Medicinal glacial acetic acid and preparation method thereof

Abstract

The invention relates to the field of pharmaceutic adjuvants, and provides a preparation method of pharmaceutical grade glacial acetic acid, which ensures that the produced glacial acetic acid meets the pharmaceutical standard and has the characteristics of high purity, low impurity content and the like through a specific process flow and strict quality control, and comprises the following steps: adding 0.5-3 parts by weight of potassium permanganate into a distillation kettle; 1500-2500 parts of a glacial acetic acid crude product is added into a distillation kettle, and medicinal glacial acetic acid is obtained through a redistillation process, a head removal process and a distillation process; the redistillation temperature ranges from 118 DEG C to 125 DEG C, and the redistillation time ranges from 0.8 h to 1.5 h; in the head removing process, front fractions at the temperature of 108-113 DEG C or below are removed; in the distillation process, fractions with the boiling point within + / -1 DEG C of glacial acetic acid are collected. According to the invention, potassium permanganate is used as a strong oxidant and can remove reducing substances in the raw materials; the charging sequence is that potassium permanganate is firstly added and then glacial acetic acid is added so as to prevent violent reaction caused by overhigh local concentration; the glacial acetic acid and potassium permanganate can be fully contacted and reacted by redistillation; and low-boiling-point impurities can be removed through head removal, and the product purity is improved.

Description

Technical Field

[0001] This invention relates to the field of pharmaceutical excipients, and more specifically, to a pharmaceutical-grade glacial acetic acid and its preparation method. Background Technology

[0002] Glacial acetic acid is an important pharmaceutical excipient, widely used in the medical field, such as as a pH adjuster and solvent. However, the quality of some glacial acetic acid products on the market is inconsistent, making it difficult to meet the stringent requirements for pharmaceutical use. To ensure the safety and efficacy of pharmaceuticals, developing a stable method for producing glacial acetic acid that meets pharmaceutical standards is of significant practical importance. Summary of the Invention

[0003] The purpose of this invention is to provide a pharmaceutical-grade glacial acetic acid and its preparation method. Through a specific process and strict quality control, the produced glacial acetic acid is ensured to meet pharmaceutical standards and has the characteristics of high purity and low impurity content.

[0004] The embodiments of the present invention are achieved through the following technical solutions:

[0005] A method for preparing pharmaceutical-grade glacial acetic acid includes: adding 0.5-3 parts by weight of potassium permanganate to a distillation vessel, then adding 1500-2500 parts by weight of crude glacial acetic acid to the distillation vessel, and obtaining pharmaceutical-grade glacial acetic acid through a reflux process, a decanting process, and a distillation process; wherein the reflux temperature is 118-125℃ and the reflux time is 0.8-1.5h; the decanting process removes the pre-distillate below 108-113℃; and the distillation process collects the fraction within the boiling point ±1℃ range of glacial acetic acid.

[0006] Preferably, the mass ratio of potassium permanganate to glacial acetic acid is 1:2000.

[0007] Preferably, the product obtained from the decapping process is filtered and then distilled.

[0008] Preferably, the filtration process includes, in sequence, membrane filtration and molecular sieve filtration; the membrane has a pore size of 0.1-0.4 μm and a transmembrane pressure difference of 400-600 kPa.

[0009] High-density polyethylene membranes can be used for membrane filtration.

[0010] Preferably, the molecular sieve filtration uses zeolite molecular sieves.

[0011] Preferably, the chemical composition of the zeolite molecular sieve includes calcium ions; the pore size of the zeolite molecular sieve is 0.4-0.6 nm; and the temperature of the crude glacial acetic acid passing through the zeolite molecular sieve is 2-10 °C.

[0012] Preferably, the distillation process is carried out under reduced pressure, with a pressure of 0.1-0.4 standard atmospheres.

[0013] Preferably, the crude glacial acetic acid contains iron ions, copper ions, cobalt ions, and manganese ions.

[0014] A pharmaceutical-grade glacial acetic acid prepared by the aforementioned method.

