Refining method and application of natural eucalyptus oil

Abstract

The invention discloses a refining method and application of natural eucalyptus oil, and relates to the technical field of plant essential oil refining. The method specifically comprises the following steps: S1, adding natural eucalyptus oil and zeolite into a distillation kettle, and sequentially carrying out total reflux under a vacuum condition; adjusting the reflux ratio, carrying out primary reflux, and collecting fractions as first fractions; adjusting the reflux ratio, refluxing for the second time, and collecting fractions to obtain refined eucalyptus oil A; s2, filling a chromatographic purification column with the filler; loading the refined eucalyptus oil A into a chromatographic purification column for circular chromatography to obtain an eluent, and carrying out reduced pressure distillation to evaporate ethanol to obtain the refined eucalyptus oil; and sub-packaging and packaging to obtain the product. The product can be applied to medical industry and spices.

Description

Technical Field

[0001] The invention relates to the technical field of plant essential oil refining, in particular to a natural eucalyptus oil refining method and application thereof. Background Art

[0002] Natural eucalyptus oil, also known as eucalyptus oil, is a colorless to light yellow clear liquid with a unique aroma, slightly similar to camphor, spicy and cool taste, almost insoluble in water, and easily soluble in ethanol; it has a wide range of uses and can be used in the pharmaceutical industry, spices, and food industries; it is mainly obtained from the leaves and twigs of plants such as Eucalyptus globulus of the Myrtaceae family or Cinnamomum camphora of the Lauraceae family, and the commonly used extraction methods are distillation, leaching, cold pressing, etc. The main component of the extracted crude eucalyptus oil is 1,8-cineole, and the impurities are mainly a small amount of aldehydes, terpene compounds and their oxygen-containing derivatives.

[0003] The refining of natural eucalyptus oil is mainly for the extraction of 1,8-cineole, which has problems such as heat sensitivity and many types of raw material impurities. The refining methods include vacuum distillation and chromatography column separation: vacuum distillation is easy to operate and efficient. It reduces the boiling point by reducing pressure to prevent the decomposition of the target product. It is very helpful for extracting the target product from a complex mixture, but it is difficult to separate substances with similar boiling points, resulting in reduced purity; and the chromatography column separation method can achieve high-purity separation effects, but the cost is high, and the adsorption groups in the fillers used in the chromatography column have poor stability and are easy to fall off during the elution process, resulting in reduced product purity.

[0004] In summary, in order to solve the above problems, it is of great significance to provide a refining method of natural eucalyptus oil and its application. Summary of the invention

[0005] The object of the present invention is to provide a refining method of natural eucalyptus oil and application thereof, so as to solve the problems proposed in the prior art.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A method for refining natural eucalyptus oil comprises the following steps:

[0008] S1: adding natural eucalyptus oil and zeolite into a distillation kettle, and performing total reflux in sequence under vacuum conditions; adjusting the reflux ratio, performing a first reflux, and collecting the fractions as the head; adjusting the reflux ratio, performing a second reflux, and collecting the fractions to obtain refined eucalyptus oil A;

[0009] S2: loading the filler into a chromatography purification column; loading the refined eucalyptus oil A into the chromatography purification column for cyclic chromatography to obtain an eluent, and distilling off the ethanol under reduced pressure to obtain refined eucalyptus oil; and packaging and obtaining the product.

[0010] More preferably, during the first reflux process, the reflux ratio is 20 to 22:1.

[0011] More preferably, during the second reflux process, the reflux ratio is 10 to 12:1.

[0012] More preferably, during the total reflux process, the vacuum degree is 4000 to 5000 Pa, and the time is 50 to 60 min.

[0013] More preferably, in the chromatography purification column, the diameter-height ratio of the packing is 1:8 to 10; during the cyclic chromatography process, the eluent is absolute ethanol.

