Method for preparing diisocyanate from dihydric alcohol

Abstract

The invention belongs to the technical field of diisocyanate preparation, and particularly relates to a method for preparing diisocyanate from dihydric alcohol. The method for preparing diisocyanate from dihydric alcohol comprises the following steps: reacting dihydric alcohol with phosgene to generate aliphatic alkane diol di (chloroformate); the method comprises the following steps: heating and decomposing aliphatic alkane diol di (chloroformate) into dichloroalkane; enabling the dichloroalkane to react with liquid ammonia to generate aliphatic primary diamine; and reacting the aliphatic primary diamine with phosgene to generate diisocyanate. According to the method, low-cost 1, 4-butanediol or 1, 5-pentanediol is used as a raw material, diisocyanate is prepared through phosgenation, thermal decomposition, ammonification and secondary phosgenation, the technical effects of mild reaction conditions, high yield and reduction of raw material cost are achieved, meanwhile, reaction byproducts can be recycled, and the method is suitable for industrial production. The technical problems that a traditional process depends on an expensive diamine raw material, reaction conditions are harsh, and continuous production is difficult are solved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of diisocyanate preparation, and particularly relates to a method for preparing diisocyanate from dihydric alcohol. BACKGROUND

[0002] Currently, the preparation method of 1,4-butyldiisocyanate mainly adopts phosgene method, that is, phosgene is reacted with 1,4-butanediamine, but the preparation process of 1,4-butanediamine is complex and the cost is high. The synthesis method of bio-based 1,4-butyldiisocyanate disclosed in Chinese patent application CN117603093A cannot realize continuous production. The preparation of 1,5-pentyldiisocyanate also faces the problems of high cost and difficulty in continuous production. SUMMARY

[0003] In view of the above deficiencies of the prior art, the purpose of the present application is to provide a method for preparing diisocyanate from dihydric alcohol, which utilizes 1,4-butanediol or 1,5-pentanediol with lower cost to react with phosgene and liquid ammonia to prepare 1,4-butyldiisocyanate or 1,5-pentyldiisocyanate.

[0004] To achieve the above purpose, the technical solution adopted is:

[0005] The method for preparing diisocyanate from dihydric alcohol comprises the following steps: dihydric alcohol is reacted with phosgene to generate aliphatic chain alkane diol di(chloroformate); the aliphatic chain alkane diol di(chloroformate) is decomposed into dichloroalkane by heating; the dichloroalkane is reacted with liquid ammonia to generate aliphatic primary diamine; and the aliphatic primary diamine is reacted with phosgene to generate diisocyanate.

[0006] Preferably, the dihydric alcohol is 1,4-butanediol or 1,5-pentanediol, and the diisocyanate is 1,4-butyldiisocyanate or 1,5-pentyldiisocyanate.

[0007] Preferably, the method for preparing diisocyanate from dihydric alcohol comprises the following specific steps:

[0008] (1) The dihydric alcohol is dissolved in a solvent and slowly added to liquid phosgene, the reaction temperature is controlled at 5-15℃, the pressure is controlled at 0.05-0.2bar(g), and the dihydric alcohol is reacted with phosgene to generate aliphatic chain alkane diol di(chloroformate);

[0009] (2) After the aliphatic chain alkane diol di(chloroformate) solution in step (1) is warmed to 30-50℃ to remove phosgene and hydrogen chloride, it is heated to 70-85℃, the pressure is controlled at 85-95Kpa(A), and after 4-6 hours of reaction, the aliphatic chain alkane diol di(chloroformate) is removed to generate dichloroalkane by removing carbon dioxide;

[0010] (3) reacting the dichloroalkane solution in step (2) with liquid ammonia at a pressure of 15-25 bar(g) and a temperature of 25-50° C. to produce aliphatic primary diamine and ammonium chloride;

[0011] (4) The ammonium chloride in step (3) is filtered off, and the remaining aliphatic primary diamine solution is reacted with liquid phosgene at a pressure of 0.6-0.7 MPa(g) and a temperature of 50-70° C. for a cold reaction, and then the temperature is raised to 155-175° C. for a thermal reaction to generate diisocyanate.

