A continuous and efficient preparation method of N, N - diethylhydroxylamine and its application

Abstract

The present invention discloses a continuous and efficient preparation method of N,N-diethylhydroxylamine and its application. The process includes: mixing triethylamine, 27.5% hydrogen peroxide and sodium bicarbonate in a ratio of 1:1.2:0.05, and reacting at 135 °C with a stirring speed of 90 rpm to prepare triethylamine oxide, and the mass fraction of the obtained triethylamine oxide is 82%; continuously injecting the obtained triethylamine oxide into a tubular reactor and reacting at 150 °C and 1-2 atm, and the injection speed of the triethylamine oxide is 5.74-11.5 g / min to obtain N,N-diethylhydroxylamine. By using the tubular reactor as the reaction medium for the cracking of triethylamine oxide, not only the use of white oil is avoided, but also the clarity of the product is improved and the production efficiency of the product is increased.

Description

[0001] This application is a divisional application of the application with the application number: CN202011210681.6, the application date: November 3, 2020, and the invention name: A preparation method of N, N - diethylhydroxylamine. The applicant is Jining Kangderui Chemical Technology Co., Ltd. Technical Field

[0002] The present invention relates to the technical field of organic chemistry, and more particularly to a continuous and efficient preparation method of N, N - diethylhydroxylamine and its application. Background Art

[0003] N, N - diethylhydroxylamine is mainly used as a polymerization inhibitor in the production and storage of conjugated olefins such as styrene, divinylbenzene, butadiene, isoprene, and acrylonitrile, as well as other monomers containing active bonds. As a polymerization inhibitor, N, N - diethylhydroxylamine has good polymerization inhibition effect, and its polymerization inhibition efficiency is not affected by temperature changes. It not only has high polymerization inhibition efficiency in the liquid phase, but also has good polymerization inhibition performance in the gas phase.

[0004] There are many synthesis methods of N, N - diethylhydroxylamine. From the industrialization perspectives of synthesis cost, raw material price, yield, and product purity, the two most common methods for synthesizing DEHA are diethylamine oxidation method and triethylamine oxidative cleavage method. At present, most domestic and foreign manufacturers mainly use the triethylamine oxidative cleavage method to produce N, N - diethylhydroxylamine. However, the method of preparing N, N - diethylhydroxylamine by oxidizing triethylamine with hydrogen peroxide through oxidation, dehydration, and cleavage has obvious disadvantages such as many reaction steps, complex production process, low total yield, low product purity, and difficulty in completely removing the water contained in the product.

[0005] US3232990 reports a preparation method of N, N - diethylhydroxylamine, which directly uses oxidized triethylamine as the raw material, and drops the oxidized triethylamine into hot white oil for cracking reaction to obtain N, N - diethylhydroxylamine, where white oil is used as the thermal cracking medium for oxidized triethylamine. However, there are the following defects in the cracking process of oxidized triethylamine: (1) Using white oil as the cracking medium, part of the white oil will be brought into the product during the cracking process, affecting the product quality; (2) It is necessary to regularly replace and treat the deteriorated white oil to avoid affecting further use; (3) The reaction is an intermittent process, and the production efficiency is low.

[0006] Therefore, how to provide a continuous and efficient preparation method of high - quality N, N - diethylhydroxylamine is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0007] In view of this, the present invention provides a continuous and efficient preparation method of high - quality N, N - diethylhydroxylamine. By using a tubular reactor as the reaction medium for the cracking of oxidized triethylamine, not only the use of white oil is avoided, but also the clarity of the product is improved, and the production efficiency of the product is increased.

[0008] To achieve the above object, the present invention adopts the following technical solutions:

[0009] A method for preparing N, N - diethylhydroxylamine, comprising the following steps:

[0010] 1) Preparation of raw materials: Triethylamine, hydrogen peroxide with a mass fraction of 27.5%, and a catalyst are used as raw materials to react to prepare triethylamine oxide;

[0011] 2) Continuous cracking: The triethylamine oxide obtained in step 1) is continuously injected into a tubular reactor and reacted at 100 - 200 °C and 1 - 2 atm to obtain N, N - diethylhydroxylamine.

