CN1944395A - Process for preparing P-nitro benzoic acid by bionically catalystically oxidizing P-nitro toluene with oxygen - Google Patents

Abstract

The invention relates to a method for preparing p-nitrobenzoic acid by biomimetic catalytic oxygen oxidation of p-nitrotoluene. The method uses p-nitrotoluene as a raw material, selects metal phthalocyanine, mononuclear metalloporphyrin or μ-oxygen binuclear metalloporphyrin as a catalyst, and the amount of the catalyst is 0.01 to 1.0% of the weight of p-nitrotoluene. 40-95% volume of ethanol aqueous solution is used as a solvent, in 1-6mol/L strong alkaline ethanol aqueous solution, 0.8-3.0MPa of oxygen is passed through, the reaction temperature is controlled to be 35-55°C, and the reaction time is 2-14h, to obtain the Nitrobenzoic acid. The method of the invention not only has low toxicity, safe operation, high yield, low cost and simple process, but also the product yield is higher than the data reported in current literature.

Description

Method for preparing p-nitrobenzoic acid by biomimetic catalytic oxygen oxidation of p-nitrotoluene

technical field

The invention relates to a preparation method of aromatic acid, in particular to a method for preparing p-nitrobenzoic acid by biomimetic catalyzing oxygen oxidation of p-nitrotoluene.

Background technique

p-Nitrobenzoic acid is an important intermediate for the preparation of medicines, dyes, veterinary drugs, photosensitive materials, pesticides and high-strength fibers and resins. The method for synthesizing p-nitrobenzoic acid reported in the literature at present mainly adopts the catalytic oxygen oxidation method in alkaline medium. She Yuanbin and others have reported that metal phthalocyanines (Org. Process Res. Dev. 2005, 9: 297-301) or metal porphyrins (Org. Process Res. Dev. 2006 , 10 (4), 757-761) is the method for synthesizing p-nitrobenzoic acid by catalyzing the oxidation of p-nitrotoluene with biomimetic catalyst, this method solves the equipment corrosion and environmental pollution existing in the synthesis of p-nitrobenzoic acid in acidic medium And other issues. Chinese patent CN 1271040C (authorized announcement date: August 23, 2006) discloses a method for selectively controlling the oxidation reaction to prepare the intermediate product p-nitrobenzaldehyde. The method is to use anhydrous methanol under alkaline conditions Metal phthalocyanines or metal porphyrins were selected as solvents as biomimetic catalysts to catalyze oxygen oxidation of p-nitrotoluene to prepare p-nitrobenzaldehyde. But its weak point is that both the preparation of p-nitrobenzoic acid and the preparation of intermediate product p-nitrobenzaldehyde all adopt anhydrous methanol as solvent, and anhydrous methanol not only has potential explosion under pure oxygen conditions (reaction or distillation) Dangerous, but also a potential threat to the health of laboratory or industrial operators.

Contents of the invention

The purpose of the present invention is to provide a method for preparing p-nitrobenzoic acid by biomimetic catalytic oxygen oxidation of p-nitrotoluene with almost no toxicity, safe operation, high yield, low cost and simple process.

The technical scheme that the present invention adopts is: take p-nitrotoluene as raw material, select the metallophthalocyanine of general formula (I) structure, the mononuclear metalloporphyrin of general formula (II), (III) structure or general formula (IV) ) structure of μ-oxygen dinuclear metal porphyrin as a catalyst, in the formula, M ₁ , M ₂ , M ₃ , M ₄ , M ₅ are transition metal atoms, M ₁ =Fe, Co, Cu, Zn , M ₂ =Fe, Mn, Co, Cu, Zn, M ₃ =Fe, Mn, Co, M ₄ and M ₅ can be the same or different, when they are the same, M ₄ =M ₅ =Fe, Mn, Co, At different times, M ₄ =Fe, M ₅ =Mn or M ₄ =Fe, M ₅ =Co, R is carboxyl or hydrogen, R ₁ and R ₂ are hydrogen, halogen, nitro, hydroxyl, alkoxy, coordination The base X is chlorine, and the consumption of the catalyst is 0.01 to 1.0% of the weight of p-nitrotoluene. With ethanol aqueous solution containing 40 to 95% volume of ethanol as the solvent, 0.8 ～3.0MPa oxygen, control the reaction temperature to 35～55°C, and the reaction time is 2～14h to obtain p-nitrobenzoic acid.