[0015] Preferably, the purity of pharmaceutical-grade glacial acetic acid is ≥99.5%, and the heavy metal content is <2ppb.

[0016] The present invention has at least the following beneficial effects:

[0017] In this invention, potassium permanganate acts as a strong oxidant, removing reducing substances from the raw materials, such as aldehydes and unsaturated compounds. The feeding sequence is potassium permanganate first, followed by glacial acetic acid, to prevent excessively high local concentrations that could trigger violent reactions. Reflux allows glacial acetic acid and potassium permanganate to fully react, promoting the oxidative decomposition of impurities and stabilizing the system temperature, thus improving subsequent distillation efficiency. De-heading removes low-boiling-point impurities such as water, formic acid, formaldehyde, and acetaldehyde, increasing product purity. Membrane filtration and molecular sieve filtration effectively enhance the purity of glacial acetic acid; molecular sieve filtration removes heavy metal ions through ion exchange. By selecting the types of cations on the molecular sieve and combining them with subsequent vacuum distillation, this invention further improves product purity. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a flowchart of the preparation method of pharmaceutical-grade glacial acetic acid in this invention. Detailed Implementation

[0020] To make the objectives, methods, and advantages of the embodiments of the present invention clearer, the methods in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0021] Example 1: As Figure 1As shown, a method for preparing pharmaceutical-grade glacial acetic acid includes: adding 0.5 parts by weight of potassium permanganate to a distillation vessel, then adding 1500 parts by weight of crude glacial acetic acid to the distillation vessel, and obtaining pharmaceutical-grade glacial acetic acid through a reflux process, a decanting process, and a distillation process; the reflux temperature is 118℃, and the reflux time is 0.8h; the decanting process removes the pre-distillate below 108℃; the distillation process collects the fraction within ±1℃ of the boiling point of glacial acetic acid; the distillation process uses vacuum distillation at a pressure of 0.1 standard atmospheres; the crude glacial acetic acid contains iron ions, copper ions, cobalt ions, and manganese ions.

[0022] Example 2: As Figure 1 As shown, a method for preparing pharmaceutical-grade glacial acetic acid includes: adding 3 parts by weight of potassium permanganate to a distillation vessel, then adding 2500 parts by weight of crude glacial acetic acid to the distillation vessel, and obtaining pharmaceutical-grade glacial acetic acid through a reflux process, a decanting process, and a distillation process; the reflux temperature is 125℃, and the reflux time is 1.5h; the decanting process removes the pre-distillate below 113℃; the distillation process collects the fraction within ±1℃ of the boiling point of glacial acetic acid; the distillation process uses vacuum distillation at a pressure of 0.4 standard atmospheres; the crude glacial acetic acid contains iron ions, copper ions, cobalt ions, and manganese ions.

[0023] Example 3: As Figure 1 As shown, a method for preparing pharmaceutical-grade glacial acetic acid includes: adding 1 part by weight of potassium permanganate to a distillation vessel, then adding 2000 parts by weight of crude glacial acetic acid to the distillation vessel, and obtaining pharmaceutical-grade glacial acetic acid through a reflux process, a decanting process, and a distillation process; the reflux temperature is 120℃, and the reflux time is 1 hour; the decanting process removes the pre-distillate below 113℃; the distillation process collects the fraction within ±1℃ of the boiling point of glacial acetic acid; the distillation process uses vacuum distillation at a pressure of 0.25 standard atmospheres; the crude glacial acetic acid contains iron ions, copper ions, cobalt ions, and manganese ions.

