Method and system for preparing electronic grade propylene glycol monomethyl ether based on alkaloid

Abstract

The invention discloses a method and a system for preparing electronic grade propylene glycol monomethyl ether based on alkaloid, and belongs to the technical field of chemical catalysis. According to the method, at least one alkaloid of quinine, berberine and betaine is used as a catalyst to catalyze epoxypropane and methanol to perform a ring-opening addition reaction; aiming at the characteristic that alkaloid is dissolved in a reaction system, the invention further provides an integrated separation system comprising a high-pressure reaction kettle, a first rectifying tower, a dissolving tank, a wiped-film evaporator and a second rectifying tower, so that efficient precipitation and recycling of a catalyst and high purification of a product are realized. According to the method, introduction of metal ions is fundamentally avoided, and a reaction system is mild alkaline; the total amount of metal ions in the prepared propylene glycol monomethyl ether product is lower than 10 ppb, the acidity (based on acetic acid) is lower than 5 ppm, the harsh requirements of electronic chemicals are completely met, the process is green, and the cost is low.

Description

Technical Field

[0001] This invention relates to the fields of chemical catalysis technology and fine chemical synthesis, specifically to a method and system for preparing propylene glycol methyl ether, particularly a method and system for preparing electronic-grade propylene glycol methyl ether based on alkaloids. Background Technology

[0002] In the high-tech electronics industry, high-purity PGME is a key component of electronic chemicals such as photoresists, stripping solutions, and etching solutions. It has extremely stringent purity requirements, especially regarding the content of metal ions (such as Na, K, Ca, Fe, Cu, etc.), which typically needs to be below 100 ppb or even 10 ppb, and the acidity below 10 ppm. Residual metal ions and acids can lead to fatal defects such as reduced PN junction withstand voltage and short circuits in integrated circuits, severely impacting product yield. Currently, the mainstream industrial route for large-scale PGME production is the ring-opening addition reaction of propylene oxide (PO) and methanol (MeOH) under catalysis. However, existing catalytic technologies have inherent limitations in meeting these extremely high purity requirements, specifically in acidic catalysts: including early homogeneous inorganic acids (such as sulfuric acid and hydrochloric acid) and later developed solid acids (such as acidic ion exchange resins, molecular sieves, and heteropoly acids). For example, patent CN114054060A uses a mixture of MgO, Al2O3, K3PO4, and Nb2O5 in a specific ratio to prepare a catalyst with silicon carbide as a support. While this catalyst is simple to operate and exhibits high purity and selectivity, it suffers from problems such as the strong corrosiveness of metal ions and potassium phosphate, difficulty in treating waste liquid, and challenges in completely removing metal residues through post-treatment. More importantly, the framework or pores of solid acids easily adsorb trace metal ions, which are slowly released under reaction conditions, contaminating the product. To avoid acidity issues, alkaline catalysts have been extensively studied, mainly including inorganic bases (such as sodium hydroxide and potassium hydroxide) and organic bases (such as sodium alkoxides and amines). Patent CN109796335A employs a supported CaO / MgO composite solid alkali catalysis, resulting in a fast reaction rate. However, it directly introduces high concentrations of metal ions into the system. After the reaction, complex processes such as acid neutralization, repeated washing with large amounts of water, and deep purification with ion exchange resins are required. This not only generates a large amount of saline organic wastewater but also makes it difficult to stably control the potassium / sodium ion content in the product below 10 ppb, failing to meet high-end electronic-grade standards. Patent CN101613259A uses triethylamine as a catalyst, reducing metal ion concentrations to below 5 ppb. However, triethylamine has a low boiling point (89.5℃) and is easily lost with light components, resulting in insufficient recovery and increased distillation difficulty and production costs. In summary, existing catalytic systems have inherent defects such as "metal ion contamination" or "complex post-processing," making it difficult to meet the purity requirements of electronic-grade PGME from the source. Therefore, developing a novel metal-free, neutral or mildly alkaline, highly efficient, and environmentally friendly catalyst system is of great significance for simplifying production processes, reducing costs, and promoting the localization of electronic chemicals. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method and system for preparing electronic-grade propylene glycol methyl ether based on alkaloids. The method of this invention has mild reaction conditions and is environmentally friendly. This method can avoid the introduction of metal ions and excess acid from the source and is particularly suitable for the synthesis of electronic-grade propylene glycol methyl ether.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: a method for preparing electronic-grade propylene glycol methyl ether based on alkaloids, comprising the following steps: Under alkaloid catalysis, propylene oxide and methanol react in a high-pressure reactor; wherein: The alkaloid catalyst is selected from one or more of quinine, betaine, and berberine, with quinine being preferred; The catalyst dosage is 0.1% - 5% of the mass of propylene oxide, preferably 0.6% - 1.2%; The reaction temperature is 60℃ - 120℃, preferably 85℃ - 115℃; the reaction pressure is 0.1 MPa to 3.0 MPa, preferably 0.5 MPa - 2.0 MPa.