[0014] More preferably, the preparation method of the packing includes the following steps:

[0015] (1) Disperse the nano-porous silica in a 60% absolute ethanol solution, add 3-(methacryloyloxy)propyltrimethoxysilane, stir at 40 to 45 °C for 5 to 6 h, filter, wash, and dry to obtain an alkenyl-modified packing;

[0016] (2) Disperse the alkenyl-modified packing evenly in deionized water, add mercaptoacetic acid and azobisisobutyronitrile, stir at 40 to 45 °C for 2 to 4 h under ultraviolet light irradiation, filter, wash, and dry to obtain a carboxyl-modified packing;

[0017] (3) Stir the carboxyl-modified packing evenly in absolute ether, add 4-aminophthalimide and an activator, stir at 50 to 60 °C for 3 to 4 h to obtain a phthalimide-modified packing;

[0018] (4) Mix tetrachlorophthalic anhydride, urea, and ammonium molybdate evenly, heat and melt, add zinc acetate and the phthalimide-modified packing, stir at 210 to 220 °C for 6 to 7 h, cool, fragment, wash with a 60% ethanol aqueous solution, filter, and dry to obtain the packing.

[0019] Among them, the alkenyl-modified packing includes the following raw materials in parts by mass: 9 to 10 parts of nano-porous silica, 40 to 50 parts of 60% absolute ethanol solution, 1 to 1.5 parts of 3-(methacryloyloxy)propyltrimethoxysilane;

[0020] The carboxyl-modified packing includes the following raw materials in parts by mass: 4 to 6 parts of alkenyl-modified packing, 40 to 50 parts of deionized water, 0.2 to 0.3 parts of mercaptoacetic acid, 0.05 to 0.1 part of azobisisobutyronitrile;

[0021] The phthalimide-modified packing includes the following raw materials in parts by mass: 4 to 6 parts of carboxyl-modified packing, 30 to 40 parts of absolute ether, 0.3 to 0.4 part of 4-aminophthalimide, 0.5 to 0.6 part of activator;

[0022] The filler includes the following raw materials in parts by mass: 1.8 - 2 parts of tetrachlorophthalic anhydride, 18 - 20 parts of urea, 0.1 - 0.2 parts of ammonium molybdate, and 4 - 6 parts of phthalimide - modified filler.

[0023] The product obtained by the refining method of a natural eucalyptus oil can be applied to the pharmaceutical industry and spices.

[0024] More preferably, the activator is 1 - (3 - dimethylaminopropyl) - 3 - ethylcarbodiimide and N - hydroxysuccinimide with a mass ratio of 1:1 - 1.5.

[0025] Compared with the prior art, the beneficial effects of this application are as follows:

[0026] (1) The main component of natural eucalyptus oil is 1,8 - cineole, with a boiling point of 178°C at normal pressure. The main impurities are α - pinene, limonene, γ - terpinene, α - terpineol, etc. Among them, the boiling point of limonene at normal pressure is 177°C, only 1°C lower than that of 1,8 - cineole. It is difficult to improve the purity through single - stage vacuum distillation. In this invention, intermittent vacuum distillation is first adopted, the reflux ratio is adjusted to remove low - boiling - point impurities such as α - pinene, and 1,8 - cineole containing limonene impurities is collected. Then, through a chromatography purification column, limonene is further removed to improve the product purity.

[0027] (2) The filler of the chromatography purification column in this invention is nano - porous silica, which has more adsorption sites, so it can fix more impurities, improve the separation efficiency, and this filler has excellent high - temperature resistance and corrosion resistance, with good stability. In this invention, vinyl silane coupling agent is introduced into the filler and mercapto acid is grafted, so that it can react with 4 - aminophthalimide to introduce phthalimide structure. Under the conditions of urea, ammonium molybdate, and zinc acetate, it reacts with tetrachlorophthalic anhydride to form a filler containing nickel phthalocyanine structure. Nickel ions are transition metal ions with unfilled d - orbitals, which can overlap with the π - electron cloud of limonene - like substances to form π - metal coordination bonds, thus realizing the fixation of limonene - like substances. Moreover, the nickel phthalocyanine structure has better stability than the complex formed by simple amino group and nickel ions, and is not easily broken due to high temperature and lose the fixation effect, thus improving the stability. The chlorine on tetrachlorophthalic anhydride becomes a substituent group of the nickel phthalocyanine structure, and also has the effect of forming a coordination bond with the π - electron cloud of limonene - like substances, enhancing the fixation effect and thus improving the separation degree. Detailed implementation manners

[0028] Based on the embodiments in this invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of this invention.

