CN109180475B - Method for synthesizing diisooctyl terephthalate through rapid esterification without alkali washing and water washing - Google Patents
Method for synthesizing diisooctyl terephthalate through rapid esterification without alkali washing and water washing Download PDFInfo
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Abstract
The invention discloses a method for synthesizing diisooctyl terephthalate by rapid esterification, which takes terephthalic acid and 2-ethylhexanol as raw materials and polystyrene-supported 1-methylene-3-butylimidazolium chlorostannate ionic liquid as a catalyst to synthesize the diisooctyl terephthalate by esterification. The synthesis method has the characteristics that the acid value of the product can directly meet the requirements of the national standard of less than 1mgKOH/g, alkali washing and water washing are not needed, the reaction speed is high, the conversion rate is high, the catalyst can be repeatedly used, and no waste water is discharged, so that the synthesis method is green and environment-friendly.
Description
Technical Field
The invention relates to the field of plasticizers, in particular to a method for synthesizing diisooctyl terephthalate through rapid esterification.
Background
Diisooctyl terephthalate (DOTP) is a novel green plasticizer for polyvinyl chloride developed in recent years, and has become the most important substitute of the toxic plasticizer diisooctyl phthalate (DOP) due to the increasing importance of the plastic industry caused by the advantages of high insulation, low volatility, heat resistance, cold resistance, extraction resistance, good flexibility, good compatibility with PVC resin and the like.
The esterification reaction using terephthalic acid (PTA) and 2-ethylhexanol (isooctanol) as raw materials is a major production route for synthesizing DOTP.
The invention discloses a method for producing plasticizers of multiple varieties and low consumption (patent No. ZL03113054.2) by using the same batch type equipment, and the used catalysts comprise tetrabutyl titanate, tetraisopropyl titanate, a tetrabutyl titanate and tetraisopropyl titanate composite catalyst, solid superacid, stannous oxide, stannous oxalate, aluminum oxide, sodium metaaluminate and other solid acids.
The Chinese invention patent 'process for preparing dioctyl terephthalate plasticizer from terephthalic acid and octanol' (patent No. ZL200410021429.5) discloses a process for preparing dioctyl terephthalate plasticizer by taking terephthalic acid and 2-ethylhexanol (isooctanol) as raw materials and performing combined catalytic esterification reaction of cobalt acetate, zinc acetate and tetrabutyl titanate.
The invention discloses a Chinese invention patent 'high-efficiency catalyst for synthesizing dioctyl terephthalate' (patent number ZL200810020424.9), and discloses a method for synthesizing diisooctyl terephthalate by esterification of a composite catalyst consisting of a titanium metal compound, a tin metal compound and other metal compounds.
The Chinese patent application No. 200810020588.6 entitled method for using catalyst stannous oxide in esterification process of plasticizer production discloses a method for spraying catalyst stannous oxide on the inner wall of a reactor and the wall of an inner coil.
The invention discloses a method for synthesizing diisooctyl terephthalate by esterification (patent number ZL201010517284.3), which discloses a method for synthesizing diisooctyl terephthalate by esterification by taking terephthalic acid and 2-ethylhexanol (isooctanol) as raw materials and butyl pyridine chlorostannate ionic liquid as a catalyst.
The invention discloses a method for catalytically synthesizing diisooctyl terephthalate under the action of ionic liquid (patent number ZL201110192001.7), and discloses a method for synthesizing diisooctyl terephthalate through esterification reaction by using tetrabutyl titanate as a main catalyst and quaternary ammonium salt ionic liquid as a cocatalyst and a solubilizer.
The Chinese patent application No. 201410459509.2 entitled "production method of diisooctyl terephthalate" discloses a process for synthesizing diisooctyl terephthalate by esterification of a butyl titanate catalyst loaded by high-surface-area mesoporous carbon or porous titanium dioxide.
None of the above patents relate to the immobilization of 1-methylene-3-butylimidazolium chlorostannate (PS-CH) with polystyrene2-Bim]Cl/nSnCl2) The ionic liquid is used as a catalyst to synthesize the diisooctyl terephthalate by esterification.