[0005] The preparation method of this invention is green and environmentally friendly. The catalyst is derived from natural renewable biomass resources, and no saline wastewater is generated, which is in line with the concept of green chemistry and sustainable development. It has high catalytic efficiency. Alkaloids such as quinine show excellent catalytic activity and selectivity for the ring-opening addition reaction of propylene oxide and methanol. It is fundamentally metal-free. The alkaloid catalyst itself does not contain any metal elements, eliminating the source of metal ion pollution in the product from the source. The total metal ion content of the product can be stably kept below 10 ppb.

[0006] Furthermore, it also includes a separation and purification step, and the separation and purification methods used in the art to prepare electronic-grade propylene glycol methyl ether are all applicable to this invention.

[0007] To further ensure product purity, the separation and purification process includes first heating and evaporating to separate unreacted propylene oxide and methanol from the product, then raising the temperature to at least 120°C to separate propylene glycol methyl ether and byproducts, and finally obtaining high-purity propylene glycol methyl ether product by vacuum distillation.

[0008] Specifically, it also includes the following steps: After the reaction is complete, the reaction product is treated according to the following steps: First distillation separation: The reaction product liquid in the high-pressure reactor is depressurized and cooled to room temperature before being transported to the first distillation column; the first distillation column is operated at atmospheric pressure, and the top temperature is controlled at 65°C (based on the requirement of sufficient methanol vaporization and avoidance of propylene glycol methyl ether volatilization, the preferred operation can be finely adjusted within the range of 62-68°C to ensure efficient recovery of unreacted propylene oxide and methanol), recovering unreacted propylene oxide and methanol; Furthermore, an anhydrous calcium chloride dryer is installed at the top of the tower to ensure that no moisture is introduced into the circulating raw material, making it easy to return it to the high-pressure reactor for recycling. Catalyst precipitation and separation: The bottom liquid of the first distillation column (containing propylene glycol methyl ether, alkaloid catalyst, and high-boiling point) flows into the wiped-film evaporator; the operating temperature of the wiped-film evaporator is controlled at 120-180℃ and the absolute pressure at 1-10 kPa (preferably 150℃ and 3-5 kPa). Propylene glycol methyl ether is distilled off in gaseous form, and the alkaloid catalyst is discharged from the bottom in solid form and sent to the dissolution tank. Catalyst recycling: Fresh methanol is added to the dissolving tank to dissolve the solid alkaloid catalyst into a solution, which is then transported back to the high-pressure reactor through a circulation pipeline to achieve catalyst recycling; Second distillation purification: The propylene glycol methyl ether vapor phase distilled from the scraped film evaporator enters the second distillation column, which is operated under reduced pressure. The absolute pressure at the top of the column is controlled at 6.7 kPa (approximately 50 mmHg), the bottom temperature at 58-60℃, and the top temperature at 52-54℃. The byproduct 2-methoxy-1-propanol is discharged from the top of the column, and high-purity propylene glycol methyl ether is obtained from the bottom of the column.

[0009] High product purity: The mild alkaline catalytic environment avoids corrosion of equipment and generation of byproducts by strong acids or bases. The product acidity (calculated as acetic acid) is less than 3 ppm and the purity is higher than 99.9%, fully meeting electronic grade standards. Sustainable production: The integrated separation system (distillation-scraped membrane evaporation-dissolution cycle) solves the problem of recovering soluble alkaloid catalysts, achieving a catalyst recovery rate of over 90%, enabling continuous processing and far exceeding the efficiency of traditional batch processes. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of a system for preparing high-purity electronic-grade propylene glycol methyl ether in an embodiment of the present invention.