[0029] It should be noted that there are no special restrictions on the manufacturers from which the raw materials involved in the present invention are purchased. Exemplarily, they include: nano-porous silica with a particle size of 70-100 nm, provided by Hangzhou Xinqiao Biotechnology Co., Ltd.; 3-(methacryloyloxy)propyltrimethoxysilane, CAS No.: 2530-85-0; thioglycolic acid, CAS: 68-11-1; 4-aminophthalimide, CAS No.: 3676-85-5; tetrachlorophthalic anhydride, CAS No.: 117-08-8; urea, CAS No.: 57-13-6; zinc acetate, zinc acetate dihydrate, CAS No.: 5970-45-6.

[0030] More preferably, in the following examples, "parts" refers to parts by mass, and the above-mentioned raw materials and the raw materials used in the following examples and comparative examples but not mentioned are all commercially available.

[0031] More preferably, the preparation method of the natural eucalyptus oil comprises the following steps: After drying the fresh eucalyptus leaves, they are crushed to 20-80 mesh, and added to a distillation container with deionized water in a mass ratio of 1:6, heated at a gentle boil for 8 h, the distillate is collected, the water layer is separated, extracted, the extractant is removed by rotary evaporation, and the water is removed to obtain natural eucalyptus oil.

[0032] Example 1: Step 1: Preparation of the filler:

[0033] (1) Disperse 10 parts of nano-porous silica in 45 parts of 60% anhydrous ethanol solution, add 1 part of 3-(methacryloyloxy)propyltrimethoxysilane, stir at 45 °C for 5 h, filter, wash, and dry to obtain an alkenyl-modified filler;

[0034] (2) Add 5 parts of the alkenyl-modified filler to 45 parts of deionized water and disperse evenly, add 0.25 part of thioglycolic acid and 0.05 part of azobisisobutyronitrile, stir at 45 °C for 3 h under ultraviolet light irradiation, filter, wash, and dry to obtain a carboxyl-modified filler;

[0035] (3) Add 5 parts of the carboxyl-modified filler to 35 parts of anhydrous ether and stir evenly, add 0.35 part of 4-aminophthalimide and 0.5 part of activator, stir at 55 °C for 3.5 h to obtain a phthalimide-modified filler;

[0036] (4) Mix 1.9 parts of tetrachlorophthalic anhydride, 20 parts of urea, and 0.1 part of ammonium molybdate evenly, heat and melt, add 0.9 part of zinc acetate and 5 parts of the phthalimide-modified filler, stir at 210 °C for 6 h, cool, crush, wash with 60% ethanol aqueous solution, filter, and dry to obtain the filler;

[0037] Step 2: Refining of the natural eucalyptus oil:

[0038] S1: Add natural eucalyptus oil and zeolite into the distillation kettle, turn on the vacuum pump, and under a vacuum of 4000 Pa, conduct total reflux for 60 min; adjust the reflux ratio to 20:1, conduct primary reflux, collect the distillate, which is the head fraction; adjust the reflux ratio to 12:1, conduct secondary reflux, collect the distillate, and obtain refined eucalyptus oil A;

[0039] S2: Load the packing into the chromatography purification column at a diameter-to-height ratio of 1:9; load the refined eucalyptus oil A onto the chromatography purification column for cyclic chromatography, obtain the eluate, conduct vacuum distillation to remove ethanol, and obtain refined eucalyptus oil; subpackage and package to obtain the product.

[0040] Example 2: Step 1: Preparation of the packing:

[0041] (1) Disperse 10 parts of nano-porous silica in 45 parts of 60% anhydrous ethanol solution, add 1 part of 3-(methacryloyloxy)propyltrimethoxysilane, stir at 45 °C for 5 h, filter, wash, and dry to obtain vinyl-modified packing;

[0042] (2) Add 5 parts of vinyl-modified packing to 45 parts of deionized water and disperse evenly, add 0.25 part of mercaptoacetic acid and 0.05 part of azobisisobutyronitrile, stir at 45 °C for 3 h under ultraviolet light irradiation, filter, wash, and dry to obtain carboxyl-modified packing;

[0043] (3) Add 5 parts of carboxyl-modified packing to 35 parts of anhydrous ether and stir evenly, add 0.35 part of 4-aminophthalimide and 0.5 part of activator, stir at 55 °C for 3.5 h to obtain phthalimide-modified packing;

