A method for directly synthesizing trioctyl trimellitate from liquid trimellitic anhydride

Abstract

The invention relates to the field of fine chemical product synthesis, and specifically to a method for synthesizing trioctyl trimellitate directly from liquid trimellitic anhydride, comprising the following steps: S1, adding isooctyl alcohol into an esterification kettle, heating the esterification kettle to above 170°C, then inputting hot refined liquid trimellitic anhydride without flakes prepared in a workshop into the esterification kettle through a pipeline, adding activated carbon after mixing and stirring, and turning on nitrogen protection, S2, adding tetraisopropyl titanate; S3, sampling and determining acid value, negative pressure dealcoholization and sampling and analysis; S4, cooling, adding a dilute alkali solution and keeping warm; S5, removing water and remaining isooctyl alcohol; S6, vacuuming and cooling, decoloring and filtering to obtain trioctyl trimellitate. The invention directly inputs hot refined liquid trimellitic anhydride without flakes prepared in a workshop into the esterification kettle through a pipeline for esterification reaction with isooctyl alcohol, which not only reduces the raw material preparation process, does not need to cool down, saves the use of a flake machine, but also does not affect the product quality of trioctyl trimellitate.

Description

Technical Field

[0001] The invention relates to the field of fine chemical product synthesis, in particular to a method for directly synthesizing trioctyl trimellitate from liquid trimellitic anhydride. Background Art

[0002] Trioctyl trimellitate is a heat-resistant and durable main plasticizer, which has the advantages of polyester plasticizer and monomer plasticizer. It is also better than polyester plasticizer in terms of compatibility, processability and low temperature resistance, and has excellent electrical properties. It is mainly used for 105℃ grade heat-resistant wire and cable materials and other products such as plates, sheets, and gaskets that require heat resistance and durability. It is also suitable for a variety of plastics such as vinyl chloride copolymers, cellulose nitrate, ethyl cellulose, and polymethyl methacrylate. As my country's safety standards for heat resistance grades of wires and cables for construction and automobiles become more and more stringent in the future, trioctyl trimellitate will gradually replace phthalate plasticizers, and its demand will grow at an average annual rate of 8%, so its development prospects are very good.

[0003] In the prior art, the production process of trioctyl trimellitate generally adopts the flake-like solid trimellitic anhydride after flake formation, which adds the flake formation step of liquid trimellitic anhydride, and the temperature needs to be raised to dissolve the solid trimellitic anhydride in the early stage of esterification, which invisibly increases the preparation time. Based on this, the present invention proposes a synthesis method for directly synthesizing trioctyl trimellitate from liquid trimellitic anhydride. Summary of the invention

[0004] The invention provides a method for synthesizing trioctyl trimellitate directly from liquid trimellitic anhydride without affecting the product quality of trioctyl trimellitate, by eliminating the step of trimellitic anhydride flake formation to reduce the cost and eliminating the process of heating and dissolving solid trimellitic anhydride in the early stage of esterification.

[0005] In order to solve the above technical problems, the present invention provides a method for synthesizing trioctyl trimellitate directly from liquid trimellitic anhydride, and the synthesis method comprises the following steps:

[0006] S1. Add isooctyl alcohol into the esterification kettle, and heat the esterification kettle to above 170°C. Then, input the hot refined liquid trimellitic anhydride prepared in the workshop into the esterification kettle through a pipeline. After mixing and stirring, add activated carbon and start nitrogen protection. Keep the esterification kettle warm and discharge water for 0.5h.

[0007] S2. Continue to add tetraisopropyl titanate into the esterification kettle, raise the temperature to 200-210°C and keep it warm for 2-6 hours;

[0008] S3, sampling and determining the acid value <0.1mgKOH / g, esterification is completed, most of the isooctyl alcohol in the reaction solution is extracted under negative pressure, and sampling and analysis are performed;

[0009] S4, when the kettle liquid is naturally cooled to 80-100°C, add the dilute alkali solution and stir for 1 hour;

[0010] S5, after the insulation is completed, the excess water and the remaining isooctyl alcohol are extracted while the temperature is increased;

[0011] S6. Evacuate the esterification kettle, cool it down and add a certain amount of diatomaceous earth. Decolorize it at 90°C for 1 hour and filter it while hot to obtain the filtrate, which is trioctyl trimellitate.

