Polynitro 1-bromine-3-fluoro-5-toluene energetic compound and preparation method thereof

Abstract

The invention belongs to the technical field of energetic materials, and discloses a multi-nitro 1-bromine-3-fluoro-5-toluene energetic compound and a preparation method of the multi-nitro 1-bromine-3-fluoro-5-toluene energetic compound. According to the invention, 1-bromine-3-fluoro-5-toluene is taken as a raw material, the multi-nitro 1-bromine-3-fluoro-5-toluene energetic compound is prepared through a direct nitration reaction, the density of the compound is 1.80-2.03 g / cm < 3 >, the melting point is 50-108 DEG C, and the compound has the characteristics of high density, high energy, simple synthesis and the like, and is suitable for energetic plasticizers and casting carrier explosives.

Description

Technical Field

[0001] The present invention relates to the technical field of energetic materials, and particularly relates to a class of polynitro 1-bromo-3-fluoro-5-toluene energetic compounds and a preparation method thereof. Background Art

[0002] Cast explosives refer to mixed explosives prepared by adding high-energy explosives or energetic particles (such as cyclotrimethylenetrinitramine (RDX), aluminum powder, etc.) into a molten liquid carrier (such as TNT) and then solidifying and forming. They are widely used in military and civilian fields. Thus, the development of carrier explosives is crucial for cast explosives.

[0003] Currently, the widely used carrier explosive is TNT, which has a low density of only 1.65 g / cm 3 , which is not conducive to improving the loading density of cast explosives. In addition, for cast explosives containing aluminum, the introduction of halogens (such as fluorine or bromine) can react with aluminum to form aluminum fluoride (AlF 3 ) or aluminum bromide (AlBr 3 ), which are in a gaseous state under the detonation reaction conditions and can well avoid the aggregation of condensed-phase aluminum particles. Therefore, the design and development of new carrier explosives containing halogens are of great significance in improving the loading density of cast explosives and the detonation performance of cast explosives containing aluminum. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a class of polynitro 1-bromo-3-fluoro-5-toluene energetic compounds and a preparation method thereof, and the polynitro 1-bromo-3-fluoro-5-toluene energetic compounds have a high density, high energy and simple synthesis.

[0005] In order to achieve the above purpose, the present invention adopts the following technical solutions.

[0006] On the one hand, the present invention provides a class of polynitro 1-bromo-3-fluoro-5-toluene energetic compounds, which include the following compounds:

[0007]

[0008] Further, the melting point of the polynitro 1-bromo-3-fluoro-5-toluene energetic compounds is 50 - 108 °C, and the density is 1.80 - 2.03 g / cm 3 .

[0009] On the other hand, the present invention provides a preparation method of the polynitro 1-bromo-3-fluoro-5-toluene energetic compounds, which includes the following steps:

[0010] 1-Bromo-3-fluoro-5-methylbenzene is added to a nitrating reagent and reacted at 20-150 °C for 0.5-24 h. Crushed ice is poured into the reactant to quench the reaction, and the product is separated by column chromatography or suction filtration, and then dried to obtain a polynitro 1-bromo-3-fluoro-5-methylbenzene energetic compound.

[0011] Preferably, the nitrating reagent is any one of a mixed acid of concentrated sulfuric acid and concentrated nitric acid, a mixed acid of 50% oleum and concentrated nitric acid, a mixed acid of concentrated sulfuric acid and concentrated nitric acid, a mixed acid of 50% oleum and concentrated nitric acid, a mixed acid of concentrated sulfuric acid and fuming nitric acid, a mixed acid of 20% oleum and concentrated nitric acid, a mixed acid of sodium nitrate and concentrated sulfuric acid, a mixed acid of sodium nitrate and 20% oleum, a mixed acid of potassium nitrate and concentrated sulfuric acid, a mixed acid of potassium nitrate and 20% oleum, and a mixed acid of potassium nitrate and 50% oleum.

