A method for preparing 2-nitropropane

Abstract

The present invention belongs to the field of organic synthesis, and specifically discloses a method for preparing 2-nitropropane, which comprises the following steps: (1) isopropylhydroxylamine is oxidized with hydrogen peroxide in the presence of a catalyst to prepare 2-nitropropane; (2) after the reaction is completed, an extractant is added for extraction, and then the extraction phase is subjected to rectification separation to obtain 2-nitropropane; the present invention provides a method for producing 2-nitropropane that is simpler, safer, more environmentally friendly, more economical and more stable than conventional methods, and has the following advantages in the production method of the present invention: (1) the process reaction conditions are mild, the reaction selectivity is high, and the by-products are few; (2) the separation is simple, the product purity is high, and it is safe and environmentally friendly; (3) the product is single and is not affected by the market of by-products.

Description

Technical Field

[0001] The present invention belongs to the field of organic synthesis, and specifically discloses a method for preparing 2-nitropropane. Specifically, isopropylhydroxylamine is oxidized with hydrogen peroxide under the action of a catalyst to obtain 2-nitropropane. Background Art

[0002] 2-Nitropropane is an important fine chemical intermediate and has broad application prospects in the fields of dyes, pigments, coatings, polymers, pharmaceuticals, etc. 2-Nitropropane is also an intermediate for synthesizing 2-amino-2-methyl-1-propanol, which is a well-known multifunctional coating additive. It is applicable to all latex paint formulations, mainly used to adjust the pH of latex paints, and at the same time has functions such as wetting and dispersing assistance.

[0003] Currently, the production methods of 2-nitropropane all adopt the nitration method of alkanes (as disclosed in Chinese Patent Application CN201080047327.4), and Chinese Patent Application CN201010592408.4 has also made certain improvements in aspects such as reactors. However, in these methods, there are still problems such as operation hazards, serious pollution, and low selectivity of the target product. To improve the defects of the above processes, CN107641084a provides a method for producing nitroalkanes and co-producing ketoxime, but there are still problems such as difficult-to-obtain catalysts, many by-products (the main by-product of the existing process is acetone oxime), and high costs. However, among the methods disclosed in the above patents, none involve a method for highly selectively producing 2-nitropropane by oxidizing isopropylhydroxylamine. Therefore, it is necessary to develop a method for producing 2-nitropropane by directly oxidizing isopropylhydroxylamine, which is green, environmentally friendly, has mild reaction conditions, high raw material conversion rate, and high product selectivity. Summary of the Invention

[0004] In view of the above problems, the present invention discloses a method for preparing 2-nitropropane, which can produce 2-nitropropane more simply, safely, environmentally friendly, economically, and stably than conventional methods.

[0005] The object of the present invention is achieved by the following technical solutions.

[0006] A method for preparing 2-nitropropane, as Figure 1 shown, includes the following steps:

[0007] (1) Isopropylhydroxylamine is oxidized with hydrogen peroxide in the presence of a catalyst to prepare 2-nitropropane;

[0008] (2) After the reaction is completed, an extractant is added for extraction, and then the extraction phase is subjected to rectification separation to obtain 2-nitropropane.

[0009] Furthermore, in the above method for preparing 2-nitropropane, the catalyst in step (1) is a tungsten-containing catalyst;

[0010] Preferably, the catalyst is one or more of tungstic acid, tungstate, and phosphotungstic acid;

[0011] More preferably, the catalyst is one or more of tungstic acid, sodium tungstate, and calcium tungstate.

[0012] Furthermore, in the above method for preparing 2-nitropropane, the amount of the tungsten-containing catalyst used is 0.1%-20% of the mass of the isopropylhydroxylamine;

[0013] Preferably, the amount of the tungsten-containing catalyst is 1%-10% of the mass of the isopropylhydroxylamine. More preferably, the amount of the tungsten-containing catalyst is 1%-5% of the mass of the isopropylhydroxylamine.

[0014] Preferably, in the above-mentioned method for preparing 2-nitropropane, the isopropylhydroxylamine used as a raw material reactant in step (1) is used in the form of a 15% isopropylhydroxylamine aqueous solution. The isopropylhydroxylamine can be added to the reaction system all at once or in batches within about 1 hour to about 12 hours, preferably added to the reaction system all at once.

[0015] Furthermore, in the above method for preparing 2-nitropropane, the hydrogen peroxide in step (1) is a hydrogen peroxide aqueous solution with a mass concentration of 20% to 50%;

[0016] Wherein, the molar ratio of hydrogen peroxide to isopropylhydroxylamine is 1-4:1, preferably 2-2.5:1.

