1. An N, N-dihydrocarbylaminocarboxylic acid compound, wherein the N, N-dihydrocarbylaminocarboxylic acid compound has the structure shown in formula I:

wherein R is₁And R₂Independently a linear or branched, substituted or unsubstituted, unsaturated hydrocarbon group;

R₃is a linear or branched, substituted or unsubstituted, saturated or unsaturated hydrocarbon group;

x is H or OH, preferably H;

n is a natural number of 1 to 10, preferably 1 to 6.

2. The N, N-dihydrocarbylaminocarboxylic acid compound of claim 1, wherein R is₁And R₂Independently, the alkyl group is a linear or branched chain unsubstituted unsaturated alkyl group with more than C4, preferably a linear or branched chain unsubstituted unsaturated alkyl group with C4-C20, more preferably a linear or branched chain unsubstituted alkenyl group with C4-C20.

3. The N, N-dihydrocarbylaminocarboxylic acid compound according to claim 1 or 2, wherein R is₁And R₂Independently any one of the following groups, wherein,represents the position of attachment of the group:

4. the N, N-dihydrocarbylaminocarboxylic acid compound of any one of claims 1 to 3, wherein R is₃Selected from C4 or above linear chain or branched chain, substituted or unsubstituted, saturatedOr an unsaturated hydrocarbon group, preferably a linear or branched, unsubstituted unsaturated hydrocarbon group of C4-C30, more preferably a linear or branched, unsubstituted alkenyl group of C4-C18.

5. The N, N-dihydrocarbylaminocarboxylic acid compound of any one of claims 1 to 4, wherein R is₃Is any one of the following groups, wherein,represents the position of attachment of the group:

6. the method for producing an N, N-dihydrocarbylaminocarboxylic acid compound according to any one of claims 1 to 5, wherein the method for producing an N, N-dihydrocarbylaminocarboxylic acid compound is:

mixing N, N-dialkyl secondary amine shown in formula II with dianhydride compound shown in formula III for reaction to obtain N, N-dialkyl amido carboxylic acid shown in formula IV, and then using NaBH₄Reducing to obtain the N, N-dialkyl amino carboxylic acid compound shown in the formula I, wherein the reaction formula is as follows:

wherein R1, R2, R3 and a group as defined in any one of claims 1 to 5, n is a natural number of 1 to 10; x is H or OH.

7. The method of claim 6, wherein the molar ratio of the N, N-dihydrocarbylaminocarboxylic acid compound of formula II to the dianhydride compound of formula III is 1: 0.8-1.2.

8. The method of claim 6 or 7, wherein the temperature of the mixing reaction of the N, N-dihydrocarbylaminocarboxylic acid compound of formula II and the dianhydride compound of formula III is 0 to 125 ℃ and the mixing reaction time is 0.5 to 4 hours.

9. The method for producing an N, N-dihydrocarbylaminocarboxylic acid compound according to any one of claims 6 to 8, wherein the mixing reaction of the N, N-dihydrocarbylaminocarboxylic acid compound represented by the formula II and the dianhydride compound represented by the formula III is carried out in the absence of a solvent; or in a solvent;

preferably, the solvent is an inert solvent selected from any one or a combination of at least two of hexane, dichloromethane, petroleum ether, toluene, xylene or kerosene.

10. Use of an N, N-dihydrocarbylaminocarboxylic acid compound according to any of claims 1 to 5, for the preparation of an extractant for separating rare earth elements.

Background

The rare earth elements refer to 15 lanthanide elements with atomic numbers of 57-71 in the periodic table, and 17 metal elements including No. 21 scandium and No. 39 yttrium with similar chemical properties. The rare earth element has unique magnetic, optical and electrical properties, is known as 'industrial vitamin', is widely applied to the fields of metallurgy, petrochemical industry, glass ceramics, energy materials, military industry and the like, and is an important fundamental raw material for the development of human society.

At present, the exploitation of rare earth ore in nature firstly needs to use a leaching agent to leach rare earth ions to obtain a rare earth leaching solution, and then the rare earth ions are extracted and separated one by one in a solvent extraction mode. The development of an extractant is the most central technology in the solvent extraction process, multiple factors such as extraction selectivity, extraction rate, extraction capacity, stability, solubility, back extraction performance, safety, synthesis method and source of a compound need to be considered in the rare earth metal extractant for industrial application, the excellent extractant can be called one of ten thousand, and the good extractant can simplify the production process, improve the separation efficiency, reduce the production cost and reduce the pollution emission.

Commercially available extractant products known in the art are mainly classified into organic phosphine extractants, carboxylic acid extractants, and amine extractants, typical organic phosphine extractants include mono (2-ethylhexyl) 2-ethylhexyl phosphonate (P507), di (2-ethylhexyl) phosphonic acid (P204), di (2, 4, 4-trimethylpentyl) phosphinic acid (C272), tributyl phosphonate (TBP), etc., amine extractants include tri-N-octylamine (N235), secondary primary amine (N1923), methyltrioctylammonium chloride (N263), etc., and carboxylic acid extractants include naphthenic acid, neodecanoic acid, secondary octylphenoxyacetic acid (CA-12), etc.

