Addition method for preparing diuron

Abstract

The invention discloses an addition method for preparing diuron, and belongs to the technical field of synthesis of diuron. Comprising the following steps: S1, dissolving 3, 4-dichlorophenyl isocyanate and NH2-MIL-101 (Fe) / Co3O4 into an organic solvent, and uniformly mixing to obtain a mixed solution; slowly dropwise adding liquid dimethylamine into the mixed solution, keeping the pH constant under constant temperature and constant pressure in a dark place, and continuously stirring for reaction; s2, after the reaction is completed, heating to recover dimethylamine, performing centrifugal filtration to recover the organic solvent, washing an obtained filter cake, and performing vacuum drying to obtain diuron; the NH2-MIL-101 (Fe) / Co3O4 is prepared by the following steps: dissolving FeCl3. 6H2O and 2-aminoterephthalic acid in DMF (Dimethyl Formamide), carrying out hydrothermal reaction, filtering, washing and carrying out vacuum drying to obtain NH2-MIL-101 (Fe); the preparation method comprises the following steps: dispersing Co (NO3) 2.6 H2O and 2-methylimidazole in methanol, uniformly mixing, standing, washing and drying; heating and calcining, and cooling to obtain Co3O4; the preparation method comprises the following steps: uniformly carrying out ball milling on NH2-MIL-101 (Fe) and Co3O4 to obtain NH2-MIL-101 (Fe) / Co3O4;

Description

Technical Field

[0001] The present invention belongs to the technical field of diuron synthesis, and particularly relates to an addition method for preparing diuron. Background Art

[0002] Diuron is a substituted urea herbicide developed by DuPont in the United States. It is prepared by the addition of 3,4-dichlorophenyl isocyanate and dimethylamine. Its mechanism of action is to inhibit the Hill reaction in photosynthesis, causing weeds to die due to blocked energy metabolism. This agent is mainly systemic and also has a contact-killing effect. After being absorbed by the roots, it is conducted to the leaves, blocking nutrient synthesis and causing the leaves to fade and wither. It is mainly used for dryland crops such as cotton, citrus, and sugarcane, and can effectively control annual weeds such as crabgrass and foxtail, as well as perennial weeds such as nutgrass flatsedge. Among them, citrus and cotton are the crops with the largest usage amounts. Common domestic dosage forms include 25%-80% wettable powders and powders.

[0003] There are mainly two methods for preparing diuron by the addition of 3,4-dichlorophenyl isocyanate and dimethylamine: (1) Dropwise add a solution of 3,4-dichlorophenyl isocyanate to an aqueous solution of dimethylamine for reaction. Since there is water in the system, this method causes the hydrolysis of 3,4-dichlorophenyl isocyanate with water, generating the by-product N,N-bis(3,4-dichlorodiphenyl)urea, resulting in low product yield and low content, and it is difficult to separate and purify. (2) Dissolve 3,4-dichlorophenyl isocyanate in an organic solvent, heat it to 40-75°C, introduce dry dimethylamine gas until the pH value of the system reaches 8-9, stir at 60-70°C for 1-3 hours, and end the reaction when the content of 3,4-dichlorophenyl isocyanate is below 0.1 wt% of the entire reaction system. Then, filter by suction and dry to obtain diuron solid. Patent CN201310555070.9 uses this method. Although this method solves the problem of the hydrolysis of 3,4-dichlorophenyl isocyanate, the boiling point of dimethylamine (101.13 kPa) is only 7.4°C, and a large amount of dimethylamine is lost during the ventilation process under normal pressure. In addition, the solubility of dimethylamine in organic solvents such as toluene and xylene is relatively low, and the reaction rate is relatively slow in the later stage of the addition reaction. In addition, in Patent CN200910185466.2, first mix an aqueous solution of dimethylamine and toluene, and then dropwise add 3,4-dichlorophenyl isocyanate to them at 25°C until the pH reaches 8-9 for reaction. After the reaction, heat it to 75°C and keep the reaction, then cool and separate to obtain diuron. Although this method has certain improvements compared with dropping a solution of 3,4-dichlorophenyl isocyanate into an aqueous solution of dimethylamine, since there is still water in the system, it does not solve the problem of "causing the hydrolysis of 3,4-dichlorophenyl isocyanate with water, generating the by-product N,N-bis(3,4-dichlorodiphenyl)urea, resulting in low product yield and low content, and it is difficult to separate and purify". Summary of the Invention

[0004] The object of the present invention is to provide an addition method for preparing diuron, so as to improve the yield and quality of the product, save costs and be beneficial to environmental protection.