[0012] Preferably, when separated by column chromatography, the eluent is any one of a mixture of ethyl acetate and petroleum ether, a mixture of ethyl acetate and n-hexane, a mixture of dichloromethane and petroleum ether, and a mixture of dichloromethane and n-hexane.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] 1) The melting point of the polynitro 1-bromo-3-fluoro-5-methylbenzene energetic compound prepared by the method of the present invention is 50-108 °C, and the density is 1.80-2.03 g / cm 3 , which has the characteristics of high density, high energy, and simple synthesis. It can improve the filling density of cast explosives and the detonation performance of aluminized cast explosives, and can be widely used in special fields such as energetic plasticizers and cast carrier explosives.

[0015] 2) The raw materials of the present invention are cheap and easily available: the raw materials and nitrating reagents used are all commercially available reagents. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is the XRD pattern of Compound I of the present invention;

[0017] Figure 2 is the XRD pattern of Compound II of the present invention;

[0018] Figure 3 is the XRD pattern of Compound III of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0019] After extensive and in-depth research, the inventor of the present invention obtained a preparation method for a class of energetic compounds of polynitro 1-bromo-3-fluoro-5-toluenes by improving the preparation process. The method of the present invention uses 1-bromo-3-fluoro-5-toluene as a raw material to obtain polynitro 1-bromo-3-fluoro-5-toluenes with different nitro substitution positions or different numbers of nitro groups through nitration reactions. The obtained polynitro 1-bromo-3-fluoro-5-toluenes have the characteristics of high density, high energy, and simple synthesis, and have application potential in energetic plasticizers and cast carrier explosives.

[0020] The following describes the specific embodiments of the present invention in detail with reference to the accompanying drawings. The provided embodiments are only used to explain the present invention and are not intended to limit the scope of the present invention.

[0021] It should be noted that the experimental methods used in the present invention are all conventional methods in the art unless otherwise specified; the reagents and materials used, unless otherwise specified, can be purchased on the market. Unless otherwise defined or explained, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the description of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0022] On the one hand, the present invention provides a class of energetic compounds of polynitro 1-bromo-3-fluoro-5-toluenes, which include the following compounds:

[0023]

[0024]

[0025] The melting points of the above-mentioned energetic compounds of polynitro 1-bromo-3-fluoro-5-toluenes are 50 - 108 °C, and the densities are 1.80 - 2.03 g / cm 3 .

[0026] The present invention also provides a preparation method for the above-mentioned energetic compounds of polynitro 1-bromo-3-fluoro-5-toluenes, which includes the following steps:

[0027] Add 1-bromo-3-fluoro-5-toluene to a nitrating reagent, react at 20 - 150 °C for 0.5 - 24 h, pour crushed ice into the reactant to quench the reaction, separate by column chromatography or suction filtration, and dry to obtain the energetic compounds of polynitro 1-bromo-3-fluoro-5-toluenes.

[0028] Among them, the nitrating reagent is any one of a mixed acid of concentrated sulfuric acid and concentrated nitric acid, a mixed acid of 50% fuming sulfuric acid and concentrated nitric acid, a mixed acid of concentrated sulfuric acid and concentrated nitric acid, a mixed acid of 50% fuming concentrated sulfuric acid and concentrated nitric acid, a mixed acid of concentrated sulfuric acid and fuming nitric acid, a mixed acid of 20% fuming concentrated sulfuric acid and concentrated nitric acid, a mixed acid of sodium nitrate and concentrated sulfuric acid, a mixed acid of sodium nitrate and 20% fuming sulfuric acid, a mixed acid of potassium nitrate and concentrated sulfuric acid, a mixed acid of potassium nitrate and 20% fuming sulfuric acid, and a mixed acid of potassium nitrate and 50% fuming sulfuric acid.

[0029] When separating by column chromatography, the eluent is any one of a mixture of ethyl acetate and petroleum ether, a mixture of ethyl acetate and n-hexane, a mixture of dichloromethane and petroleum ether, and a mixture of dichloromethane and n-hexane.

[0030] On the other hand, the present invention also provides a method for preparing the polynitro 1-bromo-3-fluoro-5-toluene-based energetic compound, which comprises the following steps:

[0031] Add 1-bromo-3-fluoro-5-toluene to the nitrating reagent, react at 20-150 °C for 0.5-24 h, pour crushed ice into the reactant to quench the reaction, separate by column chromatography or suction filtration, and dry to obtain the polynitro 1-bromo-3-fluoro-5-toluene-based energetic compound.

[0032] The present invention will be further explained and illustrated by the following specific examples.

