CN102381981B - Method for synthesizing antioxidant for gasoline - Google Patents

Abstract

The invention discloses a preparation method of an antioxidant for gasoline, which uses p-phenylenediamine and 2-bromobutane as raw materials, uses a loaded solid base catalyst as an acid-binding agent in an aprotic solvent system, and has high selectivity. Synthesized N,N'-di-sec-butyl-p-phenylenediamine. After extracting the crude product with n-hexane, the purity of the product can be further increased. The present invention adopts _Al2O3 as the carrier-loaded solid base as the acid-binding agent, which will not produce alkali waste liquid, and _the carrier can be conveniently recycled and the present invention adopts an aprotic solvent, and the solubility of the raw material in the solvent is good, The usage amount of the solvent can be reduced, the temperature of the reaction can be lowered, the reaction time can be shortened, and the reaction selectivity can be improved. The process has mild reaction conditions, simple operation and clean production process. The product yield is high, and the purity is above 95%.

Description

A kind of synthetic method of antioxidant for gasoline

technical field

The invention relates to a synthesis method of an antioxidant for gasoline, specifically a synthesis method of N,N'-di-sec-butyl-p-phenylenediamine.

Background technique

N,N'-di-sec-butyl-p-phenylenediamine (DBPD) is a widely used gasoline antioxidant. DBPD can effectively prolong the induction period of gasoline, reduce the carbon deposition of gasoline during combustion, and prevent spark plugs from being blocked And oil pipelines, DBPD can be miscible with gasoline in any ratio, has outstanding advantages compared with traditional solid antioxidants, it is easy to add, and has strong anti-oxidation performance. Adding a small amount of DBPD can achieve a very good anti-oxidation effect In addition, DBPD is also a common antiozonant for rubber and plastics, which can prevent organic compounds from deteriorating due to oxidation.

At present, the method of mass production of DBPD is mainly the reductive amination method (US3384663). Reductive amination can improve the selectivity of the product, but it will still inevitably produce aromatic rings and by-products of ketone reduction; in addition, hydrogenation catalysts generally have many It is a transition metal element or a mixture thereof, which increases the production cost, and the reaction temperature and pressure are high, the production process is complicated to operate, and the cost is high.

There are also related reports on the synthesis of p-phenylenediamine by direct N-alkylation method, ([Zhang Xiaoyun, Liu Yali, Xia Hongdao, Petroleum Refining and Chemical Industry, 35 (5), 2004, 32-34.) But the conversion rate of raw materials is not high , poor selectivity, complex post-treatment process, and the use of lye as an acid-binding agent increases the burden on subsequent sewage treatment, which cannot meet environmental protection requirements. At present, this product mainly depends on imports in China and is expensive. Therefore, DBPD has huge potential economic benefits.

Contents of the invention

The purpose of the present invention is to provide a method for preparing N,N'-di-sec-butyl-p-phenylenediamine with simple reaction conditions, good selectivity, high yield, environmental protection and easy operation.

The technical solution for realizing the present invention is: under the protection of nitrogen, select an aprotic solvent, use p-phenylenediamine and 2-bromobutane as raw materials to directly carry out N-alkylation reaction, and use a loaded solid base as an acid-binding N, N'-di-sec-butyl-p-phenylenediamine is prepared by neutralizing the generated by-product HBr at a suitable temperature and after a suitable reaction time, and the product N with high purity is obtained after extracting the crude product with n-hexane , N'-di-sec-butyl-p-phenylenediamine.

The preparation method of the supported solid base in the method is as follows: the metal salt is dissolved in deionized water, added to the carrier and impregnated for 1-2 days, distilled under reduced pressure at 50-60°C, and dried at 100-140°C under normal pressure for 4-6h , Moved into a horse boiling furnace and calcined at 400-500°C for 8-12h, the loaded solid base can be obtained.

The metal salt is preferably KF, KCl, KNO ₃ , the carrier is preferably Al ₂ O ₃ , and the metal salt loading is preferably 25-40w%.