[0024] Example 4: Figure 1As shown, a method for preparing pharmaceutical-grade glacial acetic acid includes: adding 1 part by weight of potassium permanganate to a distillation vessel, then adding 2000 parts by weight of crude glacial acetic acid to the distillation vessel, and obtaining pharmaceutical-grade glacial acetic acid through a reflux process, a decanting process, and a distillation process; the reflux temperature is 120℃, and the reflux time is 1 hour; the decanting process removes the pre-distillate below 113℃; the distillation process collects the fraction within ±1℃ of the boiling point of glacial acetic acid; the distillation process uses vacuum distillation at a pressure of 0.25 standard atmospheres; the crude glacial acetic acid contains iron ions, copper ions, cobalt ions, and manganese ions. The product obtained from the de-heading process is filtered and then enters the distillation process. The filtration process includes, in sequence, membrane filtration and molecular sieve filtration. The membrane has a pore size of 0.1 μm and a transmembrane pressure difference of 400 kPa. The molecular sieve filtration uses zeolite molecular sieves. The chemical composition of the zeolite molecular sieve includes calcium ions. The pore size of the zeolite molecular sieve is 0.4 nm. The temperature of the crude glacial acetic acid passing through the zeolite molecular sieve is 10°C.

[0025] Example 5: Figure 1 As shown, a method for preparing pharmaceutical-grade glacial acetic acid includes: adding 1 part by weight of potassium permanganate to a distillation vessel, then adding 2000 parts by weight of crude glacial acetic acid to the distillation vessel, and obtaining pharmaceutical-grade glacial acetic acid through a reflux process, a decanting process, and a distillation process; the reflux temperature is 120℃, and the reflux time is 1 hour; the decanting process removes the pre-distillate below 113℃; the distillation process collects the fraction within ±1℃ of the boiling point of glacial acetic acid; the distillation process uses vacuum distillation at a pressure of 0.25 standard atmospheres; the crude glacial acetic acid contains iron ions, copper ions, cobalt ions, and manganese ions. The product obtained from the de-heading process is filtered and then enters the distillation process. The filtration process includes, in sequence, membrane filtration and molecular sieve filtration. The membrane has a pore size of 0.4 μm and a transmembrane pressure difference of 600 kPa. The molecular sieve filtration uses zeolite molecular sieves. The chemical composition of the zeolite molecular sieve includes calcium ions. The pore size of the zeolite molecular sieve is 0.6 nm. The temperature of the crude glacial acetic acid passing through the zeolite molecular sieve is 2 °C.

[0026] Example 6: As Figure 1As shown, a method for preparing pharmaceutical-grade glacial acetic acid includes: adding 1 part by weight of potassium permanganate to a distillation vessel, then adding 2000 parts by weight of crude glacial acetic acid to the distillation vessel, and obtaining pharmaceutical-grade glacial acetic acid through a reflux process, a decanting process, and a distillation process; the reflux temperature is 120℃, and the reflux time is 1 hour; the decanting process removes the pre-distillate below 113℃; the distillation process collects the fraction within ±1℃ of the boiling point of glacial acetic acid; the distillation process uses vacuum distillation at a pressure of 0.25 standard atmospheres; the crude glacial acetic acid contains iron ions, copper ions, cobalt ions, and manganese ions. The product obtained from the de-heading process is filtered and then enters the distillation process. The filtration process includes, in sequence, membrane filtration and molecular sieve filtration. The membrane has a pore size of 0.3 μm and a transmembrane pressure difference of 500 kPa. The molecular sieve filtration uses zeolite molecular sieves. The chemical composition of the zeolite molecular sieve includes calcium ions. The pore size of the zeolite molecular sieve is 0.5 nm. The temperature of the crude glacial acetic acid passing through the zeolite molecular sieve is 6 °C.

[0027] Comparative Example 1: A method for preparing pharmaceutical-grade glacial acetic acid, comprising: adding 1 part by weight of potassium permanganate to a distillation vessel, then adding 2000 parts by weight of crude glacial acetic acid to the distillation vessel, and obtaining pharmaceutical-grade glacial acetic acid through a reflux process, a decanting process, and a distillation process; the reflux temperature is 120℃, and the reflux time is 1h; the decanting process removes the pre-distillate below 113℃; the distillation process collects the fraction within ±1℃ of the boiling point of glacial acetic acid; the distillation process uses vacuum distillation at a pressure of 0.25 standard atmospheres; the crude glacial acetic acid contains: iron ions, copper ions, cobalt ions, and manganese ions. The product obtained from the decanting process is filtered before entering the distillation process; the filtration process sequentially includes: membrane filtration; the membrane pore size is 0.3μm, and the transmembrane pressure difference is 500kPa.