As the reaction raw material PTA and isooctyl alcohol are basically immiscible, the reaction is a typical heterogeneous esterification reaction, the reaction rate is slow, and the reaction time is long. At present, titanate is mostly adopted as a catalyst in industrial production, and the reaction time is at least more than 8 hours, which becomes a bottleneck for restricting the development of DOTP industry. In addition, because the solubility of PTA in the intermediate product of monoisooctyl terephthalate is relatively high, and monoisooctyl terephthalate and DOTP are basically mutually soluble, when the activity of the catalyst is not enough to enable the reaction to be complete, the residual PTA can be dissolved in DOTP to enable the acid value of the product to be higher, the acid value of the product can be reduced to be lower than the national standard quality requirement of 1mgKOH/g only by carrying out the operations of alkaline washing and then water washing for many times, but the production time and cost are increased by carrying out the operations of alkaline washing and water washing for many times, the production efficiency is reduced, and wastewater needs to be treated and discharged, which is also a common technical problem in all existing DOTP synthesis methods, so that a production enterprise urgently needs to develop a new DOTP synthesis process method which is high in reaction speed and does not need alkaline washing and water washing.
The Chinese invention patent (patent number ZL201010517284.3) and the Chinese invention patent (patent number ZL201110192001.7) of the applicant's application disclose a method for synthesizing diisooctyl terephthalate by esterification under the action of an ionic liquid and skillfully improve the solubility of PTA in isooctyl alcohol by means of the dual functions of strong catalysis and solubilization of the ionic liquid, thereby smoothly improving the reaction speed, successfully shortening the reaction time to 2-3 hours, and ensuring that the PTA conversion rate and the DOTP yield are very high. The only disadvantage is that the ionic liquid is slightly soluble in the product DOTP after the reaction, so that the acid value of the product is slightly higher, and alkali washing and water washing operations are still needed to reduce the acid value of the product to be lower than the national standard quality requirement of 1 mgKOH/g.
Disclosure of Invention
The invention aims to provide a method for synthesizing diisooctyl terephthalate through rapid esterification without alkali washing and water washing, which has the characteristics of no alkali washing and water washing, high reaction speed, high conversion rate, reusable catalyst, no wastewater discharge, environmental protection and the like.
In order to achieve the above purpose, the solution of the invention is:
a method for synthesizing diisooctyl terephthalate by quick esterification without alkali washing and water washing takes terephthalic acid and 2-ethylhexanol as raw materials and polystyrene-supported 1-methylene-3-butylimidazolium chlorostannate (PS-CH)2-Bim]Cl/nSnCl2) The ionic liquid is used as a catalyst to synthesize the diisooctyl terephthalate by esterification.
The mass ratio of the terephthalic acid to the 2-ethylhexanol is 1: 2.1-2.3, wherein the addition amount of the polystyrene-immobilized 1-methylene-3-butylimidazolium chlorostannate ionic liquid is 8-15% of the total mass of the raw materials.
The preparation method of the polystyrene immobilized 1-methylene-3-butylimidazolium chlorostannate ionic liquid comprises the following steps: reacting chloromethylated polystyrene with equimolar amount and imidazole for 48-72 hours at the temperature of 70-80 ℃ under stirring to obtain polystyrene grafted imidazole (PS-CH)2-Im); equimolar amounts of PS-CH2the-Im and chlorobutane are stirred and reacted for 48 to 60 hours at the temperature of between 70 and 80 ℃ to prepare the polystyrene grafted butyl imidazole ([ PS-CH)2-Bim]Cl)；[PS-CH2-Bim]Stirring Cl and stannous chloride in a molar ratio of 1:2-3 at 70-80 ℃ for reaction for 60-72h to prepare the polystyrene-immobilized 1-methylene-3-butylimidazolium chlorostannate ionic liquid (PS-CH)2-Bim]Cl/nSnCl2)。
The esterification synthesis process is as follows: the reaction device used for the esterification synthesis is provided with a water separator, and water generated by the reaction is continuously evaporated through the water separator in the reaction process of the esterification synthesis; the reaction temperature of the esterification synthesis is 200-220 ℃, and the reaction time is 2-3 hours; after the esterification synthesis reaction is finished, evaporating redundant isooctyl alcohol while the reaction is hot; after the isooctanol is evaporated, the temperature is reduced to 150 ℃, a solid catalyst and a liquid-phase product are filtered and separated, and the catalyst can be continuously used in the next synthetic reaction.
