Tetrabutyl urea production process capable of reducing wastewater quantity

Abstract

The invention discloses a tetrabutylurea production process capable of reducing wastewater quantity, which comprises the following steps: (1) vaporizing di-n-butylamine, introducing the vaporized di-n-butylamine and excessive phosgene into a gas reactor for reaction, condensing after reaction, and discharging hydrogen chloride gas to obtain N, N-dibutyl carbamoyl chloride; (2) adding a sodium hydroxide solution and di-n-butylamine into a reaction container, stirring, dropwise adding the N, N-dibutyl carbamoyl chloride prepared in the step (1), and heating for reaction to obtain a tetrabutyl urea crude product; and the generation of wastewater is reduced. Through the method, the final yield of the tetrabutyl urea is greater than 95%, and the yield is high. The reaction time of the second step is shortened by about one third, and the overall efficiency is improved.

Description

Technical Field

[0001] The invention relates to a tetrabutyl urea production process capable of reducing the amount of waste water, and belongs to the field of chemical production. Background Art

[0002] Tetrabutylurea (C17H36N20) is a widely used organic synthesis intermediate. It can also be used as a solvent extractant and catalyst in organic chemistry, especially as a solvent in the production process of hydrogen peroxide. The methods for synthesizing tetrabutylurea are generally divided into phosgene method and non-phosgene method. Phosgene method includes monophosgene method, diphosgene method, triphosgene method, etc. The diphosgene method and the triphosgene method require the use of solvents in the process of preparing tetrabutyl urea. Although the monophosgene method does not use solvents during the reaction, benzene or toluene must be used for extraction in the subsequent treatment. According to relevant reports, the yield of the finished product is only 80%-85%; non-phosgene methods include the carbon monoxide method, the carbon dioxide method, the acetanilide method, etc.; the carbon monoxide method requires the use of auxiliary reagents such as oxygen or potassium iodide, and the reaction is under pressure, with a low yield and many by-products. The use of dibutyl lithium amide to react with di-n-butylamine and carbon monoxide is difficult to industrialize; the acetanilide method reacts with di-n-butylamine, although the toxicity is low, the product is an equal amount of tetrabutyl urea and by-products.

[0003] Patent CN 102702029 A previously applied by the applicant discloses a preparation process of tetrabutyl urea, which is synthesized in an alkaline organic solvent using di-n-butylamine and phosgene as the main ingredients, and the process steps are as follows: (1) adding di-n-butylamine, phosgene and an organic solvent in a reaction vessel according to a ratio; (2) adjusting the acylation reaction temperature and controlling the acylation reaction time to obtain a crude tetrabutyl urea product; (3) the crude tetrabutyl urea product is allowed to stand, separated, distilled and purified to obtain a final tetrabutyl urea product. Since di-n-butylamine and phosgene will generate two molecules of hydrogen chloride during the reaction, a large amount of 20% sodium hydroxide solution needs to be added during the reaction to neutralize it, which ultimately results in a large amount of alkaline wastewater being generated during the treatment, which adds a lot of cost to the production and subsequent wastewater treatment. Summary of the invention

[0004] In view of the above technical problems, the object of the present invention is to provide another tetrabutyl urea production process which can reduce the amount of wastewater, reduce the use of sodium hydroxide solution, and reduce the generation of wastewater.

[0005] In order to achieve the above object, the technical scheme of the present invention is: a tetrabutyl urea production process capable of reducing the amount of wastewater, characterized in that the process is produced according to the following method: (1) di-n-butylamine is vaporized and then introduced into a gas reactor together with excess phosgene for reaction, and after the reaction is completed, condensation is carried out and hydrogen chloride gas is discharged to obtain N,N-dibutylcarbamoyl chloride;

[0006] (2) Add sodium hydroxide solution and di-n-butylamine into a reaction container, stir, dropwise add N,N-dibutylcarbamoyl chloride prepared in step (1), and heat to react to obtain a crude tetrabutyl urea product.