Preferably, the mononuclear metalloporphyrin with the general formula (III) or the μ-oxygen-binuclear metalloporphyrin with the general formula (IV) is used as the catalyst.

Particularly preferred is the mononuclear metalloporphyrin of M ₃ =Mn or Fe in general formula (III), R ₁ =NO ₂ or Cl, R ₂ =H, X=Cl; M ₄ and M ₅ in general formula (IV) When the same, M ₄ =M ₅ =Fe, Mn or Co, when M ₄ and M ₅ are different, M ₄ =Fe, M ₅ =Mn, R ₁ =NO ₂ or Cl, R ₂ =μ-oxygen- Binuclear metalloporphyrins.

The initial concentration of the above-mentioned p-nitrotoluene is 0.2-1.2 mol/L.

General formula (I)

General formula (II)

General formula (III)

General formula (IV)

The invention uses ethanol aqueous solution as solvent, preferably ethanol aqueous solution containing 50-70% ethanol by volume, which is not only safe and almost non-toxic, but also cheap and easy to obtain, reducing the preparation cost of the target product.

Almost all chemical researchers believe that oxygen or air oxidation reactions are free radical reactions, and agree that only in organic solvents can the reaction process be effectively controlled, while free radical oxidation reactions in aqueous solutions are difficult to carry out because water Is a recognized free radical annihilation agent. In addition, since water cannot effectively dissolve the raw material p-nitrotoluene, the reaction cannot be effectively carried out. In the reaction that p-nitrotoluene of prior art report prepares p-nitrobenzoic acid, the methanol solvent used can generate stronger alkaline sodium methylate with sodium hydroxide, thereby more favorable to reaction, so think that methyl alcohol is for this reaction indispensable. However, methanol has serious side effects and potential explosive problems. Therefore, the present invention uses ethanol aqueous solution instead of anhydrous methanol as a solvent, solves many technical problems in the aqueous solution reaction, not only realizes biomimetic catalytic oxygen oxidation of p-nitrotoluene to produce p-nitrobenzoic acid, but also breaks free radical oxidation The law that the reaction is generally not easy to carry out in water makes the reaction medium for the oxidation of p-nitrotoluene realize the leap from organic solvent to aqueous solution. Moreover, the product yields obtained by using ethanol aqueous solution as the solvent are all higher than that of the original anhydrous methanol as the solvent.

Table 1 is a comparison of methanol, ethanol and water performance parameters. The data in Table 1 shows that the toxicity of ethanol and water is far lower than methanol; its flash point is much higher than methanol, and the explosion limit is far narrower than methanol, indicating that aqueous ethanol is a safer, almost non-toxic solvent; The boiling points of ethanol and water are much higher than methanol, indicating that ethanol aqueous solution has low volatility and less loss. Therefore, the use of ethanol, especially its aqueous solution, can greatly reduce the risk of the reaction process and solvent recovery, as well as the harm to workers and the environment.

Table 2 is a comparison of the yields of p-nitrobenzoic acid synthesized in different solvents. As can be seen from the data in Table 2, all the oxidation methods involved in the present invention in ethanol aqueous solution have product yields that are significantly higher than the data reported in the prior art and literature.

The invention uses metal phthalocyanines or metal porphyrins as biomimetic catalysts, and realizes the preparation of p-nitrobenzoic acid by catalyzing oxygen oxidation of p-nitrotoluene under mild conditions (35-55 DEG C). Experiments have proved that these catalysts have good catalytic properties for the reaction of oxygen oxidation of p-nitrotoluene to prepare p-nitrobenzoic acid.