[0033] Example 1

[0034] Synthesis of Compounds I and II:

[0035] Weigh 1-bromo-3-fluoro-5-toluene (1.89 g, 10 mmol), add it dropwise to 5 mL of 98% concentrated sulfuric acid at 0 °C, and also add 5 mL of concentrated nitric acid dropwise at the same temperature. After maintaining for 20 min, transfer it to a magnetic stirrer and raise the temperature to 60 °C, and stir for 1 h. After the reaction is completed, add ice water, and a pale yellow solid precipitates. Filter, wash, and dry to obtain a yellowish-brown solid product. Yield: 1.92 g, 68.8%.

[0036] Dissolve the obtained yellowish-brown solid product (1.92 g) in ethyl acetate, and perform column chromatography with silica gel (200-300 mesh), using petroleum ether:ethyl acetate (49:1) as the eluent, to obtain Compound I (1.234 g) and Compound II (0.686 g).

[0037] Synthesis of Compound III:

[0038] Weigh 1-bromo-3-fluoro-5-methylbenzene (1.89 g, 10 mmol), and add it dropwise to 5 mL of 50% fuming sulfuric acid at 0 °C. Then add 5 mL of concentrated nitric acid dropwise at the same temperature. After maintaining for 20 min, transfer it to a magnetic stirrer and heat up to 120 °C, and stir for 1 h. After the reaction is completed, add ice water, and white solid precipitates. Filter, wash, and dry to obtain the white solid product. Yield: 0.896 g, 27.7%.

[0039] Product structure identification:

[0040] Compound I:

[0041] Nuclear magnetic resonance spectrum: 13 C NMR (100 MHz, CDCl 3 -d 1 ): δ ppm: 154.50, 152.76, 148.42, 138.89, 127.74, 121.86, 117.69, 14.05.

[0042] Nuclear magnetic resonance spectrum: 1 H NMR (100 MHz, CDCl 3 -d 1 ): δ ppm: 8.36, 2.39.

[0043] Compound II:

[0044] Nuclear magnetic resonance spectrum: 13 C NMR (100 MHz, CDCl 3 -d 1 ): δ ppm: 154.34, 148.42, 138.65, 137.42, 120.84, 107.81, 17.73.

[0045] Nuclear magnetic resonance spectrum: 1 H NMR (100 MHz, CDCl 3 -d 1 ): δ ppm: 8.01, 2.45.

[0046] Compound III:

[0047] Nuclear magnetic resonance spectrum: 13 C NMR (100 MHz, CDCl 3 -d 1 ): δ ppm: 148.59, 148.53, 147.18, 139.4, 130.90, 112.38, 14.77.

[0048] Nuclear magnetic resonance spectrum: 1 H NMR (100 MHz, CDCl 3 -d1 ):δ ppm: 2.44.

[0049] The properties of the compound prepared in this example are shown in Table 1.

[0050] Table 1 Properties of the compound

[0051]

[0052]

[0053] In the table, Tm is the melting point, IS is the impact sensitivity, FS is the friction sensitivity, D is the detonation velocity, and P is the detonation pressure.

[0054] As can be seen from Table 1, the melting point of compound I prepared in this example is 50 °C, the melting point of compound II is 98 °C, and the melting point of compound III is 108 °C.

[0055] Example 2

[0056] Synthesis of Compounds I, II and III

[0057] Synthesis of Compounds I and II:

[0058] Weigh 1-bromo-3-fluoro-5-methylbenzene (0.945 g, 5 mmol), and drop it into 3 mL of 98% concentrated sulfuric acid at 0 °C. Then drop 3 mL of concentrated nitric acid at the same temperature. After maintaining for 20 min, transfer it to a magnetic stirrer and heat to 120 °C, and stir for 2 h. After the reaction is completed, add ice water, and a pale yellow solid precipitates. Filter, wash, and dry to obtain a yellowish-brown solid product. Yield: 1.02 g, 73.2%.

[0059] Dissolve the obtained yellowish-brown solid product (1.02 g) with petroleum ether and ethyl acetate, and perform column chromatography with silica gel (200 - 300 mesh). Petroleum ether: ethyl acetate (49:1) is used as the eluent to obtain compound I (0.692 g) and compound II (0.328 g).

