Preparation method of butyl titanate

Abstract

The invention discloses a preparation method of butyl titanate, which comprises the following steps: S1, under the protection of inert gas, sequentially adding butanol, a solvent and a high-efficiency catalyst into a reactor, stirring and dissolving, slowly dropwise adding titanium tetrachloride, carrying out reflux reaction, and after the reaction is completed, carrying out short-range evaporation to remove HCl; and S2, introducing ammonia gas into the reactor to carry out decelerated crystallization, carrying out solid-liquid separation after ammonium chloride crystallization, and carrying out reduced pressure distillation on mother liquor to obtain butyl titanate. According to the method, HCl in a system is removed through an efficient catalyst 4-dimethylaminopyridine and a short-range evaporation technology, and the yield of ammonium chloride is reduced; sodium chloride crystals grow in a mode of decelerating crystallization, so that the problems that the amount of a byproduct ammonium chloride is too large and the ammonium chloride crystals are too small in the existing butyl titanate synthesis are synergistically solved, and the single-kettle yield and the recovery rate of butyl titanate are remarkably increased.

Description

Technical Field

[0001] The invention relates to the technical field of organic synthesis, and in particular to a method for preparing butyl titanate. Background Art

[0002] Butyl titanate is a common titanate compound, mainly used as a catalyst for transesterification and condensation reactions in organic synthesis. It can be used as a Ziegler Natta catalyst in the polymerization of PP, PE, polybutadiene, epoxy resin, phenolic plastics, silicone resin, etc., with high stereoselectivity and yield; it can also be used in paints to cross-link a variety of polymers or resins to improve the corrosion resistance of coatings; at the same time, because it can promote the adhesion of coatings to surfaces, it can also be directly used as a material surface modifier, adhesion promoter, primer, etc.; it can be decomposed at high temperatures (300-650℃) to form a hard and smooth titanium dioxide film layer.

[0003] At present, the main production method of butyl phthalate is to heat and dissolve titanium tetrachloride, alcohol (ethanol, propanol, butanol, isopropanol), and ammonia (liquid ammonia or ammonia gas) in a solvent such as toluene to carry out an esterification reaction. The reaction product is filtered to remove the insoluble byproduct ammonium chloride, and the filtrate is distilled to remove the excess alkanol to obtain the finished product. Although the steps are simple, the disadvantages are also obvious: first, the neutralization of hydrogen chloride with ammonia leads to a very large amount of ammonium chloride precipitation, and the reactor is full of ammonium chloride, leaving too little space for the main product, so the single reactor production capacity is extremely low; second, the crystallization method is too simple, ammonium chloride forms powder, the crystal surface area is too large, the solid-liquid separation is difficult, the solid contains a large amount of mother liquor, the mother liquor loss is large, and the recovery rate of butyl titanate is low.

[0004] Therefore, there is an urgent need in the prior art for a method for preparing butyl titanate that can reduce the amount of by-product ammonium chloride and increase the size of ammonium chloride crystals, so as to improve the production capacity and recovery rate of butyl titanate. Summary of the invention

[0005] The present invention aims to provide a method for preparing butyl titanate, by adding a high-efficiency catalyst 4-dimethylaminopyridine and adopting a short-path evaporation technology to remove HCl in the system and reduce the output of ammonium chloride; by slowing down the crystallization, the sodium chloride crystals are grown, thereby solving the problems of excessive amount of byproduct ammonium chloride and too small ammonium chloride crystals in the existing synthesis of butyl titanate.

[0006] The present invention is achieved through the following technical solutions:

[0007] A method for preparing butyl titanate comprises the following steps:

[0008] S1. Under the protection of inert gas, butanol, solvent and high-efficiency catalyst are added to the reactor in sequence, titanium tetrachloride is slowly added dropwise after stirring and dissolving, and reflux reaction is carried out. After the reaction is completed, HCl is removed by short-path evaporation;

[0009] S2. Ammonia gas is introduced into the reactor to perform decelerated crystallization. After the ammonium chloride crystallizes, the solid and liquid are separated. The mother liquor is distilled under reduced pressure to obtain butyl titanate.

