METHOD FOR SYNTHESIZING KETOXIME

Abstract

A method for synthesizing a ketoxime is provided. In a system of an aqueous carbonate solution, a reaction is performed on a ketone, ammonia and hydrogen peroxide by using a titanium-silicon molecular sieve as a catalyst to obtain the ketoxime. Moreover, a reaction progress is judged and an optimal reaction ratio is determined by a real-time monitoring of a pH value in a reaction system during the reaction. In the present invention, by monitoring the pH value in the reaction system, the progress of the reaction is judged, thereby determining the optimal reaction ratio. The pH of the system is further adjusted by an aqueous carbonate solution to increase the reaction velocity and conversion rate of the ammonia.

Claims

1. A method for synthesizing a ketoxime, comprising: performing a reaction on a ketone, ammonia and hydrogen peroxide by using a titanium-silicon molecular sieve as a catalyst to obtain the ketoxime in a system of an aqueous carbonate solution; wherein a reaction progress is judged and an optimal reaction ratio is determined by a real-time monitoring of a pH value in a reaction system during the reaction.

2. The method for synthesizing the ketoxime of claim 1, wherein steps are as follows: gradually introducing a predetermined amount of the ammonia and a non-predetermined amount of the hydrogen peroxide into a three-phase mixed system composed of the ketone, the aqueous carbonate solution and the titanium-silicon molecular sieve, and monitoring the pH value in the reaction system by using an online pH meter; when the pH value returns to an initial pH of the aqueous carbonate solution, stopping dropwise adding the hydrogen peroxide, and after the reaction is completed, putting aside the reaction system for layering, wherein a product extracted from an upper layer of the reaction system is the ketoxime, and the a lower layer of the reaction system is an aqueous phase.

3. The method for synthesizing the ketoxime of claim 1, wherein, the aqueous carbonate solution is an aqueous solution of sodium carbonate or an aqueous solution of sodium bicarbonate.

4. The method for synthesizing the ketoxime of claim 3, wherein, a pH of the aqueous solution of sodium bicarbonate is determined by two factors including a side reaction of the ketone and a destruction of the titanium-silicon molecular sieve.

5. The method for synthesizing the ketoxime of claim 1, wherein, a pH value of the aqueous carbonate solution is 9-12.

6. The method for synthesizing the ketoxime of claim 1, wherein, a mass ratio of the ketone, the ammonia, the titanium-silicon molecular sieve and the aqueous carbonate solution is (80-90):10:2:50.

7. The method for synthesizing the ketoxime of claim 1, wherein, a temperature of the reaction is 50-70 C., and after stopping dropwise adding the hydrogen peroxide, the reaction is kept for 5 hours.

8. The method for synthesizing the ketoxime of claim 2, wherein, the ammonia is introduced simultaneously with the hydrogen peroxide, and a molar ratio of the hydrogen peroxide to the ammonia is maintained at 1.2:1.

9. The method for synthesizing the ketoxime of claim 2, wherein, the aqueous phase is continuously applied after being partially removed by a rotary evaporation.

10. The method for synthesizing the ketoxime of claim 1, wherein, the ketone is selected from ketones having a carbon number of equal to or less than 8.

11. The method for synthesizing the ketoxime of claim 2, wherein, the aqueous carbonate solution is an aqueous solution of sodium carbonate or an aqueous solution of sodium bicarbonate.

12. The method for synthesizing the ketoxime of claim 11, wherein, a pH of the aqueous solution of sodium bicarbonate is determined by two factors including a side reaction of the ketone and a destruction of the titanium-silicon molecular sieve.

13. The method for synthesizing the ketoxime of claim 2, wherein, a pH value of the aqueous carbonate solution is 9-12.

14. The method for synthesizing the ketoxime of claim 2, wherein, a mass ratio of the ketone, the ammonia, the titanium-silicon molecular sieve and the aqueous carbonate solution is (80-90):10:2:50.

15. The method for synthesizing the ketoxime of claim 2, wherein, a temperature of the reaction is 50-70 C., and after stopping dropwise adding the hydrogen peroxide, the reaction is kept for 5 hours.

16. The method for synthesizing the ketoxime of claim 2, wherein, the ketone is selected from ketones having a carbon number of equal to or less than 8.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] FIG. 1 is a gas chromatogram of a product according to embodiment 1;

[0027] FIG. 2 is a gas chromatogram of a product according to comparative example 1; and

[0028] FIG. 3 is a gas chromatogram of a product according to comparative example 2.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] The present invention is further described with reference to the accompanying drawings and embodiments. It should be noted that the following description is only used to explain the present invention and is not intended to limit the content thereof.