The mass ratio of the supported solid base to p-phenylenediamine is preferably (3-5):1.

The aprotic solvent is preferably 1-methyl-2-pyrrolidone and dimethyl sulfoxide, and the molar ratio of the aprotic solvent to p-phenylenediamine is preferably 20:1.

In the method, the molar ratio of 2-bromobutane and p-phenylenediamine is preferably (1-4): 1, the reaction temperature is preferably 50-80°C, and the reaction time is preferably 8-10h.

Compared with the prior art, the present invention has the remarkable advantages of:

This method has significant advantages over the traditional N-hydrocarbylation method: (1) This method uses Al ₂ O ₃ as the carrier of the supported solid base as the acid-binding agent, does not produce alkali waste liquid, and the carrier can be easily recycled . (2) The method adopts an aprotic solvent, and the solubility of the raw materials in the solvent is good, which can reduce the amount of solvent used; and in the reaction system, the reaction temperature can be reduced, the reaction time can be shortened, and the reaction selectivity can be improved. (3) p-phenylenediamine and 2-bromobutane are used as raw materials, the reaction operation is simple, the conditions are mild, and industrial production is convenient. (4) The post-treatment process of this method uses n-hexane as the extraction agent, and the solubility difference of the main and by-products in the extraction agent is obvious, which can improve the purity of the target product, and the solution is clearly separated, which solves the problem of using ether as the extraction agent. Obvious deficiency.

Description of drawings

Figure 1 is the mass spectrum of N,N'-di-sec-butyl-p-phenylenediamine prepared by the synthesis method of the present invention (a is the first-order mass spectrum, b is the second-order mass spectrum).

Fig. 2 is the gas chromatogram of N,N'-di-sec-butyl-p-phenylenediamine prepared by the synthetic method of the present invention.

Detailed ways

The following examples illustrate the application of the present invention, but do not represent the process conditions that limit the present invention.

The preparation method of the supported solid base in the present invention is a well-known method in the prior art.

The synthetic method of N of the present invention, N '-di-sec-butyl-p-phenylenediamine comprises the following steps:

1. Preparation of supported solid base: Dissolve metal salt in deionized water, add Al ₂ O ₃ carrier, impregnate for 24-48 hours, distill water at 50-60°C under reduced pressure, dry at normal pressure 100-140°C for 4-6 hours , moved into a horse-boiling furnace and calcined at 400-500°C for 8-12 hours to obtain a supported solid base; the loading capacity of the metal salt is 25-40w%;

2. Add an aprotic solvent, p-phenylenediamine and the above-mentioned loaded solid base into the reaction vessel, raise the temperature within 50-80°C, slowly add 2-bromobutane dropwise under stirring, and continue the reaction for 8-10 hours ;

3. After the reaction, stop heating, filter the reaction liquid, recycle Al ₂ O ₃ , and distill and recover the solvent in the filtrate to obtain crude N,N'-di-sec-butyl-p-phenylenediamine;

4. Extract the above crude product with n-hexane for 2-3 times, combine the n-hexane layers, wash with deionized water, then dry the n-hexane layer with anhydrous sodium sulfate, and distill off the n-hexane to obtain N,N'-di-sec-butyl p-Phenylenediamine.

