Preparation method of dialkyl monoether phthalate
The preparation of dialkyl monoether phthalate through esterification reaction and distillation and purification steps has solved the problems of many by-products, cumbersome post-processing and major safety hazards in the prior art, and achieved a high yield and environmentally friendly plasticizer preparation process.
Patent Information
- Application Number
- CN202411298080.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-18
- Publication Date
- 2025-03-14
AI Technical Summary
The existing methods for producing plasticizers have problems such as many by-products, complicated post-processing of crude products, and major safety hazards.
The dialkyl monoether phthalate was prepared by esterification reaction method, and the esterification reaction was carried out by heating under the catalyst concentrated sulfuric acid conditions, and the product was isolated and purified by distillation and purification steps to reduce the formation of water and acid.
This method reduces the generation of dangerous solid waste sodium sulfate and neutralized wastewater, improves product yield, and has a relatively safe and environmentally friendly process.
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Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of organic synthesis, and specifically relates to a method for preparing dialkyl monoether phthalate. Background Art
[0002] Plasticizers are important additives for polymer materials and have been widely used in many industries such as plastics, coatings, adhesives, etc., of which 90% are used in the PVC resin industry. Plasticizers, also known as plasticizers, are widely used in industry as additives for polymer materials. They are substances added to materials such as plastics, resins, and elastomers to improve their processability, plasticity, and stretchability.
[0003] However, the existing methods for producing plasticizers have various disadvantages, such as a large number of by-products, complicated post-processing of crude products, and great safety hazards. Summary of the invention
[0004] The purpose of the present application is to solve the deficiencies in the prior art and provide a method for preparing dialkyl monoether phthalate, which is beneficial to reducing hazardous solid waste sodium sulfate and neutralization wastewater and has a high yield.
[0005] The first aspect of the present application is to provide a method for preparing a dialkyl monoether phthalate, wherein the dialkyl monoether phthalate has the following structural formula (1), and the preparation method comprises the following process:
[0006]
[0007] (1) Esterification reaction: phthalic anhydride and the compound represented by formula (2) are used as raw materials, and heated in the presence of concentrated sulfuric acid as a catalyst to cause an esterification reaction. During the esterification reaction, the compound represented by formula (2) is added to the reaction system, and a mixture of the compound represented by formula (2) and water is separated from the reaction system;
[0008]
[0009] (2) distillation: transferring the mixture of the compound represented by formula (2) and water in the above step (1) to a distillation device, and transferring the compound represented by formula (2) obtained by distillation to the reaction system of the above step (1);
[0010] (3) Purification: After the esterification reaction in step (1) is completed, the organic phase is allowed to stand for separation to obtain an organic phase, and the organic phase is purified to obtain dialkyl monoether phthalate;
[0011] In the above formula (1) and formula (2), R1 is selected from any alkane of C1 to C5, and n and m are selected from any alkane of 1 to 3.
[0012] In some embodiments of the present application, in the above step (1), separating a mixture of the compound represented by formula (2) and water from the reaction system comprises:
[0013] Add salt to the reaction system, mix well and let stand, and separate a mixture of the compound represented by formula (2) and water from the bottom of the reaction system;
[0014] The above salts include one or more of sodium chloride or sodium sulfate.
[0015] In some embodiments of the present application, in the above step (1), the mass ratio between the above phthalic anhydride and the compound represented by the formula (2) is 1:(1.8-3);
[0016] and / or;
[0017] The molar ratio between the above-mentioned catalyst concentrated sulfuric acid and the above-mentioned phthalic anhydride is 1:(80-120);
[0018] and / or;
[0019] The above-mentioned concentrated sulfuric acid catalyst refers to a sulfuric acid aqueous solution with a mass fraction greater than or equal to 70%.
[0020] In some embodiments of the present application, the reaction temperature of the above step (1) is 120° C. to 160° C., and the reaction time is 4 h to 10 h.
[0021] In some embodiments of the present application, in the above step (1), the mass ratio between the above phthalic anhydride and the compound represented by the above formula (2) is 1:(2.0-2.8);
[0022] and / or;
[0023] The molar ratio between the catalyst concentrated sulfuric acid and the phthalic anhydride is 1:(90-110);
[0024] and / or;
[0025] The above reaction temperature is 130°C to 150°C, and the reaction time is 5h to 8h.
