An amino-ion liquid chromatography packing material and its preparation method

Abstract

The present invention relates to the field of chromatography technology, and in particular to an amino ionic liquid chromatographic filler and a preparation method thereof. The present invention combines an ionic liquid structure with an amino chromatographic filler to design a chromatographic filler of formula I. When n=5-9, the chromatographic filler of the present invention has a good separation effect on alkaline substances.

Description

Technical Field

[0001] The invention relates to the technical field of chromatography, and in particular to an amino ionic liquid chromatography filler and a preparation method thereof. Background Art

[0002] Ionic liquids (ILs) are ionic compounds that are liquid at room temperature, a new type of soft medium and functional material, mostly composed of large organic cations and relatively small anions. The good thermal stability, high conductivity and low viscosity of ionic liquids make them resistant to physical changes. Electric current is easy to pass through and there is no vapor pressure, which means that they are not very active. Low viscosity means that they are easy to flow and convenient for reaction synthesis. Not only can they be used as "green solvents" to replace organic volatile solvents, which is more environmentally friendly, but their unique designability can also be adjusted to meet various different needs. They have made important contributions to the development of the fields of catalysis, biotechnology and functional materials. Ionic liquids are also fully used in the field of analytical chemistry. Early exploration of the application of ionic liquids in high performance liquid chromatography (HPLC) mainly focused on the use of ionic liquids as mobile phase additives. Compared with the use as substitutes for organic modifiers in high performance liquid chromatography (HPLC), ionic liquids are more useful as low-concentration additives. When added to aqueous solutions as additives at low concentrations, ionic liquids only become regular salts. Their specific properties: low melting point, high thermal stability and low vapor pressure.

[0003] Ionic liquids (ILs) are organic salts with low melting points, high selectivity and negligible vapor pressure. Due to their unique physicochemical properties, novelty and designability, they are often used as organic functionalized monomers to modify the stationary phase of high performance liquid chromatography (HPLC). Generally, ionic liquids are bonded to silica gel fillers to form a new type of surface confined ionic liquid (SCIL) stationary phase. This new type of chromatographic stationary phase has been applied to a variety of chromatographic modes such as ion exchange chromatography (IEC), reverse phase chromatography (RPLC), hydrophilic interaction chromatography (HILIC) and mixed mode chromatography (MMC). Experiments have shown that the separation on this type of stationary phase often combines multiple separation mechanisms, including hydrophobic interaction, π-π interaction, dipole-dipole interaction, electrostatic interaction, hydrogen bonding and steric hindrance. Rationally utilizing multiple separation mechanisms and improving separation capabilities has become an important research point. The most common SCIL stationary phase is a monocationic ionic liquid modified silica stationary phase, which mainly includes two categories: one is a modified silica stationary phase bonded with imidazolium ionic liquids, and the other is a quinoline ionic liquid modified silica stationary phase.

[0004] CN108160061A discloses a graphene oxide-wrapped silica gel base modified with amino ionic liquid, and the preparation method is as follows: (1) adding silica gel containing silanol groups on the surface to a solvent of toluene, then adding aminopropyltriethoxysilane, heating and refluxing to aminize the silica gel surface, and obtaining aminopropyl silica gel; (2) adding aminopropyl silica gel to a graphene oxide aqueous solution, and reacting to obtain graphene oxide-modified silica gel; (3) preparing an ionic liquid with amino groups: 2-bromoethylamine hydrobromide and 1-methylimidazole are reacted in a solvent of acetonitrile to obtain; (4) reacting the graphene oxide-modified silica gel with an amino ionic liquid in a solvent of methanol, centrifuging, washing with deionized water, and drying to obtain. The graphene oxide-wrapped silica gel base modified with amino ionic liquid of the present invention can be used as a chromatographic stationary phase material for separation and analysis of substances, and has excellent chromatographic performance.

