Preparation method and application of guanidine ionic liquid-functionalized polycaprolactone

Abstract

The present invention discloses a preparation method of guanidine ionic liquid-functionalized polycaprolactone, and the present invention belongs to the technical field of chromatographic analysis. The specific steps of the preparation method of the guanidine ionic liquid-functionalized polycaprolactone include: a bromine substitution step, using polycaprolactone diol as a raw material, and preparing an intermediate II through a bromine substitution reaction; an amination step, preparing an intermediate III by subjecting the intermediate II to an amination reaction; and an ion exchange step, preparing the guanidine ionic liquid-functionalized polycaprolactone through an ion exchange reaction. The guanidine ionic liquid-functionalized polycaprolactone prepared by the present invention is used as a stationary phase for gas chromatography. The guanidine ionic liquid-functionalized polycaprolactone combines the advantages of guanidine ionic liquid functionalization and polycaprolactone, effectively improving the thermal stability of the guanidine ionic liquid-functionalized polycaprolactone and ensuring the effective separation of substances to be separated in gas chromatography.

Description

Technical Field

[0001] The present invention belongs to the technical field of chromatographic analysis, and particularly relates to a preparation method and application of guanidine ionic liquid-functionalized polycaprolactone. Background Art

[0002] Gas chromatography (GC) is a separation and analysis technique with fast analysis speed and high separation efficiency, and is widely used in fields such as petrochemical industry, environment, food, medicine, and physical chemistry. In recent years, the development of high-performance stationary phases to solve the problem of separating complex samples in gas chromatography has become a hot topic.

[0003] Polycaprolactone (PCL) with a semi-crystalline structure is considered the first generation of synthetic aliphatic polyesters. Polycaprolactone has characteristics such as low melting point / glass transition temperature, good film-forming ability, and easy availability from sustainable monomers, fully meeting the requirements of gas chromatography stationary phases. Secondly, due to the presence of polar ester groups in the repeating segments of polycaprolactone, the selectivity of polycaprolactone for polar compounds is higher than that of traditional polysiloxane chromatographic columns; and there are multiple active sites in the molecular structure of polycaprolactone, which can be modified by required derivatization to adjust chromatographic selectivity in practical applications. In summary, polycaprolactone can be applied to the development of high-performance stationary phases. However, polycaprolactone has the technical problem of poor thermal stability (234 °C) existing in polyester and polyether chromatographic stationary phases, and cannot ensure the effective separation of isomeric compounds in gas chromatography, seriously affecting the application of polycaprolactone in gas chromatography stationary phases.

[0004] To solve the above deficiencies, it is necessary to study a preparation method and application of guanidine ionic liquid-functionalized polycaprolactone. Summary of the Invention

[0005] The purpose of the present invention is to provide a preparation method and application of guanidine ionic liquid-functionalized polycaprolactone, prepare a guanidine ionic liquid-functionalized polycaprolactone, and solve the technical problem of poor thermal stability of polycaprolactone as a gas chromatography stationary phase in the prior art. At the same time, the present invention also gives the specific application of guanidine ionic liquid-functionalized polycaprolactone.

[0006] The first aspect of the present invention provides a preparation method of guanidine ionic liquid-functionalized polycaprolactone, including: a bromine substitution step, using polycaprolactone diol as a raw material, and preparing intermediate II through a bromine substitution reaction; an amination step, preparing intermediate III by amination reaction of intermediate II; an ion exchange step, preparing guanidine ionic liquid-functionalized polycaprolactone by ion exchange reaction of intermediate III, and the chemical formula of guanidine ionic liquid-functionalized polycaprolactone is: .

[0007] Among them, the weight average molecular weight of polycaprolactone diol is 2000.

[0008] Optionally, in the bromination step, the process of the bromination reaction is to react polycaprolactone diol with tetrabutylammonium bromide, DAST fluoroborate, 1,8-diazabicyclo[5.4.0]undec-7-ene and dichloromethane at 25 - 30 °C. After the reaction is completed, filter, distill under reduced pressure, add diethyl ether, add concentrated hydrochloric acid, stir at 0 °C, filter, and dry to obtain Intermediate II.

[0009] Optionally, in the amination step, the process of the amination reaction is to heat and react Intermediate II with 2-tert-butyl-1,1,3,3-tetramethylguanidine and acetonitrile under N2 protection. After the reaction is completed, cool down, filter by suction, distill under reduced pressure, add ethyl acetate, add diethyl ether, stir at 0 °C, filter, and dry to obtain Intermediate III.