[0007] The reaction formula is:

[0008]

[0009] After di-n-butylamine is vaporized, it is converted into di-n-butylamine gas, and then passed through a gas reactor together with phosgene, and corrosion-resistant filler (such as ceramic filler, gas reactor is prior art, and no further description is given here) is filled in the gas reactor, phosgene and di-n-butylamine react rapidly in the gas reactor, and generate N, N-dibutylcarbamoyl chloride and hydrogen chloride gas, N, N-dibutylcarbamoyl chloride (liquid state) and hydrogen chloride gas enter receiving tank 4 after condensation in condenser, and hydrogen chloride discharge pipeline is set on receiving tank 4, and after hydrogen chloride and unnecessary phosgene are discharged (can be assisted by vacuum suction, and gas is discharged as much as possible), go to subsequent destruction system processing and recovery. In this step, adopt excessive phosgene, the generation of di-n-butylamine hydrochloride solid can be avoided, thereby blocking filler. On the other hand, phosgene is excessive, thereby only generates N, N-dibutylcarbamoyl chloride (liquid state) and can generate tetrabutyl urea.

[0010] After the gas reaction is completed, one mole of di-n-butylamine and N,N-dibutylcarbamoyl chloride is added to react in a sodium hydroxide environment to generate tetrabutyl urea. At this time, the amount of sodium hydroxide can be halved (because during the gas reaction, one molecule of hydrogen chloride has been discharged in the form of gas, and only one molecule of hydrogen chloride in this step of reaction needs to be neutralized by sodium hydroxide), thereby halving the alkaline wastewater and greatly reducing the amount of wastewater to be treated.

[0011] In the above scheme: in step (1), the molar ratio of di-n-butylamine to phosgene is 1:1-1.5. A slight excess of phosgene is sufficient.

[0012] In the above scheme: in step (1), the reaction temperature of the gas reactor is 160-250° C., which is sufficient to maintain the gas state during the reaction.

[0013] In the above scheme: in step (2), the molar ratio of sodium hydroxide, di-n-butylamine and N,N-dibutylcarbamoyl chloride is 1-1.2:1:1. In principle, the molar ratio of sodium hydroxide to di-n-butylamine can be 1:1, but in the first step, there may be a small amount of hydrogen chloride gas in the N,N-dibutylcarbamoyl chloride liquid that is not discharged, so the sodium hydroxide can be slightly excessive.

[0014] In the above scheme: in step (2), the reaction temperature is 60-100° C. The mass concentration of sodium hydroxide is 20%-30%.

[0015] In the above scheme: in step (2), the reaction time is 3-5h.

[0016] In the above scheme: the crude tetrabutyl urea is subjected to standing, separation, distillation and purification to obtain the final tetrabutyl urea product. This step is a prior art, and reference may be made to the treatment method of CN 102702029 A.

[0017] Beneficial effects: In the prior art, the present invention first uses a gas reaction to allow one molecule of di-n-butylamine to react with phosgene to generate N,N-dibutylcarbamoyl chloride. At this time, the generated hydrogen chloride is a gas, which is discharged in a gaseous form and then destroyed and recovered. There is no need to consume sodium hydroxide solution, which reduces the generation of waste water. Through this method, the final yield of tetrabutyl urea is greater than 95%, and the output is high. In addition, the gas reaction is rapid, the reaction time of the second step is shortened by about one third, and the overall efficiency is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0019] The present invention will be further described below by way of embodiments and in conjunction with the accompanying drawings:

[0020] Embodiment 1, as Figure 1 As shown, the reaction system is Figure 1 As shown, the reaction system includes a di-n-butylamine vaporizer 1, a gas reactor 2, a condenser 3, a receiving tank 4, a reactor 5, and a di-n-butylamine storage tank 6.

[0021] The vaporizer is a prior art. The condenser 3 can be a condenser tube, or other condensation structures including a tube side and a shell side. The gas generated by the reaction of the gas reactor passes through the tube side and is condensed by the condensate of the shell side. The gas reactor 2 is also a prior art, and a filler is arranged inside it, and the filler is an acid-alkali resistant filler, such as ceramics. A heating interlayer is arranged outside, and steam can be passed in for heating.

[0022] The di-n-butylamine storage tank 6 is connected to the di-n-butylamine vaporizer 1 through the di-n-butylamine inlet pipeline, and a metering pump 7 and a valve are arranged on the di-n-butylamine inlet pipeline. The boiling point of di-n-butylamine is 158-160°C, and the heating temperature of the di-n-butylamine vaporizer needs to ensure the vaporization of di-n-butylamine. There are phosgene inlet pipe and di-n-butylamine gas inlet pipe on the top of the gas reactor 2, and the di-n-butylamine gas inlet pipe is connected to the gas outlet pipeline of the di-n-butylamine vaporizer, and there are valves on the phosgene inlet pipe and the di-n-butylamine gas inlet pipe. The bottom of the gas reactor 2 has a discharge port connected to the condenser 3, and the condenser 3 is connected to the receiving tank 4. The receiving tank 4 is provided with a hydrogen chloride discharge pipe, and the hydrogen chloride discharge pipe can be connected to a vacuum pipe to discharge hydrogen chloride as much as possible. Of course, a nitrogen pipeline can also be arranged on the receiving tank 4 to blow out hydrogen chloride through nitrogen.