[0005] The object of the present invention can be achieved by the following technical solutions:

[0006] An addition method for preparing diuron, comprising the following steps:

[0007] S1. Dissolve 3,4-dichlorophenyl isocyanate and NH2-MIL-101(Fe) / Co3O4 in an organic solvent, and mix them evenly to obtain a mixed solution; slowly drop liquid dimethylamine into the mixed solution, keep it away from light, keep the pH constant under constant temperature and pressure, and continuously stir and react;

[0008] S2. After the reaction is complete, heat up to recover dimethylamine, centrifugally filter to recover the organic solvent, wash the obtained filter cake, and dry it under vacuum to obtain diuron;

[0009] The NH2-MIL-101(Fe) / Co3O4 is prepared by the following steps:

[0010] Dissolve FeCl3·6H2O and 2-aminoterephthalic acid in DMF, carry out a hydrothermal reaction, filter and wash, and dry under vacuum to obtain NH2-MIL-101(Fe); disperse Co(NO3)2·6H2O and 2-methylimidazole in methanol, mix them evenly and let them stand, wash and dry; heat up and calcine, and cool to obtain Co3O4; ball-mill NH2-MIL-101(Fe) and Co3O4 evenly to obtain NH2-MIL-101(Fe) / Co3O4.

[0011] Further, the dosage ratio of FeCl3·6H2O, 2-aminoterephthalic acid and DMF is (2-3) g:(1.2-2) g:(40-60) mL.

[0012] Further, the hydrothermal reaction is carried out at 80-120 °C for 10-12 h; the filtration and washing are carried out by alternately washing 3 times with absolute ethanol and deionized water.

[0013] Further, the dosage ratio of Co(NO3)2·6H2O, 2-methylimidazole and methanol is (1.5-2.5) g:(3.5-5) g:(60-80) mL.

[0014] Further, the time for mixing and standing is 12-16 h; the heating-up calcination is to raise the temperature to 300-350 °C at a heating rate of 2-5 °C / min and keep the constant temperature for 1-2 h.

[0015] Furthermore, the dosage ratio of the NH2-MIL-101(Fe) and Co3O4 is (4 - 6) g : (0.5 - 2) g.

[0016] Furthermore, the ball milling is carried out in a ball mill at 30 Hz for 20 - 30 min.

[0017] Furthermore, the dosage ratio of the 3,4-dichlorophenyl isocyanate, NH2-MIL-101(Fe) / Co3O4, organic solvent and liquid dimethylamine is (1.8 - 2.5) g : (0.05 - 0.2) g : (40 - 60) mL : (0.5 - 0.7) g.

[0018] Furthermore, the organic solvent is a mixed solution of toluene and acetone; the dosage ratio of the toluene and acetone is (85 - 90) : (10 - 15).

[0019] Furthermore, the purity of the liquid dimethylamine is ≥99%.

[0020] Furthermore, the constant temperature range is 20 - 30 °C; the constant pressure range is 0.5 - 1.5 MPa; the pH range is 7 - 8.

[0021] Furthermore, the temperature for heating up is 70 - 80 °C; the filter cake washing is carried out by washing alternately with alkali and water until it is neutral.

[0022] Furthermore, the vacuum drying is carried out at 70 - 90 °C under vacuum.

[0023] The beneficial effects of the present invention:

[0024] (1) An addition method for preparing diuron provided by the present invention improves the solubility and reaction activity of dimethylamine gas in the solvent by adding a catalyst, catalyzes the addition reaction of isocyanate and dimethylamine, accelerates the reaction rate, and reduces the generation of by-products. The NH2-MIL-101(Fe) / Co3O4 adopted, with the double Lewis acid sites of Fe3+ and Co3+, can jointly activate the reactants, lower the reaction activation energy, and promote the progress of the reaction. Moreover, due to the high specific surface area of NH2-MIL-101(Fe) / Co3O4, the water molecules in the reaction process are dynamically adsorbed, which can effectively avoid the generation of side reactions, improve the yield and purity; and the hydrolysis resistance of -NH2 can effectively maintain the stability of the material. The surface acidity of Co3O4 and the amino basicity of NH2-NH2-MIL-101 are complementary to optimize the acid-base balance of the adsorption-catalysis process.