[0005] CN105664888A provides a method for preparing a glycosyl functionalized imidazole type ionic liquid stationary phase, first preparing a methanol homogenate of activated silica gel for standby use, dissolving D-gluconolactone and N-(3-aminopropyl) imidazole in ethanol to obtain N-imidazole propyl glucamide, mixing it with 3-isocyanate propyl trimethoxysilane and dissolving it in ethanol to obtain N-trimethylsilyl propyl-N'-glucamide propyl imidazole + iodide ion solution; then adding silica gel homogenate to the solution, heating to obtain the product N, N'-trimethoxypropyl glucamide imidazole ionic liquid bonded silica gel chromatographic stationary phase. The glycosyl functionalized imidazole type ionic liquid stationary phase chromatographic filler has both the excellent physical structure of the silica gel matrix and the special chromatographic performance of the functionalized glycosyl, has a strong separation performance for biomolecular compounds, and the separation effect is stable. The chromatographic filler has the characteristics of resistance to organic solvents, acid resistance, high temperature resistance, etc., and high separation efficiency.

[0006] CN109926034A discloses a method for preparing a benzimidazole ionic liquid functionalized silica gel liquid chromatography filler. The present invention uses a two-step chemical reaction, firstly uses a chloropropylsilane reagent to perform a silanization reaction on the surface of a fully porous spherical silica gel to obtain chloropropyl silica gel, and then uses benzimidazole (or N-alkylbenzimidazole) to perform an amination reaction on the chloropropyl silica gel to generate benzimidazole ionic liquid functionalized silica gel to obtain a liquid chromatography filler. It is a multi-mode filler, which has both reverse phase and anion exchange chromatographic separation modes, and can separate phenols, anilines, condensed ring compounds, inorganic and organic anions, respectively, and shows good selectivity and stability. Summary of the invention

[0007] The purpose of the present invention is to provide an amino ionic liquid chromatographic filler with good column efficiency and a preparation method thereof.

[0008] The purpose of the present invention is achieved through the following technical solutions.

[0009] An amino ionic liquid chromatographic filler having a structure of formula I:

[0010]

[0011] Among them, n=5-10.

[0012] A method for preparing the amino ionic liquid chromatographic filler is prepared by the following formula:

[0013]

[0014] Wherein n=5-10.

[0015] The following steps are involved:

[0016] S1: reacting formula A, formula B and a base in a solvent to obtain formula C;

[0017] S2: heating formula C, formula D, a base and a catalyst in a solvent to react to obtain formula E;

[0018] S3: reacting the compound of formula E and activated silica gel in a solvent to obtain the compound of formula I.

[0019] In some preferred embodiments, in S1, by mole, formula A:formula B:base=1-1.5:1:1-3.

[0020] In some preferred embodiments, in S1, the solvent is selected from aprotic solvents, specifically at least one selected from dichloromethane, tetrahydrofuran, N,N-dimethylformamide, and ethyl acetate.

[0021] In some preferred embodiments, in S1, the base is selected from at least one of lithium carbonate, sodium carbonate, potassium carbonate, triethylamine, diisopropylethylamine, and pyridine.

[0022] In some preferred embodiments, in said S1, the reaction temperature is 15-35°C.

[0023] In some preferred embodiments, in S2, based on molar proportions, Formula C:Formula D:base:catalyst=1-1.5:1:1-3:0.05-0.1.

[0024] In some preferred embodiments, in S2, the solvent is selected from aprotic solvents, specifically at least one selected from tetrahydrofuran, N,N-dimethylformamide, and ethyl acetate.

[0025] In some preferred embodiments, in S2, the base is selected from at least one of lithium carbonate, sodium carbonate, potassium carbonate, triethylamine, diisopropylethylamine, and pyridine.

[0026] In some preferred embodiments, in S2, the catalyst is selected from at least one of sodium iodide and potassium iodide.

[0027] In some preferred embodiments, in S2, the reaction temperature is 60-100°C.

[0028] In some preferred embodiments, in S3, the ratio of formula E to activated silica gel is 1:1-1.5 in parts by weight.

[0029] In some preferred embodiments, in S3, the solvent is at least one of methanol, ethanol, and isopropanol.

[0030] In some preferred embodiments, the activated silica gel is obtained by activating silica gel with concentrated hydrochloric acid under heating conditions.

[0031] In some preferred embodiments, the concentration of concentrated hydrochloric acid is 4-6 mol / L, and the activation temperature is 80-120°C.