The commercially available extractant still has some defects, for example, P507 is the one most widely used in the rare earth separation industry, but the separation coefficient of the extractant for adjacent rare earth elements is low, such as the separation coefficient of praseodymium-neodymium is only 1.4, which makes the praseodymium-neodymium element difficult to separate. Naphthenic acid is mainly used for separating and purifying yttrium oxide, but the naphthenic acid is a byproduct of petrochemical industry, has complex components, can extract rare earth under the condition of higher pH, and has easily changed components after long-term use, thereby reducing the concentration of an organic phase and influencing the stability of a separation process. CA-12 extractant has been tried to replace naphthenic acid, which can effectively separate yttrium from all lanthanides in rare earth element extraction separation process and overcome the problem of reduced organic phase concentration when the naphthenic acid is used for extracting and separating yttrium, but the separation coefficient of heavy rare earth and yttrium in the extraction system is low, which causes the heavy rare earth element and yttrium to be difficult to separate, thus more stages of extraction tanks are required to be designed to achieve separation effect.

In order to more effectively separate rare earth elements, it is required to develop a novel extractant having a higher separation coefficient than the prior art and capable of overcoming the disadvantages of the prior art, and an extraction separation method using the same.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide an N, N-dialkyl aminocarboxylic acid compound and a preparation method and application thereof. The N, N-dialkyl amino carboxylic acid compound can be used as an extractant for separating and purifying selected rare earth elements from mixed rare earth material liquid, and particularly yttrium element is extracted and separated from a rare earth element mixture.

In order to achieve the purpose, the invention adopts the following technical scheme:

in a first aspect, the present invention provides an N, N-dihydrocarbylaminocarboxylic acid compound having the structure shown in formula I below:

wherein R is₁And R₂Independently a linear or branched, substituted or unsubstituted, unsaturated hydrocarbon group such as (C1, C2, C3, C4, C5, C6, C7, C8, C9, C10, C11, C12, C13, C14, C15, C16, C17, C18, C19, C20, C22, C24, C26, C28, C30, C35, C40, etc.);

x is H or OH, preferably H;

R₃is a linear or branched, substituted or unsubstituted, saturated or unsaturated hydrocarbon group;

n is a natural number of 1 to 10 (for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, etc.), and preferably a natural number of 1 to 6.

The invention provides an aminocarboxylic acid compound with a structure shown in formula I as a carboxylic acid type extractant for separating rare earth metals and an extraction separation method thereof, and the compound as the rare earth metal extractant is not reported. The compound as a metal extractant has a high separation coefficient for rare earth elements, particularly has high efficiency for separating heavy rare earth and yttrium elements, and can overcome the defects existing in the process of separating yttrium from naphthenic acid.

In the present invention, the hydrocarbon group is any one of a substituted alkyl group, a substituted alkenyl group and a substituted alkynyl group, and the substituents of the alkyl group, the alkenyl group and the alkynyl group are each independently selected from any one or a combination of at least two of halogen, hydroxyl group, carboxyl group, acyl group, ester group, ether group, alkoxy group, phenyl group, phenoxy group, amino group, amide group, nitro group, cyano group, mercapto group, sulfonyl group, thiol group, imino group, sulfonyl group and sulfanyl group; preferably, the substituent is halogen.

Preferably, said R is₁And R₂Independently a linear or branched, unsubstituted unsaturated hydrocarbon group (linear or branched and unsubstituted alkenyl or alkynyl group) of C4 or more, for example (C4, C5, C6, C7, C8, C9, C10, C11, C12, C13, C14, C15, C16, C17, C18, C19, C20, C22, C24, C26, C28, C30, C35, C40, etc.), preferably a linear or branched, unsubstituted unsaturated hydrocarbon group of C4 to C20, more preferably a linear or branched, unsubstituted alkenyl group of C4 to C20.

Preferably, said R is₁And R₂Independently any one of the following groups, wherein,represents the position of attachment of the group:

preferably, said R is₃Selected from linear or branched, substituted or unsubstituted, saturated or unsaturated hydrocarbon radicals having above C4.

Preferably, said R is₃Is a linear or branched, unsubstituted, unsaturated hydrocarbon radical of C4 to C30; more preferably a C4-C18 linear or branched, unsubstituted, unsaturated hydrocarbon group; the alkenyl group can be linear chain or branched chain, unsubstituted alkenyl, further linear chain alkenyl of C4-C18; most preferably, R is₃Is a linear alkenyl of C10-C18.

Preferably, said R is₃Is any one of the following groups, wherein,represents the linking site of the group:

in a second aspect, the present invention provides a process for producing an N, N-dihydrocarbylaminocarboxylic acid compound as described in the first aspect, which comprises:

mixing N, N-dialkyl secondary amine shown in formula II with dianhydride compound shown in formula III for reaction to obtain N, N-dialkyl amido carboxylic acid shown in formula IV, and then using NaBH₄Reducing to obtain the N, N-dialkyl amino carboxylic acid compound shown in the formula I, wherein the reaction formula is as follows:

wherein R1, R2 and R3 are the groups defined in the first aspect, and n is a natural number of 1-10; x is H or OH.

Preferably, the molar ratio of the N, N-dihydrocarbyl secondary amine of formula II to the dianhydride compound of formula III is 1: 0.8-1.2, and may be, for example, 1: 0.8, 1: 0.9, 1: 1, 1: 1.1, 1: 1.2, etc.