[0025] (2) The mixed solution of toluene and acetone used in the present invention can completely avoid side hydrolysis reactions, ensuring the efficient progress of the main reaction. At the same time, the mixing of the low-polarity solvent toluene and the high-polarity solvent acetone can significantly increase the solubility of polar reactants, ensuring sufficient contact between reactants and accelerating the process of the main reaction. The amount of acetone used is small, avoiding a significant increase in cost while enhancing solubility. By adjusting the experimental conditions (keeping the pH constant under constant temperature and pressure), the components in the reaction system are maintained with high reactivity, the reaction rate is increased, and the product quality is improved. Detailed Embodiments

[0026] The following provides a detailed description of the specific embodiments of the present invention, but it should be understood that the protection scope of the present invention is not limited by the specific embodiments.

[0027] Example 1

[0028] This example provides a method for preparing diuron by addition, which is prepared through the following steps:

[0029] S1. Dissolve 2 g of FeCl3·6H2O and 1.5 g of 2-aminoterephthalic acid in 50 mL of DMF, perform hydrothermal reaction at 120 °C for 10 h, wash alternately with absolute ethanol and deionized water three times, and vacuum dry at 80 °C to obtain NH2-MIL-101(Fe); disperse 2 g of Co(NO3)2·6H2O and 4 g of 2-methylimidazole in 60 mL of methanol, mix well and let stand for 12 h, wash with methanol three times, and dry in an oven at 60 °C for 4 h; raise the temperature to 350 °C at a heating rate of 2 °C / min, keep the temperature constant for 1.5 h, and naturally cool to room temperature to obtain Co3O4; put 5 g of NH2-MIL-101(Fe) and 1 g of Co3O4 into a ball mill and ball mill at 30 Hz for 30 min to obtain NH2-MIL-101(Fe) / Co3O4;

[0030] S2. Dissolve 2 g of 3,4-dichlorophenyl isocyanate and 0.1 g of NH2-MIL-101(Fe) / Co3O4 in 50 mL of a toluene / acetone mixed solution (the dosage ratio of toluene to acetone is 90:10), mix well to obtain a mixed solution; slowly drop 0.6 g of liquid dimethylamine (purity ≥ 99%) into the mixed solution, keep it away from light, and keep the pH at 7.5 under constant temperature (25 °C) and constant pressure (0.8 MPa), and continuously stir and react;

[0031] S3. After the reaction is complete, raise the temperature to 80 °C to recover dimethylamine, centrifuge and filter to recover the organic solvent, wash the obtained filter cake alternately with alkali and water until it is neutral, and then vacuum dry at 80 °C to obtain diuron.

[0032] Example 2

[0033] Compared with Example 1, this example is different in that "5g NH2-MIL-101(Fe) and 1g Co3O4" is changed to "6g NH2-MIL-101(Fe) and 0.5g Co3O4". The specific implementation steps are as follows:

[0034] S1. Dissolve 2g of FeCl3·6H2O and 1.5g of 2-aminoterephthalic acid in 50 mL of DMF, perform hydrothermal reaction at 120 °C for 10 h, wash alternately with absolute ethanol and deionized water three times, and vacuum dry at 80 °C to obtain NH2-MIL-101(Fe); Disperse 2g of Co(NO3)2·6H2O and 4g of 2-methylimidazole in 60 mL of methanol, mix well and let stand for 12 h, wash with methanol three times, and dry in an oven at 60 °C for 4 h; Raise the temperature to 350 °C at a heating rate of 2 °C / min, keep the temperature constant for 1.5 h, and naturally cool to room temperature to obtain Co3O4; Put 6g of NH2-MIL-101(Fe) and 0.5g of Co3O4 into a ball mill, and ball mill at 30 Hz for 30 min to obtain NH2-MIL-101(Fe) / Co3O4;