After the scheme is adopted, the invention has the beneficial effects that: aiming at the technical problems of long reaction time and multiple alkali washing and water washing operation procedures after reaction commonly existing in the prior diisooctyl terephthalate industrial production, the invention skillfully loads the butylimidazole stannous chloride ionic liquid catalyst with good catalytic effect and capable of shortening the reaction time on a polystyrene carrier to prepare the polystyrene-loaded 1-methylene-3-butylimidazole chlorostannate (PS-CH) on the basis of the inventor's published Chinese invention patent ' a method for synthesizing diisooctyl terephthalate by esterification ' (patent number ZL201010517284.3) and Chinese invention ' a method for catalytically synthesizing diisooctyl terephthalate under the action of ionic liquid ' (patent number ZL201110192001.7)2-Bim]Cl/nSnCl2) The ionic liquid, by virtue of the rapid catalytic effect of the butyl imidazolium chlorostannate ionic liquid on the esterification reaction of terephthalic acid and isooctanol to synthesize DOTP and the characteristic that the ionic liquid can not be dissolved in a DOTP product when being immobilized on a polystyrene carrier, not only improves the reaction rate, shortens the reaction time (the reaction time is shortened from general 8 hours to 2-3 hours), and reduces the reaction temperature (the reaction temperature is reduced from 250 ℃ to 200 ℃ and 220 ℃, so that the energy consumption can be reduced), but also avoids the ionic liquid from being dissolved in the DOTP product, so that the acid value of the DOTP product after the reaction can directly reach the national standard quality requirement of less than 1mgKOH/g without any alkali washing and water washing operations. Because the polystyrene carries 1-methylene-3-butylimidazolium chlorostannate (PS-CH)2-Bim]Cl/nSnCl2) The ionic liquid has special effect, so that the synthesis method has the characteristics of no need of alkali washing and water washing, high reaction speed, high conversion rate, reusable catalyst, no wastewater discharge and environmental protection.
Detailed Description
Example 1
The invention relates to a method for synthesizing diisooctyl terephthalate by rapid esterification, which comprises the following steps:
1. preparation of polystyrene-immobilized butylimidazolium chlorostannate ionic liquid
In a 250mL glass three-necked flask equipped with a stirrer, a thermometer and a condenser, 5g of polystyrene (divinylbenzene (DVB) content: 1%, chlorine content: 4.1mmol/g) and 100mL of acetonitrile solvent were charged together with 1.5g of imidazole and 0.63g of sodium hydride, and the reaction was stirred at 80 ℃ for 60 hours. Filtering, washing respectively with 300mL ethyl acetate and 300mL methanol for 2 times, vacuum drying the product at 110 deg.C for 4h to obtain the final product2-Im)。
In a 250mL three-necked flask equipped with a stirrer, 5.5g of PS-CH2-Im was added to 100mL of acetonitrile, 1g of sodium hydroxide and 2.6mL of chlorobutane were added, and the reaction was stirred at 80 ℃ for 48 h. After the reaction is finished, respectively washing the reaction solution for 2 times by 300mL of water, 300mL of ethyl acetate and 300mL of methanol, and drying the reaction solution in vacuum at 110 ℃ for 4 hours to obtain the polystyrene supported butylimidazolium chloride ([ PS-CH)2-Bim]Cl)。
In a 250mL three-necked flask equipped with a stirrer, 100mL of acetonitrile was used as a solvent, and 6g of [ PS-CH ] was added2-Bim]Cl and 5.5g stannous chloride react for 60 hours at the temperature of 80 ℃, the mixture is respectively washed for 2 times by 300mL of water, 300mL of ethyl acetate and 300mL of methanol in sequence, and the product is dried for 4 hours under vacuum at the temperature of 110 ℃ to prepare the polystyrene immobilized butylimidazolium chlorostannate ionic liquid ([ PS-CH)2-Bim]Cl/nSnCl2)。
Synthesis of DOTP
16.6g of terephthalic acid, 47mL of 2-ethylhexanol (PTA:2-EH ═ 1:2.3) and 6.6g (12% by mass of the sum of the mass of terephthalic acid and 2-ethylhexanol) of a polystyrene immobilized butylimidazolium chlorostannate ionic liquid were put in a 500mL glass three-necked flask equipped with a stirrer, a thermometer, a condenser and a water separator, and the esterification synthesis reaction was carried out at 210 ℃ for 2.5 hours, and the water produced in the reaction was distilled off through the water separator.