Detailed ways

Example 1

Take 2mg of cobalt phthalocyanine (that is, R=H in the general formula (I), M ₁ =Co), 1.4g of p-nitrotoluene and 2g of sodium hydroxide, put it into a 200mL autoclave, add 55% ethanol (V/ V) Ethanol aqueous solution (95% ethanol: 22mL, water: 16mL) 38mL, feed oxygen at a pressure of 2.0MPa, and react in a water bath at a temperature of 40°C for 14h. After the reaction, samples were taken, and the reaction mixture was filtered with suction to remove the catalyst, then 15 mL of distilled water was added, neutralized with dilute hydrochloric acid, and filtered. The obtained product was analyzed and detected by high-pressure liquid chromatography, and the yield of p-nitrobenzoic acid was 96.2%.

Example 2

Take 22mg of iron phthalocyanine (that is, R=H, M ₁ =Fe in the general formula (I), 6.3g of p-nitrotoluene and 9.0g of sodium hydroxide, put it into a 200mL autoclave, add 70% ethanol (V /V) ethanol aqueous solution (95% ethanol: 28mL, water: 10mL) 38mL, reaction pressure 3.0MPa, temperature control 35°C in a water bath, react for 8h. The aftertreatment steps are the same as in Example 1, and the obtained product is analyzed and detected by high-pressure liquid chromatography, and the yield of p-nitrobenzoic acid is 96.4%.

Example 3

Take 10mg of copper phthalocyanine (that is, R=H, M ₁ =Cu in the general formula (I), 1.0g of p-nitrotoluene and 2.5g of sodium hydroxide, put it into a 200mL autoclave, add 75% ethanol (V /V) ethanol aqueous solution (95% ethanol: 30mL, water: 8mL) 38mL, oxygen pressure 2.5MPa, temperature control 40°C in a water bath, react for 10h. The aftertreatment steps are the same as in Example 1, and the obtained product is analyzed and detected by high-pressure liquid chromatography, and the yield of p-nitrobenzoic acid is 93.2%.

Example 4

Take 10mg of zinc phthalocyanine (that is, R=H, M ₁ =Zn in the general formula (I), 3.6g of p-nitrotoluene and 6.8g of sodium hydroxide, put it into a 200mL autoclave, add 95% ethanol (V /V) ethanol aqueous solution (95% ethanol: 38mL, water: 0mL) 38mL, oxygen pressure 2.0MPa, temperature control 45°C in a water bath, react for 2h. The aftertreatment steps are the same as in Example 1, and the obtained product is analyzed and detected by high-pressure liquid chromatography, and the yield of p-nitrobenzoic acid is 92.8%.

Example 5

Take 5.2 mg of tetracarboxycobalt phthalocyanine (that is, R=COOH in general formula (I), M ₁ =Co), 2.2 g of p-nitrotoluene and 4.8 g of potassium hydroxide, put them into an autoclave, and add 65% ethanol (V/V) ethanol aqueous solution (95% ethanol: 26mL, water: 20mL) 46mL, oxygen pressure 0.8MPa, temperature control 55°C in a water bath, react for 9h. The aftertreatment steps are the same as in Example 1, and the obtained product is analyzed and detected by high-pressure liquid chromatography, and the yield of p-nitrobenzoic acid is 96.0%.

Example 6

Take 2.0 mg tetrakis-(p-chlorophenyl) cobalt porphyrin (i.e. R ₁ =H in the general formula (II), R ₂ =Cl, M ₂ =Co), 4.0 g p-nitrotoluene and 9.1 g sodium hydroxide , into a 200mL autoclave, add 38mL of ethanol aqueous solution (95% ethanol: 28mL, water: 10mL) containing 70% ethanol (V/V), oxygen pressure is 2.5MPa, water bath temperature is controlled at 55°C, and reacted for 8h. The aftertreatment steps are the same as in Example 1, and the obtained product is analyzed and detected by high-pressure liquid chromatography, and the yield of p-nitrobenzoic acid is 96.4%.