Example 1. First prepare KF/Al ₂ O ₃ with a loading capacity of 40w%. Dissolve 20g KF in 100ml deionized water, add 30g Al ₂ O ₃ carrier, soak for 24h, distill water under reduced pressure at 60°C, and normal pressure 100°C After drying for 4 hours, move it into a horse boiling furnace and calcinate at 400°C for 8 hours to obtain KF/Al ₂ O ₃ . Then, 1.08g (10mmol) of p-phenylenediamine, 20mL (200mmol) of 1-methyl-2-pyrrolidone, and 3.24g of KF/Al ₂ O ₃ (mass ratio, p-Phenylenediamine: KF/Al ₂ O ₃ =1:3); warm up to 80°C, slowly add 4.8mL (40mmol) of 2-bromobutane dropwise under stirring, complete the dropwise addition within 2h, and stop after 8h of reaction Heating; filtering the reaction solution, recycling Al ₂ O ₃ , distilling and recovering the solvent 1-methyl-2-pyrrolidone in the filtrate to obtain crude N,N'-di-sec-butyl-p-phenylenediamine; extracting N,N' with n-hexane N'-di-sec-butyl-p-phenylenediamine crude product 2-3 times, combined n-hexane layer, washed with deionized water, and dried n-hexane layer with anhydrous sodium sulfate, distilled n-hexane to obtain N,N'-di 2.11 g of sec-butyl-p-phenylenediamine. The gas chromatography purity test was 95.1%, and the yield was 95.5%.

Example 2. First prepare KF/Al ₂ O ₃ with a loading capacity of 40w%. Dissolve 20g of KF in 100ml of deionized water, add 30g of Al ₂ O ₃ carrier, impregnate for 48h, distill water at 50°C under reduced pressure, and normal pressure at 140°C After drying for 6 hours, move it into a horse boiling furnace and calcinate at 500°C for 12 hours to obtain KF/Al ₂ O ₃ . The experimental conditions of the reaction synthesis steps are the same as in Example 1. The amount of 2-bromobutane added is replaced by 3.6mL (30mmol) to 4.8mL (40mmol) to obtain 2.03g of N,N'-di-sec-butyl-p-phenylenediamine with a purity of 96.0 %, yield 91.9%.

Example 3. First prepare KF/Al ₂ O ₃ with a loading capacity of 40w%. Dissolve 20g KF in 100ml deionized water, add 30g Al ₂ O ₃ carrier, soak for 36h, distill water under reduced pressure at 55°C, and normal pressure 120°C After drying for 5 hours, move it into a horse boiling furnace and calcinate at 450°C for 10 hours to obtain KF/Al ₂ O ₃ . The experimental conditions of the reaction synthesis steps are the same as in Example 1. The amount of 2-bromobutane added is replaced by 1.2mL (10mmol) to 4.8mL (40mmol) to obtain 0.89g of N,N'-di-sec-butyl-p-phenylenediamine with a purity of 96.0 %, the yield is 40.3%.

Example 4. Repeat the method of Example 1. In the synthesis step, the reaction temperature is 65°C instead of 80°C, the reaction time is 9h instead of 8h, and other conditions are unchanged. After the reaction, N,N'-di-sec-butyl-terephthalene is obtained Amine 2.01g, purity 96.1%, yield 90.9%.

Example 5. Repeat the method of Example 1. In the synthesis step, the reaction temperature is 50°C instead of 80°C, the reaction time is 10h instead of 8h, and other conditions remain unchanged. After the reaction, N,N'-di-sec-butyl-terephthalene is obtained Amine 1.95g, purity 96.0%, yield 88.2%.

Example 6. First prepare KF/Al ₂ O ₃ with a loading capacity of 30w%. Dissolve 12.9g of KF in 100ml of deionized water, add 30g of Al ₂ O ₃ carrier, soak for 24h, distill water under reduced pressure at 60°C, and normal pressure 100 ℃ drying for 4 hours, transferred to a horse boiling furnace and calcined at 400 ℃ for 8 hours to obtain KF/Al ₂ O ₃ . The experimental conditions of the reaction synthesis steps are the same as in Example 1, but the loading is replaced by 4.32g of KF/Al ₂ O ₃ (mass ratio, p-phenylenediamine: KF/Al ₂ O ₃ =1:4) with a loading of 30w%. 40w% KF/Al ₂ O ₃ 3.24g (mass ratio, p-phenylenediamine: KF/Al ₂ O ₃ =1:3), and the rest of the experimental conditions remain unchanged, after the reaction, N,N'-di-sec-butyl 2.03g of p-phenylenediamine, the purity is 95.4%, and the yield is 91.8%.