[0060] Synthesis of Compound III:

[0061] Weigh 1-bromo-3-fluoro-5-methylbenzene (1.89 g, 10 mmol), and drop it into 5 mL of 50% fuming sulfuric acid at 0 °C. Then drop 5 mL of concentrated HNO 3 , maintain for 20 min, transfer it to a magnetic stirrer, heat to 120 °C, and stir for 2 h. After the reaction is completed, add ice water, and a white solid precipitates. Filter, wash, and dry to obtain a white solid product. Yield: 1.03 g, 31.8%.

[0062] The reaction phenomena in the preparation process of this example are the same as those in Example 1.

[0063] The structural identification results of the product obtained in this example are the same as those in Example 1.

[0064] Example 3

[0065] Synthesis of Compounds I, II and III

[0066] Synthesis of Compounds I and II:

[0067] Weigh 1-bromo-3-fluoro-5-methylbenzene (0.945 g, 5 mmol), and add it dropwise to 3 mL of 98% concentrated sulfuric acid at 0 °C. Then add 3 mL of 100% fuming nitric acid dropwise at the same temperature. After maintaining for 20 min, transfer it to a magnetic stirrer and heat to 60 °C, and stir for 1 h. After the reaction is completed, add ice water, and a pale yellow solid precipitates. Filter, wash, and dry to obtain a yellowish-brown solid product. Product: 1.16 g, yield 83.5%.

[0068] Dissolve the obtained yellowish-brown solid product (1.16 g) in petroleum ether and ethyl acetate, and perform column chromatography with silica gel (200 - 300 mesh). Use petroleum ether:ethyl acetate (45:5) as the eluent to obtain Compound I (0.768 g) and Compound II (0.392 g).

[0069] Synthesis of Compound III:

[0070] Weigh 1-bromo-3-fluoro-5-methylbenzene (1.89 g, 10 mmol), and add it dropwise to 5 mL of 20% fuming sulfuric acid at 0 °C. Then add 5 mL of concentrated nitric acid dropwise at the same temperature. After maintaining for 20 min, transfer it to a magnetic stirrer and heat to 60 °C, and stir for 2 h. After the reaction is completed, add ice water, and a pale yellow solid precipitates. After spotting on a TLC plate, it is found that Compounds I and II are obtained. Weigh 1-bromo-3-fluoro-5-methylbenzene (1.89 g, 10 mmol), and add it dropwise to 5 mL of 20% fuming sulfuric acid at 0 °C. Then add 5 mL of concentrated nitric acid dropwise at the same temperature. After maintaining for 20 min, transfer it to a magnetic stirrer and heat to 120 °C, and stir for 2 h. After the reaction is completed, add ice water, and a white solid precipitates. Filter, wash, and dry to obtain a white solid product. Yield: 0.829 g, yield: 25.6%.

[0071] The reaction phenomena in the preparation process of this example are the same as those in Example 1.

[0072] The structural identification results of the product obtained in this example are the same as those in Example 1.

[0073] Example 4

[0074] Synthesis of Compounds I, II and III

[0075] Synthesis of Compounds I and II:

[0076] Weigh 1-bromo-3-fluoro-5-methylbenzene (0.945 g, 5 mmol), and drop it into 3 mL of 98% concentrated sulfuric acid at 0 °C. Add 6.12 g of sodium nitrate at the same temperature, keep it for 20 min, then transfer it to a magnetic stirrer, heat up to 60 °C, and stir for 1 h. After the reaction is completed, add ice water, and light yellow solid precipitates. Filter, wash, and dry to obtain a yellowish-brown solid product. Product: 1.19 g, yield 85.3%.

[0077] Dissolve the obtained yellowish-brown solid product (1.19 g) with petroleum ether and ethyl acetate, and perform column chromatography with silica gel (200 - 300 mesh). Use n-hexane:ethyl acetate (48:2) as the eluent to obtain compound I (0.797 g) and compound II (0.393 g).

[0078] Synthesis of compound III:

[0079] Weigh 1-bromo-3-fluoro-5-methylbenzene (1.89 g, 10 mmol), and drop it into 5 mL of 20% fuming sulfuric acid at 0 °C. Drop in 10.01 g of sodium nitrate at the same temperature, keep it for 20 min, then transfer it to a magnetic stirrer, heat up to 120 °C, and stir for 1 h. After the reaction is completed, add ice water, and white solid precipitates. Filter, wash, and dry to obtain a white solid product. Yield: 0.589 g, yield: 18.2%.