Example 7

Take 1.1mg tetrakis-(p-chlorophenyl)iron porphyrin (i.e. R ₁ =H in general formula (II), R ₂ =Cl, M ₂ =Fe), 2.2g p-nitrotoluene and 1.5g sodium hydroxide , into a 200mL autoclave, add 46mL of ethanol aqueous solution (95% ethanol: 26mL, water: 20mL) containing 65% ethanol (V/V), oxygen pressure is 0.8MPa, temperature is controlled in a water bath at 45°C, and reacted for 10h. The aftertreatment steps are the same as in Example 1, and the obtained product is analyzed and detected by high-pressure liquid chromatography, and the yield of p-nitrobenzoic acid is 96.6%.

Example 8

Take 1.0mg tetrakis-(p-hydroxyphenyl)copper porphyrin (that is, R ₁ =H, R ₂ =OH, M ₂ =Cu in the general formula (II), 2.8g p-nitrotoluene and 3.5g hydroxide Put potassium into a 200mL autoclave, add 38mL of ethanol aqueous solution (95% ethanol: 16mL, water: 22mL) containing 40% ethanol (V/V), oxygen pressure at 2.0MPa, temperature control in water bath at 40°C, and react for 14h . The aftertreatment steps are the same as in Example 1, and the obtained product is analyzed and detected by high-pressure liquid chromatography, and the yield of p-nitrobenzoic acid is 92.8%.

Example 9

Take 0.3mg tetrakis-(p-chlorophenyl) manganese porphyrin (i.e. R ₁ =H in general formula (II), R ₂ =Cl, M ₂ =Mn), 3.0g p-nitrotoluene and 3.2g sodium hydroxide , into a 200mL autoclave, add 38mL of ethanol aqueous solution (95% ethanol: 20mL, water: 18mL) containing ethanol 50% (V/V), feed oxygen at a pressure of 2.0MPa, and control the temperature in a water bath to 45°C. Reaction 12h. The aftertreatment steps are the same as in Example 1, and the obtained product is analyzed and detected by high-pressure liquid chromatography, and the yield of p-nitrobenzoic acid is 96.0%.

Example 10

Take 1.2mg tetrakis-(p-chlorophenyl) zinc porphyrin (i.e. R ₁ =H, R ₂ =Cl, M ₂ =Zn in general formula (II), 1.1g p-nitrotoluene and 2.8g sodium hydroxide , into a 200mL autoclave, add 38mL of ethanol aqueous solution (95% ethanol: 28mL, water: 10mL) containing 70% ethanol (V/V), oxygen pressure is 2.0MPa, temperature is controlled in a water bath at 50°C, and reacted for 9h. The aftertreatment steps are the same as in Example 1, and the obtained product is analyzed and detected by high-pressure liquid chromatography, and the yield of p-nitrobenzoic acid is 96.1%.

Example 11

Take 4.1 mg μ-oxygen-binuclear tetra-(o-chlorophenyl) cobalt porphyrin (that is, R ₁ =Cl, R ₂ =H, M ₄ =M ₅ =Co in the general formula (IV), 2.1 g p-nitro Put toluene and 3.5g potassium hydroxide into a 200mL autoclave, add 38mL of ethanol aqueous solution (95% ethanol: 34mL, water: 4mL) containing 85% (V/V) ethanol, and the oxygen pressure is 1.8MPa. Temperature 35 ℃, reaction 8h. The aftertreatment steps are the same as in Example 1, and the obtained product is analyzed and detected by high-pressure liquid chromatography, and the yield of p-nitrobenzoic acid is 93.0%.

Example 12

Take 2.0 mg of μ-oxygen-binuclear tetra-(o-nitrophenyl) manganese porphyrin (that is, R ₁ =NO ₂ , R ₂ =H, M ₄ =M ₅ =Mn in the general formula (IV), 2.1 g of Nitrotoluene and 5g potassium hydroxide were put into a 200mL autoclave, and 38mL of ethanol aqueous solution (95% ethanol: 28mL, water: 10mL) containing 70% (V/V) ethanol was added, and the oxygen pressure was 2.0MPa. Temperature 55 ℃, reaction 6h. The aftertreatment steps are the same as in Example 1, and the obtained product is analyzed and detected by high-pressure liquid chromatography, and the yield of p-nitrobenzoic acid is 96.2%.