[0044] (4) Mix 1.9 parts of tetrachlorophthalic anhydride, 20 parts of urea, and 0.1 part of ammonium molybdate evenly, heat and melt, add 0.9 part of zinc acetate and 5 parts of phthalimide-modified packing, stir at 210 °C for 6 h, cool, crush, wash with 60% ethanol aqueous solution, filter, and dry to obtain the packing;

[0045] Step 2: Refining of natural eucalyptus oil:

[0046] S1: Add natural eucalyptus oil and zeolite into the distillation kettle, turn on the vacuum pump, and under a vacuum of 4000 Pa, conduct total reflux for 50 min; adjust the reflux ratio to 20:1, conduct primary reflux, collect the distillate, which is the head fraction; adjust the reflux ratio to 10:1, conduct secondary reflux, collect the distillate, and obtain refined eucalyptus oil A;

[0047] S2: Load the packing into the chromatography purification column at a diameter-to-height ratio of 1:8; load the refined eucalyptus oil A onto the chromatography purification column for cyclic chromatography, obtain the eluate, conduct vacuum distillation to remove ethanol, and obtain refined eucalyptus oil; subpackage and package to obtain the product.

[0048] Example 3: Step 1: Preparation of the packing:

[0049] (1) Disperse 10 parts of nano-porous silica in 45 parts of 60% anhydrous ethanol solution, add 1 part of 3-(methacryloyloxy)propyltrimethoxysilane, stir at 45 °C for 5 h, filter, wash, and dry to obtain vinyl-modified filler;

[0050] (2) Add 5 parts of vinyl-modified filler to 45 parts of deionized water and disperse evenly, add 0.25 part of mercaptoacetic acid and 0.05 part of azobisisobutyronitrile, stir at 45 °C for 3 h under ultraviolet light irradiation, filter, wash, and dry to obtain carboxyl-modified filler;

[0051] (3) Add 5 parts of carboxyl-modified filler to 35 parts of anhydrous ether and stir evenly, add 0.35 part of 4-aminophthalimide and 0.5 part of activator, stir at 55 °C for 3.5 h to obtain phthalimide-modified filler;

[0052] (4) Mix 1.9 parts of tetrachlorophthalic anhydride, 20 parts of urea, and 0.1 part of ammonium molybdate evenly, heat to melt, add 0.9 part of zinc acetate and 5 parts of phthalimide-modified filler, stir at 210 °C for 6 h, cool, crush, wash with 60% ethanol aqueous solution, filter, and dry to obtain filler;

[0053] Step Two: Refining of natural eucalyptus oil:

[0054] S1: Add natural eucalyptus oil and zeolite to the distillation kettle, turn on the vacuum pump, under a vacuum of 5000 Pa, perform total reflux for 60 min; adjust the reflux ratio to 22:1, perform primary reflux, collect the distillate, which is the head; adjust the reflux ratio to 12:1, perform secondary reflux, collect the distillate to obtain refined eucalyptus oil A;

[0055] S2: Load the filler into the chromatography purification column with a diameter-to-height ratio of 1:10; load the refined eucalyptus oil A onto the chromatography purification column for cyclic chromatography to obtain the eluate, perform vacuum distillation to distill off ethanol to obtain refined eucalyptus oil; subpackage and package to obtain the product.

[0056] Comparative Example 1: Based on Example 1, only perform vacuum rectification, and the rest of the process remains unchanged. Specifically as follows: Step One: Refining of natural eucalyptus oil:

[0057] S1: Add natural eucalyptus oil and zeolite to the distillation kettle, turn on the vacuum pump, under a vacuum of 4000 Pa, perform total reflux for 60 min; adjust the reflux ratio to 20:1, perform primary reflux, collect the distillate, which is the head; adjust the reflux ratio to 12:1, perform secondary reflux, collect the distillate to obtain refined eucalyptus oil; subpackage and package to obtain the product.

[0058] Comparative Example 2: Based on Example 1, only use column chromatography separation, and the rest of the process remains unchanged. Specifically as follows: Step One: Preparation of filler:

[0059] (1) Disperse 10 parts of nanoporous silica in 45 parts of 60% anhydrous ethanol solution, add 1 part of 3-(methacryloyloxy)propyltrimethoxysilane, stir at 45 °C for 5 h, filter, wash, and dry to obtain an alkenyl-modified filler.