[0010] Optionally, in the ion exchange step, the process of the ion exchange reaction is to react Intermediate III, lithium bis(trifluoromethanesulfonyl)imide and dichloromethane at 25 - 30 °C. After the reaction is completed, wash with deionized water, add anhydrous magnesium sulfate for drying, filter, and distill under reduced pressure to obtain guanidinium ionic liquid-functionalized polycaprolactone.

[0011] The second aspect of the present invention provides a stationary phase for a capillary gas chromatography column, comprising the guanidinium ionic liquid-functionalized polycaprolactone as described above.

[0012] The third aspect of the present invention provides a capillary gas chromatography column, comprising the stationary phase for a capillary gas chromatography column as described above.

[0013] The fourth aspect of the present invention provides an application of a capillary gas chromatography column. The capillary gas chromatography column as described above is applied to separation, and the substances to be separated include any one of dimethylnaphthalene isomers, trimethylbenzene isomers, dimethylphenol isomers, aliphatic cis-trans isomers, alicyclic cis-trans isomers, substituted benzaldehyde isomers, and halogenated benzene isomers.

[0014] Compared with the prior art, the preparation method of guanidinium ionic liquid-functionalized polycaprolactone provided by the present invention uses polycaprolactone diol as a raw material to prepare a guanidinium ionic liquid-functionalized polycaprolactone, combining the advantages of guanidinium ionic liquid functionalization and polycaprolactone. Due to the excellent properties of guanidinium ionic liquid such as low vapor pressure, adjustable viscosity, high thermal stability and chemical stability, the thermal stability of polycaprolactone is effectively improved. Moreover, the polar ester groups in polycaprolactone and the ionic liquid can enhance the dipole-induced dipole and hydrogen bond interactions with the analyte, while the repeating caprolactone units in polycaprolactone have strong van der Waals forces on the analyte molecules, increasing the difference in the interactions between isomeric compounds, thus ensuring the effective separation of isomeric compounds in gas chromatography. At the same time, the present invention also gives the specific application of guanidinium ionic liquid-functionalized polycaprolactone. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] By referring to the following detailed description with reference to the accompanying drawings, the above and other objects, features, and advantages of the exemplary embodiments of the present invention will become readily understandable. In the drawings, several embodiments of the present invention are shown in an exemplary rather than restrictive manner, and the same or corresponding reference numerals represent the same or corresponding parts, wherein:

[0016] Figure 1 is a flowchart of the steps for preparing guanidinium ionic liquid-functionalized polycaprolactone from polycaprolactone diol according to the present invention;

[0017] Figure 2 is a synthesis flowchart of guanidinium ionic liquid-functionalized polycaprolactone prepared from polycaprolactone diol according to the present invention;

[0018] Figure 3 is a thermogravimetric analysis diagram of guanidinium ionic liquid-functionalized polycaprolactone according to the present invention;

[0019] Figure 4 is a column efficiency diagram measured at 120 °C with n-dodecane as the analyte for the capillary gas chromatography column prepared according to the present invention;

[0020] Figure 5 is a chromatogram of the separation of dimethylnaphthalenes by the capillary gas chromatography column prepared according to the present invention;

[0021] Figure 6 is a chromatogram of the separation of trimethylbenzene isomers by the capillary gas chromatography column prepared according to the present invention;

[0022] Figure 7 is the separation of dimethylphenol isomers by the capillary gas chromatography column prepared according to the present invention;

[0023] Figure 8 is the separation of aliphatic cis-trans isomers by the capillary gas chromatography column prepared according to the present invention;

[0024] Figure 9 is the separation of alicyclic cis-trans isomers by the capillary gas chromatography column prepared according to the present invention;

[0025] Figure 10 is the separation of substituted benzaldehyde isomers by the capillary gas chromatography column prepared according to the present invention;

[0026] Figure 11 is the separation of halogenated benzene isomers by the capillary gas chromatography column prepared according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0027] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present disclosure can be more thoroughly understood and the scope of the present disclosure can be fully conveyed to those skilled in the art. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art.

[0028] It should be noted that, unless otherwise stated, the technical terms or scientific terms used in the present invention should have the ordinary meaning understood by those skilled in the art to which the present invention pertains. The terms "comprising", "including" or any other variant thereof are intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements not only includes those elements but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device. Without further limitation, the elements defined by the statement "comprising..." do not exclude the presence of additional identical elements in the process, method, article or device comprising the said elements.

[0029] As Figure 1 shown, in this embodiment, polycaprolactone diol (Mw = 2000) is subjected to a bromination reaction to obtain Intermediate II. Secondly, Intermediate II is subjected to an amination reaction to obtain Intermediate III. Finally, Intermediate III is subjected to an ion exchange reaction to obtain guanidinium ionic liquid-functionalized polycaprolactone (PCL-GIL). The prepared PCL-GIL has a uniform particle size distribution on the gas chromatography column, which is beneficial to improving the separation effect of the substances to be separated on the gas chromatography column.