[0011] 1. High-pressure reactor; 2. First distillation column; 3. Dissolving tank; 4. Scraped film rotary evaporator; 5. Second distillation column Detailed Implementation

[0012] To further understand the purpose, content, and advantages of this invention, specific embodiments of the invention are described in detail below. However, these embodiments are not limited to the examples described below and should be freely combined according to actual circumstances. The endpoints and values ​​of the ranges disclosed herein are not limited to the precise ranges and values. For numerical ranges, endpoint values ​​of various ranges, endpoint values ​​of various ranges and individual point values, and individual point values ​​can be combined to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0013] The present invention will be further described in detail below with reference to the embodiments: This invention provides a method for preparing propylene glycol methyl ether based on alkaloids, comprising the following steps: propylene oxide and methanol are reacted in a high-pressure reactor under alkaloid catalysis; the alkaloid catalyst is selected from one or more of quinine, betaine, and berberine, and the amount of catalyst used is 0.1%-5% of the mass of propylene oxide, preferably 0.6-1.2%, for example 0.6%, 0.7%, 0.8%, 1.2%, etc.; the reaction temperature is 60℃-120℃, preferably 85℃-115℃, for example 85℃, 90℃, 95℃, 100℃, 105℃, 110℃, etc.; the reaction pressure is 0.1 MPa to 3.0 MPa, preferably 0.5 MPa-2.0 MPa, for example 0.6 MPa, 0.7 MPa, 0.8 MPa, 0.9 MPa, 1.0 MPa, 1.2 MPa, 1.3 MPa, 1.5 MPa, 1.6 MPa, etc. MPa, 1.7 MPa, 1.8 MPa, 1.9 MPa, etc. Under preferred conditions, the yield of propylene glycol methyl ether is above 60%.

[0014] In some preferred embodiments, the yield of propylene glycol methyl ether is above 75%, for example: the alkaloid is selected from betaine and / or quinine, the molar ratio of methanol to propylene oxide is 12~16:4~6 (e.g. 12:6, 16:4, etc.), the amount of catalyst is 0.6~1.2% of the mass of propylene oxide, the reaction temperature is 85~105℃, and the pressure is 0.5~2 MPa.

[0015] In some preferred embodiments, the yield of propylene glycol methyl ether is above 80%, for example: the alkaloid is selected from quinine, the molar ratio of methanol to propylene oxide is 12:4~6, the amount of catalyst is 0.8~1.2% of the mass of propylene oxide, the reaction temperature is 85~105℃, and the pressure is 1.0~2 MPa.

[0016] In some preferred embodiments, the yield of propylene glycol methyl ether is above 85%, for example: the alkaloid is selected from quinine, the molar ratio of methanol to propylene oxide is 12:4, the amount of catalyst is 0.8~1.2% of the mass of propylene oxide, the reaction temperature is 85~105℃, and the pressure is 1.0~2 MPa.

[0017] In some preferred embodiments, the yield of propylene glycol methyl ether is above 90%, for example: the alkaloid is selected from quinine, the molar ratio of methanol to propylene oxide is 12:4, the amount of catalyst is 1.0~1.2% of the mass of propylene oxide, the reaction temperature is 90~100℃, and the pressure is 1.0~2 MPa.

[0018] To obtain electronic-grade propylene glycol methyl ether, a separation and purification step is further included. All separation and purification methods used in the art to prepare electronic-grade propylene glycol methyl ether are applicable to this invention.

[0019] To obtain higher purity, some preferred embodiments provide separation and purification methods, such as first heating and evaporating to separate unreacted propylene oxide and methanol from the product, then heating to at least 120°C to separate propylene glycol methyl ether and byproducts, and then obtaining high-purity propylene glycol methyl ether product by vacuum distillation.

[0020] The following detailed description is provided with reference to more specific embodiments: General laboratory conditions: High-pressure reactor: 1L volume, made of 316L stainless steel, equipped with electric driven stirring (speed 0-600rpm), temperature control system (accuracy ±1℃) and metering pump feeding device; First distillation column: 15 theoretical plates, glass material, atmospheric pressure operation; Scraped film evaporator: made of glass, equipped with a vacuum system (absolute pressure adjustable range 1-10 kPa). Second distillation column: made of glass, operated under reduced pressure, equipped with a vacuum system and temperature control device; Detection method: Moisture content measured by Karl Fischer Moisture content was determined using a Fischer moisture analyzer, metal ions were determined by inductively coupled plasma mass spectrometry (ICP-MS), acidity was determined by potentiometric titration (0.01 mol / L NaOH standard solution), and purity was determined by gas chromatography (GC-2014, Shimadzu). Example 1

