Purification method of high-purity reagent cyclohexane

Abstract

The invention discloses a purification method of a high-purity reagent cyclohexane, and belongs to the technical field of purification of high-purity reagents. The purification method comprises the following steps: primarily purifying cyclohexane by virtue of a recrystallization method, then removing residual impurities by virtue of liquid-liquid extraction, adding an excessive water removal material into the obtained cyclohexane to remove residual water, and finally further removing the residual impurities in the cyclohexane by virtue of a purification material. The purity of the prepared high-purity cyclohexane can reach 99.998%, and the high-purity cyclohexane can be used as a general solvent for chemical analysis and precise instrument analysis, a cleaning agent for the electronic industry, an extraction leachate of natural medicines and the like. Wide application prospects are realized in the fields of spectral analysis, trace pollutant solvents, chemical synthesis and the like; the process is simple, and industrialization is easy to realize.

Description

Technical Field

[0001] The invention belongs to the technical field of high-purity reagent purification, and specifically relates to a method for purifying high-purity reagent cyclohexane. Background Art

[0002] With the development of modern science and technology, the demand for the purity of chemical reagents in all walks of life is constantly increasing. The characteristics of high-purity reagents are a wide variety of varieties, strict quality requirements, strict requirements on the cleanliness of the environment, packaging, transportation, and storage, rapid product updates, large development capital investment, high research and development difficulty, high product added value, high prices, and relatively small usage. A variety of high-purity reagents have been developed internationally. Other countries or foreign reagent companies have their own method standards and product standards, while my country is relatively lagging behind in the preparation and purification technology and standardization research of high-purity reagents. Especially in recent years, there is a large gap in high-purity reagents and biochemical reagents with rapidly growing domestic market demand.

[0003] As an important organic reagent and chemical raw material, cyclohexane is widely used in industrial production, organic synthesis, laboratory analysis and other fields. At present, the industrial production methods of cyclohexane are mainly petroleum fraction separation and benzene hydrogenation reaction, but both forms will introduce a large number of impurities. They have a boiling point close to cyclohexane, especially benzene and cyclohexane have a similar boiling point (△T b =0.6℃), the molecular volumes are approximately equal, and binary azeotropes are easily formed. Further increasing the purity of cyclohexane by conventional distillation will greatly increase the cost and loss. Summary of the invention

[0004] In view of this, the purpose of the present invention is to provide a method for purifying a high-purity reagent cyclohexane. The present invention utilizes the different physical and chemical properties of cyclohexane and impurities to explore a method for further improving the purity of existing cyclohexane by recrystallization or a combination of recrystallization and adsorption of purification materials, and finally obtains 99.998% cyclohexane. The reagent can be used as a universal solvent for chemical analysis and precision instrument analysis, a cleaning agent for the electronics industry, an extraction leaching solution for natural medicines, etc., and has a wide range of application prospects.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A method for purifying high-purity reagent cyclohexane comprises the following steps:

[0007] Step 1: Cooling the alcohol solution of cyclohexane and preliminarily purifying the cyclohexane by recrystallization;

[0008] Step 2: removing residual impurities from the purified cyclohexane by liquid-liquid extraction;

[0009] Step 3: Add an excess amount of dehydrating material to the cyclohexane obtained in step 2 to remove residual water to obtain the product.

[0010] Based on the above technical solution, further, the number of recrystallization in step one is at least 1 time.

[0011] Based on the above technical solution, further, the alcohol solution described in step 1 is a mixed solution of one or both of methanol and ethanol; the volume percentage of cyclohexane is 10-50%.

[0012] Based on the above technical solution, further, the freezing temperature in step one is -15°C to -90°C, and the freezing time is 0.5-6h.

[0013] Based on the above technical solution, further, the liquid-liquid extraction described in step 2 is performed at least 3 times.

[0014] Based on the above technical solution, further, the solvent for the liquid-liquid extraction in step 2 is water, and the volume ratio of cyclohexane to water is 10:1 to 1:10.

[0015] Based on the above technical solution, further, the dehydration material described in step three is anhydrous sodium sulfate, 3A molecular sieve, and 4A molecular sieve that have been calcined at 300-600° C. for 1-10 hours to remove impurities.

[0016] Based on the above technical solution, further, the purification method also includes passing the cyclohexane obtained in step three through a purification material to further remove residual impurities.

[0017] Based on the above technical solution, further, the purification material is magnesium silicate, silica gel, modified silica gel, and activated carbon that have been calcined at 300-600°C for 1-10 hours to remove impurities.

[0018] Compared with the prior art, the present invention has the following beneficial technical effects:

[0019] 1. The purity of the high-purity cyclohexane prepared by the present invention can reach 99.998%.

[0020] 2. The cyclohexane prepared by the present invention has broad application prospects in the fields of spectral analysis, trace pollutant solvents, chemical synthesis, etc.; and the cyclohexane has low biological toxicity and can be used as an alternative solvent for organic experiments.

[0021] 3. The purification method of the invention has a simple process flow and is easy to industrialize. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention, the drawings related to the embodiments are briefly introduced below.

[0023] Figure 1The present invention is a flowchart of the purification method of the high-purity reagent cyclohexane.

[0024] Figure 2 The gas chromatograms of the high-purity reagent cyclohexane purified in Example 1, wherein (A) is the gas chromatogram of the cyclohexane after purification, and (B) is the gas chromatogram of the cyclohexane before purification.