[0032] The advantages of the present invention are:

[0033] 1. The present invention simultaneously derivatizes the silica gel filler with ionic liquid and amino groups, thereby greatly improving the separation column efficiency of the chromatographic filler for alkaline substances. DETAILED DESCRIPTION

[0034] Preparation of Formula C:

[0035]

[0036] 110 mmol of Formula A, 100 mmol of Formula B and 200 mmol of potassium carbonate were mixed in 2000 mL of tetrahydrofuran, and reacted at 25-30° C. After the reaction was completed, the solvent was removed under reduced pressure, and the compound of Formula C was purified by silica gel column chromatography to obtain 88 mmol.

[0037] LC-MS (ESI) m / z: 231.2 [M+H] +

[0038] 1 H NMR(500MHz,DMSO-d6)δ7.39(s,1H),7.29(s,1H),7.12(s,1H),3.60(d,J=1 2.3Hz,1H),3.56(s,9H),3.38(d,J=12.4Hz,1H),2.23(s,2H),2.14(s,2H).

[0039] Preparation of activated silica gel

[0040] 30 g of silica gel was refluxed with 200 mL of 6 mol / L concentrated hydrochloric acid at 100° C. for 5 h, filtered, washed with water until the filtrate was pure, and vacuum dried at 120° C. for 6 h to obtain the activated silica gel;

[0041] Example 1

[0042] An amino ionic liquid chromatographic filler is prepared by the following formula:

[0043]

[0044] Where n=5.

[0045] Formula C 110mmol, Formula D1 100mmol, sodium carbonate 200mmol and sodium iodide 10mmol were mixed in 2000mL N,N-dimethylformamide, and reacted at 60-65°C. After the reaction was completed, the solvent was removed under reduced pressure and purified by silica gel column chromatography to obtain 88mmol of Formula E1 compound.

[0046] LC-MS (ESI) m / z: 316.4 [M] +

[0047] 1 H NMR(500MHz,DMSO-d6)δ8.08(s,2H),7.49(s,1H),5.82(s,2H),3.74(s,2H),3.55(s,9H),3.12(d,J=12.5Hz,1H),3.02( d,J=12.3Hz,1H),2.21(dd,J=23.1,12.5Hz,2H),2.13–2.04(m,2H),1.98(s,2H),1.90(s,2H),1.71(s,2H),1.50(s,2H).

[0048] 5 g of E1 and 5 g of activated silica gel were mixed evenly in 20 mL of methanol, refluxed for 8 hours, filtered, washed with methanol, and dried under vacuum at 80° C. for 12 hours to obtain the amino ionic liquid chromatographic filler I1.

[0049] Example 2

[0050] An amino ionic liquid chromatographic filler is prepared by the following formula:

[0051]

[0052] Wherein n=7, the preparation conditions refer to Example 1.

[0053] E2 83 mmol was obtained.

[0054] LC-MS (ESI) m / z: 344.4 [M] +

[0055] 1 H NMR(500MHz,DMSO-d6)δ8.08(s,1H),7.43(s,0H),5.56(s,1H),3.74(s,1H),3.55(s,4H),3.03(s,1H), 2.10(s,1H),2.03(s,1H),1.97(d,J=10.6Hz,3H),1.78(s,1H),1.57(s,1H),1.52(s,1H),1.47(s,1H).

[0056] Example 3

[0057] An amino ionic liquid chromatographic filler is prepared by the following formula:

[0058]

[0059] In the preparation, n=9, E3 is prepared under the conditions of 6m and ol.

[0060] LC-MS (ESI) m / z: 372.4 [M] +

[0061] 1 H NMR(500MHz,DMSO-d6)δ8.08(s,2H),7.43(s,1H),5.56(s,2H),3.74(s,2H),3.55(s,9H),3.08(s, 2H),2.10(s,2H),2.02(s,2H),1.96(d,J=7.9Hz,5H),1.78(s,2H),1.62–1.55(m,7H),1.52(s,4H).

[0062] Comparative Example 1

[0063] Alkyl-terminated ionic liquid bonded silica filler prepared in Example 1 of CN113385157A

[0064] Comparative Example 2

[0065] An amino ionic liquid chromatographic filler is prepared by the following formula:

[0066]

[0067] Wherein n=3, the preparation conditions refer to Example 1.

[0068] E4 77 mmol was obtained.