[0021] A 1L high-pressure reactor was selected, equipped with an electrically driven stirring system, temperature control system, and feeding device. First, 384.48 g (12 mol, moisture ≤0.005%) of chromatographically pure methanol was added to the reactor, followed by 2.323 g of high-purity quinine (purity ≥98%, 1.0 wt% based on propylene oxide mass). Then, 232.32 g (4 mol) of propylene oxide (purity ≥99.5%) was added. After the addition was complete, nitrogen gas was purged into the reactor three times to replace the air. Nitrogen gas served as a drying carrier gas, assisting in the removal of trace amounts of moisture or volatile impurities in the system. The reaction system pressure was adjusted to approximately 1.0 MPa, the stirring speed was adjusted to 400 rpm, and the temperature was raised to 95℃. The reaction was continued for 12 hours.

[0022] After the reaction, the system is cooled to 25°C and the pressure is slowly released. The reaction liquid is transferred to the first distillation column 2 (theoretical plate number: 15) for atmospheric distillation, with the top temperature controlled at 65°C, to recover unreacted propylene oxide and methanol (returned to the reactor). The product from the bottom of the column enters the scraped film evaporator 4, where the feed liquid is evenly distributed on the heated wall of the evaporator by a distributor, forming a thin film of uniform thickness. To achieve efficient evaporation of PGME and avoid decomposition of the heat-sensitive catalyst, the temperature of the scraped film evaporator 4 is controlled at 150°C, allowing for rapid evaporation of PGME. The scraped film evaporator 4 operates under a high vacuum. Its absolute pressure is controlled at 3-5 kPa, under which propylene glycol methyl ether distills off, and the quinine catalyst precipitates in solid form and is discharged from the bottom. The precipitated solid can be recycled back into the high-pressure reactor through the dissolution tank 3. The crude product obtained from the vapor outlet of the scraped film rotary evaporator 4 enters the second glass distillation unit 5 for vacuum distillation, with the bottom temperature controlled at 58-60°C and the top temperature at 52-54°C. A high-purity product is obtained at the top of the column by maintaining the absolute pressure at 6.7 kPa (approximately 50 mmHg) using a vacuum system, while the byproduct 2-methoxy-1-propanol is discharged from the bottom of the column. The integrated separation system (distillation-scraped evaporation-dissolution circulation) solves the problem of recovering soluble alkaloid catalysts, achieving a catalyst recovery rate of over 90%, enabling continuous processing, and significantly improving efficiency compared to traditional batch processes.

[0023] Product Analysis: Propylene glycol methyl ether yield >96.2%, propylene oxide conversion rate >96.4%. Total metal ion content in the product <8 ppb, acidity <3 ppm, purity >99.98%, moisture <0.01%. Example 2

[0024] The operating steps are the same as in Example 1, except that the catalyst is replaced with 1.856 g (purity ≥98%, 1.0 wt% based on the mass of propylene oxide) of berberine.

[0025] Product Analysis: Propylene glycol methyl ether yield >61.4%, propylene oxide conversion rate >68.7%. Total metal ion content in the product <8 ppb, acidity <3 ppm, purity >99.93%, moisture <0.01%. Example 3

[0026] The operating procedure is the same as in Example 1, except that the catalyst is replaced with 1.856 g (purity ≥98%, 1.0 wt% based on the mass of propylene oxide) of betaine.

[0027] Product Analysis: Propylene glycol methyl ether yield >78.2%, propylene oxide conversion rate >80.4%. Total metal ion content in the product <8 ppb, acidity <3 ppm, purity >99.84%, moisture <0.01%. Example 4

[0028] The operating procedure is the same as in Example 1, except that the amount of chromatographically pure methanol added is changed to 512.64 g (16 mol).

[0029] Product Analysis: Propylene glycol methyl ether yield >80.4%, propylene oxide conversion rate >87.2%. Total metal ion content in the product <8 ppb, acidity <3 ppm, purity >99.92%, moisture <0.01%. Example 5

[0030] The operating steps are the same as in Example 1, except that the amount of propylene oxide added is changed to 348.48 g (6 mol).