[0025] Figure 3 This is the infrared spectrum of the high-purity reagent cyclohexane purified in Example 1.

[0026] Figure 4 This is the ultraviolet spectrum of the high-purity reagent cyclohexane purified in Example 1. DETAILED DESCRIPTION

[0027] The present invention is described in detail below with reference to the embodiments, but the embodiments of the present invention are not limited thereto. Obviously, the embodiments described below are only partial embodiments of the present invention. For those skilled in the art, other similar embodiments obtained without creative labor all fall within the protection scope of the present invention.

[0028] Example 1

[0029] A method for purifying high-purity reagent cyclohexane comprises the following steps:

[0030] Step 1: Cooling a 30% cyclohexane-ethanol solution to -70°C, freezing for 3 hours, filtering to obtain cyclohexane crystals, and preliminarily purifying the cyclohexane by recrystallization;

[0031] Step 2: Take 500 mL of purified cyclohexane, add 100 mL of deionized water, extract and shake for 3 minutes, let stand to separate the layers, discard the water layer, and repeat the above operation four times;

[0032] Step 3: Add an excess of anhydrous sodium sulfate, which has been calcined at 500° C. for 5 hours to remove impurities, to the cyclohexane obtained in step 2, and remove residual water to obtain the product.

[0033] Example 2

[0034] A method for purifying high-purity reagent cyclohexane comprises the following steps:

[0035] Step 1: Cooling a 30% cyclohexane-ethanol solution to -70°C, freezing for 3 hours, filtering to obtain cyclohexane crystals, and preliminarily purifying the cyclohexane by recrystallization;

[0036] Step 2: Take 500 mL of purified cyclohexane, add 100 mL of deionized water, extract and shake for 3 minutes, let stand to separate the layers, discard the water layer, and repeat the above operation four times;

[0037] Step 3: adding an excess of anhydrous sodium sulfate which has been calcined at 500° C. for 5 hours to remove impurities to the cyclohexane obtained in step 2 to remove residual water and obtain dry cyclohexane;

[0038] Step 4: Pass the dried cyclohexane in step 3 through a 75 μm silica gel adsorption column that has been calcined at 500° C. for 5 hours to remove impurities at a flow rate of 1 mL / min to further remove residual impurities;

[0039] Example 3

[0040] A method for purifying high-purity reagent cyclohexane, which differs from Example 2 in that in step 1, the selected recrystallization solvent is 30% cyclohexane-methanol solution.

[0041] Example 4

[0042] A method for purifying high-purity reagent cyclohexane, which differs from Example 2 in that in step 1, the recrystallization method is repeated twice.

[0043] Example 5

[0044] A method for purifying high-purity reagent cyclohexane is different from Example 2 in that in step 4, the purification material selected is 75 μm Florisil that has been calcined at 500° C. for 5 hours to remove impurities.

[0045] The relevant technical index results of cyclohexane obtained by the purification method of Examples 1-5 are shown in Table 1.

[0046] Table 1: Technical indicators of cyclohexane obtained by the purification method of Examples 1-5

[0047]

[0048] As shown in Table 1, the results of Examples 1-5 show that the cyclohexane obtained by the present invention meets the requirements in terms of content, evaporation residue, moisture content, etc., the purity can reach 99.998%, and the absorbance at each wavelength is greatly reduced.

[0049] In summary, the cyclohexane obtained by the purification method of the present invention can meet the requirements of high-purity reagents, and the method has a simple process and is easy to industrialize; it has broad application prospects in the fields of spectral analysis, trace pollutant solvents, chemical synthesis, etc.

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for purifying high-purity reagent cyclohexane, characterized in that: The steps include: Step 1: Cooling the alcohol solution of cyclohexane and preliminarily purifying the cyclohexane by recrystallization; Step 2: removing residual impurities from the purified cyclohexane by liquid-liquid extraction; Step 3: Add an excess amount of dehydrating material to the cyclohexane obtained in step 2 to remove residual water to obtain the product.

2. The purification method according to claim 1, characterized in that The number of recrystallizations in step 1 is at least 1.

3. The purification method according to claim 1, characterized in that The alcohol solution described in step 1 is a mixed solution of one or both of methanol and ethanol; the volume percentage of cyclohexane is 10-50%.

4. The purification method according to claim 1, characterized in that The freezing temperature in step 1 is -15°C to -90°C, and the freezing time is 0.5-6h.

5. The purification method according to claim 1, characterized in that: The number of liquid-liquid extractions in step 2 is at least 3 times.

6. The purification method according to claim 1, characterized in that: The solvent for the liquid-liquid extraction in step 2 is water, and the volume ratio of cyclohexane to water is 10:1 to 1:

10.

7. The purification method according to claim 1, characterized in that: The dehydrating material described in step three is anhydrous sodium sulfate, 3A molecular sieve, and 4A molecular sieve that have been calcined at 300-600° C. for 1-10 hours to remove impurities.

8. The purification method according to claim 1, characterized in that: The purification method further comprises passing the cyclohexane obtained in step three through a purification material to further remove residual impurities.

9. The purification method according to claim 8, characterized in that: The purification material is magnesium silicate, silica gel, modified silica gel and activated carbon which are calcined at 300-600°C for 1-10 hours to remove impurities.

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