3. Product separation and ion recovery
After the esterification synthesis reaction is finished, the redundant isooctyl alcohol is evaporated while the reaction is hot. When the temperature in the glass three-neck flask is reduced to 150 ℃, the solid catalyst and the liquid phase product are filtered and separated, the acid value of the liquid phase product is 0.85mgKOH/g, the yield of DOTP is 99.1%, and the catalyst can be directly applied to the next esterification synthesis reaction for recycling.
The embodiment skillfully utilizes the rapid catalytic effect of the butylimidazolium chlorostannate ionic liquid on the esterification reaction of terephthalic acid and isooctanol to synthesize DOTP and the characteristic that the ionic liquid is immobilized on a polystyrene carrier and can not be dissolved in a DOTP product, thereby not only improving the reaction rate, shortening the reaction time (the reaction time is shortened from 8 hours to 2.5 hours in general) and reducing the reaction temperature (the reaction temperature is reduced from 250 ℃ to 210 ℃, so that the energy consumption can be reduced), but also avoiding the ionic liquid from being dissolved in the DOTP product, and ensuring that the acid value of the DOTP product after the reaction can directly reach the national standard quality requirement of less than 1mgKOH/g without any alkali washing and water washing operations. Because the polystyrene carries the 1-methylene-3-butylimidazolium chlorostannate ([ PS-CH)2-Bim]Cl/nSnCl2) The ionic liquid has special effect, so that the synthesis method has the characteristics of no need of alkali washing and water washing, high reaction speed, high conversion rate, reusable catalyst, no wastewater discharge and environmental protection.
Example 2
The invention relates to a method for synthesizing diisooctyl terephthalate by rapid esterification, which comprises the following steps:
1. preparation of polystyrene-immobilized butylimidazolium chlorostannate ionic liquid
In a 250mL glass three-necked flask equipped with a stirrer, a thermometer and a condenser, 5g of polystyrene (1% DVB, chlorine content 4.1mmol/g) and 100mL of acetonitrile solvent were charged together with 1.5g of imidazole and 0.63g of sodium hydride, and the reaction was stirred at 70 ℃ for 72 hours. Filtering, washing respectively with 300mL ethyl acetate and 300mL methanol for 2 times, vacuum drying the product at 110 deg.C for 4h to obtain the final product2-Im)。
In a 250mL three-necked flask equipped with a stirrer, 5.5g of PS-CH2-Im was added to 100mL of acetonitrile, 1g of sodium hydroxide and 2.6mL of chlorobutane were added, and the reaction was stirred at 70 ℃ for 60 hours. After the reaction was completed, 300mL of water was added,Washing with 300mL ethyl acetate and 300mL methanol for 2 times respectively, and vacuum drying at 110 deg.C for 4h to obtain polystyrene supported butyl imidazole chloride ([ PS-CH)2-Bim]Cl)。
In a 250mL three-necked flask equipped with a stirrer, 100mL of acetonitrile was used as a solvent, and 6g of [ PS-CH ] was added2-Bim]Cl and 8.3g stannous chloride react for 72h at 70 ℃, 300mL of water, 300mL of ethyl acetate and 300mL of methanol are used for washing respectively for 2 times in sequence, and the product is dried for 4h under vacuum at 110 ℃ to prepare the polystyrene-immobilized butylimidazolium chlorostannate ionic liquid ([ PS-CH)2-Bim]Cl/nSnCl2)。
Synthesis of DOTP
In a 500mL glass three-neck flask equipped with a stirrer, a thermometer, a condenser and a water separator, 79g of terephthalic acid and 203mL of 2-ethylhexanol (PTA:2-EH ═ 1:2.1) and 37g (15% by mass of the sum of the mass of terephthalic acid and 2-ethylhexanol) of polystyrene immobilized butylimidazolium chlorostannate ionic liquid were charged. The esterification synthesis reaction is carried out for 3 hours at the temperature of 200 ℃, and the water generated in the reaction is continuously distilled out through a water separator.