[0031] Product Analysis: Propylene glycol methyl ether yield >85.6%, propylene oxide conversion rate >87.5%. Total metal ion content in the product <10 ppb, acidity <3 ppm, purity >99.95%, moisture <0.01%. Example 6

[0032] The operating procedure is the same as in Example 1, except that the high-pressure reactor is adjusted to 85°C.

[0033] Product Analysis: Propylene glycol methyl ether yield >86.7%, propylene oxide conversion rate >88.3%. Total metal ion content in the product <8 ppb, acidity <3 ppm, purity >99.96%, moisture <0.01%. Example 7

[0034] The operating procedure is the same as in Example 1, except that the high-pressure reactor is heated to 105°C.

[0035] Product Analysis: Propylene glycol methyl ether yield >87.6%, propylene oxide conversion rate >88.5%. Total metal ion content in the product <8 ppb, acidity <3 ppm, purity >99.94%, moisture <0.01%. Example 8

[0036] The operating steps are the same as in Example 1, except that the amount of high-purity quinine added is changed to 1.39392g (0.6 wt% based on the mass of propylene oxide).

[0037] Product Analysis: Propylene glycol methyl ether yield >79.6%, propylene oxide conversion rate >81.9%. Total metal ion content in the product <8 ppb, acidity <3 ppm, purity >99.95%, moisture <0.01%. Example 9

[0038] The operating steps are the same as in Example 1, except that the amount of high-purity quinine added is changed to 2.3232g (0.8 wt% based on the mass of propylene oxide).

[0039] Product Analysis: Propylene glycol methyl ether yield >89.2%, propylene oxide conversion rate >90.9%. Total metal ion content in the product <8 ppb, acidity <3 ppm, purity >99.98%, moisture <0.01%. Example 10

[0040] The operating steps are the same as in Example 1, except that the amount of high-purity quinine added is changed to 2.78784 g (1.2 wt% based on the mass of propylene oxide).

[0041] Product Analysis: Propylene glycol methyl ether yield >94.4%, propylene oxide conversion rate >95.3%. Total metal ion content in the product <8 ppb, acidity <3 ppm, purity >99.96%, moisture <0.01%. Example 11

[0042] The operating steps are the same as in Example 1, except that the pressure inside the high-pressure reactor is changed to 0.5 MPa.

[0043] Product Analysis: Propylene glycol methyl ether yield >78.3%, propylene oxide conversion rate >80.6%. Total metal ion content in the product <8 ppb, acidity <3 ppm, purity >99.96%, moisture <0.01%. Example 12

[0044] The operating steps are the same as in Example 1, except that the pressure inside the high-pressure reactor is changed to 2 MPa.

[0045] Product Analysis: Propylene glycol methyl ether yield >93.2%, propylene oxide conversion rate >95.3%. Total metal ion content in the product <8 ppb, acidity <3 ppm, purity >99.95%, moisture <0.01%. Comparative Example 1

[0046] The operating steps are the same as in Example 1, using a blank experiment without a catalyst.

[0047] Product analysis: Propylene glycol methyl ether yield 25.1%, propylene oxide conversion rate 30.2%. The total metal ion content in the product is 8 ppb, acidity is 3 ppm, purity is 92.44%, and moisture content is 0.01%. Comparative Example 2

[0048] A supported CaO / MgO composite solid alkali catalyst was used as the catalyst, and a 1L high-pressure reactor (material: 316L stainless steel) was selected, equipped with an electrically driven stirring, temperature control system, and feeding device. The optimal process is as follows: First, 384.48 g (12 mol) of chromatographically pure methanol was added to the reactor, followed by 1.856 g of solid alkali (0.8 wt% based on the mass of propylene oxide). Then, 232.32 g (4 mol) of propylene oxide (purity ≥99.5%) was added. After the addition was complete, nitrogen was purged into the reactor three times to replace the air inside. The pressure of the reaction system was adjusted to approximately 1.0 MPa, the stirring speed was adjusted to 400 rpm, the temperature was raised to 85℃, and the reaction was continued for 12 hours.

[0049] After the reaction is complete, the mixture is cooled and depressurized. The reaction mixture contains a large number of suspended solid catalyst particles. First, filtration is required to remove most of the solid catalyst. Then, the filtrate is neutralized to neutral with dilute acetic acid, and washed three times repeatedly with plenty of deionized water to dissolve the generated soluble metal salts. After separating the organic phase, it is further purified using an ion exchange resin column. Finally, the purified organic phase is subjected to vacuum distillation to collect the target fraction.