[0028] Comparative Example 2: A method for preparing pharmaceutical-grade glacial acetic acid, comprising: adding 1 part by weight of potassium permanganate to a distillation vessel, then adding 2000 parts by weight of crude glacial acetic acid to the distillation vessel, and obtaining pharmaceutical-grade glacial acetic acid through a reflux process, a decanting process, and a distillation process; the reflux temperature is 120℃, and the reflux time is 1 hour; the decanting process removes the fraction below 113℃; the distillation process collects the fraction within ±1℃ of the boiling point of glacial acetic acid; the distillation process uses vacuum distillation at a pressure of 0.25 standard atmospheres; the crude glacial acetic acid contains: iron ions, copper ions, cobalt ions, and manganese ions. The product obtained from the decanting process is filtered and then enters the distillation process; the filtration process sequentially includes: molecular sieve filtration; the molecular sieve filtration uses zeolite molecular sieves; the chemical composition of the zeolite molecular sieve includes: calcium ions; the pore size of the zeolite molecular sieve is 0.5 nm; the temperature of the crude glacial acetic acid passing through the zeolite molecular sieve is 6℃.

[0029] Comparative Example 3: A method for preparing pharmaceutical-grade glacial acetic acid, comprising: adding 1 part by weight of potassium permanganate to a distillation vessel, then adding 2000 parts by weight of crude glacial acetic acid to the distillation vessel, and obtaining pharmaceutical-grade glacial acetic acid through a reflux process, a decanting process, and a distillation process; wherein the reflux temperature is 120℃ and the reflux time is 1h; the decanting process removes the pre-distillate below 113℃; the distillation process collects the fraction within the boiling point ±1℃ of glacial acetic acid; the distillation process is performed at atmospheric pressure; the crude glacial acetic acid comprises: iron ions, copper ions, cobalt ions, and manganese ions. The product obtained from the de-heading process is filtered and then enters the distillation process. The filtration process includes, in sequence, membrane filtration and molecular sieve filtration. The membrane has a pore size of 0.3 μm and a transmembrane pressure difference of 500 kPa. The molecular sieve filtration uses zeolite molecular sieves. The chemical composition of the zeolite molecular sieve includes calcium ions. The pore size of the zeolite molecular sieve is 0.5 nm. The temperature of the crude glacial acetic acid passing through the zeolite molecular sieve is 6 °C.

[0030] Comparative Example 4: A method for preparing pharmaceutical-grade glacial acetic acid, comprising: adding 1 part by weight of potassium permanganate to a distillation vessel, then adding 2000 parts by weight of crude glacial acetic acid to the distillation vessel, and obtaining pharmaceutical-grade glacial acetic acid through a reflux process, a decanting process, and a distillation process; wherein the reflux temperature is 120℃ and the reflux time is 1h; the decanting process removes the pre-distillate below 113℃; the distillation process collects the fraction within ±1℃ of the boiling point of glacial acetic acid; the distillation process employs vacuum distillation at a pressure of 0.25 standard atmospheres; the crude glacial acetic acid comprises: iron ions, copper ions, cobalt ions, and manganese ions. The product obtained from the de-heading process is filtered and then enters the distillation process. The filtration process includes, in sequence, membrane filtration and molecular sieve filtration. The membrane has a pore size of 0.3 μm and a transmembrane pressure difference of 500 kPa. The molecular sieve filtration uses zeolite molecular sieves. The chemical composition of the zeolite molecular sieve includes sodium ions. The pore size of the zeolite molecular sieve is 0.5 nm. The temperature of the crude glacial acetic acid passing through the zeolite molecular sieve is 6 °C.