3. Product separation and ion recovery
After the reaction is finished, the redundant isooctyl alcohol is evaporated while the reaction is hot. When the temperature in the glass three-neck flask is reduced to 150 ℃, the solid catalyst and the liquid phase product are filtered and separated, the acid value of the liquid phase product is 0.91mgKOH/g, the yield of DOTP is 98.6%, and the catalyst can be directly applied to the next synthetic reaction for recycling.
In the embodiment, the fast catalytic effect of the butylimidazolium chlorostannate ionic liquid on the esterification reaction of terephthalic acid and isooctanol to synthesize DOTP and the characteristic that the ionic liquid is immobilized on a polystyrene carrier and can not be dissolved in a DOTP product are utilized, so that the reaction rate is improved, the reaction time is shortened (the reaction time is shortened from 8 hours to 3 hours in general), the reaction temperature is reduced (the reaction temperature is reduced from 250 ℃ to 200 ℃, and therefore, the energy consumption is reduced), the ionic liquid is prevented from being dissolved in the DOTP product, and the acid value of the reacted DOTP product can directly reach the national standard quality of less than 1mgKOH/g without any alkali washing and water washing operationsAnd (4) requiring. Because the polystyrene carries the 1-methylene-3-butylimidazolium chlorostannate ([ PS-CH)2-Bim]Cl/nSnCl2) The ionic liquid has special effect, so that the synthesis method has the characteristics of no need of alkali washing and water washing, high reaction speed, high conversion rate, reusable catalyst, no wastewater discharge and environmental protection.
Example 3
The invention relates to a method for synthesizing diisooctyl terephthalate by rapid esterification, which comprises the following steps:
1. preparation of polystyrene-immobilized butylimidazolium chlorostannate ionic liquid
In a 250mL glass three-necked flask equipped with a stirrer, a thermometer and a condenser, 5g of polystyrene (1% DVB, chlorine content 4.1mmol/g) and 100mL of acetonitrile solvent were charged together with 1.5g of imidazole and 0.63g of sodium hydride, and the reaction was stirred at 75 ℃ for 66 hours. Filtering, washing respectively with 300mL ethyl acetate and 300mL methanol for 2 times, vacuum drying the product at 110 deg.C for 4h to obtain the final product2-Im)。
In a 250mL three-necked flask equipped with a stirrer, 5.5g of PS-CH2-Im was added to 100mL of acetonitrile, 1g of sodium hydroxide and 2.6mL of chlorobutane were added, and the reaction was stirred at 75 ℃ for 48 h. After the reaction is finished, respectively washing the reaction solution for 2 times by 300mL of water, 300mL of ethyl acetate and 300mL of methanol, and drying the reaction solution in vacuum at 110 ℃ for 4 hours to obtain the polystyrene supported butylimidazolium chloride ([ PS-CH)2-Bim]Cl)。
In a 250mL three-necked flask equipped with a stirrer, 100mL of acetonitrile was used as a solvent, and 6g of [ PS-CH ] was added2-Bim]Cl and 6.9g stannous chloride react for 60 hours at 75 ℃, the solution is respectively washed for 2 times by 300mL of water, 300mL of ethyl acetate and 300mL of methanol, and the product is dried for 4 hours under vacuum at 110 ℃ to prepare the polystyrene-immobilized butylimidazolium chlorostannate ionic liquid ([ PS-CH)2-Bim]Cl/nSnCl2)。
Synthesis of DOTP
In a 500mL glass three-necked flask equipped with a stirrer, a thermometer, a condenser and a water separator, 40g of terephthalic acid and 112mL of 2-ethylhexanol (PTA:2-EH ═ 1:2.3) and 10.5g (8% by mass of the sum of the mass of terephthalic acid and 2-ethylhexanol) of polystyrene immobilized butylimidazolium chlorostannate ionic liquid were charged. The esterification synthesis reaction is carried out for 2 hours at 220 ℃, and the water generated in the reaction is continuously distilled out through a water separator.
3. Product separation and ion recovery
After the reaction is finished, the redundant isooctyl alcohol is evaporated while the reaction is hot. When the temperature in the glass three-neck flask is reduced to 150 ℃, the solid catalyst and the liquid phase product are filtered and separated, the acid value of the liquid phase product is 0.96mgKOH/g, the yield of DOTP is 98.1%, and the catalyst can be directly applied to the next synthetic reaction for recycling.