Example 7. First prepare KF/Al ₂ O ₃ with a loading capacity of 25w%. Dissolve 10g KF in 100ml deionized water, add 30g Al ₂ O ₃ carrier, soak for 24h, distill water under reduced pressure at 60°C, and normal pressure 100°C After drying for 4 hours, move it into a horse boiling furnace and calcinate at 400°C for 8 hours to obtain KF/Al ₂ O ₃ . The experimental conditions of the reaction synthesis steps are the same as those in Example 1, but 5.4 g of KF/Al ₂ O ₃ with a loading of 25w% (mass ratio, p-phenylenediamine: KF/Al ₂ O ₃ =1:5) is used instead of the loading of 40w% KF/Al ₂ O ₃ 3.24g (mass ratio, p-phenylenediamine: KF/Al ₂ O ₃ =1:3), and the rest of the experimental conditions remain unchanged, after the reaction, N,N'-di-sec-butyl 2.08g of p-phenylenediamine, the purity is 95.0%, and the yield is 94.1%.

Example 8. Repeat the method of Example 1. In the synthesis step, the solvent uses dimethylformamide instead of 1-methyl-2-pyrrolidone, and other conditions remain unchanged. After the reaction, N,N'-di-sec-butyl-p-phenyl Diamine 1.92g. The gas chromatography purity test was 95.1%, and the yield was 86.0%.

Example 9. Repeat the method of Example 1. In the synthesis step, KCl/Al ₂ O ₃ is used to replace KF/Al ₂ O ₃ with solid base, and other conditions remain unchanged. After the reaction, N,N'-di-sec-butyl pair 0.93 g of phenylenediamine. The gas chromatography purity test was 95.2%, and the yield was 42.0%.

Example 10. Repeat the method of Example 1. In the synthesis step, KNO ₃ /Al ₂ O ₃ is used to replace KF/Al ₂ O ₃ with solid base, and other conditions remain unchanged. After the reaction, N,N'-di-sec-butyl 0.43g of p-phenylenediamine. The gas chromatography purity test was 95.0%, and the yield was 19.4%.

Claims (4)

1. a synthetic method for gasoline antioxidant, is characterized in that carrying out according to the following steps: Step 1, adding aprotic solvent 1-methyl-2 pyrrolidone or dimethylformamide, p-phenylenediamine and a loaded solid base in the reaction vessel, wherein the loaded solid base is made by the following steps: Dissolve the metal salt KF, KCl or KNO ₃ in deionized water, add the carrier Al ₂ O ₃ , the load of the metal salt is 25-40w%, impregnate for 24-48h, distill under reduced pressure at 50-60°C, under normal pressure Dry at 100-140°C for 4-6 hours, transfer to a horse boiling furnace and calcinate at 400-500°C for 8-12 hours to obtain a supported solid base; Step 2, react after stirring and dropping 2-bromobutane; Step 3, filtering the reaction solution, distilling and recovering the solvent in the filtrate to obtain the crude product of N,N'-di-sec-butyl-p-phenylenediamine; Step 4, extracting the above-mentioned crude product and then distilling the extract to obtain N,N'-di-sec-butyl-p-phenylenediamine. 2. the synthetic method of a kind of antioxidant for gasoline according to claim 1 is characterized in that the mol ratio of aprotic solvent described in step 1 and p-phenylenediamine is 20:1, and described load The mass ratio of type solid base to p-phenylenediamine is (3-5):1. 3. the synthetic method of a kind of gasoline antioxidant according to claim 1 is characterized in that the mol ratio of 2-bromobutane described in step 2 and p-phenylenediamine is (1-4): 1 , the reaction temperature is 50-80°C, and the reaction time is 8-12h. 4. the synthetic method of a kind of antioxidant for gasoline according to claim 1 is characterized in that used extraction agent is normal hexane in step 4.

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