[0012] Preferably, the hot refined unflaked liquid trimellitic anhydride in S1 is synthesized into a crude trimellitic anhydride by reacting trimellitic acid and acetic acid, and then dehydrated, dealcoholized and distilled to obtain the product, and the temperature of the liquid trimellitic anhydride is 170°C.

[0013] Preferably, the mass ratio of liquid trimellitic anhydride to isooctyl alcohol in S1 is 1:2.5-3, and the amount of activated carbon is 0.1-0.5% of trioctyl trimellitate.

[0014] Preferably, the amount of tetraisopropyl titanate added to S2 is 0.1-1% of the product amount.

[0015] Preferably, the dilute alkaline solution in S4 is a Na2CO3 solution, and the added amount is 0.5% of trioctyl trimellitate.

[0016] Preferably, the amount of diatomaceous earth added in S6 is 0.1-0.5% of trioctyl trimellitate.

[0017] The beneficial effects of the present invention are:

[0018] The synthesis method proposed by the present invention saves the process of cooling and flake formation of trimellitic anhydride and heating and dissolving solid trimellitic anhydride in the early stage of esterification without affecting the product quality of trioctyl trimellitate, thereby greatly saving the cost and preparation efficiency.

[0019] Specifically, the present invention directly inputs the hot refined unflaked liquid trimellitic anhydride prepared in the workshop into the esterification kettle through a pipeline for esterification reaction with isooctyl alcohol, thereby reducing the raw material preparation and feeding processes, eliminating the need for cooling, and eliminating the use of a flake forming machine, which greatly saves costs. The production line of the refined unflaked liquid trimellitic anhydride in the workshop can be linked with the preparation of trioctyl trimellitate, eliminating the step of storing flake trimellitic anhydride, and improving the production efficiency of trioctyl trimellitate. In addition, various indicators of the finished product of trioctyl trimellitate synthesized by refining the unflaked liquid trimellitic anhydride in the present invention meet the industry indicators. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] A method for directly synthesizing trioctyl trimellitate from liquid trimellitic anhydride, the method comprising the following steps:

[0022] S1. Add 450g of isooctyl alcohol to the esterification kettle, and heat the esterification kettle to above 170°C, and then deliver 170g of 170°C refined unflaked liquid trimellitic anhydride prepared in the workshop into the esterification kettle through a pipeline, turn on the stirring device of the esterification kettle to mix and stir the two, then add 1.2g of activated carbon and turn on nitrogen protection, and keep the esterification kettle warm and discharge water for 0.5h;

[0023] S2. Continue to add 0.5 g of tetraisopropyl titanate to the esterification kettle, raise the temperature to 200-210° C. and keep warm for 2-6 hours;

[0024] S3, sampling and determining the acid value <0.1mgKOH / g, esterification is completed, most of the isooctyl alcohol in the reaction solution is extracted under negative pressure, and sampling and analysis are performed;

[0025] S4, when the kettle liquid is naturally cooled to 80-100°C, 0.2g of dilute alkali solution is added and the mixture is stirred for 1h at the same temperature;

[0026] S5, after the insulation is completed, the excess water and the remaining isooctyl alcohol are extracted while the temperature is increased;

[0027] S6. Evacuate the esterification kettle, cool it down and add 2 g of diatomaceous earth. Decolorize it at 90° C. for 1 hour and filter it while hot to obtain the filtrate, which is trioctyl trimellitate.

[0028] The following are five batches of parallel tests implemented according to the above synthesis method, and the specific data are as follows:

[0029]

[0030]

[0031] Note: The finished product gas phase analysis adopts the detection method of trioctyl trimellitate finished product.