In the embodiment, the fast catalytic effect of the butylimidazolium chlorostannate ionic liquid on the esterification reaction of terephthalic acid and isooctanol to synthesize DOTP and the characteristic that the ionic liquid is immobilized on a polystyrene carrier and can not be dissolved in a DOTP product are utilized, so that the reaction rate is improved, the reaction time is shortened (the reaction time is shortened from 8 hours to 2 hours in general) and the reaction temperature is reduced (the reaction temperature is reduced from 250 ℃ to 220 ℃, so that the energy consumption is reduced), the ionic liquid is prevented from being dissolved in the DOTP product, and the acid value of the reacted DOTP product can directly reach the national standard quality requirement of less than 1mgKOH/g without any alkali washing and water washing operations. Because the polystyrene carries the 1-methylene-3-butylimidazolium chlorostannate ([ PS-CH)2-Bim]Cl/nSnCl2) The ionic liquid has special effect, so that the synthesis method has the characteristics of no need of alkali washing and water washing, high reaction speed, high conversion rate, reusable catalyst, no wastewater discharge and environmental protection.
Example 4
The invention relates to a method for synthesizing diisooctyl terephthalate by rapid esterification, which comprises the following steps:
1. preparation of polystyrene-immobilized butylimidazolium chlorostannate ionic liquid
In a 250mL glass three-necked flask equipped with a stirrer, a thermometer and a condenser, 5g of polystyrene (1% DVB, chlorine content 4.1mmol/g) and 100mL of acetonitrile solvent were charged together with 1.5g of imidazole and 0.63gSodium hydride, stirred at 75 ℃ for 72 h. Filtering, washing respectively with 300mL ethyl acetate and methanol for 2 times, vacuum drying the product at 110 deg.C for 4h to obtain the final product2-Im)。
In a 250mL three-necked flask equipped with a stirrer, 5.5g of PS-CH2-Im was added to 100mL of acetonitrile, 1g of sodium hydroxide and 2.6mL of chlorobutane were added, and the reaction was stirred at 80 ℃ for 48 h. After the reaction is finished, respectively washing the reaction solution for 2 times by 300mL of water, 300mL of ethyl acetate and 300mL of methanol, and drying the reaction solution in vacuum at 110 ℃ for 4 hours to obtain the polystyrene supported butylimidazolium chloride ([ PS-CH)2-Bim]Cl)。
In a 250mL three-necked flask equipped with a stirrer, 100mL of acetonitrile was used as a solvent, and 6g of [ PS-CH ] was added2-Bim]Cl and 5.5g stannous chloride react for 72h at 70 ℃, the mixture is respectively washed for 2 times by 300mL of water, 300mL of ethyl acetate and 300mL of methanol in turn, and the product is dried for 4h under vacuum at 110 ℃ to prepare the polystyrene-immobilized butylimidazolium chlorostannate ionic liquid ([ PS-CH)2-Bim]Cl/nSnCl2)。
Synthesis of DOTP
In a 500mL glass three-neck flask equipped with a stirrer, a thermometer, a condenser and a water separator, 50g of terephthalic acid and 134mL of 2-ethylhexanol (PTA:2-EH ═ 1:2.2) and 16g (10% by mass of the sum of the mass of terephthalic acid and 2-ethylhexanol) of polystyrene immobilized butylimidazolium chlorostannate ionic liquid were charged. The esterification synthesis reaction is carried out for 2.5h at the temperature of 210 ℃, and the water generated by the reaction is continuously distilled out through a water separator.
3. Product separation and ion recovery
After the reaction is finished, the redundant isooctyl alcohol is evaporated while the reaction is hot. When the temperature in the glass three-neck flask is reduced to 150 ℃, the solid catalyst and the liquid phase product are filtered and separated, the acid value of the liquid phase product is 0.81mgKOH/g, the yield of DOTP is 99.5 percent, and the catalyst can be directly applied to the next synthetic reaction for recycling.
