural formula of compound I-15 is: [ka] The synthetic route of compound I-15 is as follows. [ka] The synthesis method can be carried out in a solvent or in solvent-free conditions, and the synthesis method in a solvent is described below. (1) N,N-dialkyl secondary amine (92.8 g, 0.10 mol) represented by formula II-15 was dissolved in toluene (20 mL) to obtain solution 1, and decylsuccinic anhydride compound (22.2 g, 0.10 mol) represented by formula III-15 was dissolved in toluene (30 mL) to obtain solution 2. (2) Solution 1 was added to solution 2, the solution was stirred, and the temperature was raised to 80°C. This reaction temperature was maintained for 1 h. After the reaction was completed, the mixture was concentrated in vacuum to remove toluene, and compound IV-15 was obtained. (3) Compound IV-15 was reduced in a tetrahydrofuran solution containing sodium borohydride (NaBH4) and to give compound I-15. The present application analyzed compound I-15 by NMR. 1 HNMR(500MHz,CDCl3),δ12.01(1H),5.31(1H),4.60(1H),3.54(4H),2.84(2H),2.81(1H),2.4 6(2H), 1.96(2H), 1.44(2H), 1.31(4H), 1.29(2H), 1.28(4H), 1.26(96H), 1.25(8H), 0.88(9H). 13 CNMR(500MHz,CDCl3),δ177.3,86.5,86.3,80.8,58.6(2C),50.9(2C),36.7,31.9(2C),31.2(2C) ,30.9,29.6(44C),29.3(2C),29.0,28.1,27.1,26.5(2C),22.7(2C),22.7,19.4,14.1(2C),14.1.

[0020] [Comparative Example 1] This example provides compound I-d1 as shown in formula I, and the structural formula of compound I-d1 is as follows: [ka] The synthetic route for compound I-d1 is as follows. [ka] The synthesis method is as follows. (1) N,N-dialkyl secondary amine (18.5 g, 0.10 mol) shown in formula II-d1 was dissolved in toluene (20 mL) to obtain solution 1, and octenyl glutaric anhydride compound (22.4 g, 0.10 mol) shown in formula III-d1 was dissolved in toluene (30 mL) to obtain solution 2. (2) Solution 1 was added to solution 2, the solution was stirred, and the temperature was raised to 80°C. This reaction temperature was maintained for 1 h. After the reaction was completed, the mixture was concentrated in vacuum to remove toluene, and compound IV-d1 was obtained. (3) Compound IV-d1 was reduced in a tetrahydrofuran solution containing sodium borohydride-zinc chloride (NaBH4-ZnCl2) to obtain compound I-d1. The present application analyzed compound I-d1 by NMR. 1 HNMR(500MHz,CDCl3),δ12.01(1H),5.48(1H),5.43(1H),2.63(2H),2.46(2H),2.33(2H),2.0 3(1H), 1.94(2H), 1.54(2H), 1.33(2H), 1.31(12H), 1.29(2H), 1.25(4H), 1.06(6H), 0.88(9H). 13 CNMR(500MHz,CDCl3),δ178.4,134.9,129.3,61.3(2C),59.0,38.2,34.6(2C),34.0, 31.9,31.2,29.9,29.7(2C),29.4,27.5,22.7(2C),22.7,21.0(2C),14.1(2C),14.1.