[0026] In some embodiments of the present application, in the above step (1), concentrated sulfuric acid is added under stirring conditions, and the stirring speed is 800r / min to 1200r / min, preferably, the stirring speed is 900r / min to 1000r / min.
[0027] In some embodiments of the present application, in the above step (2), the concentration of the compound represented by formula (2) in the above distillation device is detected, and when the mass percentage content of the compound represented by formula (2) in the mixture is greater than 96%, it is transferred to the reaction system of the above step (1).
[0028] In some embodiments of the present application, in the above step (2), the transfer is performed through a series reaction device.
[0029] In some embodiments of the present application, in the above step (3), after the above esterification reaction is completed, an alkaline solution is added, and then static separation is performed;
[0030] The alkaline solution is one or both of sodium hydroxide solution and potassium hydroxide solution.
[0031] In some embodiments of the present application, R1 in the above formula (1) and formula (2) is selected from any straight-chain alkane of C1 to C5, n is 2, and m is 1;
[0032] Preferably, R1 is methyl or ethyl.
[0033] Obviously, based on the above content of this application, in accordance with the common technical knowledge and customary means in this field, without departing from the above basic technical ideas of this application, other various forms of modifications, replacements or changes can be made.
[0034] Beneficial technical effects of this application:
[0035] The present application uses the alkyl glycol dialkyl ether and phthalic anhydride as raw materials to synthesize phthalic acid dialkyl monoether ester, and the preparation method has the advantage of high yield. And through the external circulation method, the water generated in the reaction process is removed, which is not only conducive to the occurrence of the reaction, but also saves the use of catalyst acid. In addition, the preparation method provided by the present application not only recycles the alkyl glycol dialkyl ether of the raw material formula (2), but also reduces the acid content in the water, greatly saving the neutralization cost, so it is conducive to reducing hazardous solid waste sodium sulfate and neutralization wastewater. BRIEF DESCRIPTION OF THE DRAWINGS
[0036] Figure 1 A process flow chart of the preparation method provided in the embodiment of the present application;
[0037] Figure 2 A nuclear magnetic resonance characterization spectrum of the target product diethylene glycol monomethyl ether phthalate provided in the examples of the present application;
[0038] Figure 3 Another nuclear magnetic resonance characterization spectrum of the target product diethylene glycol monomethyl ether phthalate provided in the examples of the present application;
[0039] Figure 4 A nuclear magnetic resonance characterization spectrum of diethylene glycol monobutyl phthalate of some examples of this application;
[0040] Figure 5This is another nuclear magnetic resonance characterization spectrum of diethylene glycol monobutyl phthalate according to some examples of this application. DETAILED DESCRIPTION
[0041] Plasticizers are important additives for polymer materials and have been widely used in many industries such as plastics, coatings, adhesives, etc., of which 90% of plasticizers are used in the PVC resin industry. Plasticizers, also known as plasticizers, are widely used in industry as polymer material additives. They are substances added to plastics, resins, elastomers and other materials to improve their processability, plasticity, and stretchability. The main function of plasticizers is to weaken the van der Waals forces between molecules of the material being acted on, increase the mobility of the molecular bonds of the material being acted on, and reduce the crystallinity of the molecular chains of the material being acted on, thereby increasing the plasticity of the resin. After adding plasticizers to the material being acted on, its melt viscosity, glass transition temperature and elastic modulus of the product will decrease, while the basic chemical properties of the material will not change.
[0042] Plasticizers are usually substances that dissolve materials. Most plasticizers are high-boiling organic liquids or low-melting solids. There are hundreds of types of plasticizers, which can be divided into aliphatic dibasic acid esters, phthalic acid esters (including phthalic acid esters and terephthalic acid esters), polybenzoic acid esters, benzoic acid esters, polyol esters, chlorinated hydrocarbons, epoxies, citrates, polyesters, etc. At present, the most commonly used are still phthalic acid ester compounds. Phthalates are the most produced and used type of plasticizers. They are general-purpose and used as the main plasticizer. They have the characteristics of light color, low toxicity, good electrical properties, low volatility, low odor, and good low temperature resistance.