Preferably, the temperature of the mixing reaction of the N, N-dihydrocarbyl secondary amine of formula II and the dianhydride compound of formula III is 0-125 deg.C, such as 0 deg.C, 5 deg.C, 10 deg.C, 15 deg.C, 20 deg.C, 25 deg.C, 30 deg.C, 35 deg.C, 40 deg.C, 50 deg.C, 60 deg.C, 70 deg.C, 80 deg.C, 90 deg.C, 100 deg.C, 105 deg.C, 110 deg.C, 115 deg.C, 120 deg.C, 125 deg.C, and the mixing reaction time is 0.5-4h, such as 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 mixing reaction of the N, N-dihydrocarbyl secondary amine shown in the formula II and the dianhydride compound shown in the formula III is carried out in the absence of a solvent; or in a solvent.

In the present invention, it is worth mentioning that the reaction can also be carried out under the solvent-free condition, and the compound with the structure shown in formula II and the compound with the structure shown in formula III are directly mixed and reacted.

Preferably, the solvent is an inert solvent selected from any one or a combination of at least two of hexane, dichloromethane, petroleum ether, toluene, xylene or kerosene.

In a third aspect, the present invention provides the use of an N, N-dihydrocarbylaminocarboxylic acid compound as defined in the first aspect, in the preparation of an extractant for separating rare earth elements.

Preferably, the separation of the rare earth element is specifically extraction separation of yttrium element from a rare earth element mixture.

Compared with the prior art, the invention has the following beneficial effects:

(1) the aminocarboxylic acid provided by the invention can be used for enriching rare earth elements from low-concentration rare earth raw materials, separating and purifying yttrium elements from mixed rare earth raw materials, removing elements such as aluminum, iron, radioactive thorium, radioactive uranium, actinium and the like from the mixed rare earth raw materials, and other fields.

(2) The amino carboxylic acid provided by the invention has good chemical stability, and can tolerate strong acid and strong alkali without decomposition.

Detailed Description

The technical solution of the present invention is further explained by the following embodiments. It should be understood by those skilled in the art that the specific embodiments are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.

Example 1

This example provides a compound I-1 of formula I, wherein the formula of compound I-1 is shown below:

the synthetic route of compound I-1 is shown below:

the synthesis method comprises the following steps:

(1) dissolving N, N-dihydrocarbyldiamine represented by the formula II-1 (12.5g, 0.10mol) in toluene (20mL) to obtain a solution I; dissolving a dodecenyl succinic anhydride compound shown as a formula III-1 (26.6g, 0.10mol) in toluene (30mL) to obtain a solution II;

(2) adding the solution I into the solution II, stirring the solution, raising the temperature to 80 ℃, maintaining the temperature for 2 hours, and after the reaction is finished, concentrating in vacuum to remove the toluene to obtain a compound IV-1.

(3) Dissolving compound IV-1 in sodium borohydride (NaBH)₄-ZnCl₂) Reducing in tetrahydrofuran solution to obtain the compound I-1.

The invention carries out nuclear magnetic resonance analysis on the compound I-1:

¹H NMR(500MHz，CDCl₃)，δ10.49(1H)，5.82(2H)，5.42(1H)，5.34(1H)，5.13(2H)，4.88(2H)，2.56(2H)，2.46(2H)，2.45(1H)，2.40(4H)，2.06(4H)，1.94(2H)，1.33(2H)，1.30(4H)，1.29(2H)，1.26(8H)，0.88(3H)。

¹³C NMR(500MHz，CDCl₃)，6177.3，135.8(2C)，134.9，129.3，116.4(2C)，63.9，59.3(2C)，40.4，31.9，31.4(2C)，29.9，29.7，29.7，29.6，29.6，29.3，28.0，27.0，22.7，14.1。

example 2

This example provides a compound I-2 of formula I, the structural formula of compound I-2 is shown below:

the synthetic route of compound I-2 is shown below:

the synthesis method comprises the following steps:

(1) dissolving N, N-dihydrocarbyldiamine represented by the formula II-2 (15.3g, 0.10mol) in toluene (20mL) to obtain a solution I; dissolving a dodecenylglutaric anhydride compound (28.0g, 0.10mol) shown in formula III-2 in toluene (30mL) to obtain a solution II;

(2) adding the solution I into the solution II, stirring the solution, raising the temperature to 80 ℃, maintaining the temperature for 2 hours, and after the reaction is finished, concentrating in vacuum to remove the toluene to obtain a compound IV-2.

(3) Dissolving compound IV-2 in sodium borohydride (NaBH)₄) Reducing in tetrahydrofuran solution to obtain the compound I-2.