[0010] The present invention is capable of removing up to half of the hydrogen chloride in gaseous form from the reaction mixture in a relatively short period of time. Therefore, the amount of ammonia gas that must be used to neutralize the hydrogen chloride, the amount of by-product ammonium chloride formed per mole of alkyl titanate produced, and the time spent removing the by-product ammonium chloride are greatly reduced.

[0011] Furthermore, the inert gas in step S1 is one or more of nitrogen, helium, neon, argon, krypton, and xenon.

[0012] Furthermore, the butanol in step S1 is one or more of n-butanol, isobutanol, sec-butanol or tert-butanol.

[0013] Furthermore, the solvent in step S1 is one or more of dichloromethane, chloroform, ethyl acetate, dimethyl carbonate, ether, acetone, pentane or heptane.

[0014] Furthermore, in step S1, the high-efficiency catalyst is 4-dimethylaminopyridine; the molar ratio of the high-efficiency catalyst to titanium tetrachloride is 1:10 to 1:100, preferably 1:50 to 1:80. The high-efficiency catalyst in this dosage range can effectively reduce the content of HCl, avoid the treatment of residual high-efficiency catalyst in post-treatment, and reduce the difficulty of post-treatment.

[0015] Furthermore, in step S1, the molar ratio of butanol to titanium tetrachloride is 1:1 to 30:1, preferably 1:1 to 20:1, and more preferably 5:1 to 10:1. The amount of butanol used within this range can ensure that titanium tetrachloride is fully reacted, and the structure of the product is more uniform and stable.

[0016] When the above molar ratios are used, a considerable proportion of the hydrogen chloride is liberated during simple mixing of the reactants. Thus, the time required to remove the hydrogen chloride from the reaction mixture and the amount of ammonia used are greatly reduced, leaving a small amount of hydrogen chloride that can be removed by a subsequent short-path evaporation process.

[0017] Furthermore, in step S1, the reaction temperature is controlled not to exceed 25° C. during the dropwise addition of titanium tetrachloride; the stirring speed is maintained at 200 r / min to 400 r / min, preferably 300 r / min; and the dropwise addition time is 2 h to 10 h, preferably 3 h to 5 h.

[0018] Furthermore, the temperature of the reflux reaction in step S1 is 10°C to 80°C, preferably 20°C to 60°C.

[0019] Furthermore, the temperature of the short-path evaporation in step S1 is 35°C to 60°C, preferably 40°C to 50°C.

[0020] Furthermore, when ammonia is introduced in step S2 for decelerated crystallization, the reaction endpoint is controlled by the pH value of the system, and the reaction endpoint is reached when the pH value of the system gradually changes from <7 to 7-8; the flow rate of the ammonia is 5ml / min-80ml / min, preferably 10ml / min-40ml / min, and more preferably 15ml / min-30ml / min.

[0021] Furthermore, the deceleration crystallization in step S2 is carried out in a deceleration crystallization reactor, and the sodium chloride crystals are grown by deceleration crystallization, which can reduce the content of ammonium chloride product in the mother liquor and the content of mother liquor carried away by ammonium chloride, and increase the recovery rate of butyl titanate.

[0022] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0023] 1. The present invention provides a method for preparing butyl titanate. The high-efficiency catalyst 4-dimethylaminopyridine used can consume HCl in time during the reaction process. At the same time, a short-range evaporation operation is added before the ammonia gas is passed for neutralization. The combination of the two can effectively evaporate and remove the HCl in the system, thereby greatly reducing the generation of by-product ammonium chloride. The reduction of by-product ammonium chloride releases a large amount of space in the reactor. The improvement of space utilization is conducive to increasing the single reactor capacity of butyl titanate; at the same time, due to the reduction of HCl, the amount of ammonia gas is also reduced, thereby reducing the production cost;

[0024] 2. The present invention adopts a deceleration crystallization method. By controlling the introduction rate of ammonia gas, the crystallization rate of ammonium chloride crystals can be controlled. The deceleration crystallization method significantly increases the size of ammonium chloride crystals, reduces the content of ammonium chloride product in the mother liquor and the content of mother liquor carried away by the ammonium chloride crystals, and simplifies the subsequent separation and purification process, thereby greatly improving the yield and purity of butyl titanate.

