A method for purifying 1-methoxy-2-propanol by selective covalent reaction

Abstract

The present application relates to propylene glycol monomethyl ether crude purification technical field, specifically to a kind of method for purifying 1-methoxy-2-propanol by selective covalent reaction.The method comprises: first mixed nucleophilic substrate and the crude product of propylene glycol monomethyl ether to be purified, to obtain first solution;Second mixed alkali and the crude product of propylene glycol methyl ether to be purified, to obtain second solution;Second solution is added to first solution and carried out selective covalent reaction, and then the reaction system is distilled, and the distillate is the target product;The crude product of propylene glycol monomethyl ether to be purified includes 1-methoxy-2-propanol and 2-methoxy-1-propanol.The present application utilizes the pKa of 2-methoxy-1-propanol is less than 1-methoxy-2-propanol, and the former steric hindrance is less than the latter;In nucleophilic substitution reaction, the reactivity of the former is higher than that of the latter, and it is easy to generate higher boiling point compound with nucleophilic substrate, to realize the separation and purification with 1-methoxy-2-propanol.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of propylene glycol monomethyl ether purification, and particularly relates to a method for purifying 1-methoxy-2-propanol through selective covalent reaction. BACKGROUND

[0002] Propylene glycol methyl ether (Propylene glycol methyl ether, abbreviated as PGME) is a fine chemical with excellent performance. Electronic grade PGME and its acetate are used as cleaning liquid or stripping liquid in liquid crystal panel, and are used as cleaning liquid in semiconductor manufacturing, and the market demand gradually increases. PGME is usually obtained by ring-opening reaction of methyl alcohol and propylene oxide. Due to the limited selectivity in synthesis, it is difficult to avoid side reactions in the synthesis of PGME, so the crude product of PGME contains two isomers (formula I and formula II) of 1-methoxy-2-propanol (denoted as PM) and 2-methoxy-1-propanol (denoted as MP), wherein the content of 1-methoxy-2-propanol is usually 85% to 99.9%, but as an electronic chemical, the requirement for the purity of the single component is higher.

[0003]

[0004] The existing removal of 2-methoxy-1-propanol in the isomer is based on rectification, but due to the very small difference between the boiling points of 1-methoxy-2-propanol and 2-methoxy-1-propanol (the boiling point of 1-methoxy-2-propanol is 118℃, and the boiling point of 2-methoxy-1-propanol is about 130℃), and the formation of azeotrope is easy, so the direct purification by rectification has high energy consumption, low efficiency and large product loss. SUMMARY

[0005] In order to solve the problems in the prior art, the present application provides a method for purifying 1-methoxy-2-propanol through selective covalent reaction, which has low energy consumption and can obtain 1-methoxy-2-propanol with high purity.

[0006] In order to achieve the above-mentioned application purposes, the present application provides the following technical solutions:

[0007] The present application provides a method for purifying 1-methoxy-2-propanol through selective covalent reaction, comprising the following steps:

[0008] The nucleophilic substrate and the crude propylene glycol monomethyl ether to be purified are first mixed to obtain a first solution;

[0009] The basic substance and the crude propylene glycol monomethyl ether to be purified are secondly mixed to obtain a second solution;

[0010] After the second solution is added into the first solution for selective covalent reaction, the reaction system is distilled, and the distillate is collected as the target product.

[0011] The 1-methoxy-2-propanol and 2-methoxy-1-propanol are contained in the crude propylene glycol monomethyl ether to be purified.

[0012] Preferably, the nucleophilic substrate includes one or several of maleic anhydride-styrene copolymer, benzoic anhydride, dimethoxytriphenylchloromethane, triphenylchloromethane and polymethyl acrylate.

[0013] Preferably, the basic substance includes one or several of potassium alcoholate, sodium alcoholate and organic amine.

[0014] Preferably, the organic amine includes diisopropylethylamine or triethylamine.

[0015] Preferably, the molar ratio of the basic substance to the nucleophilic substrate is 0.1-10:1.

[0016] Preferably, the temperature of the selective covalent reaction is 15-80℃, and the time is 0.5-48h.

[0017] Preferably, the distillation is reduced pressure distillation, and the temperature of the reduced pressure distillation is 80-120℃.

[0018] Preferably, the mass percentage of 2-methoxy-1-propanol in the crude propylene glycol monomethyl ether to be purified is 0.01-15%.