[0030] The polycaprolactone diol with a weight average molecular weight of 2000 in this embodiment is a commercially available compound, that is, Mw = 2000. Therefore, for the guanidinium ionic liquid-functionalized polycaprolactone prepared from polycaprolactone diol, the degrees of polymerization n and m in the chemical formula of the guanidinium ionic liquid-functionalized polycaprolactone are unknown. However, the guanidinium ionic liquid-functionalized polycaprolactone can be prepared by using the commercially available polycaprolactone diol with a weight average molecular weight of 2000 according to the synthesis method of this embodiment. The values of the degrees of polymerization n and m do not affect the implementation of the preparation method nor the obtained guanidinium ionic liquid-functionalized polycaprolactone.

[0031] The preparation method of the guanidinium ionic liquid-functionalized polycaprolactone in this embodiment includes: a bromination step, using polycaprolactone diol as a raw material to prepare Intermediate II through a bromination reaction; an amination step, preparing Intermediate III by subjecting Intermediate II to an amination reaction; and an ion exchange step, preparing the guanidinium ionic liquid-functionalized polycaprolactone by subjecting Intermediate III to an ion exchange reaction. The chemical formula of the guanidinium ionic liquid-functionalized polycaprolactone is: 。

[0032] Among them, the weight-average molecular weight of the polycaprolactone diol is 2000.

[0033] In this example, the guanidinium ionic liquid-functionalized polycaprolactone (PCL-GIL) prepared combines the structural characteristics of polycaprolactone (PCL) and the advantages of guanidinium ionic liquid functionalization. Among them, the good film-forming property, low melting point and glass transition temperature of PCL provide the prerequisite for it to become a gas chromatography stationary phase, and the repeated caprolactone unit structure can improve the interaction between the stationary phase and the substances to be separated; secondly, the introduction of guanidinium ionic liquid improves the chromatographic selectivity of the stationary phase. The combination of guanidinium ionic liquid and polycaprolactone endows the stationary phase with stable physical and chemical properties and excellent isomer separation ability.

[0034] In a possible embodiment, in the bromination step, the process of the bromination reaction is to react polycaprolactone diol with tetrabutylammonium bromide, DAST tetrafluoroborate, 1,8-diazabicyclo[5.4.0]undec-7-ene and dichloromethane at 25 - 30 °C. After the reaction is completed, filter, distill under reduced pressure, add diethyl ether, add concentrated hydrochloric acid with a concentration of 37%, stir at 0 °C, filter, and dry to obtain Intermediate II.

[0035] Exemplarily, the reaction temperature of the bromination step in this example is 25 - 30 °C; the reaction time range is 44 - 48 h; the molar ratio of polycaprolactone diol (Mw equal to 2000) to tetrabutylammonium bromide is 1:6 - 6.1; the molar ratio of polycaprolactone diol (Mw = 2000) to DAST tetrafluoroborate is 1:6 - 6.1; the molar ratio of polycaprolactone diol (Mw = 2000) to 1,8-diazabicyclo[5.4.0]undec-7-ene is 1:2 - 2.1; the mass-to-volume ratio of polycaprolactone diol (Mw = 2000), tetrabutylammonium bromide, DAST tetrafluoroborate, 1,8-diazabicyclo[5.4.0]undec-7-ene and dichloromethane is 0.6 g:0.58 - 0.59 g:0.41 - 0.42 g:0.09 - 0.1 g:10 mL.

[0036] In a possible embodiment, in the amination step, the process of the amination reaction is to heat and react Intermediate II with 2-tert-butyl-1,1,3,3-tetramethylguanidine and acetonitrile under N2 protection. After the reaction is completed, cool down, filter by suction, distill under reduced pressure, add ethyl acetate, add diethyl ether, stir at 0 °C, filter, and dry to obtain Intermediate III.

[0037] Exemplarily, in the amination step of this embodiment, the temperature of the heating reaction is 80 - 85 °C; the reaction time range is 72 - 84 h; the temperature is reduced to 25 °C; the mass-to-volume ratio of intermediate II, 2-tert-butyl-1,1,3,3-tetramethylguanidine, and acetonitrile is 0.35 - 0.36 g : 0.180 - 0.185 g : 10 mL.

[0038] In a possible embodiment, in the ion exchange step, the ion exchange reaction process is to react intermediate III, lithium bis(trifluoromethanesulfonyl)imide, and dichloromethane at 25 - 30 °C. After the reaction is completed, it is washed with deionized water, dried by adding anhydrous magnesium sulfate, filtered, and guanidinium ionic liquid-functionalized polycaprolactone is obtained after vacuum distillation.