The invention carries out nuclear magnetic resonance analysis on the compound I-2:

¹H NMR(500MHz，CDCl₃)，δ12.01(1H)，5.82(2H)，5.42(1H)，5.34(1H)，5.31(1H)，5.13(2H)，4.88(2H)，4.66(1H)，2.43(4H)，2.33(2H)，2.16(4H)，2.03(1H)，1.94(2H)，1.54(2H)，1.43(4H)，1.33(2H)，1.30(4H)，1.29(2H)，1.26(8H)，0.88(3H)。

¹³C NMR(500MHz，CDCl₃)，δ178.4，136.5(2C)，134.9，129.3，115.8(2C)，94.1，51.5(2C)，36.9，31.9，31.6(2C)，29.9，29.7，29.7，29.6，29.6，29.3，28.9(2C)，28.0，22.7，21.5，21.3，14.1。

example 3

This example provides a compound I-3 of formula I, wherein the formula of compound I-3 is shown below:

the synthetic route of compound I-3 is shown below:

the synthesis method comprises the following steps:

(1) dissolving N, N-dihydrocarbyldiamine represented by formula II-3 (15.3g, 0.10mol) in toluene (20mL) to obtain solution one; dissolving a dodecenylglutaric anhydride compound (28.0g, 0.10mol) shown in formula III-3 in toluene (30mL) to obtain a solution II;

(2) adding the solution I into the solution II, stirring the solution, raising the temperature to 80 ℃, maintaining the temperature for 2 hours, and after the reaction is finished, concentrating in vacuum to remove the toluene to obtain a compound IV-3.

(3) Dissolving compound IV-3 in sodium borohydride (NaBH)₄-ZnCl₂) Reducing in tetrahydrofuran solution to obtain the compound I-3.

The invention carries out nuclear magnetic resonance analysis on the compound I-3:

¹H NMR(500MHz，CDCl₃)，δ12.01(1H)，5.82(2H)，5.42(1H)，5.34(1H)，5.13(2H)，4.88(2H)，2.76(2H)，2.46(2H)，2.33(2H)，2.13(4H)，2.03(1H)，1.94(2H)，1.54(2H)，1.33(2H)，1.30(4H)，1.29(2H)，1.26(8H)，1.11(6H)，0.88(3H)。

¹³C NMR(500MHz，CDCl₃)，6178.4，134.9，133.0(2C)，129.3，115.8(2C)，59.8(2C)，59.2，41.0(2C)，32.2，31.9，31.2，29.9，29.7，29.7，29.6，29.6，29.3，28.0，27.5，22.7，18.1(2C)，14.1。

example 4

This example provides a compound I-4 of formula I, wherein the formula of compound I-4 is shown below:

the synthetic route of compound I-4 is shown below:

the synthesis method comprises the following steps:

(1) dissolving N, N-diisohydrocarbylsecondary amine represented by formula II-4 (26.5g, 0.10mol) in toluene (20mL) to obtain a solution I; dissolving a dodecenylglutaric anhydride compound (28.0g, 0.10mol) shown in formula III-4 in toluene (30mL) to obtain a solution II;

(2) adding the solution I into the solution II, stirring the solution, raising the temperature to 80 ℃, maintaining the temperature for 2 hours, and after the reaction is finished, concentrating in vacuum to remove the toluene to obtain a compound IV-4.

(3) Dissolving compound IV-4 in sodium borohydride (NaBH)₄-ZnCl₂) Reducing in tetrahydrofuran solution to obtain the compound I-4.

The invention carries out nuclear magnetic resonance analysis on the compound I-4:

¹H NMR(500MHz，CDCl₃)，δ12.01(1H)，5.82(2H)，5.42(1H)，5.34(1H)，5.13(2H)，4.88(2H)，2.63(2H)，2.46(2H)，2.33(2H)，2.13(4H)，2.03(1H)，1.94(2H)，1.54(2H)，1.33(2H)，1.31(4H)，1.30(4H)，1.29(4H)，1.29(2H)，1.26(8H)，1.25(8H)，1.06(6H)，0.88(3H)。

¹³C NMR(500MHz，CDCl₃)，δ178.4，139.1(2C)，134.9，129.3，115.7(2C)，61.3(2C)，59.0，34.9(2C)，33.9(2C)，32.2，31.9，31.2，29.9，29.7(2C)，29.7，29.7，29.6(2C)，29.6，29.6，29.3，28.0，27.5，27.1(2C)，22.7，21.0(2C)，14.1。

example 5

This example provides a compound I-5 of formula I, wherein the formula of compound I-5 is shown below:

the synthetic route of compound I-5 is shown below:

the synthesis method comprises the following steps:

(1) dissolving N, N-diisohydrocarbylsecondary amine represented by the formula II-5 (26.5g, 0.10mol) in toluene (20mL) to obtain a solution I; dissolving a hexaalkenylazelaic anhydride compound (25.2g, 0.10mol) shown as formula III-5 in toluene (30mL) to obtain a solution II;

(2) adding the solution I into the solution II, stirring the solution, raising the temperature to 80 ℃, maintaining the temperature for 2 hours, and after the reaction is finished, concentrating in vacuum to remove the toluene to obtain a compound IV-5.

(3) Dissolving compound IV-5 in sodium borohydride (NaBH)₄-ZnCl₂) Reducing in tetrahydrofuran solution to obtain the compound I-5.