Example 13

Take 1 mg μ-oxygen-binuclear tetra-(o-chlorophenyl) manganese porphyrin (that is, R ₁ =Cl, R ₂ =H, M ₄ =M ₅ =Mn in the general formula (IV), 1.4 g p-nitrotoluene and 2.5g of sodium hydroxide, put into a 200mL autoclave, add 38mL of ethanol aqueous solution (95% ethanol: 30mL, water: 8mL) containing ethanol 75% (V/V), oxygen pressure 2.5MPa, temperature control in water bath 45 °C, react for 10h. The aftertreatment steps are the same as in Example 1, and the obtained product is analyzed and detected by high-pressure liquid chromatography, and the yield of p-nitrobenzoic acid is 93.1%.

Example 14

Take 10 mg μ-oxygen-binuclear tetra-(o-chlorophenyl)iron-cobalt porphyrin (that is, R ₁ =Cl, R ₂ =H, M ₄ =Fe, M ₅ =Co in the general formula (IV), 2.8g Put p-nitrotoluene and 3.5g potassium hydroxide into a 200mL autoclave, add 38mL of ethanol aqueous solution (95% ethanol: 32mL, water: 6mL) containing 80% (V/V) ethanol, and the oxygen pressure is 2.5MPa, Control the temperature in a water bath at 50°C and react for 8 hours. The aftertreatment steps are the same as in Example 1, and the obtained product is analyzed and detected by high-pressure liquid chromatography, and the yield of p-nitrobenzoic acid is 93.5%.

Example 15

Take 14 mg μ-oxygen-binuclear tetra-(o-nitrophenyl)iron-manganese porphyrin (that is, R ₁ =NO ₂ , R ₂ =H, M ₄ =Fe, M ₅ =Mn in the general formula (IV), Put 1.4g p-nitrotoluene and 2.6g potassium hydroxide into a 200mL autoclave, add 42mL of ethanol aqueous solution (95% ethanol: 36mL, water: 6mL) containing 90% (V/V) ethanol, oxygen pressure 3.0MPa , the temperature was controlled at 45°C in a water bath, and the reaction was carried out for 6 hours. Post-processing steps are the same as in Example 1. The obtained product was analyzed and detected by high-pressure liquid chromatography, and the yield of p-nitrobenzoic acid was 93.0%.

Example 16

Take 12 mg μ-oxygen-binuclear tetra-(o-chlorophenyl)iron-manganese porphyrin (i.e. R ₁ =Cl, R ₂ =H, M ₄ =Fe, M ₅ =Mn in general formula (IV), 2.8g Put p-nitrotoluene and 4.5g potassium hydroxide into a 200mL autoclave, add 46mL of ethanol aqueous solution (95% ethanol: 26mL, water: 20mL) containing ethanol 65% (V/V), oxygen pressure 2.0MPa, water bath The temperature was controlled at 45°C, and the reaction was carried out for 10 hours. Post-processing steps are the same as in Example 1. The obtained product was analyzed and detected by high-pressure liquid chromatography, and the yield of p-nitrobenzoic acid was 96.8%.

Example 17

Take 2 mg μ-oxygen-binuclear tetrakis-(o-chlorophenyl)iron-manganese porphyrin (that is, R ₁ =Cl, R ₂ =H, M ₄ =Fe, M ₅ =Mn in the general formula (IV), 1.5 g Put p-nitrotoluene and 3.5g sodium hydroxide into a 200mL autoclave, add 38mL of ethanol aqueous solution (95% ethanol: 28mL, water: 10mL) containing 70% ethanol (V/V), oxygen pressure 0.8MPa, water bath The temperature was controlled at 35°C, and the reaction was carried out for 14 hours. Post-processing steps are the same as in Example 1. The obtained product was analyzed and detected by high-pressure liquid chromatography, and the yield of p-nitrobenzoic acid was 96.7%.