In the embodiment, the fast catalytic effect of butylimidazolium chlorostannate ionic liquid on the esterification reaction of terephthalic acid and isooctanol for synthesizing DOTP and the ionic liquidThe characteristic that the subphase liquid is immobilized on the polystyrene carrier and can not be dissolved in the DOTP product not only improves the reaction rate, shortens the reaction time (the reaction time is shortened from 8 hours to 2.5 hours generally), reduces the reaction temperature (the reaction temperature is reduced from 250 ℃ to 210 ℃, thereby reducing the energy consumption), but also avoids the ionic liquid from being dissolved in the DOTP product, so that the acid value of the DOTP product after the reaction can directly reach the national standard quality requirement of less than 1mgKOH/g without any alkali washing and water washing operations. Because the polystyrene carries the 1-methylene-3-butylimidazolium chlorostannate ([ PS-CH)2-Bim]Cl/nSnCl2) The ionic liquid has special effect, so that the synthesis method has the characteristics of no need of alkali washing and water washing, high reaction speed, high conversion rate, reusable catalyst, no wastewater discharge and environmental protection.
The above-described embodiments of the present invention are merely examples for clearly illustrating the invention and are not to be construed as limiting the embodiments of the present invention, and it is apparent to those skilled in the art that other variations or modifications can be made on the basis of the above description. And are neither required nor exhaustive of all embodiments. And such obvious variations or modifications which fall within the spirit of the invention are intended to be covered by the scope of the present invention.
Claims (3)
1. A method for synthesizing diisooctyl terephthalate by rapid esterification is characterized in that terephthalic acid and 2-ethylhexanol are taken as raw materials, and polystyrene is used for immobilizing 1-methylene-3-butylimidazolium chlorostannate ([ PS-CH)2-Bim]Cl/nSnCl2) The ionic liquid is used as a catalyst to synthesize diisooctyl terephthalate through esterification;
the esterification synthesis process is as follows: the reaction device used for the esterification synthesis is provided with a water separator, and water generated by the reaction is continuously evaporated through the water separator in the reaction process of the esterification synthesis; the reaction temperature of the esterification synthesis is 200-220 ℃, and the reaction time is 2-3 hours; after the esterification synthesis reaction is finished, evaporating redundant isooctyl alcohol while the reaction is hot; after the isooctanol is evaporated, the temperature is reduced to 150 ℃, a solid catalyst and a liquid-phase product are filtered and separated, and the catalyst can be continuously used in the next synthetic reaction.
2. The method for synthesizing di-isooctyl terephthalate through rapid esterification according to claim 1, wherein the mass ratio of the terephthalic acid to the 2-ethylhexanol is 1: 2.1-2.3, wherein the addition amount of the polystyrene-immobilized 1-methylene-3-butylimidazolium chlorostannate ionic liquid is 8-15% of the total mass of the raw materials.
3. The method for synthesizing diisooctyl terephthalate through rapid esterification according to claim 1 or 2, characterized in that the polystyrene-supported 1-methylene-3-butylimidazolium chlorostannate ionic liquid is prepared by the following method: reacting chloromethylated polystyrene with equimolar amount and imidazole for 60-72 hours under the condition of stirring at the temperature of 70-80 ℃ to obtain the polystyrene grafted imidazole (PS-CH)2-Im); equimolar amounts of PS-CH2The mixture of-Im and chlorobutane is stirred and reacted for 48 to 60 hours at the temperature of 70 to 80 ℃ to prepare the polystyrene grafted butyl imidazole ([ PS-CH)2-Bim]Cl)；[PS-CH2-Bim]Stirring Cl and stannous chloride in a molar ratio of 1:2-3 at the temperature of 70-80 ℃ for reaction for 48-72h to prepare the polystyrene-immobilized 1-methylene-3-butylimidazolium chlorostannate ionic liquid ([ PS-CH)2-Bim]Cl/nSnCl2)。
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| CN102001948A (en) * | 2010-10-18 | 2011-04-06 | 华侨大学 | Method for synthesizing dioctyl terephthalate through esterification |
| WO2012106701A1 (en) * | 2011-02-04 | 2012-08-09 | Novozymes A/S | Fatty acid esterification process |
| CN104193621A (en) * | 2014-08-28 | 2014-12-10 | 福州大学 | Method for synthesizing glycol diacetate under catalytic action of acidic immobilized ionic liquid |
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