[0030] The reaction equation of the present invention is as follows:

##STR00001##

Embodiment 1

[0031] First, 50 g of an aqueous solution of NaHCO.sub.3 having a pH of 10 was prepared and placed in a three-necked flask, then 2 g of a TS-1 catalyst and 80 g of cyclohexanone were successively added, a water bath temperature was 50 C. and a detection electrode of a pH meter was inserted. After starting a stirring, ammonia gas and hydrogen peroxide were simultaneously introduced, wherein an introducing amount of the ammonia gas was 10 g, and an introducing time was 1 hour; the hydrogen peroxide was introduced at a speed where a molar ratio of the hydrogen peroxide to the ammonia solution was maintained to be 1.2:1 until the pH value returned from 12 in the reaction process to the initial pH value of 10. The temperature was kept on for 5 hours, and then the reaction was stopped. After cooling to room temperature, the light phase in the upper layer was extracted, which was the product oxime, and part of the aqueous phase in the lower layer was discharged to remove 70% of water by a rotary evaporation, and then returned to the reaction kettle for recycle. The gas chromatogram of the product is shown in FIG. 1.

Embodiment 2

[0032] First, 50 g of an aqueous solution of NaHCO.sub.3 having a pH of 9 was prepared and placed in a three-necked flask, then 2 g of a TS-1 catalyst and 87 g of acetone were successively added, a water bath temperature was 70 C. and a detection electrode of a pH meter was inserted. After starting a stirring, ammonia gas and hydrogen peroxide were simultaneously introduced, wherein an introducing amount of the ammonia gas was 10 g, and an introducing time was 1 hour; the hydrogen peroxide was introduced at a speed where a molar ratio of the hydrogen peroxide to the ammonia solution was maintained to be 1.2:1 until the pH value returned from 12 in the reaction process to the initial pH value of 9. The temperature was kept on for 5 hours, and then the reaction was stopped. After cooling to room temperature, the light phase in the upper layer was extracted, which was the product oxime, and part of the aqueous phase in the lower layer was discharged to remove 70% of water by a rotary evaporation, and then returned to the reaction kettle for recycle.

Embodiment 3

[0033] First, 50 g of an aqueous solution of Na.sub.2CO.sub.3 having a pH of 12 was prepared and placed in a three-necked flask, then 2 g of a TS-1 catalyst and 90 g of butanone were successively added, a water bath temperature was 50 C., and a detection electrode of a pH meter was inserted. After starting a stirring, ammonia gas and hydrogen peroxide were simultaneously introduced, wherein an introducing amount of the ammonia gas was 10 g, and an introducing time was 1 hour; the hydrogen peroxide was introduced at a speed where a molar ratio of the hydrogen peroxide to the ammonia solution was maintained to be 1.2:1 until the pH value returned from 13 in the reaction process to the initial pH value of 12. The temperature was kept on for 5 hours, and then the reaction was stopped. After cooling to room temperature, the light phase in the upper layer was extracted, which was the product oxime, and part of the aqueous phase in the lower layer was discharged to remove 70% of water by a rotary evaporation, and then returned to the reaction kettle for recycle.

Embodiment 4

[0034] First, 50 g of an aqueous solution of Na.sub.2CO.sub.3 having a pH of 11 was prepared and placed in a three-necked flask, then 2 g of a TS-1 catalyst and 83 g of 2-pentanone were successively added, a water bath temperature was 60 C. and a detection electrode of a pH meter was inserted. After starting a stirring, ammonia gas and hydrogen peroxide were simultaneously introduced, wherein an introducing amount of the ammonia gas was 10 g, and an introducing time was 1 hour; the hydrogen peroxide was introduced at a speed where a molar ratio of the hydrogen peroxide to the ammonia solution was maintained to be 1.2:1 until the pH value returned from 12 in the reaction process to the initial pH value of 11. The temperature was kept on for 5 hours, and then the reaction was stopped. After cooling to room temperature, the light phase in the upper layer was extracted, which was the product oxime, and part of the aqueous phase in the lower layer was discharged to remove 70% of water by a rotary evaporation, and then returned to the reaction kettle for recycle.