[0039] Exemplarily, the reaction temperature of the ion exchange step in this embodiment is 25 - 30 °C; the reaction time range is 24 - 36 h; the mass-to-volume ratio of intermediate III, lithium bis(trifluoromethanesulfonyl)imide, and dichloromethane is 0.105 - 0.110 g : 0.100 g : 5 mL.

[0040] In a possible embodiment, the stationary phase of the capillary gas chromatography column includes the guanidinium ionic liquid-functionalized polycaprolactone in this embodiment.

[0041] In a possible embodiment, the capillary gas chromatography column includes the stationary phase of the capillary gas chromatography column in this embodiment.

[0042] In a possible embodiment, this embodiment provides the application of the capillary gas chromatography column. The capillary gas chromatography column is applied to separation, and the substances to be separated include any one of dimethylnaphthalene isomers, trimethylbenzene isomers, dimethylphenol isomers, aliphatic cis-trans isomers, alicyclic cis-trans isomers, substituted benzaldehyde isomers, and halogenated benzene isomers.

[0043] Exemplarily, the capillary gas chromatography column is applied to separate dimethylnaphthalene isomers, and the dimethylnaphthalene isomers include: 2,6-dimethylnaphthalene, 1,3-dimethylnaphthalene, 2,3-dimethylnaphthalene, 1,2-dimethylnaphthalene.

[0044] Exemplarily, the capillary gas chromatography column is applied to separate trimethylbenzene isomers, and the trimethylbenzene isomers include: 1,2,4-trimethylbenzene, 1,2,3-trimethylbenzene, 1,3,5-trimethylbenzene.

[0045] Exemplarily, the capillary gas chromatography column is applied to separate dimethylphenol isomers, and the dimethylphenol isomers include: 2,6-dimethylphenol, 2,5-dimethylphenol, 2,3-dimethylphenol, 3,5-dimethylphenol, 3,4-dimethylphenol.

[0046] Exemplarily, a capillary gas chromatography column is applied to separate aliphatic cis-trans isomers, which include: cis-1,2,3-trichloropropene and trans-1,2,3-trichloropropene, cis-crotonyl chloride and trans-crotonyl chloride, cis-2-butenenitrile and trans-2-butenenitrile, cis-nerolidol and trans-nerolidol, cis-2-butene-1,4-diol and trans-2-butene-1,4-diol, cis-3,7-dimethyl-2,6-octadien-1-ol and trans-3,7-dimethyl-2,6-octadien-1-ol.

[0047] Exemplarily, a capillary gas chromatography column is applied to separate alicyclic cis-trans isomers, which include: cis-1,3-dimethylcyclohexane and trans-1,3-dimethylcyclohexane, cis-1,4-dimethylcyclohexane and trans-1,4-dimethylcyclohexane, cis-2,5-dimethyltetrahydrofuran and trans-2,5-dimethyltetrahydrofuran, cis-2,5-dimethoxytetrahydrofuran and trans-2,5-dimethoxytetrahydrofuran, cis-2-methyl-4-propyl-1,3-oxathiane and trans-2-methyl-4-propyl-1,3-oxathiane, cis-4-methyl-2-(2-methyl-1-propenyl)tetrahydropyran and trans-4-methyl-2-(2-methyl-1-propenyl)tetrahydropyran, cis-4-tert-butylcyclohexanol and trans-4-tert-butylcyclohexanol, and cis-decalin and trans-decalin.

[0048] Exemplarily, a capillary gas chromatography column is applied to separate substituted benzaldehyde isomers, which include: nitrobenzaldehyde isomers: o-nitrobenzaldehyde, m-nitrobenzaldehyde, p-nitrobenzaldehyde; methylbenzaldehyde isomers: o-methylbenzaldehyde, m-methylbenzaldehyde, p-methylbenzaldehyde; cyanobenzaldehyde isomers: o-cyanobenzaldehyde, m-cyanobenzaldehyde, p-cyanobenzaldehyde.

[0049] Exemplarily, a capillary gas chromatography column is applied to separate halogenated benzene isomers, which include:

[0050] Dichlorobenzene isomers: o-dichlorobenzene, m-dichlorobenzene, p-dichlorobenzene; trichlorobenzene isomers: 1,2,3-trichlorobenzene, 1,2,4-trichlorobenzene, 1,3,5-trichlorobenzene;

[0051] Chloronitrobenzene isomers: o-chloronitrobenzene, m-chloronitrobenzene, p-chloronitrobenzene;

[0052] Bromonitrobenzene isomers: o-bromonitrobenzene, m-bromonitrobenzene, p-bromonitrobenzene;

[0053] Dichlorobenzaldehyde isomers: 2,4-dichlorobenzaldehyde, 2,5-dichlorobenzaldehyde, 2,3-dichlorobenzaldehyde, 3,4-dichlorobenzaldehyde, 2,6-dichlorobenzaldehyde.