[0012] More preferably, the solvent in step (1) is chlorobenzene or dichlorobenzene.

[0013] The reaction equations involved are as follows:

[0014] A. HO(CH2) x OH+2COCl2→ClCOO(CH2) x OOCCl+2HCL

[0015] B. ClCOO(CH2) x OOCCl→Cl(CH2) x Cl+CO2

[0016] C, Cl(CH2) x Cl+4NH3→H2N(CH2) x NH2+2NH4Cl

[0017] D. H2N(CH2) x NH2+2COCl2→OCN(CH2) x NCO+4HCl

[0018] x is 4 or 5.

[0019] Preferably, the yield of the 1,4-butanediisocyanate is greater than 70%, and the yield of the 1,5-pentanediisocyanate is greater than 65%.

[0020] Compared with the existing technology, the beneficial effects of the present invention are: the present invention uses low-cost 1,4-butanediol or 1,5-pentanediol as raw materials, and prepares diisocyanate through four steps of phosgenation, thermal decomposition, amination and secondary phosgenation, achieving the technical effects of mild reaction conditions, high yield (65.8%-80.1%), and reduced raw material costs. At the same time, the reaction by-products can be recycled, solving the technical problems of traditional processes that rely on expensive diamine raw materials, have harsh reaction conditions and are difficult to continuously produce. DETAILED DESCRIPTION

[0021] The present invention is described below with reference to examples, which are only used to explain the present invention and are not used to limit the scope of the present invention.

[0022] Example 1

[0023] The reactor was evacuated to remove air therein, and then was filled with nitrogen to control the pressure of the reactor to 0.1 bar(g). 10 kg of chlorobenzene was added into the reactor, and stirring was started at a speed of 180 r / min. Then, 40 kg of liquid phosgene was added, and 50 kg of 1,4-butanediol-chlorobenzene solution containing 10 wt% of 1,4-butanediol was slowly added into the reactor after uniform stirring, and the reaction temperature was controlled at 5°C. After the addition was completed, the stirring was continued for 2 h, and then the reaction liquid was heated to 50°C, and the pressure was controlled at normal pressure. At the same time, nitrogen was introduced into the reaction liquid to remove a small amount of hydrogen chloride and excess phosgene. After the removal of hydrogen chloride and phosgene was completed, the temperature of the reactor was increased to 80°C, and the pressure was controlled at 90 kPa(A) to remove carbon dioxide generated in the reaction. When no carbon dioxide gas was released, the heating was stopped, and at this time, the 1,4-butanediol solution was basically converted into 1,4-dichlorobutane solution. Then, the pressure of the reactor was increased to 15 bar(g), the reaction temperature was controlled at 38-40°C, the stirring speed was 150 r / min, and 8 kg of liquid ammonia was introduced. After the addition was completed, the reaction was continued for 4 h. After the reaction was completed, the pressure of the reactor was gradually reduced to normal pressure, and the temperature was increased to 50°C to remove most of the ammonia. Then, nitrogen was introduced into the reaction liquid to remove the remaining ammonia. After the removal of nitrogen was completed, the reaction liquid was transferred to a filtration system to filter out ammonium chloride, and thus a 1,4-butanediamine-chlorobenzene solution was obtained.

[0024] The reactor was filled with nitrogen, and the reaction pressure was controlled at 0.65 MPa. 10 kg of chlorobenzene was added into the reactor, and then 50 kg of liquid phosgene was added. The stirring speed was controlled at 200 r / min, and then the 1,4-butanediamine-chlorobenzene solution was slowly added into the reactor. The reaction temperature was controlled at 60°C, and after the addition was completed, the temperature was cooled for 1 h. Then, the temperature was increased to 160°C, and the thermal reaction was continued for 2 h. After the reaction was completed, nitrogen was introduced into the reaction liquid to remove a small amount of hydrogen chloride and excess phosgene, and thus a 1,4-butyldiisocyanate-chlorobenzene solution was obtained, and the yield was 71.0%.