[0060] (2) Add 5 parts of the alkenyl-modified filler to 45 parts of deionized water and disperse evenly, add 0.25 part of mercaptoacetic acid and 0.05 part of azobisisobutyronitrile, stir at 45 °C for 3 h under ultraviolet light irradiation, filter, wash, and dry to obtain a carboxyl-modified filler.

[0061] (3) Add 5 parts of the carboxyl-modified filler to 35 parts of anhydrous ether and stir evenly, add 0.35 part of 4-aminophthalimide and 0.5 part of an activator, stir at 55 °C for 3.5 h to obtain a phthalimide-modified filler.

[0062] (4) Mix 1.9 parts of tetrachlorophthalic anhydride, 20 parts of urea, and 0.1 part of ammonium molybdate evenly, heat to melt, add 0.9 part of zinc acetate and 5 parts of the phthalimide-modified filler, stir at 210 °C for 6 h, cool, crush, wash with 60% ethanol aqueous solution, filter, and dry to obtain a filler.

[0063] Step 2: Refining of natural eucalyptus oil:

[0064] S1: Load the filler into a chromatographic purification column with a diameter-to-height ratio of 1:9; load the refined eucalyptus oil A onto the chromatographic purification column for cyclic chromatography to obtain an eluate, distill off ethanol under reduced pressure to obtain refined eucalyptus oil; subpackage and package to obtain the product.

[0065] Comparative Example 3: Based on Example 1, the filler in the chromatographic column is commercially available silica gel, and the rest of the process remains unchanged. Specifically as follows: Step 1: Refining of natural eucalyptus oil:

[0066] S1: Add natural eucalyptus oil and zeolite to a distillation kettle, turn on the vacuum pump, and under a vacuum of 4000 Pa, perform total reflux for 60 min; adjust the reflux ratio to 20:1 for the first reflux, collect the distillate, which is the head fraction; adjust the reflux ratio to 12:1 for the second reflux, collect the distillate to obtain refined eucalyptus oil A.

[0067] S2: Load the silica gel into a chromatographic purification column with a diameter-to-height ratio of 1:9; load the refined eucalyptus oil A onto the chromatographic purification column for cyclic chromatography to obtain an eluate, distill off ethanol under reduced pressure to obtain refined eucalyptus oil; subpackage and package to obtain the product.

[0068] Comparative Example 4: Based on Example 1, the chromatographic column packing used in Example 1 was washed and reused, and the rest of the process remained unchanged. The specific steps are as follows: Step 1: Preparation of the packing: The packing used in Example 1 was washed with absolute ethanol at 65°C and dried to obtain the packing for Comparative Example 4;

[0069] Step 2: Refining of natural eucalyptus oil:

[0070] S1: Add natural eucalyptus oil and zeolite into the distillation kettle, turn on the vacuum pump, and under a vacuum degree of 4000 Pa, perform total reflux for 60 min; adjust the reflux ratio to 20:1, perform primary reflux, collect the distillate, which is the head fraction; adjust the reflux ratio to 12:1, perform secondary reflux, and collect the distillate to obtain refined eucalyptus oil A;

[0071] S2: Pack the packing for Comparative Example 4 into the chromatographic purification column at a diameter-to-height ratio of 1:9; load the refined eucalyptus oil A onto the chromatographic purification column for cyclic chromatography to obtain the eluate, and perform vacuum distillation to distill off ethanol to obtain refined eucalyptus oil; divide it into portions and package to obtain the product.

[0072] Performance test: After measuring and calculating the purity and yield of each example and comparative example, the experimental data are shown in Table 1.

[0073] Table 1

[0074]

[0075]

[0076] Conclusion: As can be seen from Table 1, in Comparative Example 1, only vacuum rectification was performed, and the yield was relatively high, but the purity was lower than that of Example 1; in Comparative Example 2, only chromatographic column separation was used, and there were many impurities to be separated in the chromatographic column, resulting in a decrease in yield; in Comparative Example 3, silica gel was used as the packing in the chromatographic column, and the separation effect was poor, resulting in a decrease in purity; in Comparative Example 4, the packing washed and used in Example 1 was used, and there was no obvious change in purity and yield, indicating that the packing prepared by the present invention can be reused twice and has good stability.