[0069] LC-MS (ESI) m / z: 288.6 [M] +

[0070] 1 H NMR(500MHz,DMSO-d6)δ8.08(s,1H),7.58(s,1H),7.49(s,1H),5.10(s,1H),4.92(s,1H),3.69(s,2H),3.56(s,9H),3.02(d,J =12.3Hz,1H),2.92(d,J=12.5Hz,1H),2.48(s,2H),2.23(d,J=12.5Hz,1H),2.10(d,J=12.5Hz,1H),1.99(s,2H),1.95(s,2H).

[0071] Chromatographic column manufacturing

[0072] The products prepared in Examples 1-3 and Comparative Examples 1-2 were prepared into analytical HPLC columns of 150 mm x 4.6 mm using high pressure homogenization technology and setting the column packing pressure to 2500 psi.

[0073] Test Case

[0074] The fillers prepared in Examples 1-3 and Comparative Examples 1-2 of the present invention were used to prepare chromatographic columns, and the performance of the chromatographic columns was evaluated by the separation effects of the chromatographic columns on ephedrine, quinine and theophylline samples.

[0075] Prepare a mixed solution of methanol with a concentration of 10 mg / L of each substance and test it under the following chromatographic conditions:

[0076] Mobile phase: methanol / potassium dihydrogen phosphate buffer (20 mM pH 7.8), 30:70 (v:v);

[0077] Chromatographic time: 30min;

[0078] Detection wavelength: 254nm;

[0079] Column temperature: 40℃.

[0080] Calculate the theoretical plate number and asymmetry factor (As) of the chromatographic column for each substance.

[0081] Theoretical plate number = 5.54x(t R / W h / 2 ) 2 x1000 / L

[0082] where t R :Retention time (min)

[0083] W h / 2 :Half peak width (min)

[0084] L: Column length (mm)

[0085] As=b / a

[0086] a and b are the lengths of the two line segments intercepted by the two sides of the peak and the peak height of the straight line passing through the peak height of 1 / 10h and parallel to the peak bottom.

[0087] The test results are shown in Table 1.

[0088] Table 1 Column test data

[0089]

[0090] It can be seen that in the present invention, when n=5-9, the obtained chromatographic filler has better column efficiency and separation effect for alkaline substances, while when n=3, the effect is poor, indicating that the alkyl chain length has a greater influence on the column efficiency of the final filler. In Comparative Example 1, the filler with alkyl end-capping is not suitable for the separation of alkaline substances.

[0091] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions of the technical solution of the present invention by ordinary technicians in this field do not deviate from the essence and scope of the technical solution of the present invention.

Claims

1. An application of an amino ionic liquid chromatographic filler in the separation of alkaline substances, characterized in that: The alkaline substance is selected from one of ephedrine, quinine and theophylline, and the amino ionic liquid chromatographic filler has a structure of Formula I: Among them, n=5-10.

2. The use according to claim 1, characterized in that: The preparation method of the amino ionic liquid chromatographic filler is prepared by the following formula: Where n=5-10; The following steps are involved: S1: reacting formula A, formula B and a base in a solvent to obtain formula C; S2: heating formula C, formula D, a base and a catalyst in a solvent to react to obtain formula E; S3: reacting the compound of formula E and activated silica gel in a solvent to obtain the compound of formula I.

3. The use according to claim 2, characterized in that: In the S1, based on molar ratio, formula A:formula B:base=1-1.5:1:1-3.

4. The use according to claim 2, characterized in that: In S1 or S2, the solvent is selected from aprotic solvents, specifically at least one selected from dichloromethane, tetrahydrofuran, N,N-dimethylformamide, and ethyl acetate.

5. The use according to claim 2, characterized in that: In S1 or S2, the base is selected from at least one of lithium carbonate, sodium carbonate, potassium carbonate, triethylamine, diisopropylethylamine, and pyridine.

6. The use according to claim 2, characterized in that: In the step S1, the reaction temperature is 15-35°C.

7. The use according to claim 2, characterized in that: In the S2, based on molar proportions, formula C:formula D:base:catalyst=1-1.5:1:1-3:0.05-0.

1.

8. The use according to claim 2, characterized in that: In S2, the catalyst is selected from at least one of sodium iodide and potassium iodide.

9. The use according to claim 2, characterized in that: In the step S2, the reaction temperature is 60-100°C.

10. The use according to claim 2, characterized in that: By weight, formula E: activated silica gel = 1:1-1.5.

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