[0080] The reaction phenomenon in the preparation process of this example is the same as that in Example 1.

[0081] The product structure identification result obtained in this example is the same as that in Example 1.

[0082] Example 5

[0083] Synthesis of compounds I, II and III

[0084] Synthesis of compounds I and II:

[0085] Weigh 1-bromo-3-fluoro-5-methylbenzene (0.945 g, 5 mmol), and drop it into 3 mL of 98% concentrated sulfuric acid at 0 °C. Add 7.27 g of potassium nitrate at the same temperature, keep it for 20 min, then transfer it to a magnetic stirrer, heat up to 60 °C, and stir for 1 h. After the reaction is completed, add ice water, and light yellow solid precipitates. Filter, wash, and dry to obtain a yellowish-brown solid product. Product: 1.13 g, yield 81.2%.

[0086] The obtained yellowish-brown solid product (1.13 g) was dissolved in petroleum ether and ethyl acetate, and column chromatography was carried out using silica gel (200 - 300 mesh). Petroleum ether:dichloromethane (44:6) was used as the eluent to obtain compound I (0.746 g) and compound II (0.384 g).

[0087] Synthesis of compound III:

[0088] 1-Bromo-3-fluoro-5-methylbenzene (1.89 g, 10 mmol) was weighed and added dropwise to 5 mL of 20% fuming sulfuric acid at 0 °C. 12.12 g of potassium nitrate was added dropwise at the same temperature. After maintaining for 20 min, it was transferred to a magnetic stirrer and heated to 120 °C, and stirred for 1 h. After the reaction was completed, ice water was added and a white solid precipitated. It was filtered, washed, and dried to obtain a white solid product. Yield: 0.634 g, yield rate: 19.6%.

[0089] The reaction phenomenon in the preparation process of this example was the same as that in Example 1.

[0090] The product structure identification result obtained in this example was the same as that in Example 1.

[0091] Example 6

[0092] Synthesis of compounds I, II and III

[0093] Synthesis of compounds I and II:

[0094] 1-Bromo-3-fluoro-5-methylbenzene (0.945 g, 5 mmol) was weighed and added dropwise to 3 mL of 20% fuming sulfuric acid at 0 °C. 7.27 g of potassium nitrate was added at the same temperature. After maintaining for 20 min, it was transferred to a magnetic stirrer and heated to 60 °C, and stirred for 1 h. After the reaction was completed, ice water was added and a pale yellow solid precipitated. It was filtered, washed, and dried to obtain a yellowish-brown solid product. Yield: 1.25 g, yield rate: 90.1%.

[0095] The obtained yellowish-brown solid product (1.25 g) was dissolved in petroleum ether and ethyl acetate, and column chromatography was carried out using silica gel (200 - 300 mesh). n-Hexane:dichloromethane (40:10) was used as the eluent to obtain compound I (0.875 g) and compound II (0.375 g).

[0096] Synthesis of compound III:

[0097] Weigh 1-bromo-3-fluoro-5-methylbenzene (1.89 g, 10 mmol), and drop it into 5 mL of 50% fuming sulfuric acid at 0 °C. Then add 12.12 g of potassium nitrate dropwise at the same temperature. After maintaining for 20 min, transfer it to a magnetic stirrer, heat up to 120 °C, and stir for 1 h. After the reaction is completed, add ice water, and white solid precipitates. Filter, wash, and dry to obtain a white solid product. Yield: 1.368 g, yield rate: 42.3%.

[0098] The reaction phenomenon in the preparation process of this example is the same as that in Example 1.

[0099] The product structure identification result of this example is the same as that in Example 1.

[0100] Example 7

[0101] Synthesis of Compounds I, II and III

[0102] Synthesis of Compounds I and II:

[0103] Weigh 1-bromo-3-fluoro-5-methylbenzene (0.945 g, 5 mmol), and drop it into 3 mL of 20% fuming sulfuric acid at 0 °C. Then add 7.27 g of potassium nitrate at the same temperature. After maintaining for 20 min, transfer it to a magnetic stirrer, heat up to 60 °C, and stir for 2 h. After the reaction is completed, add ice water, and light yellow solid precipitates. Filter, wash, and dry to obtain a yellowish-brown solid product. Product: 1.29 g, yield rate 92.7%.