[0035] S2. Dissolve 2g of 3,4-dichlorophenyl isocyanate and 0.1g of NH2-MIL-101(Fe) / Co3O4 in 50 mL of a toluene / acetone mixed solution (the dosage ratio of toluene and acetone is 90:10), and mix well to obtain a mixed solution; Slowly drop 0.6g of liquid dimethylamine (purity ≥ 99%) into the mixed solution, keep it away from light, and keep the pH at 7.5 under constant temperature (25 °C) and constant pressure (0.8 MPa), and continuously stir and react;

[0036] S3. After the reaction is complete, raise the temperature to 80 °C to recover dimethylamine, centrifuge and filter to recover the organic solvent, wash the obtained filter cake alternately with alkali and water until it is neutral, and then vacuum dry at 80 °C to obtain diuron.

[0037] The remaining raw materials and the preparation process are the same as those in Example 1.

[0038] Example 3

[0039] Compared with Example 1, this example is different in that "5g NH2-MIL-101(Fe) and 1g Co3O4" is changed to "4g NH2-MIL-101(Fe) and 2g Co3O4". The specific implementation steps are as follows:

[0040] S1. Dissolve 2 g of FeCl3·6H2O and 1.5 g of 2-aminoterephthalic acid in 50 mL of DMF, carry out hydrothermal reaction at 120 °C for 10 h, wash alternately with absolute ethanol and deionized water three times, and dry in vacuum at 80 °C to obtain NH2-MIL-101(Fe); Disperse 2 g of Co(NO3)2·6H2O and 4 g of 2-methylimidazole in 60 mL of methanol, mix well and let stand for 12 h, wash with methanol three times, and dry in an oven at 60 °C for 4 h; Raise the temperature to 350 °C at a heating rate of 2 °C / min, keep the temperature constant for 1.5 h, and naturally cool to room temperature to obtain Co3O4; Put 4 g of NH2-MIL-101(Fe) and 2 g of Co3O4 into a ball mill, ball mill at 30 Hz for 30 min to obtain NH2-MIL-101(Fe) / Co3O4;

[0041] S2. Dissolve 2 g of 3,4-dichlorophenyl isocyanate and 0.1 g of NH2-MIL-101(Fe) / Co3O4 in 50 mL of a toluene / acetone mixed solution (the dosage ratio of toluene and acetone is 90:10), and mix well to obtain a mixed solution; Slowly drop 0.6 g of liquid dimethylamine (purity ≥ 99%) into the mixed solution, keep it away from light, and keep the pH at 7.5 under constant temperature (25 °C) and constant pressure (0.8 MPa), and continuously stir and react;

[0042] S3. After the reaction is complete, raise the temperature to 80 °C to recover dimethylamine, centrifuge and filter to recover the organic solvent. Wash the obtained filter cake alternately with alkali and water until it is neutral, and then dry in vacuum at 80 °C to obtain diuron.

[0043] The remaining raw materials and the preparation process are the same as those in Example 1.

[0044] Example 4

[0045] The main difference between this example and Example 1 is that the amount of 3,4-dichlorophenyl isocyanate is increased. The specific implementation steps are as follows:

[0046] S1. Dissolve 2 g of FeCl3·6H2O and 1.5 g of 2-aminoterephthalic acid in 50 mL of DMF, perform hydrothermal reaction at 120 °C for 10 h, wash alternately with absolute ethanol and deionized water three times, and dry in vacuum at 80 °C to obtain NH2-MIL-101(Fe); Disperse 2 g of Co(NO3)2·6H2O and 4 g of 2-methylimidazole in 60 mL of methanol, mix well and let stand for 12 h, wash with methanol three times, and dry in an oven at 60 °C for 4 h; Raise the temperature to 350 °C at a heating rate of 2 °C / min, keep the temperature constant for 1.5 h, and naturally cool to room temperature to obtain Co3O4; Put 5 g of NH2-MIL-101(Fe) and 1 g of Co3O4 into a ball mill, ball mill at 30 Hz for 30 min to obtain NH2-MIL-101(Fe) / Co3O4;