[0043] Among them, dibutyl phthalate (DBP for short) is one of the main varieties of phthalate plasticizers. As a plasticizer with excellent performance, dibutyl phthalate is widely used in toys, building materials, auto parts, electronic and medical plastic products to give the products flexibility. In addition, many new applications of DBP have been developed, such as: used in the manufacture of paints, adhesives, artificial leather, printing inks, safety glass, celluloid, dyes, pesticides, fragrance solvents, fabric lubricants, etc. Due to its relatively low price and good processability, it has a strong solubility for a variety of resins. Therefore, the demand for DBP is very large and it is one of the most widely used plasticizers in industrial production.
[0044] At present, there are two main methods for producing plasticizer products such as DBP at home and abroad, which are distinguished by the type of catalyst used: acidic catalysis using protonic acid such as sulfuric acid as a catalyst and non-acid catalyst catalysis. The former has the advantages of low sulfuric acid price, high catalytic activity, mature process and high product yield; but a large amount of waste acid is produced in the reaction, which not only corrodes the equipment and pollutes the environment, but also has a large number of by-products, and the post-processing of the crude product is cumbersome, and there are also great safety hazards. The advantages of the latter are low equipment corrosion, high product quality, small amount of wastewater and easy treatment, easy alcohol recovery and low total investment cost, but there are disadvantages such as low catalyst activity, high reaction temperature and inability to achieve zero sewage discharge. Faced with the increasingly severe situation of environmental, energy, resource and sustainable development issues, a new type of plasticizer is needed to solve the problems of poor safety, serious equipment corrosion, three wastes pollution and difficult product quality control in the production process of phthalates.
[0045] At present, the research on phthalate plasticizers is mainly focused on the screening of catalysts, with less research on substrate optimization, and there has been no good method for waste treatment and process optimization.
[0046] In order to solve the above technical problems, the present application provides a method for preparing dialkyl monoether phthalate, wherein the dialkyl monoether phthalate has the following structural formula (1), and the preparation method comprises the following process:
[0047]
[0048] (1) Esterification reaction: Phthalic anhydride and the compound shown in formula (2) are used as raw materials, the mass ratio of the two is 1:(1.8-3), preferably 1:(2.0-2.8), and the esterification reaction is carried out by heating under the condition of concentrated sulfuric acid as a catalyst, and the molar ratio between the concentrated sulfuric acid as the catalyst and the above-mentioned phthalic anhydride is 1:(80-120); preferably 1:(90-110); the concentrated sulfuric acid as the catalyst refers to a sulfuric acid aqueous solution with a mass fraction greater than or equal to 70%. The esterification reaction temperature is 120°C-160°C, and the reaction time is 4h-10h. Preferably, the reaction temperature is 130°C-150°C, and the reaction time is 5h-8h.
[0049] The present application discloses in some embodiments that concentrated sulfuric acid is added under stirring conditions, and the stirring speed is 800 r / min to 1200 r / min.
[0050] During the esterification reaction, the compound represented by formula (2) is added to the reaction system, and a mixture of the compound represented by formula (2) and water is separated from the reaction system. Specifically, salt is added to the reaction system, mixed and allowed to stand, and a mixture of the compound represented by formula (2) and water is separated from the bottom of the reaction system; the salt includes one or more of sodium chloride or sodium sulfate.
[0051]
[0052] (2) Distillation: The mixture of the compound represented by formula (2) and water in the above step (1) is transferred to a distillation device, and the compound represented by formula (2) obtained by distillation is transferred to the reaction system of the above step (1); specifically, the concentration of the compound represented by formula (2) in the above distillation device is detected, and when the mass percentage content of the compound represented by formula (2) in the mixture is greater than 96%, it is transferred to the reaction system of the above step (1). The transfer is carried out through a series of reaction devices.
[0053] (3) Purification: After the esterification reaction in step (1) is completed, an alkaline solution is added, and the mixture is allowed to stand for separation to obtain an organic phase, and the organic phase is purified to obtain dialkyl monoether phthalate; the alkaline solution is one or both of a sodium hydroxide solution and a potassium hydroxide solution.