[0021] [Comparative Example 2] This example provides compound I-d2 as shown in formula I, and the structural formula of compound I-d1 is: [ka] The synthetic route for compound I-d2 is as follows. [ka] The synthesis method is as follows. (1) N,N-dialkyl secondary amine (18.5 g, 0.10 mol) shown in formula II-d2 was dissolved in toluene (20 mL) to obtain solution I, and decaenyl glutaric anhydride compound (25.2 g, 0.10 mol) shown in formula III-d2 was dissolved in toluene (30 mL) to obtain solution II. (2) Solution 1 was added to solution 2, the solution was stirred, and the temperature was raised to 80°C. This reaction temperature was maintained for 1 h. After the reaction was completed, the mixture was concentrated in vacuum to remove toluene, and compound IV-d2 was obtained. (3) Compound IV-d2 was reduced in a tetrahydrofuran solution containing sodium borohydride-zinc chloride (NaBH4-ZnCl2) to obtain compound I-d2. The present application analyzed compound I-d2 by NMR. 1 HNMR(500MHz,CDCl3),δ12.01(1H),5.48(1H),5.43(1H),2.46(2H),2.43(4H),2.33(2H),2.03(1H ), 1.94 (2H), 1.54 (2H), 1.36 (4H), 1.33 (2H), 1.30 (2H), 1.29 (6H), 1.28 (8H), 1.26 (6H), 0.88 (9H). 13 CNMR(500MHz,CDCl3),δ178.4,134.9,129.3,64.0,57.6(2C),37.6,34.0,31.9,31.5(2C), 31.2,29.9,29.7,29.7,29.3,28.3(2C),27.5,27.0(2C),22.7(2C),22.7,14.1(2C),14.1.

[0022] [Comparative Example 3] This example provides compound I-d3 as shown in formula I, and the structural formula of compound I-d1 is as follows: [ka] The synthetic route for compound I-d3 is as follows. [ka] The synthesis method is as follows. (1) N,N-dialkenyl secondary amine (15.3 g, 0.10 mol) represented by formula II-d3 was dissolved in toluene (20 mL) to obtain solution 1, and octadecanyl dianhydride compound (47.6 g, 0.10 mol) represented by formula III-d3 was dissolved in toluene (30 mL) to obtain solution 2. (2) Solution 1 was added to solution 2, the solution was stirred, and the temperature was raised to 80°C. This reaction temperature was maintained for 1 h. After the reaction was completed, the mixture was concentrated in vacuum to remove toluene, and compound IV-d3 was obtained. (3) Compound IV-d3 was reduced in a tetrahydrofuran solution containing sodium borohydride-zinc chloride (NaBH4-ZnCl2) to obtain compound I-d3. The present application analyzed compound I-d3 by NMR. 1 HNMR(500MHz,CDCl3),δ11.87(1H),5.82(2H),5.48(1H),5.43(1H),5.13(2H),4.88(2H),2.76(2H),2.46(2H),2.21(2H) ,2.13(4H),2.03(1H),1.94(2H),1.54(2H),1.33(4H),1.30(4H),1.29(6H),1.26(26H),1.25(4H),1.11(6H),0.88(3H). 13 CNMR(500MHz,CDCl3),δ178.4,133.5,133.0(2C),132.4,115.8(2C),59.8(2C),59.5,41.1(2C),38.8,34.0,34. 0,33.2,31.9,30.0,29.9,29.7,29.7,29.6(3C),29.6(8C),29.3,29.3,29.0,27.2,24.7,22.7,18.1(2C),14.1.

[0023] [Test Example 1] Rare earth element enrichment test (1) The masses of the compounds prepared in the above Examples 1 to 15 and Comparative Examples d1 to d3 used were (5.51, 6.24, 8.08, 11.52, 11.36, 6.91, 9.83, 9.44, 12.53, 10.96, 10.23, 10.98, 9.36, 6.42, 14.78 and 5.15, 5.51, 8.01) g, respectively. (2) Each of the above extractants was mixed with 0.96 mL of 10.8 mol / L aqueous sodium hydroxide solution and saponified at 25°C for 5 minutes to obtain a saponified extractant as a viscous liquid with a saponification degree of 80%. (3) At room temperature, the saponified extractant as a viscous liquid was mixed with 2000 mL of ionic rare earth leaching solution, and the concentration time was 0.5 h. The components of the ionic rare earth leaching solution were lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, and yttrium, a total of 15 rare earth elements, with a total molar concentration of 0.00636 mol / L. pH=6.0. The concentrations of rare earth ions in the aqueous phase before and after concentration were measured, and the total concentration rate E% of rare earth ions was calculated. Specific test results (total concentration rate of rare earth ions) are shown in Table 1. [Table 1] The test data in Table 1 show that the enrichment rate of the N,N-dihydrocarbylaminocarboxylic acid prepared in the present application is more than 95%, and can be used to enrich rare earth elements from low-concentration rare earth raw materials.