[0031] Comparative Example 5: A method for preparing pharmaceutical-grade glacial acetic acid, comprising: adding 1 part by weight of potassium permanganate to a distillation vessel, then adding 2000 parts by weight of crude glacial acetic acid to the distillation vessel, and obtaining pharmaceutical-grade glacial acetic acid after a decanting and distillation process; the decanting process removes the pre-distillate below 113°C; the distillation process collects the fraction within ±1°C of the boiling point of glacial acetic acid; the distillation process employs vacuum distillation at a pressure of 0.25 standard atmospheres; the crude glacial acetic acid contains iron ions, copper ions, cobalt ions, and manganese ions. The product obtained from the decanting process is filtered before entering the distillation process; the filtration process sequentially includes membrane filtration and molecular sieve filtration; the membrane has a pore size of 0.3 μm and a transmembrane pressure difference of 500 kPa; the molecular sieve filtration uses a zeolite molecular sieve; the chemical composition of the zeolite molecular sieve includes calcium ions; the pore size of the zeolite molecular sieve is 0.5 nm; the temperature of the crude glacial acetic acid passing through the zeolite molecular sieve is 6°C.

[0032] Comparative Example 6: A method for preparing pharmaceutical-grade glacial acetic acid, comprising: adding 1 part by weight of potassium permanganate to a distillation vessel, then adding 2000 parts by weight of crude glacial acetic acid to the distillation vessel, and obtaining pharmaceutical-grade glacial acetic acid through a reflux process, a decanting process, and a distillation process; wherein the reflux temperature is 120℃ and the reflux time is 1h; the decanting process removes the pre-distillate below 113℃; the distillation process collects the fraction within the boiling point ±1℃ of glacial acetic acid; the distillation process employs vacuum distillation at a pressure of 0.25 standard atmospheres; the crude glacial acetic acid comprises: iron ions, copper ions, cobalt ions, and manganese ions. The product obtained from the de-heading process is filtered and then enters the distillation process. The filtration process includes, in sequence, membrane filtration and molecular sieve filtration. The membrane has a pore size of 0.3 μm and a transmembrane pressure difference of 500 kPa. The molecular sieve filtration uses zeolite molecular sieves. The chemical composition of the zeolite molecular sieve includes calcium ions. The pore size of the zeolite molecular sieve is 0.5 nm. The temperature of the crude glacial acetic acid passing through the zeolite molecular sieve is 25°C.

[0033] Comparative Example 7: A method for preparing pharmaceutical-grade glacial acetic acid, comprising: adding 1 part by weight of potassium permanganate to a distillation vessel, then adding 2000 parts by weight of crude glacial acetic acid to the distillation vessel, and obtaining pharmaceutical-grade glacial acetic acid through a reflux process, a decanting process, and a distillation process; wherein the reflux temperature is 120℃ and the reflux time is 1h; the decanting process removes the pre-distillate below 113℃; the distillation process collects the fraction within ±1℃ of the boiling point of glacial acetic acid; the distillation process employs vacuum distillation at a pressure of 0.25 standard atmospheres; the crude glacial acetic acid comprises: iron ions, copper ions, cobalt ions, and manganese ions. The product obtained from the de-heading process is filtered and then enters the distillation process. The filtration process includes, in sequence, membrane filtration and molecular sieve filtration. The membrane has a pore size of 0.3 μm and a transmembrane pressure difference of 500 kPa. The molecular sieve filtration uses zeolite molecular sieves. The chemical composition of the zeolite molecular sieve includes calcium ions. The pore size of the zeolite molecular sieve is 1 nm. The temperature of the crude glacial acetic acid passing through the zeolite molecular sieve is 6 °C.

[0034] Comparative Example 8: A method for preparing pharmaceutical-grade glacial acetic acid, comprising: adding 2000 parts by weight of crude glacial acetic acid to a distillation vessel, and obtaining pharmaceutical-grade glacial acetic acid through a reflux process, a decanting process, and a distillation process; wherein the reflux temperature is 120℃ and the reflux time is 1h; the decanting process removes the pre-distillate below 113℃; the distillation process collects the distillate within the boiling point ±1℃ range of glacial acetic acid; the distillation process employs vacuum distillation at a pressure of 0.25 standard atmospheres; the crude glacial acetic acid comprises: iron ions, copper ions, cobalt ions, and manganese ions. The product obtained from the de-heading process is filtered and then enters the distillation process. The filtration process includes, in sequence, membrane filtration and molecular sieve filtration. The membrane has a pore size of 0.3 μm and a transmembrane pressure difference of 500 kPa. The molecular sieve filtration uses zeolite molecular sieves. The chemical composition of the zeolite molecular sieve includes calcium ions. The pore size of the zeolite molecular sieve is 0.5 nm. The temperature of the crude glacial acetic acid passing through the zeolite molecular sieve is 6 °C.