[0054] In this example, the inner surface of the capillary column was pretreated by the traditional sodium chloride microcrystal deposition method to roughen the chromatographic column. Secondly, the column was prepared by the static coating method to uniformly disperse the stationary liquid on the inner wall of the capillary column. Finally, the coated capillary chromatographic column was aged by the method of programmed temperature rise under nitrogen protection, thus completing the preparation of the PCL-GIL capillary chromatographic column.

[0055] Example 1:

[0056] Bromine substitution step: Add 10 mL of dichloromethane to a 50 mL single-necked flask, add molecular sieve and stir for 1 h. Add 0.6 g (0.3 mmol) of polycaprolactone diol (Mw equal to 2000), 0.585 g (1.81 mmol) of tetrabutylammonium bromide, 0.415 g (1.81 mmol) of DAST fluoroborate, and 0.095 g (0.62 mmol) of 1,8-diazabicyclo[5.4.0]undec-7-ene to the single-necked flask containing dichloromethane, react at 25 °C for 48 h, filter, distill under reduced pressure, add the residue to 10 mL of diethyl ether, add concentrated hydrochloric acid with a concentration of 37%, stir at 0 °C for 4 h, filter, and dry to obtain intermediate II. Intermediate II is a white solid: 0.405 g. 1 H NMR (400 MHz, CDCl3) δ : 4.28 (s, 4H), 4.06 (t, 28H, J J = 6.6 Hz), 3.33 - 3.23 (m, 8H), 2.31 (t, 32H, J J = 7.6 Hz), 1.64 (s), 1.48 - 1.38 (m, 60H), 1.02 (t, 32H, J J = 7.2 Hz). IR (KBr, cm -1 ): 1045.62 (C-O-C), 1107.10 (C-O-C), 1175.35 (C-O), 1239.21 (C-O), 1721.89 (C=O), 2865.97 (CH2), 2943.09 (CH2).

[0057]

[0058] Amination step: 0.355 g (0.167 mmol) of Intermediate II obtained in the bromination step, 0.182 g (1.06 mmol) of 2-tert-butyl-1,1,3,3-tetramethylguanidine, 10 mL of acetonitrile and molecular sieve were added to a 50 mL single-necked flask, and the reaction was carried out at 85 °C for 72 h. After cooling to room temperature, filtration was performed under suction, the filtrate was evaporated to dryness, 2 mL of ethyl acetate was added, and then 10 mL of diethyl ether was added. Stirring was carried out at 0 °C for 1 h, followed by filtration, and the filter cake was dried to obtain Intermediate III, which was a yellow oil: 0.296 g. 1 H NMR (400 MHz, CDCl3) δ : 4.28 (s, 4H), 4.07 (d, 28H, J J = 6.4 Hz), 3.30 (s), 2.97 (s, 24H), 2.32 (d, 32H, J J = 7.2 Hz), 1.67 (s), 1.46 (s, 60H), 1.21 - 0.90 (m, 50H). IR (KBr, cm -1 ): 1045.95 (C - O - C), 1093.78 (C - O - C), 1188.50 (C - O), 1241.00 (C - O), 1567.80 (C = N), 1611.87 (C = N), 1722.27 (C = O), 2869.25 (CH2), 2942.76 (CH2).

[0059]

[0060] Ion exchange step: 0.108 g (0.051 mmol) of Intermediate III obtained in the amination step, 0.100 g (0.348 mmol) of lithium bis(trifluoromethanesulfonyl)imide, and 5 mL of dichloromethane were added to a 50 mL single-necked flask. The reaction was carried out at 25 °C for 24 h, then 3×10 mL of deionized water was added for washing. Anhydrous magnesium sulfate was added to the organic phase for drying, followed by filtration. The filtrate was distilled under reduced pressure to obtain the final product, guanidinium ionic liquid-functionalized polycaprolactone, which was a dark brown oil: 0.105 g. 1 H NMR (400 MHz, CDCl3) δ : 4.28 (s, 4H), 4.07 (d, J J = 6.0 Hz), 3.04 - 3.18 (m, 36H), 2.32 (d, 32H, J J = 7.2 Hz), 1.65 (s), 1.41 (d, 60H, J= 7.4 Hz), 1.02 (d, 50H, J = 6.4 Hz). IR (KBr, cm -1 ): 1044.45 (C - O - C), 1107.38 (C - O - C), 1163.37 (C - O), 1238.47 (C - O), 1568.26 (C = N), 1615.23 (C = N), 1721.87 (C = O), 2864.82 (CH2), 2942.29 (CH2).