[0025] 3. The present invention simultaneously removes HCl to reduce the ammonium chloride production and slows down the crystallization to increase the size of the ammonium chloride crystals. The synergistic effect of the two significantly increases the production and recovery rate of butyl titanate. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with embodiment, and the illustrative embodiments of the present invention and its description are only used to explain the present invention, and are not used as limitation of the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper limit and the lower limit of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the range is also included in the present invention. The upper limit and lower limit of these smaller ranges can be independently included or excluded in the scope.

[0027] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0028] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to the skilled artisan. The present invention description and examples are exemplary only.

[0029] As used herein, "include", "comprising", "having", "containing", etc. are all open terms, i.e., including but not limited to. The "parts" indicated in the following examples are all parts by weight.

[0030] Example 1

[0031] S1. Under nitrogen protection, 5920 parts of n-butanol, 6000 parts of dichloromethane and 15 parts of 4-dimethylaminopyridine were added to the reactor in sequence, and after stirring and dissolving, 1500 parts of titanium tetrachloride were slowly added dropwise within 3 hours. During the addition, the temperature in the system was controlled not to exceed 20°C. After the addition was completed, the reflux reaction was continued at 40°C for 4 hours, and then HCl was removed by short-path evaporation at 40°C.

[0032] S2. Ammonia gas is introduced into the reactor at a rate of 30 ml / min to decelerate crystallization. When the pH value of the system becomes 8, the aeration is stopped, and ammonium chloride crystals are separated and the mother liquor is distilled under reduced pressure to obtain the product butyl titanate.

[0033] Example 2

[0034] S1. Under nitrogen protection, 4673 parts of n-butanol, 7300 parts of dichloromethane and 20 parts of 4-dimethylaminopyridine were added to the reactor in sequence, and after stirring and dissolving, 1500 parts of titanium tetrachloride were slowly added dropwise within 3 hours. During the addition, the temperature in the system was controlled not to exceed 20°C. After the addition was completed, the reflux reaction was continued at 40°C for 4 hours, and then HCl was removed by short-path evaporation at 40°C.

[0035] S2. Ammonia gas is introduced into the reactor at a rate of 40 ml / min to decelerate crystallization. When the pH value of the system becomes 8, the aeration is stopped, and ammonium chloride crystals are separated and the mother liquor is distilled under reduced pressure to obtain the product butyl titanate.

[0036] Example 3

[0037] S1. Under nitrogen protection, 6000 parts of n-butanol, 6800 parts of dichloromethane and 15 parts of 4-dimethylaminopyridine were added to the reactor in sequence, and after stirring and dissolving, 1500 parts of titanium tetrachloride were slowly added dropwise within 3 hours. During the addition, the temperature in the system was controlled not to exceed 20°C. After the addition was completed, the reflux reaction was continued at 40°C for 4 hours, and then HCl was removed by short-path evaporation at 40°C.

[0038] S2. Ammonia gas is introduced into the reactor at a rate of 20 ml / min to decelerate crystallization. When the pH value of the system becomes 8, the aeration is stopped, and ammonium chloride crystals are separated and the mother liquor is distilled under reduced pressure to obtain the product butyl titanate.

[0039] Comparative Example 1

[0040] S1. Under nitrogen protection, 3000 parts of n-butanol and 3500 parts of dichloromethane were added to the reactor in sequence. After stirring and dissolving, 750 parts of titanium tetrachloride were slowly added dropwise within 3 hours. During the addition, the temperature in the system was controlled not to exceed 20°C. After the addition was completed, the reaction was continued under reflux at 40°C for 4 hours.