[0019] Preferably, the mass percentage of 1-methoxy-2-propanol in the target product is ≥98%.

[0020] Preferably, the water content in the target product is ≤200ppm.

[0021] The application provides a method for purifying 1-methoxy-2-propanol through a selective covalent reaction, comprising the following steps: first mixing a nucleophilic substrate and a crude propylene glycol monomethyl ether to be purified to obtain a first solution; second mixing an alkaline substance and the crude propylene glycol monomethyl ether to be purified to obtain a second solution; adding the second solution into the first solution to perform a selective covalent reaction, and then distilling the reaction system to collect a distillate, which is a target product; and the crude propylene glycol monomethyl ether to be purified containing 1-methoxy-2-propanol and 2-methoxy-1-propanol.

[0022] The data from the examples show that the mass fraction purity content of the single 1-methoxy-2-propanol in the purified propylene glycol monomethyl ether provided by the application can be realized from 85.0% to 99.0% or more. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 A graph showing the change of 2-methoxy-1-propanol in the products of examples 1-5 with the molar ratio of polymethyl acrylate to 2-methoxy-1-propanol. DETAILED DESCRIPTION

[0024] The application provides a method for purifying 1-methoxy-2-propanol through a selective covalent reaction, comprising the following steps:

[0025] First mixing a nucleophilic substrate and a crude propylene glycol monomethyl ether to be purified to obtain a first solution;

[0026] Second mixing an alkaline substance and the crude propylene glycol monomethyl ether to be purified to obtain a second solution;

[0027] Adding the second solution into the first solution to perform a selective covalent reaction, and then distilling the reaction system to collect a distillate, which is a target product; and the crude propylene glycol monomethyl ether to be purified containing 1-methoxy-2-propanol and 2-methoxy-1-propanol.

[0028] The application first mixes a nucleophilic substrate and a crude propylene glycol monomethyl ether to be purified to obtain a first solution.

[0029] As an implementation form, the mass percentage of 2-methoxy-1-propanol in the crude propylene glycol monomethyl ether to be purified is 0.01-15%.

[0030] As an implementation form, the nucleophilic substrate includes one or more of maleic anhydride-styrene copolymer, benzoic anhydride, dimethoxytriphenylchloromethane, triphenylchloromethane and polymethyl acrylate.

[0031] As an implementation form, the molar ratio of the nucleophilic substrate to 2-methoxy-1-propanol in the crude propylene glycol monomethyl ether to be purified is ≥1:1, and as another implementation form, the molar ratio of the nucleophilic substrate to 2-methoxy-1-propanol in the crude propylene glycol monomethyl ether to be purified is 4-50:1.

[0032] The basic substance and the propylene glycol monomethyl ether to be purified are mixed to obtain a second solution.

[0033] As an implementation form, the basic substance includes potassium alcoholate, sodium alcoholate and / or organic amine, and in specific embodiments, the potassium alcoholate can be potassium tert-butoxide, and the sodium alcoholate can be sodium tert-butoxide. As an implementation form, the organic amine includes diisopropylethylamine or triethylamine.

[0034] As an implementation form, the molar ratio of the basic substance to the nucleophilic substrate is 0.1-10:1, and in specific embodiments, the molar ratio of the basic substance to the nucleophilic substrate can be 1:1.

[0035] After obtaining the first solution and the second solution, the second solution is added to the first solution to perform a selective covalent reaction, and then the reaction system is distilled to collect the distillate as the target product.

[0036] As an implementation form, the temperature of the selective covalent reaction is 15-80°C, and the time is 0.5-48h, and in specific embodiments, the temperature can be room temperature, and the time can be 4h.

[0037] As an implementation form, the distillation is reduced pressure distillation, and the temperature of the reduced pressure distillation is 80-120°C.

[0038] The technical solutions provided by the present application will be described in detail below in combination with embodiments, but they should not be understood as limitations to the protection scope of the present application.