[0047] S2. Dissolve 2.5 g of 3,4-dichlorophenyl isocyanate and 0.1 g of NH2-MIL-101(Fe) / Co3O4 in 50 mL of a toluene / acetone mixed solution (the dosage ratio of toluene and acetone is 90:10), and mix well to obtain a mixed solution; Slowly drop 0.5 g of liquid dimethylamine (purity ≥99%) into the mixed solution, avoid light, and keep the pH at 7.5 under constant temperature (25 °C) and constant pressure (0.8 MPa), and continuously stir and react;

[0048] S3. After the reaction is complete, raise the temperature to 80 °C to recover dimethylamine, centrifuge and filter to recover the organic solvent, wash the obtained filter cake alternately with alkali and water until it is neutral, and then dry in vacuum at 80 °C to obtain diuron.

[0049] The remaining raw materials and the preparation process are the same as those in Example 1.

[0050] Example 5

[0051] The main difference between this example and Example 1 is that the amount of 3,4-dichlorophenyl isocyanate is reduced. The specific implementation steps are as follows:

[0052] S1. Dissolve 2 g of FeCl3·6H2O and 1.5 g of 2-aminoterephthalic acid in 50 mL of DMF, carry out hydrothermal reaction at 120 °C for 10 h, wash alternately with absolute ethanol and deionized water three times, and vacuum dry at 80 °C to obtain NH2-MIL-101(Fe); disperse 2 g of Co(NO3)2·6H2O and 4 g of 2-methylimidazole in 60 mL of methanol, mix well and let stand for 12 h, wash with methanol three times, and dry in an oven at 60 °C for 4 h; raise the temperature to 350 °C at a heating rate of 2 °C / min, keep the temperature constant for 1.5 h, and naturally cool to room temperature to obtain Co3O4; put 5 g of NH2-MIL-101(Fe) and 1 g of Co3O4 into a ball mill and ball mill at 30 Hz for 30 min to obtain NH2-MIL-101(Fe) / Co3O4;

[0053] S2. Dissolve 1.8 g of 3,4-dichlorophenyl isocyanate and 0.1 g of NH2-MIL-101(Fe) / Co3O4 in 50 mL of a toluene / acetone mixed solution (the dosage ratio of toluene and acetone is 90:10), and mix well to obtain a mixed solution; slowly drop 0.7 g of liquid dimethylamine (purity ≥ 99%) into the mixed solution, keep it away from light, and keep the pH at 7.5 under constant temperature (25 °C) and constant pressure (0.8 MPa), and continuously stir and react;

[0054] S3. After the reaction is complete, raise the temperature to 80 °C to recover dimethylamine, centrifuge and filter to recover the organic solvent, wash the obtained filter cake alternately with alkali and water until it is neutral, and then vacuum dry at 80 °C to obtain diuron.

[0055] The remaining raw materials and the preparation process are the same as those in Example 1.

[0056] Example 6

[0057] This example is different from Example 1 in that the ratio of toluene and acetone is reduced. The specific implementation steps are as follows:

[0058] S1. Dissolve 2 g of FeCl3·6H2O and 1.5 g of 2-aminoterephthalic acid in 50 mL of DMF, carry out hydrothermal reaction at 120 °C for 10 h, wash alternately with absolute ethanol and deionized water three times, and dry under vacuum at 80 °C to obtain NH2-MIL-101(Fe); Disperse 2 g of Co(NO3)2·6H2O and 4 g of 2-methylimidazole in 60 mL of methanol, mix well and let stand for 12 h, wash with methanol three times, and dry in an oven at 60 °C for 4 h; Raise the temperature to 350 °C at a heating rate of 2 °C / min, keep the temperature constant for 1.5 h, and naturally cool to room temperature to obtain Co3O4; Put 5 g of NH2-MIL-101(Fe) and 1 g of Co3O4 into a ball mill and mill at 30 Hz for 30 min to obtain NH2-MIL-101(Fe) / Co3O4;

[0059] S2. Dissolve 2 g of 3,4-dichlorophenyl isocyanate and 0.1 g of NH2-MIL-101(Fe) / Co3O4 in 50 mL of a toluene / acetone mixed solution (the dosage ratio of toluene and acetone is 85:15), and mix well to obtain a mixed solution; Slowly drop 0.6 g of liquid dimethylamine (purity ≥99%) into the mixed solution, keep it away from light, and keep the pH at 7.5 under constant temperature (25 °C) and constant pressure (0.8 MPa), and continuously stir and react;

[0060] S3. After the reaction is complete, raise the temperature to 80 °C to recover dimethylamine, centrifuge and filter to recover the organic solvent. Wash the obtained filter cake alternately with alkali and water until it is neutral, and then dry under vacuum at 80 °C to obtain diuron.