[0041] S2. Ammonia gas is introduced into the reactor at a rate of 500 ml / min for crystallization. When the pH value of the system becomes 8, the aeration is stopped. The ammonia neutralization reaction time does not exceed 1 hour. Ammonium chloride crystals are separated and the mother liquor is distilled under reduced pressure to obtain the product butyl titanate.

[0042] The yields of Example 1 and Comparative Example 1 are shown in Table 1.

[0043] Table 1 Comparison of output between Example 1 and Comparative Example 1

[0044]

[0045] It can be seen that, when the single-pot output of ammonium chloride in Example 1 is not much different from that in Comparative Example 1, the single-pot output of butyl phthalate in Example 1 is as high as 211% times that of Comparative Example 1, and the amount of ammonium chloride produced per portion of butyl titanate is only about 55% of that in Comparative Example 1, and the recovery rate of butyl phthalate is also increased by more than 5%. This shows that the present application adopts the high-efficiency catalyst 4-dimethylaminopyridine and short-range evaporation operation, which can effectively evaporate and remove the HCl in the system, greatly reduce the generation of by-product ammonium chloride, successfully release the effective space in the reactor, solve the problem of limited available space in the reactor due to excessive by-product ammonium chloride crystals in the production of butyl phthalate, and significantly improve the single-pot production capacity of butyl titanate; at the same time, the present invention also adopts the method of deceleration crystallization, by controlling the introduction rate of ammonia, increasing the size of ammonium chloride crystals, reducing the content of ammonium chloride product in the mother liquor and the content of mother liquor taken away by the ammonium chloride crystals, and successfully improving the recovery rate of butyl titanate.

[0046] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing butyl titanate, comprising the following steps: S1. Under the protection of inert gas, butanol, solvent and high-efficiency catalyst are added to the reactor in sequence, titanium tetrachloride is slowly added dropwise after stirring and dissolving, and reflux reaction is carried out. After the reaction is completed, HCl is removed by short-path evaporation; S2. Ammonia gas is introduced into the reactor to perform decelerated crystallization. After the ammonium chloride crystallizes, the solid and liquid are separated. The mother liquor is distilled under reduced pressure to obtain butyl titanate.

2. The method for preparing butyl titanate according to claim 1, characterized in that: The high-efficiency catalyst in step S1 is 4-dimethylaminopyridine.

3. The method for preparing butyl titanate according to claim 2, characterized in that: The molar ratio of the high-efficiency catalyst to titanium tetrachloride in step S1 is 1:50 to 1:

80.

4. The method for preparing butyl titanate according to claim 3, characterized in that: The molar ratio of butanol to titanium tetrachloride in step S1 is 5:1 to 10:

1.

5. The method for preparing butyl titanate according to claim 2, characterized in that: In step S1, the reaction temperature is controlled not to exceed 25° C. during the dropwise addition of titanium tetrachloride, the stirring speed is 200 r / min to 400 r / min, and the dropwise addition time is 2 h to 10 h.

6. The method for preparing butyl titanate according to claim 2, characterized in that: The temperature of the reflux reaction in step S1 is 10°C to 80°C, and the temperature of the short-path evaporation is 35°C to 60°C.

7. The method for preparing butyl titanate according to claim 2, characterized in that: The solvent in step S1 is one or more of dichloromethane, chloroform, ethyl acetate, dimethyl carbonate, ether, acetone, pentane or heptane.

8. The method for preparing butyl titanate according to claim 2, characterized in that: The flow rate of the ammonia gas in step S2 is 5 ml / min to 80 ml / min.

9. The method for preparing butyl titanate according to claim 8, characterized in that: When ammonia gas is introduced to perform decelerated crystallization in step S2, the reaction endpoint is controlled by the pH value of the system, and the reaction endpoint is reached when the pH value of the system gradually changes from <7 to 7-8.

10. Butyl phthalate prepared by the method for preparing butyl titanate according to any one of claims 1 to 9.

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