[0039] Example 1

[0040] (1) Polyacrylic acid methyl ester was added to a flask, and then the crude propylene glycol monomethyl ether to be purified (the mass fraction of 2-methoxy-1-propanol in the crude propylene glycol monomethyl ether to be purified was 0.56%, and the molar ratio of polyacrylic acid methyl ester to 2-methoxy-1-propanol was 1:1) was added. The polyacrylic acid methyl ester was stirred to dissolve, to obtain a first solution;

[0041] (2) Potassium tert-butoxide (the molar ratio of potassium tert-butoxide to polyacrylic acid methyl ester was 1:1) was added to a beaker, and then the propylene glycol monomethyl ether to be purified was added. The mixture was stirred to form a uniform solution, to obtain a second solution;

[0042] (3) The second solution was quickly added to the first solution under rapid stirring, and stirred at room temperature for 4 h.

[0043] (4) The purified product was collected by distillation under reduced pressure (the distillation temperature was 100°C). The isomer and other impurities in the purified product were analyzed by gas chromatography, and the water content was analyzed by a Karl Fischer water meter.

[0044] The water content in the target product of Example 1 was 182 ppm.

[0045] Example 2

[0046] The difference from Example 1 was that the molar ratio of polyacrylic acid methyl ester to 2-methoxy-1-propanol was 2:1, and the water content was 155 ppm.

[0047] Example 3

[0048] The difference from Example 1 was that the molar ratio of polyacrylic acid methyl ester to 2-methoxy-1-propanol was 4:1, and the water content was 100 ppm.

[0049] Example 4

[0050] The difference from Example 1 was that the molar ratio of polyacrylic acid methyl ester to 2-methoxy-1-propanol was 6:1, and the water content was 70 ppm.

[0051] Example 5

[0052] The difference from Example 1 was that the molar ratio of polyacrylic acid methyl ester to 2-methoxy-1-propanol was 8:1, and the water content was 110 ppm.

[0053] Figure 1 The graph of the change of 2-methoxy-1-propanol in the products of Examples 1-5 with the molar ratio of polyacrylic acid methyl ester to 2-methoxy-1-propanol is shown in Figure Figure 1 It can be seen that as the reaction proceeds, the content of 2-methoxy-1-propanol continues to decrease, and as the reactants increase, the rate of decrease of 2-methoxy-1-propanol content also accelerates accordingly.

[0054] Example 6

[0055] (1) 6.4 g of triphenylmethyl chloride was added into a flask, then the crude propylene glycol monomethyl ether to be purified (the mass percentage of 2-methoxy-1-propanol in the crude propylene glycol monomethyl ether to be purified was 0.5%, and the molar ratio of triphenylmethyl chloride to 2-methoxy-1-propanol was 4:1) was added, and triphenylmethyl chloride was dissolved by stirring to obtain a first solution;

[0056] (2) 1.42 g of diisopropylethylamine was added into a beaker, then the propylene glycol methyl ether to be purified was added, and stirring was performed to form a uniform solution to obtain a second solution;

[0057] (3) The second solution was quickly added into the first solution under rapid stirring, and stirring was performed at room temperature for 4 h.

[0058] (4) The purified product was collected by distillation under reduced pressure (the distillation temperature was 120°C), the isomer and other impurities in the purified product were analyzed by gas chromatography, and the water content was analyzed by a Karl Fischer water meter.

[0059] It was detected that the mass percentage of 2-methoxy-1-propanol in the purified product was 0.3%, and the water content was 180 ppm.

[0060] Example 7

[0061] (1) 7.78 g of dimethoxytriphenylmethyl chloride was added into a flask, then the crude propylene glycol monomethyl ether to be purified (the mass percentage of 2-methoxy-1-propanol in the crude propylene glycol monomethyl ether to be purified was 0.36%, and the molar ratio of dimethoxytriphenylmethyl chloride to 2-methoxy-1-propanol was 6:1) was added, and dimethoxytriphenylmethyl chloride was dissolved by stirring to obtain a first solution;

[0062] (2) 1.42 g of diisopropylethylamine was added into a beaker, then the propylene glycol methyl ether to be purified was added, and stirring was performed to form a uniform solution to obtain a second solution;

[0063] (3) The second solution was quickly added into the first solution under rapid stirring, and stirring was performed at room temperature for 4 h.

[0064] (4) The purified product was collected by distillation under reduced pressure (the distillation temperature was 90°C), the isomer and other impurities in the purified product were analyzed by gas chromatography, and the water content was analyzed by a Karl Fischer water meter.

[0065] It was detected that the mass percentage of 2-methoxy-1-propanol in the purified product was 0.22%, and the water content was 100 ppm.