[0061] The remaining raw materials and the preparation process are the same as those in Example 1.

[0062] Comparative Example 1

[0063] Compared with Example 1, the difference in this comparative example is that the organic solvent is changed to toluene, and the specific implementation steps are as follows:

[0064] S1. Dissolve 2 g of FeCl3·6H2O and 1.5 g of 2-aminoterephthalic acid in 50 mL of DMF, carry out a hydrothermal reaction at 120 °C for 10 h, wash alternately with absolute ethanol and deionized water three times, and dry in vacuo at 80 °C to obtain NH2-MIL-101(Fe); Disperse 2 g of Co(NO3)2·6H2O and 4 g of 2-methylimidazole in 60 mL of methanol, mix well and let stand for 12 h, wash with methanol three times, and dry in an oven at 60 °C for 4 h; Raise the temperature to 350 °C at a heating rate of 2 °C / min, keep the temperature constant for 1.5 h, and naturally cool to room temperature to obtain Co3O4; Put 5 g of NH2-MIL-101(Fe) and 1 g of Co3O4 into a ball mill and mill at 30 Hz for 30 min to obtain NH2-MIL-101(Fe) / Co3O4;

[0065] S2. Dissolve 2 g of 3,4-dichlorophenyl isocyanate and 0.1 g of NH2-MIL-101(Fe) / Co3O4 in 50 mL of toluene, and mix well to obtain a mixed solution; Slowly drop 0.6 g of liquid dimethylamine (purity ≥ 99%) into the mixed solution, keep it away from light, and keep the pH at 7.5 under constant temperature (25 °C) and constant pressure (0.8 MPa), and continuously stir and react;

[0066] S3. After the reaction is complete, raise the temperature to 80 °C to recover dimethylamine, centrifuge and filter to recover the organic solvent, wash the obtained filter cake alternately with alkali and water until it is neutral, and then dry in vacuo at 80 °C to obtain diuron.

[0067] The remaining raw materials and the preparation process are the same as those in Example 1.

[0068] Comparative Example 2

[0069] The difference between this comparative example and Example 1 is that 2-aminoterephthalic acid is replaced by terephthalic acid. The specific implementation steps are as follows:

[0070] S1. Dissolve 2 g of FeCl3·6H2O and 1.5 g of terephthalic acid in 50 mL of DMF, carry out a hydrothermal reaction at 120 °C for 10 h, wash alternately with absolute ethanol and deionized water three times, and dry in vacuo at 80 °C to obtain NH2-MIL-101(Fe); Disperse 2 g of Co(NO3)2·6H2O and 4 g of 2-methylimidazole in 60 mL of methanol, mix well and let stand for 12 h, wash with methanol three times, and dry in an oven at 60 °C for 4 h; Raise the temperature to 350 °C at a heating rate of 2 °C / min, keep the temperature constant for 1.5 h, and naturally cool to room temperature to obtain Co3O4; Put 5 g of NH2-MIL-101(Fe) and 1 g of Co3O4 into a ball mill and mill at 30 Hz for 30 min to obtain NH2-MIL-101(Fe) / Co3O4;

[0071] S2. Dissolve 2 g of 3,4-dichlorophenyl isocyanate and 0.1 g of NH2-MIL-101(Fe) / Co3O4 in 50 mL of a toluene / acetone mixed solution (the dosage ratio of toluene to acetone is 90:10), and mix well to obtain a mixed solution; slowly drop 0.6 g of liquid dimethylamine (purity ≥ 99%) into the mixed solution, keep it away from light, and maintain the pH at 7.5 under constant temperature (25 °C) and constant pressure (0.8 MPa), and continuously stir and react;

[0072] S3. After the reaction is complete, raise the temperature to 80 °C to recover dimethylamine, centrifuge and filter to recover the organic solvent, wash the obtained filter cake alternately with alkali and water until it is neutral, and then dry it under vacuum at 80 °C to obtain diuron.