[0025] Example 2

[0026] The reactor was evacuated to remove air therein, and then was filled with nitrogen to control the pressure of the reactor to 0.1 bar (g). 10 kg of chlorobenzene was added into the reactor, and stirring was started with the speed of 180 r / min. Then 40 kg of liquid phosgene was added, and 50 kg of 1,4-butanediol-chlorobenzene solution containing 10 wt% of 1,4-butanediol was slowly added into the reactor after uniform stirring, and the reaction temperature was controlled at 10 °C. After the addition was completed, the stirring was continued for 2 h, and then the reaction liquid was heated to 50 °C, and the pressure was controlled at normal pressure. At the same time, nitrogen was introduced into the reaction liquid to remove a small amount of hydrogen chloride and excess phosgene. After the removal of hydrogen chloride and phosgene was completed, the temperature of the reactor was increased to 80 °C, and the pressure was controlled at 90 kPa (A) to remove carbon dioxide generated in the reaction. When no carbon dioxide gas was released, the heating was stopped, and at this time, the 1,4-butanediol solution was basically converted into 1,4-dichlorobutane solution. Then the pressure of the reactor was increased to 15 bar (g), the reaction temperature was controlled at 38-40 °C, the stirring speed was 150 r / min, and 8 kg of liquid ammonia was introduced. After the addition was completed, the reaction was continued for 4 h. After the reaction was completed, the pressure of the reactor was gradually reduced to normal pressure, and the temperature was increased to 50 °C to remove most of the ammonia. Then nitrogen was introduced into the reaction liquid to remove the remaining ammonia. After the removal of nitrogen was completed, the reaction liquid was transferred to a filtration system to filter out ammonium chloride, and thus a 1,4-butanediamine-chlorobenzene solution was obtained.

[0027] The reactor was filled with nitrogen, and the reaction pressure was controlled at 0.65 MPa. 10 kg of chlorobenzene was added into the reactor, and then 50 kg of liquid phosgene was added. The stirring speed was controlled at 200 r / min. Then the 1,4-butanediamine-chlorobenzene solution was slowly added into the reactor, and the reaction temperature was controlled at 55 °C. After the addition was completed, the reaction was cooled for 1 h, and then the temperature was increased to 165 °C for further thermal reaction for 2 h. After the reaction was completed, nitrogen was introduced into the reaction liquid to remove a small amount of hydrogen chloride and excess phosgene, and thus a 1,4-butyldiisocyanate-chlorobenzene solution was obtained, and the yield was 76.2%.

[0028] Example 3

[0029] The reactor was evacuated to remove air therein, and then was filled with nitrogen to control the pressure of the reactor to 0.1 bar (g). 10 kg of chlorobenzene was added into the reactor, and stirring was started with a speed of 200 r / min. Then 50 kg of liquid phosgene was added, and 50 kg of 1,4-butanediol solution containing 10 wt% of 1,4-butanediol was slowly added into the reactor after the solution was stirred uniformly. The reaction temperature was controlled at 10°C. After the addition was completed, the stirring was continued for 2 h, and then the reaction solution was heated to 50°C. The pressure was controlled at normal pressure, and nitrogen was introduced into the reaction solution to remove a small amount of hydrogen chloride and excess phosgene. After the removal of hydrogen chloride and phosgene was completed, the temperature of the reactor was increased to 85°C, and the pressure was controlled at 90 kPa (A) to remove carbon dioxide generated in the reaction. When no carbon dioxide gas was released, the heating was stopped, and at this time, the 1,4-butanediol solution was basically converted into 1,4-dichlorobutane solution. Then the pressure of the reactor was increased to 15 bar (g), the reaction temperature was controlled at 38-40°C, the stirring speed was 150 r / min, and 8 kg of liquid ammonia was introduced. After the introduction was completed, the reaction was continued for 4 h. After the reaction was completed, the pressure of the reactor was gradually decreased to normal pressure, and the temperature was increased to 50°C to remove most of the ammonia. Then nitrogen was introduced into the reaction solution to remove the remaining ammonia. After the removal of nitrogen was completed, the reaction solution was transferred to a filtration system to filter out ammonium chloride, and thus a 1,4-butanediamine-chlorobenzene solution was obtained.