[0077] In summary, the present invention successfully provides a method for refining natural eucalyptus oil by combining vacuum distillation and chromatographic column separation. The obtained product has a relatively high purity, and the packing prepared for the chromatographic column has good stability and adsorption effect.

[0078] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A refining method for natural eucalyptus oil, characterized in that, It includes the following steps: S1: Add natural eucalyptus oil and zeolite into a distillation kettle. Under vacuum conditions, conduct total reflux in sequence; adjust the reflux ratio, conduct primary reflux, collect the distillate, which is the head fraction; adjust the reflux ratio, conduct secondary reflux, and collect the distillate to obtain refined eucalyptus oil A; S2: Load the packing into a chromatography purification column; load the refined eucalyptus oil A onto the chromatography purification column for cyclic chromatography, obtain the eluent, distill off ethanol under reduced pressure to obtain refined eucalyptus oil; subpackage and package to obtain the product.

2. The refining method of natural eucalyptus oil according to claim 1, characterized in that: During the process of the primary reflux, the reflux ratio is 20 - 22:

1.

3. The refining method of natural eucalyptus oil according to claim 1, characterized in that: During the process of the secondary reflux, the reflux ratio is 10 - 12:

1.

4. The refining method of natural eucalyptus oil according to claim 1, characterized in that: During the process of the total reflux, the vacuum degree is 4000 - 5000 Pa, and the time is 50 - 60 min.

5. A refining method of natural eucalyptus oil according to claim 1, characterized in that: In the chromatography purification column, the diameter-to-height ratio of the packing is 1:8 - 10; during the process of the cyclic chromatography, the eluent is anhydrous ethanol.

6. The refining method of natural eucalyptus oil according to claim 1, characterized in that: The preparation method of the packing includes the following steps: (1) Disperse nano-porous silica in a 60% anhydrous ethanol solution, add 3-(methacryloyloxy)propyltrimethoxysilane, stir at 40 - 45 °C for 5 - 6 h, filter, wash, and dry to obtain alkenyl-modified packing; (2) Add the alkenyl-modified packing into deionized water and disperse evenly, add mercaptoacetic acid and azobisisobutyronitrile, stir at 40 - 45 °C for 2 - 4 h under ultraviolet light irradiation, filter and wash, and dry to obtain carboxyl-modified packing; (3) Add the carboxyl-modified packing into anhydrous ether and stir evenly, add 4-aminophthalimide and an activator, stir at 50 - 60 °C for 3 - 4 h to obtain phthalimide-modified packing; (4) Mix tetrachlorophthalic anhydride, urea, and ammonium molybdate evenly, heat to melt, add zinc acetate and phthalimide-modified packing, stir at 210 - 220 °C for 6 - 7 h, cool, crush, wash with a 60% ethanol aqueous solution, filter, and dry to obtain the packing.

7. A refining method of natural eucalyptus oil according to claim 6, characterized in that: The alkenyl-modified packing includes the following raw materials in parts by mass: 9 - 10 parts of nano-porous silica, 40 - 50 parts of 60% anhydrous ethanol solution, 1 - 1.5 parts of 3-(methacryloyloxy)propyltrimethoxysilane; The carboxyl-modified packing includes the following raw materials in parts by mass: 4 - 6 parts of alkenyl-modified packing, 40 - 50 parts of deionized water, 0.2 - 0.3 parts of mercaptoacetic acid, 0.05 - 0.1 parts of azobisisobutyronitrile; The phthalimide-modified packing includes the following raw materials in parts by mass: 4 - 6 parts of carboxyl-modified packing, 30 - 40 parts of anhydrous ether, 0.3 - 0.4 parts of 4-aminophthalimide, 0.5 - 0.6 parts of activator; The packing includes the following raw materials in parts by mass: 1.8 - 2 parts of tetrachlorophthalic anhydride, 18 - 20 parts of urea, 0.1 - 0.2 parts of ammonium molybdate, 4 - 6 parts of phthalimide-modified packing.

8. The product obtained by the refining method of a natural eucalyptus oil according to any one of claims 1 - 7 can be applied to the pharmaceutical industry and perfumery.

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