SYNTHESIS METHOD OF INDOLE DERIVATIVE CAPABLE OF EFFICIENTLY DEGRADING PERFLUORINATED COMPOUND (PFC) AND THE USE OF THE INDOLE DERIVATIVE

Abstract

A synthesis method of an indole derivative capable of efficiently degrading a perfluorinated compound (PFC) and a use of the indole derivative are provided. The synthesis method includes dissolving an appropriate amount of indole, alkylamine, and formaldehyde in an ethanol solution, conducting a reaction at reflux under suitable conditions for a specified period of time with ZnCl.sub.2 or glacial acetic acid as a catalyst to form a reaction product, vacuum-drying the reaction product, and purifying the reaction product through column chromatography to obtain a novel indole derivative with a hydrophobic alkyl branch. The present indole derivative has some hydrophobicity and a positively charged amino group that can effectively capture PFCs in contaminated water to produce a sub-nanoscale self-assembled aggregate. Hydrated electrons generated by light irradiation can directly attack PFCs in the aggregate without long-distance mass transfer, improving the utilization rate of hydrated electrons and reduces the ratio of fed materials.

Claims

1. A synthesis method of an indole derivative comprising the following steps: dissolving indole, alkylamine, and formaldehyde in an ethanol solution, and conducting a reaction under reflux with ZnCl.sub.2 or glacial acetic acid as a catalyst to form a reaction product; and vacuum-drying the reaction product, and purifying the reaction product through a column chromatography to obtain the indole derivative.

2. The synthesis method of the indole derivative according to claim 1, wherein the alkylamine comprises n-hexadecylamine, n-dodecylamine, n-octylamine, or n-amylamine,

3. The synthesis method of the indole derivative according to claim 1, wherein the indole, the alkylamine, and the formaldehyde are in a molar ratio of 1:0.5:1.

4. The synthesis method of the indole derivative according to claim 1, wherein a molar ratio of the indole to the ZnCl.sub.2 is 1:0.2.

5. The synthesis method of the indole derivative according to claim 1, wherein a molar ratio of the indole to the glacial acetic acid is 1:2.

6. The synthesis method of the indole derivative according to claim 1, wherein the reaction under reflux is conducted at 50° C. to 60° C. for 10 h.

7. A use of the indole derivative synthesized by the synthesis method according to claim 1 in an efficient degradation of a perfluorinated compound (PFC).

8. A method for degrading a PFC with the indole derivative synthesized by the synthesis method according to claim 1 comprising the following steps: under aerobic conditions, adding the indole derivative with isopropyl alcohol (IPA) as a cosolvent directly to a perfluorooctanoic acid (PFOA)-containing aqueous solution to obtain a resulting mixture, thoroughly stirring the resulting mixture for 2 h to obtain a reaction solution with suspended particles, and irradiating the reaction solution with a 36 W low-pressure mercury lamp for an excitation to allow a reaction for 24 h under stirring.

9. The method for degrading the PFS with the indole derivative according to claim 8, wherein a molar concentration of the indole derivative is 5 to 10 times a concentration of the PFOA; the reaction solution has a pH of 4 to 7; and the reaction is conducted at 2555° C.

10. The use according to claim 7, wherein in a synthesis of the indole derivative, the alkylamine comprises n-hexadecylamine, n-dodecylamine, n-octylamine, or n-amylamine.

11. The use according to claim 7, wherein in a synthesis of the indole derivative, the indole, the alkylamine, and the formaldehyde are in a molar ratio of 1:0.5:1.

12. The use according to claim 7, wherein in a synthesis of the indole derivative, a molar ratio of the indole to the ZnCl.sub.2 is 1:0.2.

13. The use according to claim 7, wherein in a synthesis of the indole derivative, a molar ratio of the indole to the glacial acetic acid is 1:2.

14. The use according to claim 7, wherein in a synthesis of the indole derivative, the reaction under reflux is conducted at 50° C. to 60° C. for 10 h.

15. The method according to claim 8, wherein in a synthesis of the indole derivative, the alkylamine comprises n-hexadecylamine, n-dodecylamine, n-octylamine, or n-amylamine.

16. The method according to claim 8, wherein in a synthesis of the indole derivative, the indole, the alkylamine, and the formaldehyde are in a molar ratio of 1:0.5:1.

17. The method according to claim 8, wherein in a synthesis of the indole derivative, a molar ratio of the indole to the ZnCl.sub.2 is 1:0.2.

18. The method according to claim 8, wherein in a synthesis of the indole derivative, a molar ratio of the indole to the glacial acetic acid is 1:2.

19. The method according to claim 8, wherein in a synthesis of the indole derivative, the reaction under reflux is conducted at 50° C. to 60° C. for 10 h.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG. 1 is a schematic diagram illustrating a synthetic route of the indole derivatives;

[0024] FIG. 2 shows a liquid chromatography-mass spectrometry (LC-MS) spectrum of the synthetic indole derivative;

[0025] FIG. 3 shows a nuclear magnetic resonance (NMR) spectrum of the synthetic indole derivative; and

[0026] FIG. 4 shows a defluodnation rate of the synthesized indole derivative in PFOA degradation.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] The present disclosure is further described below with reference to specific examples.

Example 1

[0028] Chemical synthesis of a novel indole derivative:

[0029] 5 g of indole, 5.2 g of n-hexadecylamine, and 3.3 mL of formaldehyde solution with the concentration of 35% were dissolved in 50 mL ethanol. Then, 1.2 g of ZnCl.sub.2 was added as the catalyst. The reaction was lasted for 10 h under reflux condition at 55° C. The resulting reaction system was filtered, rotary-evaporated to 10 mL, and subjected to purification through a silica gel column (200 mesh to 300 mesh). Finally, product A (FIG. 1) with a yield of 60% (equals to 3 g).