[0035] Experiment 1: The purity of pharmaceutical-grade glacial acetic acid prepared according to the preparation methods provided in Examples 1-6 and Comparative Examples 1-8 was tested. The test methods are as follows:

[0036] The test was conducted using an automatic titrator. The specific method was as follows: accurately weigh 1g of sample, add purified water to make up to 250ml volumetric flask, transfer 10ml of test solution to 70ml of water, and titrate with sodium hydroxide standard solution to the endpoint. The test results are shown in Table 1.

[0037] Table 1

[0038] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative Example 1 Acetic acid concentration (wt%) 96.17 96.75 96.82 97.84 98.26 98.78 89.47 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Comparative Example 7 Comparative Example 8 Acetic acid concentration (wt%) 92.39 81.11 83.06 93.61 87.34 89.57 92.76

[0039] As can be seen from the test results of Examples 1-6, the acetic acid prepared according to the preparation method provided by the present invention meets the requirements for pharmaceutical grade.

[0040] As can be seen from the comparison between Comparative Example 1 and Example 6, molecular sieve filtration can significantly improve the purity of acetic acid products.

[0041] As can be seen from the comparison between Comparative Example 2 and Example 6, membrane filtration can improve the purity of acetic acid products to a certain extent.

[0042] As can be seen from the comparison between Comparative Example 3 and Example 6, vacuum distillation can significantly improve the purity of acetic acid products.

[0043] As can be seen from the comparison between Comparative Example 4 and Example 6, the types of cations used for exchange on the zeolite molecular sieve affect the purity of the final acetic acid product.

[0044] As can be seen from the comparison between Comparative Example 5 and Example 6, the reflux process affects the purity of the acetic acid product.

[0045] As can be seen from the comparison between Comparative Example 6 and Example 6, the temperature of the crude glacial acetic acid affects the filtration effect during the zeolite molecular sieve filtration process.

[0046] As can be seen from the comparison between Comparative Example 7 and Example 6, the pore size of the zeolite molecular sieve affects the final filtration effect.

[0047] As can be seen from the comparison between Comparative Example 8 and Example 6, the purity of the final product can be improved by using potassium permanganate to oxidize and reduce substances.

[0048] Experiment 2: The total content of metal ions (aluminum ions, arsenic ions, antimony ions, barium ions, beryllium ions, boron ions, cadmium ions, calcium ions, chromium ions, cobalt ions, copper ions, germanium ions, gold ions, indium ions, iron ions, lead ions, lithium ions, magnesium ions, manganese ions, nickel ions, potassium ions, platinum ions, silicon ions, silver ions, sodium ions, strontium ions, tin ions, tantalum ions, titanium ions, thallium ions, and zinc ions) of pharmaceutical-grade glacial acetic acid prepared according to the preparation methods provided in Examples 1-6 and Comparative Examples 1-8 was tested. The test method is as follows:

[0049] Inductively coupled plasma mass spectrometry (ICP-MS) was used for detection and analysis. 5g of sample, accurate to 0.01g, was slowly placed into a 50mL volumetric flask containing a small amount of ultrapure water. The flask was cooled to room temperature, diluted to the mark with water, and then shaken well. The signal intensity of each element in the sample was measured under the same analytical conditions as the standard solution series. The experimental results are shown in Table 2.