[0061] Example 2 - 16: The difference from Example 1 is that the feed amounts in the bromination step, amination step, and ion exchange step are different, and the remaining experimental steps, reaction conditions, and post - treatment processes are the same as those in Example 1, and the specific steps are not elaborated here. Specifically, the feed amounts in the bromination step, amination step, and ion exchange step of each example are shown in Tables 1 to 15 below.

[0062]

[0063]

[0064]

[0065]

[0066]

[0067]

[0068]

[0069]

[0070]

[0071]

[0072]

[0073]

[0074]

[0075]

[0076]

[0077] Examples 17 - 22: Different from Example 1, the reaction times of the bromination step, amination step, and ion exchange step are different. For the remaining experimental operations, reaction conditions, feed ratios, and post-treatment processes, they are the same as those in Example 1 and will not be elaborated here. Specifically, the reaction times of the bromination step, amination step, and ion exchange step in each example can be seen in Tables 16 to 21 below.

[0078]

[0079]

[0080] Examples 23 - 28: Different from Example 1, the reaction temperatures of the bromination step, amination step, and ion exchange step are different. For the remaining experimental operations, reaction conditions, feed ratios, and post-treatment processes, they are the same as those in Example 1 and will not be elaborated here. Specifically, the reaction temperatures of the bromination step, amination step, and ion exchange step in each example can be seen in Tables 22 to 27 below.

[0081]

[0082]

[0083] Example 29: Preparation of the capillary chromatographic column in this example:

[0084] (1) Cut a quartz capillary with a length of 5 m and an inner diameter of 250 μm. First, rinse it with dichloromethane for 10 min, and then age it at 200 °C for 2 - 3 h under nitrogen protection, so that the impurities in the capillary column flow out with nitrogen at high temperature.

[0085] (2) Weigh 1.31 g of ground NaCl powder and dissolve it in 10 mL of anhydrous methanol solution to obtain a saturated sodium chloride methanol solution. Take 6 mL of the saturated solution and add 16 mL of chloroform solution and 0.6 mL of anhydrous methanol solution to obtain a saturated sodium chloride solution.

[0086] (3) Under appropriate nitrogen pressure, press this saturated colloidal solution into the capillary, observe the state of the liquid flowing out of the capillary outlet. When the turbidity of the flowing liquid is the same as that of the original saturated solution, it is considered that the NaCl particles have been completely deposited on the inner wall of the column. Then blow out the solution in the column with nitrogen and recrystallize it at 200 °C for 3 h under nitrogen protection, thereby completing the roughening of the inner surface of the capillary column.

[0087] (4) In this example, the static column preparation method is adopted. Dissolve PCL - GIL in dichloromethane solution to prepare a stationary liquid with a concentration of 0.3% (w / v), and ultrasonically treat it for 5 min to remove the bubbles in the stationary liquid, otherwise the vacuum pumping cannot be carried out.

[0088] (5) Push the stationary liquid into the capillary chromatographic column with a syringe until the stationary liquid fills the entire chromatographic column. Then seal one end of the capillary and connect the other end to a vacuum system. In a constant temperature water bath at 40 °C, let the solvent slowly evaporate, and the stationary liquid can be evenly dispersed on the inner wall of the capillary column.

[0089] (6) Under nitrogen protection, age the coated capillary chromatographic column by means of programmed temperature rise: maintain at 40 °C for 30 min, then increase the temperature to 160 °C at a rate of 1 °C / min and maintain for 7 h, thus completing the aging of the chromatographic column and obtaining a capillary gas chromatographic column.

[0090] Example 30: Example of the separation effect of a capillary chromatographic column

[0091] (1) As Figure 4 shown, use the capillary gas chromatographic column prepared in Example 4 to measure the column efficiency diagram (Golay curve) of n-dodecane. The specific chromatographic conditions are: column oven temperature 120 °C, carrier gas: nitrogen, carrier gas flow rate: 0.3 mL / min, and the lowest theoretical plate height is: 0.25 mm.

[0092] (2) Separate dimethylnaphthalene isomers with the capillary gas chromatographic column prepared in the example

[0093] Figure 5 is the separation of dimethylnaphthalene isomers: 2,6-dimethylnaphthalene, 1,3-dimethylnaphthalene, 2,3-dimethylnaphthalene, 1,2-dimethylnaphthalene by a capillary gas chromatographic column. Chromatographic separation conditions: maintain at 40 °C for 1 min, increase the temperature to 160 °C at a heating rate of 10 °C / min, and the carrier gas flow rate is 0.6 mL / min.