[0054] In the above formula (1) and formula (2), R1 is selected from any alkane of C1 to C5, and n and m are selected from any alkane of 1 to 3.
[0055] The present application discloses in some embodiments that dialkyl monoether phthalate comprises the structural formula shown in Table 1 below:
[0056] Table 1
[0057]
[0058]
[0059] In the following specific embodiments, the present application focuses on formula (1)-3 and formula (1)-6 as examples to discuss the preparation method of the present application, but other types of compounds are also within the scope of protection of the present application.
[0060] The present application discloses in the following embodiments: phthalic anhydride and ethylene glycol monomethyl ether are used as raw materials to undergo an esterification reaction under the action of a catalyst, sulfuric acid. In order to promote the occurrence of the reaction, during the reaction process, the ethylene glycol dimethyl ether and water in the reactor are separated, and then the separated mixture is added to a distillation device, and distilled under the condition of adding zeolite, and then the ethylene glycol monomethyl ether obtained by distillation is added back to the reactor to complete the recycling. After the esterification reaction is completed, an alkaline solution is added to the reaction solution to neutralize it to remove the catalyst, sulfuric acid, and after stirring, solid-liquid separation is performed, and the filtrate is subjected to subsequent refining steps. The specific reaction process is as follows:
[0061]
[0062] The present application provides a green synthesis process for preparing phthalate plasticizers by an external circulation method, and the process flow is as follows: Figure 1 Hint.
[0063] In the present application, the reaction between phthalic anhydride and the compound shown in formula (2) is a reversible endothermic reaction. In order to promote the rapid progress of the reaction, the present application is designed to separate the mixture of water and the compound shown in formula (2) generated during the reaction process (water and the compound shown in formula (2) are infinitely miscible), and at the same time, the compound shown in formula (2) is continuously added to the reactor to ensure the occurrence of esterification reaction in the reactor. Moreover, the mixture of water and the compound shown in formula (2) is directly transferred to the distillation system through the series-connected reaction devices, and the compound shown in formula (2) with higher purity (>96%) obtained by distillation can be returned to the reactor for reaction.
[0064] When removing water from the reactor, the miscible product of water and ethylene glycol monomethyl ether is originally in the upper layer, and the product is in the lower layer. In order to facilitate the separation of the mixture of water and ethylene glycol monomethyl ether, we added salt (sodium chloride or sodium sulfate) to it, so that the density of the water phase increased and it was transferred to the lower layer for separation. When the mixture of water and ethylene glycol monomethyl ether separated in the lower layer was distilled, water was removed to obtain ethylene glycol monomethyl ether with acid, which was then put back into the reactor for reaction.
[0065] In the present application, in addition to sulfuric acid catalysis, acid catalysts such as p-toluenesulfonic acid, hydrochloric acid and phosphoric acid were also tried in the esterification reaction.
[0066] Obviously, based on the above content of this application, in accordance with the common technical knowledge and customary means in this field, without departing from the above basic technical ideas of this application, other various forms of modifications, replacements or changes can be made.
[0067] The present application is further described below by way of examples, but is not intended to limit the present application.
[0068] Example 1
[0069] 1) Esterification reaction: In a reaction kettle equipped with a thermometer, a reflux condenser and a stirrer, 296.24 g (2.00 mol) of phthalic anhydride, 334.84 g (4.40 mol) of ethylene glycol monomethyl ether and 2.07 g (0.02 mol) of concentrated sulfuric acid were added in sequence under stirring, and then gradually heated to 150° C. and reacted for 7 hours. During the reaction, 350.0 g of ethylene glycol monomethyl ether was added to the reaction kettle, and then a certain amount of sodium chloride solution was added, and 203.88 g of a mixture of ethylene glycol monomethyl ether and water was discharged from the bottom of the reaction kettle, and the product yield (calculated as phthalic anhydride) was sampled and determined to be 77.9%, and the heating was stopped to terminate the esterification reaction.
[0070] 2) Distillation: The separated mixture of ethylene glycol monomethyl ether and water is transferred to a distillation tower, and water is removed by distillation to obtain a single component of ethylene glycol monomethyl ether (with a purity of 96.5%), which is then transferred back to an esterification reactor for reaction.