[0017] The hydrogen peroxide is added to the reaction system within 2 to 15 hours, preferably within 3 to 8 hours; the specific addition rate is adjusted according to the heat release of the reaction and the heat transfer of the reaction equipment, and is controlled at the set reaction temperature.

[0018] Furthermore, in the above method for preparing 2-nitropropane, the reaction in step (1) is carried out at a temperature of -10°C to 100°C, preferably 15°C to 55°C.

[0019] Furthermore, in the above method for preparing 2-nitropropane, the reaction in step (1) is carried out using a batch process, a series reaction of multiple reactors (CSTR), or a continuous tubular reaction (PFR) process.

[0020] Furthermore, in the above method for preparing 2-nitropropane, step (2) comprises: extracting the reaction solution containing 2-nitropropane obtained after the reaction with a solvent.

[0021] Further, in the above method for preparing 2-nitropropane, the solvent used for extraction in step (2) is one or more of benzene series, chloroalkanes, esters, ethers and hydrocarbon solvents;

[0022] Preferably, it is one or more of toluene, dichloromethane, dichloroethane, ethyl acetate, dimethyl carbonate, isopropyl ether and cyclohexane.

[0023] A 2-nitropropane is obtained by the above method.

[0024] Compared with the existing technology, the present invention has the following advantages and beneficial effects:

[0025] The present invention discloses a method for preparing 2-nitropropane. Compared with the traditional method for producing 2-nitropropane and co-producing ketoxime by nitrating alkanes, the production method according to the present invention has the following advantages: (1) The process reaction conditions are mild, the reaction selectivity is high, and the by-products are few; (2) The separation is simple, the product purity is high, and it is safe and environmentally friendly; (3) The product is single and not affected by the market of by-products. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Process flow chart of the present invention;

[0027] Figure 2 HPLC spectrum. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] To make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the drawings and embodiments. However, it should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the scope of the present invention. In addition, in the following description, the descriptions of well-known structures and technologies are omitted to avoid unnecessarily confusing the concepts of the present invention.

[0029] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the embodiments.

[0030] Example 1

[0031] A 1000 mL three-necked glass flask equipped with mechanical stirring and a glass condenser was used as the reactor. The condensation temperature was set at 15 °C. 5 g of tungstic acid catalyst and 500 g of 15% isopropylhydroxylamine were added thereto in sequence. Then, 270 g of an aqueous hydrogen peroxide solution with a concentration of 27.5% was pumped in within 3 h using a peristaltic pump. The reaction temperature was set at 20 °C, the mechanical stirring was 500 revolutions per minute, and the reaction pressure was atmospheric pressure. After the feeding of the aqueous hydrogen peroxide solution was completed, the reaction conditions were maintained and the reaction continued for 3 h. The reaction results were that the conversion rate of isopropylhydroxylamine was about 100%, and the selectivity of 2-nitropropane was about 99.7%. The reaction mixture was filtered, and the catalyst was recovered for reuse. The filtrates were combined, 500 mL of dimethyl carbonate was added for extraction, and the extract was fed into a distillation column for separation operation. The temperature at the bottom of the distillation column was set at 100 °C. First, dimethyl carbonate was recovered, and then 2-nitropropane was distilled out under reduced pressure (-0.098 MPa) with a content of 99.7%. The HPLC chromatogram is shown in Figure 2 .

[0032] Example 2

[0033] A 1000 mL three-necked glass flask equipped with mechanical stirring and a glass condenser was used as the reactor. The condensation temperature was set at 15 °C. 0.5 g of tungstic acid catalyst and 500 g of 15% isopropylhydroxylamine were added thereto in sequence. Then, 270 g of an aqueous hydrogen peroxide solution with a concentration of 27.5% was pumped in within 3 h using a peristaltic pump. The reaction temperature was set at 20 °C, the mechanical stirring was 500 revolutions per minute, and the reaction pressure was atmospheric pressure. After the feeding of the aqueous hydrogen peroxide solution was completed, the reaction conditions were maintained and the reaction continued for 3 h. The reaction results were that the conversion rate of isopropylhydroxylamine was about 89%, and the selectivity of 2-nitropropane was about 98.0%.

[0034] Example 3

[0035] A 1000 mL three-necked glass flask equipped with mechanical stirring and a glass condenser was used as the reactor. The condensation temperature was set at 15 °C. 5 g of sodium tungstate catalyst and 500 g of 15% isopropylhydroxylamine were added thereto in sequence. Then, 270 g of an aqueous hydrogen peroxide solution with a concentration of 27.5% was pumped in within 1 h using a peristaltic pump. The reaction temperature was set at -10 °C, the mechanical stirring was 500 revolutions per minute, and the reaction pressure was atmospheric pressure. After the feeding of the aqueous hydrogen peroxide solution was completed, the reaction conditions were maintained and the reaction continued for 8 h. The reaction results were that the conversion rate of isopropylhydroxylamine was about 99%, and the selectivity of 2-nitropropane was about 99.5%.