[0012] The technical effects achieved by the above technical solutions are as follows: In the traditional batch reaction, a small amount of white oil will be distilled out together with the product and mixed into the product, affecting the clarity of the product. By using a tubular reactor as the reaction medium for the cracking of triethylamine oxide in the present invention, the use of white oil is avoided, and the clarity of the product is improved; moreover, in the method of the present invention, the raw materials continuously enter the reactor and the product comes out, eliminating the process of regularly cleaning the deteriorated white oil in the batch reactor, thereby achieving the purpose of improving production efficiency.

[0013] As a preferred technical solution of the present invention, in step 1), the mass ratio of the triethylamine, 27.5% hydrogen peroxide, and the catalyst is 1:(1 - 1.5):(0.01 - 0.1).

[0014] As a preferred technical solution of the present invention, in step 1), the reaction temperature is 130 - 140 °C, the stirring speed is 80 - 100 rpm, and the time is 5 - 10 h.

[0015] As a preferred technical solution of the present invention, in step 2), the injection rate of triethylamine oxide is 5.74 - 34.5 g / min.

[0016] As a preferred technical solution of the present invention, in step 2), the residence time of triethylamine oxide in the reactor is 60 - 360 s.

[0017] As a preferred technical solution of the present invention, in step 2), the specification of the tubular reactor is Φ8*1*1000 mm.

[0018] As can be seen from the above technical solutions, compared with the prior art, the present invention discloses a method for preparing N, N - diethylhydroxylamine. This method can continuously prepare N, N - diethylhydroxylamine instead of intermittently. A tubular reactor is a continuous - operation reactor in the shape of a tube with a large length - to - diameter ratio, belonging to a plug - flow reactor. It has high volumetric efficiency. Under suitable reaction conditions of 100 - 200 °C, 1 - 2 atm, and a residence time of 60 - 360 s, it reduces the accumulation of materials in the reaction system, significantly improves the yield and clarity of N, N - diethylhydroxylamine, and increases the production efficiency. Detailed Embodiments

[0019] Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present invention.

[0020] Example 1

[0021] Triethylamine, 27.5% hydrogen peroxide, and sodium bicarbonate were mixed in a ratio of 1:1.2:0.05 and reacted at 135 °C with a stirring speed of 90 rpm to prepare triethylamine oxide. The mass fraction of the obtained triethylamine oxide was 82%.

[0022] Example 2

[0023] The test tubular reactor had a specification of Φ8*1*1000 mm and a reaction pressure of 1 atm. The reactor was heated to an internal temperature of 100 °C with the heat - conducting oil in the jacket, and triethylamine oxide with a mass fraction of 82% was fed in at a speed of 5.74 g / min using a peristaltic pump. The reaction time was 60 s, and samples were analyzed after stabilizing the reaction system for 10 min.

[0024] Example 3

[0025] The test tubular reactor had a specification of Φ8*1*1000 mm and a reaction pressure of 1.5 atm. The reactor was heated to an internal temperature of 200 °C with the heat - conducting oil in the jacket, and triethylamine oxide with a mass fraction of 82% was fed in at a speed of 34.5 g / min using a peristaltic pump. The reaction time was 360 s, and samples were analyzed after stabilizing the reaction system for 10 min.

[0026] Example 4

[0027] The test tubular reactor had a specification of Φ8*1*1000 mm and a reaction pressure of 1 atm. The reactor was heated to an internal temperature of 150 °C with the heat - conducting oil in the jacket, and triethylamine oxide with a mass fraction of 82% was fed in at a speed of 11.5 g / min using a peristaltic pump. The reaction time was 180 s, and samples were analyzed after stabilizing the reaction system for 10 min.

[0028] Example 5

[0029] The tubular reactor for the experiment has a specification of Φ8*1*1000mm, the reaction pressure is 2 atm, the reactor is heated by the heat transfer oil in the jacket to an internal temperature of 150 °C, triethylamine oxide with a mass fraction of 82% is introduced at a speed of 5.74 g / min by a peristaltic pump, the reaction time is 300 s, and samples are taken for analysis after stabilizing the reaction system for 10 min.

[0030] Samples are taken from the cracking reaction products obtained in Examples 2 - 5 and subjected to gas chromatography analysis to calculate the conversion rate % of triethylamine oxide.