[0071] 3) Collecting the product: After the esterification reaction is completed, the stirring of the reactor is stopped, and an appropriate amount of sodium hydroxide solution is added. After standing, the organic phase is separated, and then the product is refined by vacuum distillation, and the 140°C / 705mmHg fraction is collected to obtain diethylene glycol monomethyl ether phthalate with a yield of 85.49%. 1 HNMR (400MHz, CDCl3) δ7.73(dd,J=8.0,4.0Hz,2H),7.52(dd,J=8.0,4.0Hz,2H),4.45(t,J=8.0Hz,4H),3.67(t,J=8.0Hz,4H),3.37(s,6H); 13 C NMR(100MHz, CDCl3)δ167.10,131.67,130.77,128.64,69.88,64.30,58.52; FT-IR(KBr)ν:2932.26,2889.12,2 821.06,1727.53,1599.97,1449.42,1368.85,1287.73,1122.59,1072.46,1040.80,866.13,745.29,705.17cm -1 , hydrogen spectrum and carbon spectrum refer to the attached figure of the specification Figure 2 and Figure 3 .
[0072] Example 2
[0073] 1) Esterification reaction: In a reaction kettle equipped with a thermometer, a reflux condenser and a stirrer, 296.24 g (2.00 mol) of phthalic anhydride, 365.28 g (4.80 mol) of ethylene glycol monomethyl ether and 2.07 g (0.02 mol) of concentrated sulfuric acid were added in sequence under stirring at a stirring speed of 900 r / min, and then gradually heated to 150° C. and reacted for 5 h. During the reaction, 263.31 g of ethylene glycol monomethyl ether was added to the reaction kettle, and then a certain amount of sodium chloride solution was added and 199.85 g of a mixture of ethylene glycol monomethyl ether and water was discharged from the bottom of the reaction kettle. The product yield (calculated as phthalic anhydride) was 63.82% when sampled and measured, and the heating was stopped to terminate the esterification reaction.
[0074] 2) Distillation: The separated mixture of ethylene glycol monomethyl ether and water is transferred to a distillation tower, and water is removed by distillation to obtain a single component of ethylene glycol monomethyl ether (purity of 96.1%), which is then transferred back to an esterification reactor for reaction.
[0075] 3) Collecting the product: After the esterification reaction is completed, the stirring of the reactor is stopped, and an appropriate amount of sodium hydroxide solution is added. After standing, the organic phase is separated, and then the product is refined by vacuum distillation, and the 140°C / 705mmHg fraction is collected to obtain diethylene glycol monomethyl ether phthalate with a yield of 88.33%.
[0076] Example 3
[0077] 1) Esterification reaction: In a reaction kettle equipped with a thermometer, a reflux condenser and a stirrer, 296.24 g (2.00 mol) of phthalic anhydride, 365.28 g (4.80 mol) of ethylene glycol monomethyl ether and 2.07 g (0.02 mol) of concentrated sulfuric acid were added in sequence under stirring at a stirring speed of 1000 r / min, and then gradually heated to 150° C. and reacted for 5 h. During the reaction, 263.31 g of ethylene glycol monomethyl ether was added to the reaction kettle, and then a certain amount of sodium sulfate solution was added and 188.19 g of a mixture of ethylene glycol monomethyl ether and water was discharged from the bottom of the reaction kettle. The product yield (calculated as phthalic anhydride) was measured by sampling and was 69.08%. Heating was stopped to terminate the esterification reaction.
[0078] 2) Distillation: The separated mixture of ethylene glycol monomethyl ether and water is transferred to a distillation tower, and water is removed by distillation to obtain a single component of ethylene glycol monomethyl ether (purity of 96.0%), which is then transferred back to an esterification reactor for reaction.
[0079] 3) Collecting the product: After the esterification reaction is completed, the stirring of the reactor is stopped, and an appropriate amount of sodium hydroxide solution is added. After standing, the organic phase is separated, and then the product is refined by vacuum distillation, and the 140°C / 705mmHg fraction is collected to obtain diethylene glycol monomethyl ether phthalate with a yield of 89.03%.