[0024] [Test Example 2] Yttrium separation test (1) The compounds prepared in the above Examples 1-15 and Comparative Examples 1-3 are mixed into an extractant solution, and the specific method for preparing the extractant solution is as follows. The extractant of Examples 1-15 and Comparative Examples 1-3 was taken in (5.51, 6.24, 8.08, 11.52, 11.36, 6.91, 9.83, 9.44, 12.53, 10.96, 10.23, 10.98, 9.36, 6.42, 14.78 and 5.15, 5.51, 8.01) g, and toluene was taken in (19.5, 18.8, 16.9, 13.5, 13.6, 18.1, 15.2, 15.6, 12.5, 14.0, 14.8, 14.0, 15.6, 18.6, 10.2 and 19.9, 19.5, 17.0) g, respectively, and the two were mixed to obtain an extractant solution, the total volume of which was 25 mL, and the concentration of the extractant was 0.52 mol / L. (2) Each of the above extractant solutions was mixed with 0.96 mL of 10.8 mol / L aqueous sodium hydroxide solution and saponified at 25°C for 5 minutes to obtain a saponified extractant solution with a saponification degree of 80%. (3) At room temperature, 25 mL of the saponified extractant solution was mixed with 25 mL of the mixed rare earth solution, and the extraction time was 0.5 h. The components of the mixed rare earth solution were lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, and yttrium, a total of 15 rare earth elements, each of which had a concentration of 0.020 mol / L. The concentrations of rare earth ions in the aqueous phase before and after extraction were measured, and the relative separation coefficients of each rare earth ion (Ln) to yttrium ion (Y) were calculated as β Ln / Y I calculated it. Specific test results (relative separation factor of rare earth ion (Ln) to yttrium ion (Y) is β Ln / Y ) are shown in Table 2. [Table 2] From the data in Table 2, it can be seen that the aminocarboxylic acids provided by the present application can be used to separate and purify yttrium from mixed rare earth elements.

[0025] [Test Example 3] Stability testing The compound I-1 prepared in the above Example 1 is subjected to stability test, the specific test method is as follows: Compound I-1 is prepared into extractant solution, the specific preparation method of the extractant solution is as follows: 43.9g is taken and mixed with 100mL toluene to prepare extractant solution with a concentration of 1.0mol / L; 50mL of extractant solution is taken and mixed with 50mL of 6mol / L hydrochloric acid solution and stirred; another 50mL of extractant solution is taken and mixed with 50mL of 6mol / L sodium hydroxide solution and stirred, and maintained for 15 days, after which the loss rate of the extractant in the test is detected by NMR. The test methods for the stability of the compounds in Examples 2 to 15 and Comparative Examples d1 to d3 were the same as those for Compound I-1. Specific test results (loss rate of extractant in hydrochloric acid medium and liquid base) are shown in Table 3. [Table 3] From the test data in Table 3, it can be seen that the N,N-dihydrocarbylaminocarboxylic acid of the present application has an extractant loss rate of less than 0.04% in hydrochloric acid medium and less than 0.05% in liquid base, which proves that the N,N-dihydrocarbylaminocarboxylic acid prepared in the present application has very good chemical stability and can withstand strong acids and strong bases without decomposition. It should be noted that, in the present application, the N,N-dihydrocarbylaminocarboxylic acid of the present application and its preparation method and use are described using the above examples, but the present application is not limited to the above examples, and the embodiments of the present application are not limited to the above examples. The scope of protection of the present application is defined by the claims.