[0032] In the above table, the trioctyl trimellitate products prepared by five batches of parallel experiments are compared with the comparison 1. From the gas phase state of the reaction liquid, the post-treatment situation and the index analysis of the trioctyl trimellitate obtained subsequently, there is basically no difference, and all the indicators meet the industry indicators, which proves that the synthesis method proposed by the present invention not only saves the process of cooling and flake formation of trimellitic anhydride and heating and dissolving solid trimellitic anhydride in the early stage of esterification, saving costs, but also does not affect the quality of the trioctyl trimellitate product, and improves the preparation efficiency;

[0033] Specifically, the invention directly inputs the hot refined unflaked liquid trimellitic anhydride prepared in a workshop into an esterification kettle through a pipeline for esterification reaction with isooctyl alcohol, thereby reducing the raw material preparation process, eliminating the need for cooling, and eliminating the use of a flake forming machine, thereby greatly saving costs. The invention can also link the production line of the refined unflaked liquid trimellitic anhydride in the workshop with the preparation of trioctyl trimellitate, eliminating the step of storing flake trimellitic anhydride, and improving the production efficiency of trioctyl trimellitate. The invention has great economic production benefits and is suitable for popularization and use in workshops.

[0034] The above disclosure is only the preferred embodiment of the present invention, which certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention.

Claims

1. A method for synthesizing trioctyl trimellitate directly from liquid trimellitic anhydride, characterized in that: The synthesis method comprises the following steps: S1. Add isooctyl alcohol into the esterification kettle, and heat the esterification kettle to above 170°C. Then, input the hot refined liquid trimellitic anhydride prepared in the workshop into the esterification kettle through a pipeline. After mixing and stirring, add activated carbon and start nitrogen protection. Keep the esterification kettle warm and discharge water for 0.5h. S2. Add tetraisopropyl titanate into the esterification kettle, raise the temperature to 200-210°C and keep it warm for 2-6 hours; S3, sampling and determining the acid value <0.1mgKOH / g, esterification is completed, most of the isooctyl alcohol in the reaction solution is extracted under negative pressure, and sampling and analysis are performed; S4, when the kettle liquid is naturally cooled to 80-100°C, dilute alkali solution is added and stirred for 1 hour; S5. After the insulation is completed, the excess water and the remaining isooctyl alcohol are extracted while the temperature is increased; S6. The esterification kettle is evacuated, the temperature is lowered, and a certain amount of diatomaceous earth is added. After decolorization at 90°C for 1 hour, the filtrate is filtered while hot to obtain trioctyl trimellitate.

2. The method for synthesizing trioctyl trimellitate directly from liquid trimellitic anhydride according to claim 1, characterized in that: The hot refined unflaked liquid trimellitic anhydride in S1 is synthesized into a crude trimellitic anhydride by reacting trimellitic acid and acetic acid, and then dehydrated, dealcoholized and distilled to obtain the obtained product. The temperature of the liquid trimellitic anhydride is 170°C.

3. The method for synthesizing trioctyl trimellitate directly from liquid trimellitic anhydride according to claim 1, characterized in that: The mass ratio of liquid trimellitic anhydride to isooctyl alcohol in S1 is 1:2.5-3, and the amount of activated carbon added is 0.1-0.5% of trioctyl trimellitate.

4. The method for synthesizing trioctyl trimellitate directly from liquid trimellitic anhydride according to claim 1, characterized in that: The amount of tetraisopropyl titanate added in S2 is 0.1-1% of trioctyl trimellitate.

5. The method for synthesizing trioctyl trimellitate directly from liquid trimellitic anhydride according to claim 1, characterized in that: The dilute alkali solution in S4 is a Na2CO3 solution, and the added amount is 0.5% of trioctyl trimellitate.

6. The method for synthesizing trioctyl trimellitate directly from liquid trimellitic anhydride according to claim 1, characterized in that: The amount of diatomaceous earth added in S6 is 0.1-0.5% of trioctyl trimellitate.

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