[0030] The reactor was filled with nitrogen, and the reaction pressure was controlled at 0.65 MPa. 10 kg of chlorobenzene was added into the reactor, and then 50 kg of liquid phosgene was added. The stirring speed was controlled at 250 r / min. Then the 1,4-butanediamine-chlorobenzene solution was slowly added into the reactor, and the reaction temperature was controlled at 55°C. After the addition was completed, the reaction was cooled for 1 h, and then the temperature was increased to 170°C to continue the thermal reaction for 2 h. After the reaction was completed, nitrogen was introduced into the reaction solution to remove a small amount of hydrogen chloride and excess phosgene, and thus a 1,4-butyldiisocyanate-chlorobenzene solution was obtained, and the yield was 80.1%.

[0031] Example 4

[0032] The reactor was evacuated to remove air therein, and then was filled with nitrogen to control the pressure of the reactor to 0.1 bar (g). 10 kg of chlorobenzene was added into the reactor, and stirring was started with the speed of 180 r / min. Then 40 kg of liquid phosgene was added, and 40 kg of 1,5-pentanediol-chlorobenzene solution containing 5 wt% of 1,5-pentanediol was slowly added into the reactor after uniform stirring, and the reaction temperature was controlled at 10 °C. After the addition was completed, the stirring was continued for 2 h, and then the reaction liquid was heated to 50 °C, and the pressure was controlled at normal pressure. At the same time, nitrogen was introduced into the reaction liquid to remove a small amount of hydrogen chloride and excess phosgene. After the removal of hydrogen chloride and phosgene was completed, the temperature of the reactor was increased to 80 °C, and the pressure was controlled at 90 kPa (A) to remove carbon dioxide generated in the reaction. When no carbon dioxide gas was released, the heating was stopped, and at this time, the 1,5-pentanediol solution was basically converted into 1,5-dichloropentane solution. Then the pressure of the reactor was increased to 20 bar (g), the reaction temperature was controlled at 40-45 °C, the stirring speed was 180 r / min, and 5 kg of liquid ammonia was introduced. After the addition was completed, the reaction was continued for 4 h. After the reaction was completed, the pressure of the reactor was gradually decreased to normal pressure, and the temperature was increased to 50 °C to remove most of the ammonia. Then nitrogen was introduced into the reaction liquid to remove the remaining ammonia. After the removal of nitrogen was completed, the reaction liquid was transferred to a filtration system to filter out ammonium chloride, and thus a 1,5-pentanediamine-chlorobenzene solution was obtained.

[0033] The reactor was filled with nitrogen, and the reaction pressure was controlled at 0.65 MPa. 10 kg of chlorobenzene was added into the reactor, and then 50 kg of liquid phosgene was added. The stirring speed was controlled at 200 r / min, and then the 1,5-pentanediamine-chlorobenzene solution was slowly added into the reactor. The reaction temperature was controlled at 60 °C. After the addition was completed, the reaction was cooled for 1 h, and then the temperature was increased to 160 °C to continue the thermal reaction for 2 h. After the reaction was completed, nitrogen was introduced into the reaction liquid to remove a small amount of hydrogen chloride and excess phosgene, and thus a 1,5-pentanediisocyanate-chlorobenzene solution was obtained, and the yield was 65.8%.