The invention carries out nuclear magnetic resonance analysis on the compound I-5:

¹H NMR(500MHz，CDCl₃)，δ11.87(1H)，5.82(2H)，5.20(1H)，5.13(2H)，4.88(2H)，2.63(1H)，2.46(2H)，2.43(2H)，2.21(2H)，2.13(4H)，2.03(1H)，1.94(2H)，1.66(3H)，1.54(2H)，1.46(2H)，1.37(2H)，1.33(4H)，1.31(4H)，1.30(2H)，1.29(4H)，1.26(2H)，1.25(8H)，1.06(3H)，0.95(3H)。

¹³C NMR(500MHz，CDCl₃)，δ178.4，139.1(2C)，138.1，126.3，115.7(2C)，63.8，59.3，55.1，37.1，34.7，34.0，33.9(2C)，30.7，30.4，29.7，29.7，29.7，29.7，29.6(2C)，29.3，29.0，28.6，27.5，27.3，24.7，23.6，20.9，14.2，14.1。

example 6

This example provides a compound I-6 of formula I, wherein the formula of compound I-6 is shown below:

the synthetic route of compound I-6 is shown below:

the synthesis method comprises the following steps:

(1) dissolving N, N-diisohydrocarbylsecondary amine represented by the formula II-6 (18.1g, 0.10mol) in toluene (20mL) to obtain a solution I; dissolving a dodecenyladipic anhydride compound shown as formula II1-6 (18.4g, 0.10mol) in toluene (30mL) to obtain a solution II;

(2) adding the solution I into the solution II, stirring the solution, raising the temperature to 80 ℃, maintaining the temperature for 2 hours, and after the reaction is finished, concentrating in vacuum to remove the toluene to obtain a compound IV-6.

(3) Dissolving compound IV-4 in sodium borohydride (NaBH)₄-ZnCl₂) Reducing in tetrahydrofuran solution to obtain the compound I-6.

The invention carries out nuclear magnetic resonance analysis on the compound I-6:

¹H NMR(500MHz，CDCl₃)，δ11.87(1H)，5.83(1H)，5.82(1H)，5.23(1H)，5.19(1H)，5.13(1H)，4.88(1H)，3.41(1H)，2.43(2H)，2.40(2H)，2.33(2H)，2.13(2H)，1.55(2H)，1.54(2H)，1.37(2H)，1.33(2H)，1.30(1H)，1.29(4H)，1.19(2H)，1.15(1H)，1.01(3H)，0.99(3H)，0.88(3H)。

¹³C NMR(500MHz，CDCl₃)，δ178.4，139.1，131.4，117.7，115.7，72.5，56.6，55.1，40.7，39.6，34.3，33.9，29.8，29.6，29.4，28.7，27.4，26.5，22.5，18.2，17.5，11.9。

example 7

This example provides a compound I-7 of formula I, wherein the formula of compound I-7 is shown below:

the synthetic route of compound I-7 is shown below:

the synthesis method comprises the following steps:

(1) dissolving N, N-docosaoctaenylsecondary amine represented by the formula II-7 (51.8g, 0.10mol) in toluene (20mL) to obtain a solution I; dissolving a decadecenylheptanedioic anhydride compound represented by the formula III-7 (28.0g, 0.10mol) in toluene (30mL) to obtain a solution II;

(2) adding the solution I into the solution II, stirring the solution, raising the temperature to 80 ℃, maintaining the temperature for 2 hours, and after the reaction is finished, concentrating in vacuum to remove the toluene to obtain a compound IV-7.

(3) Dissolving compound IV-7 in sodium borohydride (NaBH)₄) In tetrahydrofuran solution to obtain the compound I-7.

The invention carries out nuclear magnetic resonance analysis on the compound I-7:

¹H NMR(500MHz，CDCl₃)，δ11.87(1H)，5.82(2H)，5.31(1H)，5.20(1H)，5.13(2H)，4.88(2H)，4.66(1H)，2.43(4H)，2.21(2H)，2.13(4H)，2.03(1H)，1.94(2H)，1.66(3H)，1.54(2H)，1.37(4H)，1.33(6H)，1.30(12H)，1.29(10H)，1.27(4H)，1.26(36H)，1.25(4H)，0.88(3H)。

¹³C NMR(500MHz，CDCl₃)，δ178.4，139.1(2C)，138.0，128.9，115.7(2C)，91.9，51.4(2C)，42.1，34.0，33.9(2C)，31.9，30.2，29.7(4C)，29.7，29.7，29.6(18C)，29.6，29.6，29.3(2C)，29.3，28.6(2C)，27.5，27.3(2C)，27.2，25.1，24.2，22.7，21.2，14.1。

example 8

This example provides a compound I-8 of formula I, wherein the formula of compound I-8 is shown below:

the synthetic route of compound I-8 is shown below:

the synthesis method comprises the following steps:

(1) dissolving N, N-dialkynyl secondary amine represented by the formula II-8 (57.0g, 0.10mol) in toluene (20mL) to obtain a solution I; dissolving a dicarbenylglutaric anhydride compound (14.0g, 0.10mol) shown in formula III-8 in toluene (30mL) to obtain a solution II;

(2) adding the solution I into the solution II, stirring the solution, raising the temperature to 80 ℃, maintaining the temperature for 2 hours, and after the reaction is finished, concentrating in vacuum to remove the toluene to obtain a compound IV-8.

(3) Dissolving the compound IV-8 in sodium borohydride-zinc chloride (NaBH)₄-ZnCl₂) Reducing in tetrahydrofuran solution to obtain the compound I-8.