Table 1 Comparison of solvent properties solvent Explosion limit (%) Flash point (°C) Melting point (°C) Boiling point (°C) LD ₅₀ (mg·kg ^-1 ) Methanol 5.50～36.00 12.22 -97.80 64.65 5628 ethanol 4.30～19.00 14.00 -117.30 78.40 7060 water - - 0 100 -

Table 2 Comparison of yields of p-nitrobenzoic acid synthesized in different solvents example Catalyst used solvent Yield (%) Comparative example 1 cobalt phthalocyanine Anhydrous Methanol 89.6 Example 1 Aqueous ethanol 96.2 Comparative example 2 Iron phthalocyanine Anhydrous Methanol 89.5 Example 2 Aqueous ethanol 96.4 Comparative example 3 Tetrakis-(p-chlorophenyl)cobalt porphyrin Anhydrous Methanol 90.0 Example 6 Aqueous ethanol 96.4 Comparative example 4 Tetrakis-(p-chlorophenyl)iron porphyrin Anhydrous Methanol 90.2 Example 7 Aqueous ethanol 96.6 Comparative example 5 μ-oxygen-binuclear tetrakis-(o-chlorophenyl)iron-manganese porphyrin Anhydrous Methanol 90.8 Example 16 Aqueous ethanol 96.8

For ratios 1 to 5, anhydrous methanol is used as a solvent, and the addition amount is 38 mL, and other steps are the same as those in the corresponding examples.

Claims (4)

1. a kind of biomimetic catalytic oxygen oxidation p-nitrotoluene prepares the method for p-nitrobenzoic acid, it is characterized in that take p-nitrotoluene as raw material, select the metal phthalocyanine of general formula (I) structure, general formula (II), The mononuclear metalloporphyrin of (III) structure or the μ-oxygen binuclear metalloporphyrin of general formula (IV) structure is used as a catalyst, wherein, M ₁ , M ₂ , M ₃ , M ₄ , M ₅ are transition metal atoms, M ₁ =Fe, Co, Cu, Zn, M ₂ =Fe, Mn, Co, Cu, Zn, M ₃ =Fe, Mn, Co, M ₄ and M ₅ can be the same or different, when they are the same, M ₄ =M ₅ =Fe, Mn, Co, if different, M ₄ =Fe, M ₅ =Mn or M ₄ =Fe, M ₅ =Co, R is carboxyl or hydrogen, R ₁ and R ₂ are hydrogen, halogen, nitric acid group, hydroxyl group, alkoxy group, and the ligand X is chlorine, the amount of catalyst used is 0.01-1.0% of the weight of p-nitrotoluene, and the ethanol aqueous solution containing 40-95% of ethanol is used as a solvent at 1-6mol/L In the strong alkaline ethanol aqueous solution, 0.8-3.0 MPa of oxygen is introduced, the reaction temperature is controlled at 35-55°C, and the reaction time is 2-14 hours to obtain p-nitrobenzoic acid. General formula (I)

General formula (II) General formula (III) General formula (IV) 2. according to the method for claim 1, it is characterized in that with the ethanol aqueous solution that contains ethanol 50～70% volume as solvent. 3. according to the method for claim 1 or 2, it is characterized in that selecting the mononuclear metalloporphyrin with general formula (III) structure or the μ-oxygen-binuclear metalloporphyrin of general formula (IV) structure for use as catalyst. 4. According to any method according to claims 1 to 3, it is characterized in that the single nucleus of M ₃ =Mn or Fe, R ₁ =NO ₂ or Cl, R ₂ =H, X=Cl in the general formula (III) is selected for use Metalloporphyrin; when M ₄ and M ₅ are the same in general formula (IV), M ₄ =M ₅ =Fe, Mn or Co, when M ₄ and M ₅ are different, M ₄ =Fe, M ₅ =Mn, R ₁ =NO ₂ or Cl, R ₂ =H μ-oxygen-binuclear metalloporphyrin as catalyst.