Claims

1. Having the structure shown in Formula I, 【Chemistry 1】 Here, R １ and R ２ are independently a hydrocarbyl group having 7 or more carbon atoms, which is linear or branched, saturated or unsaturated, and substituted or unsubstituted with any one or a combination of at least two or more selected from the group consisting of halogen, hydroxyl, carboxyl, acyl, ester, ether, alkoxy, phenyl, phenoxy, amino, amido, nitro, cyano, mercapto, sulfonyl, thiol, imino, sulfoacyl, and sulfanyl; R ３ is a hydrocarbyl group in which the carbon atoms are linear or branched, saturated or unsaturated, and substituted or unsubstituted with any one or a combination of at least two or more selected from the group consisting of halogen, hydroxyl, carboxyl, acyl, ester, ether, alkoxy, phenyl, phenoxy, amino, amido, nitro, cyano, mercapto, sulfonyl, thiol, imino, sulfoacyl, and sulfanyl, X is H or OH; n is a natural number from 1 to 10 An N,N-dihydrocarbylaminocarboxylic acid,

2. The R １ and R ２ are independently a hydrocarbyl group having C7 to C30 carbon atoms, which is linear or branched, saturated or unsaturated, and substituted or unsubstituted with any one or a combination of at least two or more selected from the group consisting of halogen, hydroxyl, carboxyl, acyl, ester, ether, alkoxy, phenyl, phenoxy, amino, amido, nitro, cyano, mercapto, sulfonyl, thiol, imino, sulfoacyl, and sulfanyl. The N,N-dihydrocarbylaminocarboxylic acid according to claim 1 .

3. The R ３ is selected from hydrocarbyl groups having carbon atoms of 6 or more, which are linear or branched, saturated or unsaturated, and substituted or unsubstituted with any one or a combination of at least two or more selected from the group consisting of halogen, hydroxyl, carboxyl, acyl, ester, ether, alkoxy, phenyl, phenoxy, amino, amido, nitro, cyano, mercapto, sulfonyl, thiol, imino, sulfoacyl, and sulfanyl. The N,N-dihydrocarbylaminocarboxylic acid according to claim 1 or 2.

4. The R １ and R ２ are independently a hydrocarbyl group having C7 to C18 carbon atoms which is linear or branched, saturated or unsaturated, and substituted or unsubstituted with any one or a combination of at least two or more of halogen, hydroxyl, carboxyl, acyl, ester, ether, alkoxy, phenyl, phenoxy, amino, amido, nitro, cyano, mercapto, sulfonyl, thiol, imino, sulfoacyl, or sulfanyl. The N,N-dihydrocarbylaminocarboxylic acid according to claim 2 or 3.

5. The R １ and R ２ are independently straight or branched chain, saturated or unsaturated, unsubstituted hydrocarbyl groups having carbon atoms of 7 or more; 4. The N,N-hydrocarbyl amino carboxylic acid according to claim 1 or 3.

6. The R １ and R ２ are independently C7-C30 carbon atom branched, saturated or unsaturated, unsubstituted hydrocarbyl groups; The N,N-dihydrocarbylaminocarboxylic acid according to claim 5 .

7. The R １ and R ２ are independently C7-C12 carbon atoms branched, saturated or unsaturated, unsubstituted hydrocarbyl groups; The N,N-dihydrocarbylaminocarboxylic acid according to claim 6 .

8. The R １ and R ２ are independently unsubstituted alkyl groups having C7 to C30 carbon atoms in a straight or branched chain; 6. The N,N-dihydrocarbylaminocarboxylic acid according to claim 1 ,

9. The R １ and R ２ are independently straight or branched, unsubstituted alkyl groups having carbon atoms from C7 to C18; The N,N-dihydrocarbylaminocarboxylic acid according to claim 8.

10. The R １ and R ２ are independently unsubstituted alkyl groups having carbon atoms of C7-C10, either linear or branched; The N,N-dihydrocarbylaminocarboxylic acid according to claim 9 .

11. The X is H, and the n is a natural number from 1 to 6. The N,N-dihydrocarbylaminocarboxylic acid according to any one of claims 1 to 10.