The invention carries out nuclear magnetic resonance analysis on the compound I-8:

¹H NMR(500MHz，CDCl₃)，δ12.01(1H)，5.70(1H)，5.07(1H)，5.03(1H)，2.87(2H)，2.46(4H)，2.46(2H)，2.43(4H)，2.33(2H)，2.03(1H)，1.54(2H)，1.44(4H)，1.36(4H)，1.29(8H)，1.27(4H)，1.26(44H)。

¹³C NMR(500MHz，CDCl₃)，δ178.4，142.2，111.2，83.7(2C)，68.6(2C)，63.7，57.6(2C)，37.8，31.2，29.6(20C)，29.3(2C)，28.7(4C)，28.4(2C)，28.3(2C)，27.3(2C)，27.2，18.4(2C)。

example 9

This example provides a compound I-9 of formula I, wherein the formula of compound I-9 is shown below:

the synthetic route of compound I-9 is shown below:

the synthesis method comprises the following steps:

(1) dissolving N, N-dialkynyl secondary amine represented by the formula II-9 (12.1g, 0.10mol) in toluene (20mL) to obtain a solution I; dissolving a decyl glutaric anhydride compound (25.4g, 0.10mol) shown in formula III-9 in toluene (30mL) to obtain a solution II;

(2) adding the solution I into the solution II, stirring the solution, raising the temperature to 80 ℃, maintaining the temperature for 2 hours, and after the reaction is finished, concentrating in vacuum to remove the toluene to obtain a compound IV-9.

(3) Dissolving the compound IV-9 in sodium borohydride-zinc chloride (NaBH)₄-ZnCl₂) Reducing in tetrahydrofuran solution to obtain the compound I-9.

The invention carries out nuclear magnetic resonance analysis on the compound I-9:¹H NMR(500MHz，CDCl₃)，812.12(1H)，3.77(2H)，2.40(2H)，2.33(2H)，2.27(2H)，1.76(2H)，1.26(12H)，1.25(1H)，1.25(4H)，1.19(2H)，1.07(6H)，0.88(3H)。

¹³C NMR(500MHz，CDCl₃)，δ178.4，85.5(2C)，69.7(2C)，53.8，52.1(2C)，34.0，32.6，31.9，31.2，29.9，29.6，29.6，29.6，29.3，29.2，27.1，22.7，19.3(2C)，14.1。

example 10

This example provides a compound I-10 of formula I, wherein the formula of compound I-10 is shown below:

the synthetic route of compound I-10 is shown below:

the synthesis method comprises the following steps:

(1) dissolving N, N-dichlorododecenylsecondary amine represented by the formula II-10 (41.7g, 0.10mol) in toluene (20mL) to obtain a solution I; dissolving a hexa-carbon alkenyl dianhydride compound shown in formula III-10 (28.0g, 0.10mol) in toluene (30mL) to obtain a solution II;

(2) adding the solution I into the solution II, stirring the solution, raising the temperature to 80 ℃, maintaining the temperature for 2 hours, and after the reaction is finished, concentrating in vacuum to remove the toluene to obtain a compound IV-10.

(3) Dissolving compound IV-10 in sodium borohydride (NaBH)₄) Reducing in tetrahydrofuran solution to obtain the compound I-10.

The invention carries out nuclear magnetic resonance analysis on the compound I-10:

¹H NMR(500MHz，CDCl₃)，δ11.87(1H)，5.71(2H)，5.70(2H)，5.48(1H)，5.43(1H)，5.31(1H)，4.66(1H)，4.05(4H)，2.63(2H)，2.21(2H)，2.16(4H)，2.03(1H)，1.94(2H)，1.54(2H)，1.38(2H)，1.33(6H)，1.31(4H)，1.30(4H)，1.29(6H)，1.26(4H)，1.25(14H)，1.06(6H)，0.93(3H)。

¹³C NMR(500MHz，CDCl₃)，δ178.4，136.2(2C)，133.5，132.4，127.5(2C)，89.4，55.1(2C)，45.3(2C)，38.1，35.2(2C)，34.0，32.9(2C)，32.1，30.0，29.9(2C)，29.7(4C)，29.6(2C)，29.6，29.3，29.0，27.7，27.5，27.0(2C)，27.0，24.7，22.8，21.3(2C)，14.2。

example 11

This example provides a compound I-11 of formula I, wherein the formula of compound I-11 is shown below:

the synthetic route of compound I-11 is shown below:

the synthesis method comprises the following steps:

(1) dissolving N, N-dialkynyl secondary amine represented by the formula II-11 (18.9g, 0.10mol) in toluene (20mL) to obtain a solution one; the decyl glutaric anhydride compound (37.8g, 0.10mol) shown in formula III-11 was dissolved in toluene (30mL) to obtain a solution II;

(2) adding the solution I into the solution II, stirring the solution, raising the temperature to 80 ℃, maintaining the temperature for 2 hours, and after the reaction is finished, concentrating in vacuum to remove the toluene to obtain a compound IV-11.

(3) Dissolving the compound IV-11 in sodium borohydride-zinc chloride (NaBH)₄-ZnCl₂) In tetrahydrofuran solution to obtain the compound I-11.