Example 2

[0030] Chemical synthesis of a novel indole derivative:

[0031] (1) The same indole, n-hexadecylamine, and formaldehyde as in Example 1 were adopted as raw materials, 5.1 g of glacial acetic acid was adopted as a catalyst, and the same preparation and purification methods were adopted to finally obtain 9.2 g of product A with the yield of 87%.

[0032] (2) Product A was dissolved in IPA at a concentration of 10 mg/L. The purity of product A was determined by liquid chromatography-mass spectrometry (LC-MS). The LC-MS system includes an Agilent 1200 HPLC system, and an Agilent 6120 mass spectrometer equipped with an electrospray ionization (ESI) source. The Waters X-Bridge Shield C18 column (50 mm*4.6 mm*3.5 um) was used for separation. Water (including 0.5% trifluoroacetic acid (TFA)) and acetonitrile (including 0.5% TFA) were adopted as mobile phases for gradient elution at a flow rate of 2 mL/min. The ratio of organic phase increased from 5% to 100% within 1.6 min and held for 1.4 min. The final product A had a purity of >88%. The chromatography-total ion current-mass spectrometry results are shown in FIG. 2.

[0033] (3) Product A was dissolved in dimethyl sulfoxide (DMSO), and a chemical shift of 1 H was measured on a Bruker 400 (400 MHz) NMR spectrometer. An NMR spectrum is shown in FIG. 3.

Example 3

[0034] The synthesis method is also suitable for the synthesis of derivatives with different alkyl chain lengths. The n-hexadecylamine in Example 2 was replaced by an alkylamine of another carbon chain length, including n-dodecylamine (H.sub.2N—C.sub.12H.sub.25), n-octylamine (H.sub.2N—C.sub.8H.sub.17), and n-amylamine (H.sub.2N—O.sub.5H.sub.11). Glacial acetic acid was adopted as the catalyst, The same preparation and purification methods were adopted to synthesize products B, C, and D respectively (FIG. 1), whose yields were each higher than 80%.

Example 4

[0035] A method for efficiently degrading PFOA with the synthetic novel indole derivative:

[0036] (1) The photodegradation performance of product A on PFCs was tested. The synthetic indole derivative (product A) was firstly dissolved into IPA. The resulting mixture was subjected to an ultrasonic treatment for 10 min to completely dissolve the product A to obtain the IPA based stock solution of the product A with fixed concentration. Under aerobic conditions, a certain amount of the IPA based stock solution of the product A was added to a PFOA containing water with a specified concentration. In the final reaction solution (300 mL), the concentration of PFOA was 10 mg/L (24.2 μmol/L) or 5 mg/L (12.1 μmol/L), the concentration of product A was 121 μmol/L, and the concentration of the IPA as a cosolvent was <0.2% (v/v). The pH of the reaction system was adjusted to 7.0 with 0.1 mol/L NaOH and HCl. The prepared solution was magnetically stirred for 2 h to stabilize the self-assembly system. The reaction solution was transferred into a cylindrical shaped photo-reactor (with a diameter of 5 cm and a height of 25 cm) and magnetically stirred. The reaction temperature was controlled at 25° C. by a constant-temperature water bath in the inner and outer interlayers of the vessel. A 36 W low-pressure mercury lamp was inserted into the cylindrical reaction vessel as the light source to initiate the reaction. The reaction control group was set, that is, only 0.2% IPA (without the synthetic indole derivative) was added to a PFOA reaction solution at 10 mg/L or 5 mg/L. As the reaction proceeding, aliquots were sampled every 1 h to 2 h to determine the residual PFOA concentration and the yield of P ion in the reaction solution.

[0037] (2) 5 mL aliquot was collected at each sampling point to determine the residual PFOA concentration and the yield of F.sup.− ion. 2 mL of the sample was transferred to an 8 mL glass bottle, 4 mL of acetonitrile was added, and the resulting mixture was shaken for 30 min to allow extraction, passed through a 0.22 μm PES membrane, and tested by HPLC (Waters 2695). A Waters X-Bridge Shield C18 column (50 mm*4.6 mm*3.5 μm) was used as a separation column, 40% acetonitrile and a 60% ammonium acetate aqueous solution (0.02 mol/L) were adopted as mobile phases, a flow rate was 1 mL/min, a column temperature was 35° C., and a conductivity detector was adopted. The remaining 3 mL of the sample was taken to determine an F.sup.− ion concentration, The sample was diluted 3 times with ultrapure water (UPW) to 9 mL, then passed through a 0.22 μm nylon filter membrane, a P column, an RP column, and a Na column successively, and subjected to IC (ICS-900, DIONEX). An anion-exchange column (DionexIonPac AS23, 4 mm×250 mm) was used as a separation column. NaHCO.sub.3 (1.6 mmol/L) and Na.sub.2CO.sub.3 (10 mmol/L) aqueous solutions were adopted as the mobile phase at a flow rate of 1 mL/min. The suppressor current was set as 51 mA. The PFOA and F.sup.− ion concentrations were quantified by an external standard method.

[0038] The above descriptions are merely preferred examples of the present disclosure, but do not impose restrictions to the present disclosure in any form. Any person skilled in the art can make any simple modifications, equivalent replacements, and improvements to the above examples according to the technical essence of the present disclosure without departing from the scope of the technical solutions of the present disclosure. Such simple modifications, equivalent replacements, and improvements still fall within the protection scope of the technical solutions of the present disclosure.