[0080] Example 4
[0081] 1) Esterification reaction: In a reaction kettle equipped with a thermometer, a reflux condenser and a stirrer, phthalic anhydride 296.24 g (2.00 mol), ethylene glycol monomethyl ether 426.15 g (5.60 mol) and concentrated sulfuric acid 2.07 g (0.02 mol) were added in sequence under stirring at a stirring speed of 1100 r / min, and then gradually heated to 150° C. and reacted for 5 h. During the reaction, ethylene glycol monomethyl ether 250.41 g was added to the reaction kettle, and then a certain amount of sodium sulfate solution was added and 87.47 g of a mixture of ethylene glycol monomethyl ether and water was discharged from the bottom of the reaction kettle. The product yield (calculated as phthalic anhydride) was 73.67% and the heating was stopped to terminate the esterification reaction.
[0082] 2) Distillation: The separated mixture of ethylene glycol monomethyl ether and water is transferred to a distillation tower, and water is removed by distillation to obtain a single component of ethylene glycol monomethyl ether (purity of 96.4%), which is then transferred back to an esterification reactor for reaction.
[0083] 3) Collecting the product: After the esterification reaction is completed, the stirring of the reactor is stopped, and an appropriate amount of potassium hydroxide solution is added. After standing, the organic phase is separated, and then the product is refined by vacuum distillation, and the 140°C / 705mmHg fraction is collected to obtain diethylene glycol monomethyl ether phthalate with a yield of 88.07%.
[0084] Example 5
[0085] 1) Esterification reaction: In a reaction kettle equipped with a thermometer, a reflux condenser and a stirrer, phthalic anhydride 296.24 g (2.00 mol), ethylene glycol monomethyl ether 410.94 g (5.40 mol) and concentrated sulfuric acid 2.07 g (0.02 mol) were added in sequence under stirring at a stirring speed of 1200 r / min, and then gradually heated to 150° C. and reacted for 7 h. During the reaction, ethylene glycol monomethyl ether 71.84 g was added to the reaction kettle, and then a certain amount of sodium sulfate solution was added, and 69.61 g of a mixture of ethylene glycol monomethyl ether and water was discharged from the bottom of the reaction kettle. The product yield (calculated as phthalic anhydride) was sampled and determined to be 75.49%, and the heating was stopped to terminate the esterification reaction.
[0086] 2) Distillation: The separated mixture of ethylene glycol monomethyl ether and water is transferred to a distillation tower, and water is removed by distillation to obtain a single component of ethylene glycol monomethyl ether (purity of 96.4%), which is then transferred back to an esterification reactor for reaction.
[0087] 3) Collecting the product: After the esterification reaction is completed, the stirring of the reactor is stopped, and an appropriate amount of potassium hydroxide solution is added. After standing, the organic phase is separated, and then the product is refined by vacuum distillation, and the 140°C / 705mmHg fraction is collected to obtain diethylene glycol monomethyl ether phthalate with a yield of 89.56%.
[0088] Example 6
[0089] A method for preparing a compound of formula (1)-6 is provided. The preparation method is the same as that of Example 1. The yield is 84.25%,
[0090] The hydrogen spectrum and carbon spectrum of the compound of formula (1)-6 are shown in the attached drawings of the specification. Figure 4 and Figure 5 , combined with the attached drawings, it can be seen that the hydrogen element and the carbon element have their own attributes, proving that the present application prepared the compound of formula (1)-6.
[0091] Comparative Example 1
[0092] A method for preparing a compound of formula (1)-3 is provided, which differs from Example 1 in that:
[0093] 1) Esterification reaction: In a reaction kettle equipped with a thermometer, a reflux condenser and a stirrer, 296.24 g (2.00 mol) of phthalic anhydride, 410.94 g (5.40 mol) of ethylene glycol monomethyl ether and 2.07 g (0.02 mol) of concentrated sulfuric acid were added in sequence under stirring at a stirring speed of 900 r / min, and then gradually heated to 150° C. and reacted for 7 h. During the reaction, 71.84 g of ethylene glycol monomethyl ether was added to the reaction kettle. During the solution reaction, the product yield (calculated as phthalic anhydride) was sampled and measured at 35.6%. Heating was stopped to terminate the reaction.