12. The R １ and R ２ are independently: 【Chemistry 2】 The N,N-dihydrocarbylaminocarboxylic acid according to any one of claims 1 to 6, 8 to 9 and 11.

13. The R １ and R ２ are independently any of the following groups: 【Chemistry 3】 The N,N-dihydrocarbylaminocarboxylic acid according to any one of claims 1 to 9, 11 to 12.

14. The R ３ is a hydrocarbyl group having C6 to C30 carbon atoms, which is linear or branched, saturated or unsaturated, and substituted or unsubstituted with any one or a combination of at least two or more of halogen, hydroxyl, carboxyl, acyl, ester, ether, alkoxy, phenyl, phenoxy, amino, amido, nitro, cyano, mercapto, sulfonyl, thiol, imino, sulfoacyl, or sulfanyl.

14. The N,N-dihydrocarbylaminocarboxylic acid according to any one of claims 2 to 13.

15. The R ３ is an unsaturated, unsubstituted hydrocarbyl having a straight or branched chain of carbon atoms C6 or higher; 14. The N,N-dihydrocarbylaminocarboxylic acid according to any one of claims 1 to 13.

16. The R ３ is a straight-chain alkenyl group having 10 or more carbon atoms. The N,N-dihydrocarbylaminocarboxylic acid according to claim 15.

17. The R ３ is a straight-chain alkenyl group having C10-C18 carbon atoms The N,N-dihydrocarbylaminocarboxylic acid according to claim 16 .

18. The R ３ is one of the following groups: 【Chemistry 4】 16. The N,N-dihydrocarbylaminocarboxylic acid according to any one of claims 1 to 15.

19. A process for preparing the N,N-dihydrocarbylamino carboxylic acid according to any one of claims 1 to 10, 12 to 18, comprising the steps of: The N,N-dihydrocarbyl secondary amine of formula II is mixed with the dicarboxylic anhydride compound of formula III to react to obtain the N,N-dihydrocarbyl amido carboxylic acid of formula IV, which is reduced with a reducing agent to obtain the N,N-dihydrocarbyl amino carboxylic acid of formula I; The reaction formula is as follows: 【Chemistry 5】 Here, R １ , R ２ , R ３ is a group defined in any one of claims 1 to 10, 12 to 18, n is a natural number from 1 to 10, and X is H or OH. A process for preparing an N,N-dihydrocarbylamino carboxylic acid, comprising the steps of:

20. The molar ratio of the N,N-dihydrocarbyl secondary amine represented by the formula II to the dicarboxylic anhydride compound represented by the formula III is 1:(0.8-1.2). A process for preparing the N,N-dihydrocarbylaminocarboxylic acid according to claim 19.

21. The temperature for mixing and reacting the N,N-dihydrocarbyl secondary amine represented by formula II and the dicarboxylic anhydride compound represented by formula III is 0-125° C., and the time for mixing and reacting is 0.5-4 hours. A process for preparing the N,N-dihydrocarbylaminocarboxylic acid according to claim 19 or 20,

22. The reaction of the N,N-dihydrocarbyl secondary amine represented by formula II with the dicarboxylic anhydride compound represented by formula III is carried out in the absence of a solvent. A process for the preparation of N,N-dihydrocarbylaminocarboxylic acids according to any one of claims 19 to 21.

23. The reaction of the N,N-dihydrocarbyl secondary amine represented by formula II with the dicarboxylic anhydride compound represented by formula III is carried out in a solvent. A process for the preparation of N,N-dihydrocarbylaminocarboxylic acids according to any one of claims 19 to 21.

24. All of the solvents are inert solvents, and the inert solvents are any one selected from the group consisting of hexane, dichloromethane, petroleum ether, toluene, xylene, and kerosene, or a combination of at least two of them. A process for the preparation of N,N-dihydrocarbylaminocarboxylic acids according to claim 23, characterized in that

25. Use of the N,N-dihydrocarbylaminocarboxylic acid according to any one of claims 1 to 18 in the preparation of an extractant for separating rare earth elements.

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