Embodiment 5

[0035] First, 50 g of an aqueous solution of Na.sub.2CO.sub.3 having a pH of 11 was prepared and placed in a three-necked flask, then 2 g of a TS-1 catalyst and 80 g of cyclohexanone were successively added a water bath temperature was 50 C. and a detection electrode of a pH meter was inserted. After starting a stirring, ammonia gas and hydrogen peroxide were simultaneously introduced, wherein an introducing amount of the ammonia gas was 10 g, and an introducing time was 1 hour; the hydrogen peroxide was introduced at a speed where a molar ratio of the hydrogen peroxide to the ammonia solution was maintained to be 1.2:1 until the pH value returned from 12 to the initial pH value of 11. The temperature was kept on for 5 hours, and then the reaction was stopped. After cooling to room temperature, the light phase in the upper layer was extracted, which was the product oxime, and part of the aqueous phase in the lower layer was discharged to remove 70% of water by a rotary evaporation and then returned to the reaction kettle for recycle.

[0036] In order to verify the advantages and effectiveness of the method in the present invention over conventional oximation experimental methods, two conventional experimental methods for preparing ketoxime (without adding the aqueous carbonate solution or using a pH meter to monitor the pH of the system) were added as comparative examples.

COMPARATIVE EXAMPLE 1

[0037] 2 g of TS-1 catalyst, 80 g of cyclohexanone and 50 g of water were successively added to a three-necked flask and a water bath temperature was 50 C. After starting a stirring, ammonia gas and hydrogen peroxide were simultaneously introduced, wherein an introducing amount of the ammonia gas was 10 g, an introducing amount of the hydrogen peroxide (27%) was 50 g and an introducing time was 1 hour. The temperature was kept on for 5 hours and then the reaction was stopped. After cooling to room temperature, the light phase in the upper layer was extracted, which was the product cyclohexanone-oxime. The gas chromatogram of the product is shown in FIG. 2.

COMPARATIVE EXAMPLE 2

[0038] 2 g of TS-1 catalyst, 80 g of cyclohexanone and 50 g of water were successively added to a three-necked flask and a water bath temperature was 50 C. After starting a stirring, ammonia gas and hydrogen peroxide were simultaneously introduced, wherein an introducing amount of the ammonia gas was 10 g, an introducing amount of the hydrogen peroxide (27%) was 50 g and an introducing time was 1 hour. The temperature was kept on for 5 hours, and then the reaction was stopped. After cooling to room temperature, the light phase in the upper layer was extracted, which was the product cyclohexanone-oxime. The gas chromatogram of the product is shown in FIG. 3.

TEST EXAMPLE

[0039] 1. Product content test: the products of embodiments 1-5 and comparative examples 1-2 were subjected to quantitative analysis of gas chromatography and the test results are shown in Table 1.

TABLE-US-00001 TABLE 1 Test results of contents of products of various embodiments and comparative examples Item Color Ketone content (%) Oxime content (%) Embodiment 1 Transparent 2.3 95.1 and clarified Embodiment 2 Transparent 2.9 93.0 and clarified Embodiment 3 Transparent 3.1 92.5 and clarified Embodiment 4 Transparent 2.8 93.1 and clarified Embodiment 5 Transparent 7.1 90.1 and clarified Comparative Turbid and 14.3 81.2 example 1 yellowish Comparative Turbid and 10.5 85.1 example 2 yellowish

[0040] 2. Raw material conversion rate calculation: the products oximes of embodiments 1-5 and comparative examples 1-2 were subjected to material balance to obtain conversion rates of the three raw materials and the results are shown in Table 2.

TABLE-US-00002 TABLE 2 Conversion rate data of each embodiment and comparative example Hydrogen Conversion rate Ketone (%) Ammonia (%) peroxide Embodiment 1 95.1 87.0 90.2 Embodiment 2 92.5 82.4 87.6 Embodiment 3 91.8 81.9 88.6 Embodiment 4 90.7 81.6 85.7 Embodiment 5 87.3 78.2 81.5 Comparative example 80.3 71.9 75.8 Comparative example 84.5 73.4 79.7

[0041] The specific embodiments of the present invention have been described with reference to the accompanying drawings above, which are not intended to limit the scope of the present invention. Based on the technical solutions of the present invention, various modifications or variations that can be made by those skilled in the art without any creative effort are still within the scope of the present invention.