[0031] The conversion rate % of triethylamine oxide = (converted triethylamine oxide / total triethylamine oxide) * 100%), the yield % of N,N - diethylhydroxylamine = (conversion rate of triethylamine oxide * selectivity of diethylhydroxylamine) * 100%, and the clarity is tested by visual inspection after diluting diethylhydroxylamine to 20%). The results are shown in Table 1;

[0032] Table 1

[0033]

[0034] As can be seen from Table 1, when using a tubular reactor for the cracking reaction of triethylamine oxide, with appropriate temperature, reaction time and pressure, the conversion rate of triethylamine oxide and the yield of N,N - diethylhydroxylamine can be significantly improved, and the clarity of the product is enhanced.

[0035] Example 6

[0036] Comparative Example 1

[0037] N,N - diethylhydroxylamine is prepared by the method of Example 4, except that the tubular reactor is replaced with a cracking reaction kettle;

[0038] Comparative Example 2

[0039] N,N - diethylhydroxylamine is prepared by the method of Example 4, except that the reaction temperature is controlled at 60 °C;

[0040] Comparative Example 3

[0041] N,N - diethylhydroxylamine is prepared by the method of Example 4, except that the reaction temperature is controlled at 80 °C;

[0042] Comparative Example 4

[0043] N,N - diethylhydroxylamine is prepared by the method of Example 4, except that the reaction temperature is controlled at 220 °C; Comparative Example 5

[0044] N,N - diethylhydroxylamine is prepared by the method of Example 4, except that the reaction temperature is controlled at 250 °C.

[0045] Samples were taken from the cracking reaction products obtained in Comparative Examples 1-5 and subjected to gas chromatography analysis. The conversion rate % of triethylamine oxide, the yield % of N,N-diethylhydroxylamine, and the clarity were calculated, and the results are shown in Table 2;

[0046] Table 2

[0047]

[0048] Example 7

[0049] Comparative Example 6

[0050] N,N-Diethylhydroxylamine was prepared by the method of Example 4, except that the injection rate was 3 g / min; in Comparative Example 7, N,N-Diethylhydroxylamine was prepared by the method of Example 4, except that the injection rate was 5 g / min; Comparative Example 8

[0051] N,N-Diethylhydroxylamine was prepared by the method of Example 4, except that the injection rate was 37 g / min; Comparative Example 9

[0052] N,N-Diethylhydroxylamine was prepared by the method of Example 4, except that the injection rate was 40 g / min.

[0053] Samples were taken from the cracking reaction products obtained in Comparative Examples 6-9 and subjected to gas chromatography analysis. The conversion rate % of triethylamine oxide, the yield % of N,N-diethylhydroxylamine, and the clarity were calculated, and the results are shown in Table 3;

[0054] Table 3

[0055]

[0056]

[0057] As can be seen from Table 3, the injection rate of triethylamine oxide has a significant effect on the conversion rate of triethylamine oxide and the yield of N,N-diethylhydroxylamine. It has been proved that when the injection rate of triethylamine oxide is 5.74 - 34.5 g / min, the yield is relatively high.

[0058] In this specification, the various examples are described in a progressive manner. Each example focuses on the differences from other examples. For the same or similar parts between the examples, reference can be made to each other. For the devices disclosed in the examples, since they correspond to the methods disclosed in the examples, the description is relatively simple, and for the relevant parts, reference can be made to the description in the method section.

[0059] The foregoing description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing N, N - diethylhydroxylamine, characterized in that, It includes the following steps: 1) Preparation of raw materials: Triethylamine, 27.5% hydrogen peroxide and sodium bicarbonate are mixed in a ratio of 1:1.2:0.05, and the mass fraction of the obtained triethylamine oxide is 82%; 2) Continuous cracking: The triethylamine oxide obtained in step 1) is continuously injected into a tubular reactor with a specification of Φ8*1*1000 mm, and the reaction is carried out at 100°C - 200°C and 1 - 2 atm. The injection rate of the triethylamine oxide is 5.74 - 11.5 g / min to obtain N,N-diethylhydroxylamine.

2. The preparation method of N, N - diethylhydroxylamine according to claim 1, characterized in that, In step 2), during the continuous injection process, the residence time of triethylamine oxide in the reactor is 60 - 360 s.

3. The preparation method of N, N - diethylhydroxylamine according to claim 1, characterized in that, In step 1), triethylamine oxide is prepared under the conditions of a reaction temperature of 130 - 140°C and a stirring speed of 80 - 100 rpm.

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