[0036] Example 4

[0037] A 1000 mL three-necked glass flask equipped with mechanical stirring and a glass condenser was used as the reactor. The condensation temperature was set at 5°C. 10 g of calcium tungstate catalyst and 500 g of 15% isopropylhydroxylamine were added thereto in sequence. Then, 150 g of 50% hydrogen peroxide aqueous solution was pumped in within 3 hours using a peristaltic pump. The reaction temperature was set at 55°C, the mechanical stirring speed was 500 rpm, and the reaction pressure was at atmospheric pressure. After the feeding of the hydrogen peroxide aqueous solution was completed, the reaction conditions were maintained and the reaction continued for 1 h. The reaction results showed that the conversion rate of isopropylhydroxylamine was approximately 97%, and the selectivity for 2-nitropropane was approximately 99%.

[0038] Example 5

[0039] A 1000 mL three-necked glass flask equipped with mechanical stirring and a glass condenser was used as the reactor. The condensation temperature was set at 5°C. 5 g of phosphotungstic acid catalyst and 500 g of 15% isopropylhydroxylamine were added thereto in sequence. Then, 150 g of 50% hydrogen peroxide aqueous solution was pumped in within 3 h using a peristaltic pump. The reaction temperature was set at 55°C, the mechanical stirring speed was 500 rpm, and the reaction pressure was at atmospheric pressure. After the feeding of the hydrogen peroxide aqueous solution was completed, the reaction conditions were maintained and the reaction continued for 3 h. The reaction results showed that the conversion rate of isopropylhydroxylamine was approximately 98%, and the selectivity for 2-nitropropane was approximately 97%.

[0040] It can be seen from the above examples that the present invention discloses a method for preparing 2-nitropropane. Compared with the traditional method for producing 2-nitropropane and co-producing ketoxime by nitrating alkanes, the production method according to the present invention has the following advantages: (1) The process reaction conditions are mild, the reaction selectivity is high, and the by-products are few; (2) The separation is simple, the product purity is high, and it is safe and environmentally friendly; (3) The product is single and not affected by the market of by-products.

[0041] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present invention and not to limit the protection scope of the present invention. Therefore, based on the innovative concept of the present invention, any changes and modifications made to the embodiments described herein, or equivalent structural or equivalent process transformations made using the content of the specification and drawings of the present invention, and directly or indirectly applying the above technical solutions to other related technical fields, are all included in the protection scope of the present invention patent.

Claims

1. A method for preparing 2-nitropropane, characterized in that, It includes the following steps: (1) 2-Nitropropane is prepared by oxidizing isopropylhydroxylamine with hydrogen peroxide in the presence of a catalyst; the catalyst is one or more of tungstic acid, sodium tungstate, and calcium tungstate; (2) After the reaction is completed, an extractant is added for extraction, and then the extraction phase is subjected to rectification separation to obtain 2-nitropropane.

2. The method according to claim 1, characterized in that, The dosage of the catalyst is 0.1%-20% of the mass of isopropylhydroxylamine.

3. The method according to claim 2, wherein The dosage of the catalyst is 1%-10% of the mass of isopropylhydroxylamine.

4. The method according to claim 1, characterized in that: In step (1), the hydrogen peroxide used is an aqueous hydrogen peroxide solution with a mass concentration of 20% to 50%; wherein, the molar ratio of the hydrogen peroxide to isopropylhydroxylamine is 1-4:

1.

5. The method according to claim 1, characterized in that The reaction in step (1) is carried out at -10°C to 100°C.

6. The method according to claim 1, characterized in that, The reaction in step (1) is carried out by a single-pot batch process, a multi-pot series connection, or a tubular continuous process.

7. The method according to claim 1, characterized in that, Step (2) includes: extracting the reaction solution containing 2-nitropropane obtained after the reaction is completed with an extractant.

8. The method according to claim 7, characterized in that The extractant used for extraction in step (2) is one or more of benzene series, chloroalkanes, esters, ethers, and hydrocarbon solvents.

9. The method according to claim 8, wherein The extractant used for extraction in step (2) is one or more of toluene, dichloromethane, dichloroethane, ethyl acetate, dimethyl carbonate, isopropyl ether, and cyclohexane.

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