[0094] (3) Separate trimethylbenzene isomers with the capillary gas chromatographic column prepared in the example

[0095] Figure 6 is the separation of trimethylbenzene isomers: 1,2,4-trimethylbenzene, 1,2,3-trimethylbenzene, 1,3,5-trimethylbenzene by a capillary gas chromatographic column. Chromatographic separation conditions: maintain at 40 °C for 1 min, increase the temperature to 160 °C at a heating rate of 10 °C / min, and the carrier gas flow rate is 0.6 mL / min.

[0096] (4) Separate dimethylphenol isomers with the capillary gas chromatographic column prepared in the example

[0097] Figure 7Chromatogram of separating dimethylphenol isomers: 2,6-dimethylphenol, 2,5-dimethylphenol, 2,3-dimethylphenol, 3,5-dimethylphenol, 3,4-dimethylphenol by the capillary gas chromatographic column prepared in the example. The capillary gas chromatographic column prepared in the example can effectively separate dimethylphenol isomers. Chromatographic separation conditions: maintain at 40 °C for 1 min, raise the temperature to 160 °C at a rate of 10 °C / min, and the carrier gas flow rate is 0.6 mL / min.

[0098] (5)Separation of aliphatic cis-trans isomers by the capillary gas chromatographic column prepared in the example

[0099] Figure 8 Chromatogram of separating aliphatic cis-trans isomers by the capillary gas chromatographic column prepared in the example includes: a is cis-1,2,3-trichloropropene and trans-1,2,3-trichloropropene, b is cis-crotonyl chloride and trans-crotonyl chloride, c is cis-2-butenenitrile and trans-2-butenenitrile, d is cis-nerolidol and trans-nerolidol, e is cis-2-butene-1,4-diol and trans-2-butene-1,4-diol, f is cis-3,7-dimethyl-2,6-octadien-1-ol and trans-3,7-dimethyl-2,6-octadien-1-ol. The capillary gas chromatographic column prepared in the example can effectively separate the above isomers. Chromatographic separation conditions: maintain at 40 °C for 1 min, raise the temperature to 160 °C at a rate of 10 °C / min, and the carrier gas flow rate is 0.6 mL / min.

[0100] (6)Separation of alicyclic cis-trans isomers by the capillary gas chromatographic column prepared in the example

[0101] Figure 9 Chromatogram of separating alicyclic cis-trans isomers by the capillary gas chromatographic column prepared in the example includes: a is cis-1,3-dimethylcyclohexane and trans-1,3-dimethylcyclohexane, b is cis-1,4-dimethylcyclohexane and trans-1,4-dimethylcyclohexane, c is cis-2,5-dimethyltetrahydrofuran and trans-2,5-dimethyltetrahydrofuran, d is cis-2,5-dimethoxytetrahydrofuran and trans-2,5-dimethoxytetrahydrofuran, e is cis-2-methyl-4-propyl-1,3-oxathiane and trans-2-methyl-4-propyl-1,3-oxathiane, f is cis-4-methyl-2-(2-methyl-1-propenyl)tetrahydropyran and trans-4-methyl-2-(2-methyl-1-propenyl)tetrahydropyran, g is cis-4-tert-butylcyclohexanol and trans-4-tert-butylcyclohexanol, h is cis-decalin and trans-decalin. The capillary gas chromatographic column prepared in the example can effectively separate the above isomers. Chromatographic separation conditions: maintain at 40 °C for 1 min, raise the temperature to 160 °C at a rate of 10 °C / min, and the carrier gas flow rate is 0.6 mL / min.

[0102] (7) Separation of substituted benzaldehyde isomers by the capillary gas chromatography column prepared in the example

[0103] Substituted benzaldehyde isomers were selected, including nitrobenzaldehyde isomers: o-nitrobenzaldehyde, m-nitrobenzaldehyde, p-nitrobenzaldehyde; methylbenzaldehyde isomers: o-methylbenzaldehyde, m-methylbenzaldehyde, p-methylbenzaldehyde; cyanobenzaldehyde isomers: o-cyanobenzaldehyde, m-cyanobenzaldehyde, p-cyanobenzaldehyde as the analytes. Chromatographic separation conditions: hold at 40 °C for 1 min, increase the temperature to 160 °C at a heating rate of 10 °C / min, and the carrier gas flow rate is 0.6 mL / min.