[0050] Table 2

[0051] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative Example 1 Total amount of metal ions (ppb) 1.58 1.55 1.54 1.07 0.98 0.94 3.76 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Comparative Example 7 Comparative Example 8 Total amount of metal ions (ppb) 2.45 4.01 3.52 1.33 2.06 2.14 1.38

[0052] As can be seen from the test results of Examples 1-6, the total amount of metal ions in the acetic acid prepared by the preparation method provided by the present invention is low, which meets the requirements for pharmaceutical grade.

[0053] As can be seen from the comparison between Comparative Example 1 and Example 6, molecular sieve filtration can significantly reduce the content of metal ions in acetic acid products.

[0054] As can be seen from the comparison between Comparative Example 2 and Example 6, membrane filtration can reduce the content of metal ions in acetic acid products to a certain extent.

[0055] As can be seen from the comparison between Comparative Example 3 and Example 6, vacuum distillation can significantly reduce the content of metal ions in acetic acid products.

[0056] As can be seen from the comparison between Comparative Example 4 and Example 6, the types of cations used for exchange on the zeolite molecular sieve affect the content of metal ions in the final acetic acid product.

[0057] As can be seen from the comparison between Comparative Example 5 and Example 6, the reflux process affects the content of metal ions in the acetic acid product.

[0058] As can be seen from the comparison between Comparative Example 6 and Example 6, during the zeolite molecular sieve filtration process, the temperature of the crude glacial acetic acid product affects the content of metal ions in the acetic acid product.

[0059] As can be seen from the comparison between Comparative Example 7 and Example 6, the pore size of the zeolite molecular sieve affects the final metal ion removal effect.

[0060] As can be seen from the comparison between Comparative Example 8 and Example 6, the content of metal ions in acetic acid products can be reduced to a certain extent after potassium permanganate is used to oxidize and reduce substances.

[0061] The above are merely preferred embodiments of the present invention and are not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing pharmaceutical-grade glacial acetic acid, characterized in that, include: By weight, 0.5-3 parts of potassium permanganate are added to the distillation vessel, and then 1500-2500 parts of crude glacial acetic acid are added to the distillation vessel. Pharmaceutical grade glacial acetic acid is obtained by reflux, decapsulation and distillation. The reflux temperature is 118-125℃, and the reflux time is 0.8-1.5h; The de-heading process removes the fore fraction below 108-113℃; The distillation process collects fractions within the boiling point ±1℃ of glacial acetic acid.

2. In the method for preparing pharmaceutical-grade glacial acetic acid according to claim 1, the mass ratio of potassium permanganate to crude glacial acetic acid is 1:2000.

3. The method for preparing pharmaceutical-grade glacial acetic acid according to claim 1, characterized in that, The product obtained from the de-heading process is then filtered and distilled.

4. The method for preparing pharmaceutical-grade glacial acetic acid according to claim 3, characterized in that, The filtration process includes, in sequence, membrane filtration and molecular sieve filtration; the membrane has a pore size of 0.1-0.4 μm and a transmembrane pressure difference of 400-600 kPa.

5. The method for preparing pharmaceutical-grade glacial acetic acid according to claim 4, characterized in that, The molecular sieve filtration uses zeolite molecular sieves.

6. The method for preparing pharmaceutical-grade glacial acetic acid according to claim 5, characterized in that, The chemical composition of the zeolite molecular sieve includes calcium ions; the pore size of the zeolite molecular sieve is 0.4-0.6 nm; and the temperature of the crude glacial acetic acid passing through the zeolite molecular sieve is 2-10℃.

7. The method for preparing pharmaceutical-grade glacial acetic acid according to claim 6, characterized in that, The distillation process employs vacuum distillation, with a pressure of 0.1-0.4 standard atmospheres.

8. The method for preparing pharmaceutical-grade glacial acetic acid according to any one of claims 1-7, characterized in that, The crude glacial acetic acid contains iron ions, copper ions, cobalt ions, and manganese ions.

9. Pharmaceutical-grade glacial acetic acid prepared by the method according to any one of claims 1-8.

10. The pharmaceutical-grade glacial acetic acid according to claim 9, characterized in that, Purity ≥ 99.5%, heavy metal content < 2 ppb.

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