[0023] The reactor 5 is provided with a sodium hydroxide solution adding pipeline, a di-n-butylamine adding pipeline, and may also be provided with an N, N-dibutylcarbamoyl chloride adding pipeline or a di-n-butylamine dropping funnel. If the N, N-dibutylcarbamoyl chloride adding pipeline is adopted, a flow control valve and a metering pump 7 may be provided on the N, N-dibutylcarbamoyl chloride adding pipeline. Figure 1 N, N-dibutylcarbamoyl chloride is added into the pipeline) to control the addition speed of N, N-dibutylcarbamoyl chloride. Of course, a di-n-butylamine dropping funnel can also be used. When the production volume is small, a dropping funnel can be used. When the production volume is large, a flow control valve is directly used to control the addition speed. A stirring device is provided in the reactor 5, and a heating interlayer is provided outside the reactor 5. A discharge pipe is provided on the reactor 5. The sodium hydroxide solution adding pipeline is connected to the sodium hydroxide storage tank 8, and a metering pump and a valve are provided on the sodium hydroxide solution adding pipeline. The di-n-butylamine adding pipeline of the reactor is connected to the di-n-butylamine storage tank 6, and a metering pump and a valve are provided on the di-n-butylamine adding pipeline.

[0024] Example 2

[0025] The tetrabutyl urea production process capable of reducing the amount of wastewater is prepared according to the following method:

[0026] Di-n-butylamine is vaporized and then introduced into a gas reactor together with excess phosgene for reaction. After the reaction is completed, it is condensed and hydrogen chloride gas is discharged to obtain N,N-dibutylcarbamoyl chloride. The molar ratio of di-n-butylamine to phosgene is 1:1.1. The reaction temperature of the gas reactor is 160°C.

[0027] (2) Add 20% sodium hydroxide solution and di-n-butylamine to a reaction container, stir, heat to 100° C., dropwise add N,N-dibutylcarbamoyl chloride prepared in step (1), and after completion of the dropwise addition, continue heating the reaction for 3 h to obtain a crude tetrabutyl urea product. The molar ratio of sodium hydroxide, di-n-butylamine and N,N-dibutylcarbamoyl chloride is 1.1:1:1.

[0028] (3) After the reaction, the crude tetrabutyl urea was allowed to stand for 30 minutes, the mother liquid water in the lower layer was separated, and the separated crude tetrabutyl urea was distilled at a vacuum degree of -0.096 MPa and a kettle temperature of 220° C. to obtain the final tetrabutyl urea product. The yield was 95.8% and the purity was 99.8%.

[0029] Example 3

[0030] The tetrabutyl urea production process capable of reducing the amount of wastewater is prepared according to the following method:

[0031] Di-n-butylamine is vaporized and then introduced into a gas reactor together with excess phosgene for reaction. After the reaction, it is condensed and hydrogen chloride gas is discharged to obtain N,N-dibutylcarbamoyl chloride. The molar ratio of di-n-butylamine to phosgene is 1:1.5. The reaction temperature of the gas reactor is 250°C (the heating temperature of the gas reactor).

[0032] (2) Add 30% sodium hydroxide solution and di-n-butylamine to a reaction container, stir, heat to 60° C., dropwise add N,N-dibutylcarbamoyl chloride prepared in step (1), and after completion of the dropwise addition, continue heating and reacting for 5 h to obtain a crude tetrabutyl urea product. The molar ratio of sodium hydroxide, di-n-butylamine and N,N-dibutylcarbamoyl chloride is 1.2:1:1.

[0033] (3) After the reaction, the crude tetrabutyl urea was allowed to stand for 30 minutes, the mother liquid water in the lower layer was separated, and the separated crude tetrabutyl urea was distilled at a vacuum degree of -0.096 MPa and a kettle temperature of 220° C. to obtain the final tetrabutyl urea product. The yield was 96.2% and the purity was 99.7%.

[0034] Example 4

[0035] The tetrabutyl urea production process capable of reducing the amount of wastewater is prepared according to the following method:

[0036] Di-n-butylamine is vaporized and then introduced into a gas reactor together with excess phosgene for reaction. After the reaction, it is condensed and hydrogen chloride gas is discharged to obtain N,N-dibutylcarbamoyl chloride. The molar ratio of di-n-butylamine to phosgene is 1:1.2. The reaction temperature of the gas reactor is 200°C (the heating temperature of the gas reactor).