[0104] Figure 10 is the chromatogram of the separation of substituted benzaldehyde isomers by the capillary gas chromatography column prepared in the example. Among them, a is the nitrobenzaldehyde isomer, b is the methylbenzaldehyde isomer, and c is the cyanobenzaldehyde isomer. As Figure 10 shown, the capillary gas chromatography column prepared in the example can effectively separate the above-mentioned substituted benzaldehyde isomers.

[0105] (8) Separation of halogenated benzene isomers by the capillary gas chromatography column prepared in the example

[0106] A variety of halogenated benzene isomers were selected, including dichlorobenzene isomers: o-dichlorobenzene, m-dichlorobenzene, p-dichlorobenzene; trichlorobenzene isomers: 1,2,3-trichlorobenzene, 1,2,4-trichlorobenzene, 1,3,5-trichlorobenzene; chloronitrobenzene isomers: o-chloronitrobenzene, m-chloronitrobenzene, p-chloronitrobenzene; bromonitrobenzene isomers: o-bromonitrobenzene, m-bromonitrobenzene, p-bromonitrobenzene; dichlorobenzaldehyde isomers: 2,4-dichlorobenzaldehyde, 2,5-dichlorobenzaldehyde, 2,3-dichlorobenzaldehyde, 3,4-dichlorobenzaldehyde, 2,6-dichlorobenzaldehyde as the analytes, and the above samples were separated using the capillary gas chromatography column prepared in the example. Chromatographic separation conditions: hold at 40 °C for 1 min, increase the temperature to 160 °C at a heating rate of 10 °C / min, and the carrier gas flow rate is 0.6 mL / min.

[0107] Figure 11 is the chromatogram of the separation of halogenated benzene isomers by the capillary gas chromatography column prepared in the example. Among them, a is the dichlorobenzene isomer, b is the trichlorobenzene isomer, c is the chloronitrobenzene isomer, d is the bromonitrobenzene isomer, and e is the dichlorobenzaldehyde isomer. The capillary gas chromatography column prepared in the example effectively separated the above-mentioned halogenated benzene isomers.

[0108] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, and all should be covered by the protection scope of the present invention.

Claims

1. A preparation method of guanidine ionic liquid-functionalized polycaprolactone, characterized in that, Comprising: A bromination step, using polycaprolactone diol as a raw material, to prepare intermediate II through a bromination reaction; An amination step, preparing intermediate III by subjecting intermediate II to an amination reaction; An ion exchange step, preparing guanidinium ionic liquid-functionalized polycaprolactone by subjecting intermediate III to an ion exchange reaction. The chemical formula of the guanidinium ionic liquid-functionalized polycaprolactone is: Wherein, the weight-average molecular weight of the polycaprolactone diol is 2000.

2. The preparation method of guanidine ionic liquid-functionalized polycaprolactone according to claim 1, characterized in that: In the bromination step, the process of the bromination reaction is to react polycaprolactone diol with tetrabutylammonium bromide, DAST fluoroborate, 1,8-diazabicyclo[5.4.0]undec-7-ene and dichloromethane at 25 - 30 °C. After the reaction is completed, filter, perform vacuum distillation, add ether, add concentrated hydrochloric acid, stir at 0 °C, filter, and dry to obtain intermediate II.

3. The preparation method of guanidine ionic liquid-functionalized polycaprolactone according to claim 2, characterized in that: In the amination step, the process of the amination reaction is to heat and react intermediate II with 2-tert-butyl-1,1,3,3-tetramethylguanidine and acetonitrile under N2 protection. After the reaction is completed, cool down, perform suction filtration, perform vacuum distillation, add ethyl acetate, add ether, stir at 0 °C, filter, and dry to obtain intermediate III.

4. The preparation method of guanidine ionic liquid-functionalized polycaprolactone according to claim 3, characterized in that: In the ion exchange step, the process of the ion exchange reaction is to react intermediate III, lithium bis(trifluoromethanesulfonyl)imide and dichloromethane at 25 - 30 °C. After the reaction is completed, wash with deionized water, add anhydrous magnesium sulfate for drying, filter, and perform vacuum distillation to obtain guanidinium ionic liquid-functionalized polycaprolactone.

5. A stationary phase of a capillary gas chromatography column, characterized in that, Comprising the guanidinium ionic liquid-functionalized polycaprolactone as described in claim 4.

6. A capillary gas chromatography column, characterized in that, Comprising the stationary phase of the capillary gas chromatography column as described in claim 5.

7. An application of a capillary gas chromatography column, characterized in that, Comprising the application of the capillary gas chromatography column as described in claim 6 for separation. The substances to be separated include any one of dimethylnaphthalene isomers, trimethylbenzene isomers, dimethylphenol isomers, aliphatic cis-trans isomers, alicyclic cis-trans isomers, substituted benzaldehyde isomers, and halogenated benzene isomers.

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