[0050] Product Analysis: Propylene glycol methyl ether yield >95.3%, propylene oxide conversion rate >95.7%. Total metal ion content in the product <75 ppb, acidity <9 ppm, purity >99.97%, moisture <0.05%.

[0051] Table 1. Reaction parameters for each example and comparative example.

[0052] Table 2. Analysis results of propylene glycol methyl ether

[0053] This invention uses alkaloid catalysts (especially quinine). Under optimal conditions (Example 1: quinine dosage 1.0 wt%, reaction temperature 95℃, pressure 1.0 MPa, methanol-propylene oxide molar ratio 3:1), the yield and conversion rate of propylene glycol methyl ether both exceed 96%, which is significantly better than berberine, betaine and catalyst-free systems. The metal ion content (≤10 ppb) and acidity (≤3 ppm) of the product of this invention are superior to those of the solid base catalytic system of Comparative Example 2, and it does not require complicated water washing and ion exchange processes, fully meeting the electronic grade standards. The integrated separation and purification system developed by this invention for quinine catalysts has successfully achieved efficient recovery of homogeneous catalysts and continuous process operation, with product purity reaching electronic grade level, fully demonstrating the industrialization potential and outstanding progress of the technical solution of this invention.

[0054] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for preparing electronic-grade propylene glycol methyl ether based on alkaloids, characterized in that, The reaction includes the following steps: reacting propylene oxide and methanol under the catalysis of an alkaloid catalyst, wherein the alkaloid catalyst is selected from at least one of quinine, berberine, and betaine, the amount of catalyst used is 0.1% - 5% of the mass of propylene oxide, the reaction temperature is 60℃ - 120℃, and the reaction pressure is 0.1 MPa to 3.0 MPa.

2. The method for preparing electronic-grade propylene glycol methyl ether based on alkaloids as described in claim 1, characterized in that, It also includes separation and purification steps, which include: performing a first distillation separation on the reaction product liquid to recover unreacted propylene oxide and methanol from the top of the column, and sending the bottom liquid to a scraped membrane evaporator for treatment to precipitate and separate the alkaloid catalyst in solid form to obtain crude propylene glycol methyl ether; and performing a second distillation separation on the crude propylene glycol methyl ether to obtain electronic grade propylene glycol methyl ether.

3. The method for preparing electronic-grade propylene glycol methyl ether based on alkaloids as described in claim 2, characterized in that, The operating temperature of the scraped film evaporator is 120-180℃, and the absolute pressure is 1-10 kPa.

4. The method for preparing electronic-grade propylene glycol methyl ether based on alkaloids as described in claim 2 or 3, characterized in that, The residue rich in quinine catalyst discharged from the bottom of the scraped film evaporator is dissolved in methanol and then returned to the reaction step for recycling.

5. The method for preparing electronic-grade propylene glycol methyl ether based on alkaloids as described in claim 1, characterized in that, The alkaloids are selected from betaine and / or quinine, the molar ratio of methanol to propylene oxide is 12~16:4~6, the amount of catalyst is 0.6~1.2% of the mass of propylene oxide, the reaction temperature is 85~105℃, and the pressure is 0.5~2 MPa.

6. The method for preparing electronic-grade propylene glycol methyl ether based on alkaloids as described in claim 1, characterized in that, The alkaloids are selected from quinine, the molar ratio of methanol to propylene oxide is 12:4~6, the amount of catalyst is 0.8~1.2% of the mass of propylene oxide, the reaction temperature is 85~105℃, and the pressure is 1.0~2 MPa.

7. The method for preparing electronic-grade propylene glycol methyl ether based on alkaloids as described in claim 1, characterized in that, The alkaloids are selected from quinine, the molar ratio of methanol to propylene oxide is 12:4, the amount of catalyst is 0.8~1.2% of the mass of propylene oxide, the reaction temperature is 85~105℃, and the pressure is 1.0~2 MPa.

8. The method for preparing electronic-grade propylene glycol methyl ether based on alkaloids as described in claim 1, characterized in that, The alkaloids are selected from quinine, the molar ratio of methanol to propylene oxide is 12:4, the amount of catalyst is 1.0~1.2% of the mass of propylene oxide, the reaction temperature is 90~100℃, and the pressure is 1.0~2 MPa.

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