The invention carries out nuclear magnetic resonance analysis on the compound I-11:

¹H NMR(500MHz，CDCl₃)，δ11.87(1H)，5.48(1H)，5.43(1H)，4.47(2H)，3.68(2H)，2.90(4H)，2.46(2H)，2.21(2H)，2.03(1H)，1.94(2H)，1.54(2H)，1.33(4H)，1.30(4H)，1.29(2H)，1.26(14H)，1.25(6H)，0.88(3H)。

¹³C NMR(500MHz，CDCl₃)，δ178.4，133.5，132.4，85.5(2C)，69.7(2C)，61.6(2C)，61.5，47.0(2C)，38.2，34.0，34.0，33.2，31.9，30.0，29.9，29.7，29.7，29.6，29.6，29.6，29.6，29.3，29.3，29.0，27.2，24.7，22.7，14.1。

comparative example 1

This example provides a compound I-d1 of formula I, wherein the structural formula of compound I-d1 is shown below:

the synthetic route of compound I-d1 is shown below:

the synthesis method comprises the following steps:

(1) dissolving a N, N-dihydrocarbyldiamine of formula II-d1 (12.9g, 0.10mol) in toluene (20mL) to give solution one; dissolving a dodecenyl succinic anhydride compound shown in formula III-d1 (26.6g, 0.10mol) in toluene (30mL) to obtain a solution II;

(2) adding the first solution into the second solution, stirring the solution, raising the temperature to 80 ℃, maintaining the reaction temperature for 2h, and after the reaction is finished, concentrating in vacuum to remove toluene to obtain a compound IV-d 1.

(3) Dissolving the compound IV-d1 in sodium borohydride (NaBH)₄) To obtain the compound I-d 1.

The nuclear magnetic resonance analysis of the compound I-d1 is carried out by the invention:

¹H NMR(500MHz，CDCl₃)，δ10.49(1H)，5.42(1H)，5.34(1H)，2.56(2H)，2.46(2H)，2.45(1H)，2.43(4H)，1.94(2H)，1.37(4H)，1.33(2H)，1.30(4H)，1.29(6H)，1.26(8H)，0.91(6H)，0.88(3H)。

¹³C NMR(500MHz，CDCl₃)，δ177.3，134.9，129.3，51.1(2C)，40.4，34.2，32.3，31.9，30.8(2C)，29.9，29.7，29.7，29.6，29.6，29.3，28.0，22.7，20.4(2C)，14.1，13.8(2C)。

comparative example 2

This example provides a compound I-d2 of formula I, wherein the structural formula of compound I-d2 is shown below:

the synthetic route of compound I-d2 is shown below:

the synthesis method comprises the following steps:

(1) dissolving a N, N-dihydrocarbyldiamine of formula II-d2 (15.7g, 0.10mol) in toluene (20mL) to give solution one; a dodecenylglutaric anhydride compound represented by formula III-d2 (28.0g, 0.10mol) was dissolved in toluene (30mL) to give a second solution;

(2) adding the first solution into the second solution, stirring the solution, raising the temperature to 80 ℃, maintaining the reaction temperature for 2h, and after the reaction is finished, concentrating in vacuum to remove toluene to obtain a compound IV-d 2.

(3) Dissolving the compound IV-d2 in sodium borohydride (NaBH)₄) To obtain the compound I-d 2.

The nuclear magnetic resonance analysis of the compound I-d2 is carried out by the invention:

¹H NMR(500MHz，CDCl₃)，δ10.49(1H)，5.42(1H)，5.34(1H)，5.31(1H)，4.66(1H)，2.56(2H)，2.45(1H)，2.43(4H)，1.94(2H)，1.37(4H)，1.33(2H)，1.30(4H)，1.29(6H)，1.26(8H)，0.91(6H)，0.88(3H)。

¹³C NMR(500MHz，CDCl₃)，δ178.4，134.9，129.3，94.1，51.4(2C)，36.9，31.9，31.5，29.9，29.7，29.7，29.6，29.6，29.5(2C)，29.3，28.3(2C)，28.0，22.7，22.4(2C)，21.3，14.1(2C)，14.1。

comparative example 3

This example provides a compound I-d3 of formula I, wherein the structural formula of compound I-d3 is shown below:

the synthetic route of compound I-d3 is shown below:

the synthesis method can be carried out under the condition of solvent or no solvent, and the synthesis method with the solvent comprises the following steps:

(1) dissolving a N, N-dihydrocarbyldiamine of formula II-d3 (19.9g, 0.10mol) in toluene (20mL) to give solution one; dissolving dodecenylglutaric anhydride compound represented by formula III-d3 (18.4g, 0.10mol) in toluene (30mL) to obtain solution II;

(2) adding the first solution into the second solution, stirring the solution, raising the temperature to 80 ℃, maintaining the reaction temperature for 2h, and after the reaction is finished, concentrating in vacuum to remove toluene to obtain a compound IV-d 3.

(3) Dissolving the compound IV-d3 in sodium borohydride-zinc chloride (NaBH)₄-ZnCl₂) To obtain the compound I-d 3.

The nuclear magnetic resonance analysis of the compound I-d3 is carried out by the invention:

¹HNMR(500MHz，CDCl₃)，δ11.87(1H)，2.63(1H)，2.43(2H)，2.40(2H)，2.33(2H)，1.55(2H)，1.54(2H)，1.46(2H)，1.37(2H)，1.30(1H)，1.29(2H)，1.26(8H)，1.24(2H)，1.19(2H)，1.15(1H)，1.06(3H)，0.99(3H)，0.88(6H)，0.87(3H)。

¹³CNMR(500MHz，CDCl₃)，δ178.4，65.9，56.5，55.0，40.7，39.5，34.3，31.9，29.8，29.6，29.3，29.3，28.6，28.1，27.3，26.5，22.7，22.5，18.2，14.1，13.8，11.9，10.7。

test example 1

Test for enriching rare earth elements

(1) The compounds prepared in the above examples 1 to 11 and comparative example 1 were taken as (4.95, 5.48, 6.89, 6.54, 4.62, 10.09, 8.89, 4.74, 8.81, 7.17 and 4.99, 5.53, 4.84) g by mass, respectively.