[0037] (2) Add 20% sodium hydroxide solution and di-n-butylamine to a reaction container, stir, heat to 70° C., dropwise add N,N-dibutylcarbamoyl chloride prepared in step (1), and after completion of the dropwise addition, continue heating and reacting for 4 h to obtain a crude tetrabutyl urea product. The molar ratio of sodium hydroxide, di-n-butylamine and N,N-dibutylcarbamoyl chloride is 1.2:1:1.

[0038] (3) After the reaction, the crude tetrabutyl urea was allowed to stand for 30 minutes, the mother liquid water in the lower layer was separated, and the separated crude tetrabutyl urea was distilled at a vacuum degree of -0.096 MPa and a kettle temperature of 220° C. to obtain the final tetrabutyl urea product. The yield was 96.5% and the purity was 99.7%.

[0039] Example 5

[0040] The tetrabutyl urea production process capable of reducing the amount of wastewater is prepared according to the following method:

[0041] Di-n-butylamine is vaporized and then introduced into a gas reactor together with excess phosgene for reaction. After the reaction, it is condensed and hydrogen chloride gas is discharged as much as possible to obtain N,N-dibutylcarbamoyl chloride. The molar ratio of di-n-butylamine to phosgene is 1:1.2, and the reaction temperature of the gas reactor is 200°C (the heating temperature of the gas reactor).

[0042] (2) Add 20% sodium hydroxide solution and di-n-butylamine to a reaction container, stir, heat to 80° C., dropwise add N,N-dibutylcarbamoyl chloride prepared in step (1), and after completion of the dropwise addition, continue heating and reacting for 4 hours to obtain a crude tetrabutyl urea product, wherein the molar ratio of sodium hydroxide, di-n-butylamine and N,N-dibutylcarbamoyl chloride is 1:1:1.

[0043] (3) After the reaction, the crude tetrabutyl urea was allowed to stand for 30 minutes, the mother liquid water in the lower layer was separated, and the separated crude tetrabutyl urea was distilled at a vacuum degree of -0.096 MPa and a kettle temperature of 220° C. to obtain the final tetrabutyl urea product. The yield was 94.8% and the purity was 99.6%.

[0044] The present invention is not limited to the above embodiments. The above-mentioned preparation equipment of salicylonitrile can be other equipment as long as it can produce salicylonitrile. Those skilled in the art can understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principle and purpose of the present invention. The scope of the present invention is defined by the claims and their equivalents.

Claims

1. A tetrabutyl urea production process capable of reducing the amount of wastewater, characterized in that: The production method is as follows: (1) di-n-butylamine is vaporized and then introduced into a gas reactor together with excess phosgene for reaction. After the reaction is completed, condensation is performed and hydrogen chloride gas is discharged to obtain N,N-dibutylcarbamoyl chloride; (2) Add sodium hydroxide solution and di-n-butylamine into a reaction container, stir, dropwise add N,N-dibutylcarbamoyl chloride prepared in step (1), and heat to react to obtain a crude tetrabutyl urea product.

2. The tetrabutyl urea production process capable of reducing the amount of wastewater according to claim 1, characterized in that: In step (1), the molar ratio of di-n-butylamine to phosgene is 1:1-1.

5.

3. The tetrabutyl urea production process capable of reducing the amount of wastewater according to claim 1 or 2, characterized in that: In step (1), the reaction temperature of the gas reactor is 160-250°C.

4. The tetrabutyl urea production process capable of reducing the amount of wastewater according to claim 3, characterized in that: In step (2), the molar ratio of sodium hydroxide, di-n-butylamine and N,N-dibutylcarbamoyl chloride is 1-1.2:1:

1.

5. The tetrabutyl urea production process capable of reducing the amount of wastewater according to claim 4, characterized in that: In step (2), the reaction temperature is 60-100° C., and the mass concentration of sodium hydroxide is 20%-30%.

6. The tetrabutyl urea production process capable of reducing the amount of wastewater according to claim 5, characterized in that: In step (2), the reaction time is 3-5h.

7. The tetrabutyl urea production process capable of reducing the amount of wastewater according to claim 1, characterized in that: The crude tetrabutyl urea is subjected to standing, separation, distillation and purification to obtain the final tetrabutyl urea product.

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