[0094] In this example, sulfuric acid is used as a catalyst. When a mixture of ethylene glycol monomethyl ether and water is no longer separated during the reaction, the esterification reaction cannot occur because ethylene glycol monomethyl ether and water are infinitely miscible.
[0095] It can be seen that the preparation method provided in the present application is beneficial to reducing hazardous solid waste sodium sulfate and neutralization wastewater, and has a high yield.
[0096] The above is only a preferred specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.
Claims
1. A method for preparing a dialkyl monoether phthalate, wherein the dialkyl monoether phthalate has the following structural formula (1), characterized in that: The preparation method comprises the following steps: (1) Esterification reaction: phthalic anhydride and the compound represented by formula (2) are used as raw materials, and heated in the presence of concentrated sulfuric acid as a catalyst to cause an esterification reaction. During the esterification reaction, the compound represented by formula (2) is added to the reaction system, and a mixture of the compound represented by formula (2) and water is separated from the reaction system; (2) distillation: transferring the mixture of the compound represented by formula (2) and water in step (1) to a distillation device, and transferring the compound represented by formula (2) obtained by distillation to the reaction system of step (1); (3) Purification: After the esterification reaction in step (1) is completed, the organic phase is allowed to stand for separation to obtain an organic phase, and the organic phase is purified to obtain dialkyl monoether phthalate; In the formula (1) and the formula (2), R1 is selected from any alkane of C1 to C5, and n and m are selected from any alkane of 1 to 3.
2. The preparation method according to claim 1, characterized in that: In the step (1), separating a mixture of the compound represented by formula (2) and water from the reaction system comprises: Add salt to the reaction system, mix well and let stand, and separate a mixture of the compound represented by formula (2) and water from the bottom of the reaction system; The salt includes one or more of sodium chloride or sodium sulfate.
3. The preparation method according to any one of claims 1 to 2, characterized in that: In the step (1), the mass ratio between the phthalic anhydride and the compound represented by the formula (2) is 1:(1.8-3); and / or; The molar ratio between the catalyst concentrated sulfuric acid and the phthalic anhydride is 1:(80-120); and / or; The catalyst concentrated sulfuric acid refers to a sulfuric acid aqueous solution with a mass fraction greater than or equal to 70%.
4. The preparation method according to any one of claims 1 to 3, characterized in that: The reaction temperature of step (1) is 120° C. to 160° C., and the reaction time is 4 h to 10 h.
5. The preparation method according to any one of claims 1 to 4, characterized in that: In the step (1), the mass ratio between the phthalic anhydride and the compound represented by formula (2) is 1:(2.0-2.8); and / or; The molar ratio between the catalyst concentrated sulfuric acid and the phthalic anhydride is 1:(90-110); and / or; The reaction temperature is 130° C. to 150° C., and the reaction time is 5 h to 8 h.
6. The preparation method according to any one of claims 1 to 5, characterized in that: In the step (1), concentrated sulfuric acid is added under stirring conditions, and the stirring speed is 800 r / min to 1200 r / min, preferably, the stirring speed is 900 r / min to 1000 r / min.
7. The preparation method according to any one of claims 1 to 6, characterized in that: In the step (2), the concentration of the compound represented by formula (2) in the distillation device is detected, and when the mass percentage content of the compound represented by formula (2) in the mixture is greater than 96%, it is transferred to the reaction system of the step (1).
8. The preparation method according to any one of claims 1 to 7, characterized in that: In the step (2), the transfer is performed through a series reaction device.
9. The preparation method according to any one of claims 1 to 8, characterized in that: In the step (3), after the esterification reaction is completed, an alkaline solution is added, and then the mixture is allowed to stand for separation; The alkaline solution is one or both of a sodium hydroxide solution and a potassium hydroxide solution.
10. The preparation method according to any one of claims 1 to 9, characterized in that: R1 in the formula (1) and formula (2) is selected from any straight-chain alkane of C1 to C5, n is 2, and m is 1; Preferably, R1 is methyl or ethyl.