[0104] Dissolve the obtained yellowish-brown solid product (1.29 g) in petroleum ether and ethyl acetate, and perform column chromatography with silica gel (200 - 300 mesh). Use n-hexane:dichloromethane (40:10) as the eluent to obtain Compound I (0.9 g) and Compound II (0.390 g).

[0105] Synthesis of Compound III:

[0106] Weigh 1-bromo-3-fluoro-5-methylbenzene (1.89 g, 10 mmol), and drop it into 5 mL of 50% fuming sulfuric acid at 0 °C. Then add 12.12 g of potassium nitrate dropwise at the same temperature. After maintaining for 20 min, transfer it to a magnetic stirrer, heat up to 150 °C, and stir for 2 h. After the reaction is completed, add ice water, and white solid precipitates. Filter, wash, and dry to obtain a white solid product. Yield: 1.562 g, yield rate: 48.3%.

[0107] The reaction phenomenon in the preparation process of this example is the same as that in Example 1.

[0108] The product structure identification result of this example is the same as that in Example 1.

[0109] The melting points of Compounds I, II and III are 50 - 108 °C, and the density is 1.82 - 2.03 g / cm 3 , and the impact sensitivity, friction sensitivity, detonation velocity, and detonation pressure data meet the requirements of the carrier explosive, and the detonation performance is excellent. These results indicate that Compounds I, II and III are excellent candidate materials for carrier explosives.

[0110] It should be noted that the above-described embodiments are only the preferred embodiments of the present invention. For those of ordinary skill in the art, without departing from the principle of the present invention, several modifications, improvements and equivalent substitutions can be made to the present invention, and these modifications, improvements and equivalent substitutions are also regarded as falling within the protection scope of the claims of the present invention.

Claims

1. A polynitro 1-bromo-3-fluoro-5-toluene energetic compound, characterized in that: Includes the following compounds:

2. The polynitro 1-bromo-3-fluoro-5-toluene energetic compound according to claim 1, characterized in that: The melting point of the polynitro 1-bromo-3-fluoro-5-toluene energetic compound is 50-108°C and the density is 1.82-2.03 g / cm 3 .

3. A method for preparing the polynitro 1-bromo-3-fluoro-5-toluene energetic compound according to claim 1, characterized in that: The steps include: Add 1-bromo-3-fluoro-5-toluene to a nitrating agent, react at 20-150° C. for 0.5-24 h, pour crushed ice into the reactant to quench the reaction, separate by column chromatography or suction filtration, and dry to obtain a polynitro 1-bromo-3-fluoro-5-toluene energetic compound.

4. The method for preparing the polynitro 1-bromo-3-fluoro-5-toluene energetic compound according to claim 3, characterized in that: The nitrating agent is any one of a mixed acid of concentrated sulfuric acid and concentrated nitric acid, a mixed acid of 50% fuming sulfuric acid and concentrated nitric acid, a mixed acid of concentrated sulfuric acid and concentrated nitric acid, a mixed acid of 50% fuming concentrated sulfuric acid and concentrated nitric acid, a mixed acid of concentrated sulfuric acid and fuming nitric acid, a mixed acid of 20% fuming concentrated sulfuric acid and concentrated nitric acid, a mixed acid of sodium nitrate and concentrated sulfuric acid, a mixed acid of sodium nitrate and 20% fuming sulfuric acid, a mixed acid of potassium nitrate and concentrated sulfuric acid, a mixed acid of potassium nitrate and 20% fuming sulfuric acid, and a mixed acid of potassium nitrate and 50% fuming sulfuric acid.

5. The method for preparing the polynitro 1-bromo-3-fluoro-5-toluene energetic compound according to claim 4, characterized in that: When separation is performed by column chromatography, the eluent is any one of a mixture of ethyl acetate and petroleum ether, a mixture of ethyl acetate and n-hexane, a mixture of dichloromethane and petroleum ether, and a mixture of dichloromethane and n-hexane.

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