[0034] Example 5

[0035] The reactor is vacuumed to remove air in it, and then filled with nitrogen to control the pressure of the reactor to 0.1 bar(g). 10 kg of chlorobenzene is added into the reactor, and the stirring is started with the speed of 180 r / min. Then 40 kg of liquid phosgene is added, and after the stirring is uniform, 40 kg of 1,5-pentanediol-chlorobenzene solution with 5 wt% of 1,5-pentanediol is slowly added into the reactor, and the reaction temperature is controlled to be 10℃. After the addition is completed, the stirring is kept for 2 h, and then the reaction solution is heated to 50℃, and the pressure is controlled to be normal pressure. At the same time, the reaction solution is blown with nitrogen to remove a small amount of hydrogen chloride and excess phosgene. After the removal of hydrogen chloride and phosgene is completed, the temperature of the reactor is increased to 80℃, and the pressure is controlled to be 90 kPa(A) to remove carbon dioxide generated in the reaction. When no carbon dioxide gas is discharged, the heating is stopped, and at this time, the 1,5-pentanediol solution is basically converted into 1,5-dichloropentane solution. Then the pressure of the reactor is increased to 20 bar(g), the reaction temperature is controlled to be 40-45℃, the stirring speed is 180 r / min, and 5 kg of liquid ammonia is blown in. After the addition is completed, the reaction is carried out for 4 h. After the reaction is completed, the pressure of the reactor is gradually reduced to normal pressure, and the temperature is increased to 50℃ to remove most of the ammonia. Then the reaction solution is blown with nitrogen to remove the remaining ammonia. After the nitrogen removal is completed, the reaction solution is transferred to a filtration system to filter out ammonium chloride, and 1,5-pentanediamine-chlorobenzene solution is obtained.

[0036] The reactor is filled with nitrogen, and the reaction pressure is controlled to be 0.65 MPa. 10 kg of chlorobenzene is added into the reactor, and then 50 kg of liquid phosgene is added. The stirring speed is controlled to be 250 r / min. Then 1,5-pentanediamine-chlorobenzene solution is slowly added into the reactor, and the reaction temperature is controlled to be 60℃. After the addition is completed, the reaction is cooled for 1 h. Then the temperature is increased to 175℃, and the thermal reaction is continued for 2 h. After the reaction is completed, the reaction solution is blown with nitrogen to remove a small amount of hydrogen chloride and excess phosgene, and 1,5-pentane diisocyanate-chlorobenzene solution is obtained with the yield of 77.3%.

[0037] The above only describes the preferred embodiments of the present application, and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing diisocyanate from diols, characterized in that: The following steps are involved: The diol reacts with phosgene to form aliphatic alkanediol di(chloroformate); the aliphatic alkanediol di(chloroformate) is decomposed into dichloroalkanes upon heating; the dichloroalkanes react with liquid ammonia to form aliphatic primary diamines; the aliphatic primary diamines react with phosgene to form diisocyanates.

2. The method for preparing diisocyanate from diol according to claim 1, wherein: The diol is 1,4-butanediol or 1,5-pentanediol, and the corresponding diisocyanate is 1,4-butanediisocyanate or 1,5-pentanediisocyanate.

3. The method for preparing diisocyanate from diol according to claim 1, characterized in that: The specific steps include: (1) Dissolve the diol in a solvent and slowly add it dropwise to the liquid phosgene. Control the reaction temperature to 5-15°C and the pressure to 0.05-0.2 bar(g). The diol reacts with the phosgene to form aliphatic alkanediol di(chloroformate). (2) heating the aliphatic alkanediol bis(chloroformate) solution in step (1) to 30-50° C. to remove phosgene and hydrogen chloride, then heating to 70-85° C. and controlling the pressure to 85-95 kPa(A). After 4-6 hours of reaction, the aliphatic alkanediol bis(chloroformate) removes carbon dioxide to generate dichloroalkanes; (3) reacting the dichloroalkane solution in step (2) with liquid ammonia at a pressure of 15-25 bar(g) and a temperature of 25-50° C. to produce aliphatic primary diamine and ammonium chloride; (4) The ammonium chloride in step (3) is filtered off, and the remaining aliphatic primary diamine solution is reacted with liquid phosgene at a pressure of 0.6-0.7 MPa(g) and a temperature of 50-70° C. for a cold reaction, and then the temperature is raised to 155-175° C. for a thermal reaction to generate diisocyanate.

4. The method for preparing diisocyanate from diol according to claim 1, characterized in that: The solvent in step (1) is chlorobenzene or dichlorobenzene.

5. The method for preparing diisocyanate from diol according to claim 1, characterized in that: The yield of the 1,4-butanediisocyanate is greater than 70%, and the yield of the 1,5-pentanediisocyanate is greater than 65%.