[0066] Example 8

[0067] (1) 2.18 g of benzoic anhydride was added into a flask, and then the crude propylene glycol monomethyl ether to be purified (the mass percentage of 2-methoxy-1-propanol in the crude propylene glycol monomethyl ether to be purified was 0.55%, and the molar ratio of benzoic anhydride to 2-methoxy-1-propanol was 6:1) was added, and the benzoic anhydride was stirred to dissolve to obtain a first solution;

[0068] (2) 1.12 g of triethylamine was added into a beaker, and then the propylene glycol methyl ether to be purified was added, and the mixture was stirred to form a uniform solution to obtain a second solution;

[0069] (3) The second solution was quickly added into the first solution under rapid stirring, and the mixture was stirred at room temperature for 4 h.

[0070] (4) The purified product was collected by distillation under reduced pressure (the distillation temperature was 80°C), the isomer and other impurities in the purified product were analyzed by gas chromatography, and the water content was analyzed by a Karl Fischer water meter.

[0071] It was detected that the mass percentage of 2-methoxy-1-propanol in the purified product was 0.37%, and the water content was 80 ppm.

[0072] Example 9

[0073] (1) 3.66 g of maleic anhydride-styrene copolymer was added into a flask, and then the crude propylene glycol monomethyl ether to be purified (the mass percentage of 2-methoxy-1-propanol in the crude propylene glycol monomethyl ether to be purified was 0.55%, and the molar ratio of maleic anhydride-styrene copolymer to 2-methoxy-1-propanol was 5:1) was added, and the maleic anhydride-styrene copolymer was stirred to dissolve to obtain a first solution;

[0074] (2) 1.42 g of diisopropylethylamine was added into a beaker, and then the propylene glycol methyl ether to be purified was added, and the mixture was stirred to form a uniform solution to obtain a second solution;

[0075] (3) The second solution was quickly added into the first solution under rapid stirring, and the mixture was stirred at room temperature for 4 h.

[0076] (4) The purified product was collected by distillation under reduced pressure, the isomer and other impurities in the purified product were analyzed by gas chromatography, and the water content was analyzed by a Karl Fischer water meter.

[0077] It was detected that the mass percentage of 2-methoxy-1-propanol in the purified product was 0.35%, and the water content was 100 ppm.

[0078] Example 10

[0079] The difference from Example 9 is only that the mass percentage of 2-methoxy-1-propanol in the crude propylene glycol monomethyl ether to be purified was 15%.

[0080] The mass percentage of 2-methoxy-1-propanol in the purified product was 0.27%, and the water content was 200 ppm.

[0081] It should be noted that the purity of the product in this embodiment was detected by GC-MS method.

[0082] Although the above embodiment has made a detailed description of the present application, it is only a part of the embodiments of the present application, but not all the embodiments, and other embodiments can be obtained according to the embodiment without creativity, which belong to the protection scope of the present application.

Claims

1. A method for purifying 1-methoxy-2-propanol by selective covalent reaction, comprising the following steps: The nucleophilic substrate and the crude propylene glycol monomethyl ether to be purified were first mixed to obtain the first solution; The alkaline substance and the crude propylene glycol monomethyl ether to be purified were mixed to obtain a second solution; After adding the second solution to the first solution to carry out a selective covalent reaction, the reaction system is distilled, and the distillate is the target product. The crude propylene glycol monomethyl ether to be purified contains 1-methoxy-2-propanol and 2-methoxy-1-propanol; The nucleophilic substrate is dimethoxytriphenylchloromethane or triphenylchloromethane; The alkaline substance is potassium tert-butoxide, diisopropylethylamine, or triethylamine; The molar ratio of the basic substance to the nucleophilic substrate is 0.1 to 10:

1.

2. The method as described in claim 1, characterized in that, The selective covalent reaction is carried out at a temperature of 15–80 °C for a time of 0.5–48 h.

3. The method as described in claim 1, characterized in that, The distillation is vacuum distillation; the temperature of the vacuum distillation is 80–120°C.

4. The method as described in claim 1, characterized in that, The crude propylene glycol monomethyl ether to be purified contains 0.01–15% 2-methoxy-1-propanol by mass.

5. The method as described in claim 1, characterized in that, The target product contains ≥98% by mass of 1-methoxy-2-propanol.

6. The method as described in claim 1, characterized in that, The moisture content of the target product is ≤200ppm.

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