(2) Mixing the above extractive agents with 0.96mL of 10.8mol/L sodium hydroxide aqueous solution, and saponifying at 25 deg.C for 5min to obtain saponified extractive agent viscous liquid with saponification degree of 80%;

(3) and (3) mixing the saponified extractant viscous liquid with 2000mL of ionic rare earth leaching solution at room temperature, and enriching for 0.5 h. The ionic rare earth leaching solution comprises the following components: lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium and yttrium, wherein the total molar concentration is 0.00636 mol/L. pH 6.0. Testing the concentration of the rare earth ions in the water phase before and after enrichment, and calculating the total enrichment rate E% of the rare earth ions;

the specific test results (total enrichment of rare earth ions) are shown in table 1:

TABLE 1

Item	Example 1	Example 2	Example 3	Example 4	Example 5	Example 6
							The total enrichment rate E%	97.5	97.8	98.5	97.2	98.9	98.6
Item	Example 7	Example 8	Example 9	Example 10	Example 11
							The total enrichment rate E%	97.5	97.3	96.7	95.6	96.6
Item	Comparative example 1	Comparative example 2	Comparative example 3
							The total enrichment rate E%	94.2	93.3	94.1

The test data in Table 1 show that the enrichment rate of the N, N-dialkyl aminocarboxylic acid prepared by the method is more than 95%, and the N, N-dialkyl aminocarboxylic acid can be used for enriching rare earth elements from low-concentration rare earth raw materials.

Test example 2

Isolated yttrium ion test

(1) The compounds prepared in the above examples 1 to 11 and comparative examples 1 to 3 were prepared into extractant solutions, respectively, by the following specific preparation methods: the extraction agent used in examples 1 to 11 and comparative examples 1 to 3 was (4.95, 5.48, 6.89, 6.54, 4.62, 10.09, 8.89, 4.74, 8.81, 7.17, 4.99, 5.53, 4.84) g in mass, and the toluene used was (20.05, 19.52, 18.11, 18.46, 20.38, 14.91, 16.11, 20.26, 16.19, 17.83, and 20.01, 19.47, 20.16) g in volume, and the two were mixed to prepare an extraction agent solution having an extraction agent concentration of 0.52 mol/L;

(2) mixing each extractant solution with 0.96mL of 10.8mol/L sodium hydroxide aqueous solution, and saponifying at 25 deg.C for 5min to obtain saponified extractant solution with saponification degree of 80%;

(3) 25mL of saponified extractant solution and 25mL of mixed rare earth solution are mixed at room temperature, and the extraction time is 0.5 h. The mixed rare earth solution comprises the following components: lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium and yttrium, wherein the concentration of each element is 0.020 mol/L. The concentrations of rare earth ions in the aqueous phase before and after extraction were measured, and the relative separation coefficient beta of each rare earth ion (Ln) with respect to yttrium ion (Y) was calculated_Ln/Y；

Specific test results (relative separation coefficient beta of rare earth ions (Ln) relative to yttrium ions (Y))_Ln/Y) As shown in table 2:

TABLE 2

As shown in the test data in Table 2, the aminocarboxylic acid provided by the invention can be used for separating and purifying yttrium element from mixed rare earth raw materials.

Test example 3

Stability test

The compound I-1 prepared in the above example 1 was subjected to a stability test, which specifically comprises the following steps: preparing a compound I-1 into an extractant solution, wherein the specific preparation method of the extractant solution comprises the following steps: mixing 39.1g of extractant with 100mL of toluene to prepare an extractant solution with the concentration of 1.0 mol/L; 50mL of the extractant solution is mixed with 50mL of hydrochloric acid solution with the concentration of 6mol/L and stirred, and another 50mL of the extractant solution is mixed with 50mL of sodium hydroxide solution with the concentration of 6mol/L and stirred, the stirring is maintained for 15 days, and then the loss rate of the extractant is tested by nuclear magnetic detection.

The stability test methods for the compounds of examples 2 to 11 and comparative example are the same as those for compound I-1.

The specific test results (loss of extractant in hydrochloric acid medium and liquid caustic medium) are shown in table 3 below:

TABLE 3

As can be seen from the test data in Table 3, the loss rate of the N, N-dihydrocarbylaminocarboxylic acid of the present invention in hydrochloric acid medium is below 0.05%; the loss rate in a liquid caustic soda medium is below 0.06 percent; it is fully demonstrated that the N, N-dihydrocarbylaminocarboxylic acids prepared in accordance with the present invention are excellent in chemical stability and are able to withstand strong acids and strong bases without decomposition.

The applicants state that the present invention is illustrated by the above examples of the N, N-dihydrocarbylaminocarboxylic acids, processes for their preparation and their use, but the invention is not limited to the above examples, which means that the invention must not be construed as being limited thereto. It should be understood by those skilled in the art that any modification of the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.