[0073] The remaining raw materials and the preparation process are the same as those in Example 1.

[0074] Comparative Example 3

[0075] The difference between this comparative example and Example 1 is that Co3O4 is not added. The specific implementation steps are as follows:

[0076] S1. Dissolve 2 g of FeCl3·6H2O and 1.5 g of 2-aminoterephthalic acid in 50 mL of DMF, carry out a hydrothermal reaction at 120 °C for 10 h, wash alternately with absolute ethanol and deionized water 3 times, and dry under vacuum at 80 °C to obtain NH2-MIL-101(Fe);

[0077] S2. Dissolve 2 g of 3,4-dichlorophenyl isocyanate and 0.1 g of NH2-MIL-101(Fe) in 50 mL of a toluene / acetone mixed solution (the dosage ratio of toluene to acetone is 90:10), and mix well to obtain a mixed solution; slowly drop 0.6 g of liquid dimethylamine (purity ≥ 99%) into the mixed solution, keep it away from light, and maintain the pH at 7.5 under constant temperature (25 °C) and constant pressure (0.8 MPa), and continuously stir and react;

[0078] S3. After the reaction is complete, raise the temperature to 80 °C to recover dimethylamine, centrifuge and filter to recover the organic solvent, wash the obtained filter cake alternately with alkali and water until it is neutral, and then dry it under vacuum at 80 °C to obtain diuron.

[0079] The remaining raw materials and the preparation process are the same as those in Example 1.

[0080] Comparative Example 4

[0081] The difference between this comparative example and Example 1 is that no catalyst is added. The specific implementation steps are as follows:

[0082] S1. Dissolve 2 g of 3,4-dichlorophenyl isocyanate in 50 mL of a toluene / acetone mixed solution (the dosage ratio of toluene to acetone is 90:10), and mix well to obtain a mixed solution; slowly drop 0.6 g of liquid dimethylamine (purity ≥ 99%) into the mixed solution, avoid light, and maintain the pH at 7.5 under constant temperature (25 °C) and constant pressure (0.8 MPa), and continuously stir and react;

[0083] S2. After the reaction is complete, raise the temperature to 80 °C to recover dimethylamine, centrifuge and filter to recover the organic solvent. Wash the obtained filter cake alternately with alkali and water until it is neutral, and then dry it under vacuum at 80 °C to obtain diuron.

[0084] The remaining raw materials and the preparation process are the same as those in Example 1.

[0085] Result Analysis

[0086] Test the purity and yield of the diuron obtained in Examples 1 - 6 and Comparative Examples 1 - 4. The results are shown in Table 1:

[0087] Table 1

[0088] Project Example 1 Example 2 Example 3 Example 4 Example 5 Purity (%) 99.4 99.3 99.2 99.1 99.2 Yield (%) 98.9 98.6 98.4 98.5 98.3 Project Example 6 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Purity (%) 99.1 99.0 99.0 99.0 99.0 Yield (%) 98.7 97.8 98.0 97.6 97.5

[0089] As can be seen from Table 1, compared with Example 1, in Examples 2 - 6, the diuron obtained only by adjusting the parameters within a reasonable range has high purity and high yield. Compared with Example 1, in Comparative Example 1, although the solvent does not contain water, the low-polarity toluene will cause the solubility of isocyanate and dimethylamine to decrease, resulting in a decrease in yield; compared with Example 1, in Comparative Example 2, MIL-101 with amino groups has better hydrolysis resistance than that without amino groups; compared with Example 1, in Comparative Examples 3 - 4, it can be seen that not only the added catalyst can adsorb the moisture in the system (the solution added when adjusting the pH), but also the double Lewis acid sites of Fe3+ and Co3+ can promote the reaction, improve the efficiency, and increase the yield and purity.

[0090] The above discloses only several specific embodiments of the present invention. However, the embodiments of the present invention are not limited thereto, and any changes that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. An addition method for preparing diuron, characterized in that, It includes the following steps: S1. Dissolve 3,4-dichlorophenyl isocyanate and NH2-MIL-101(Fe) / Co3O4 in an organic solvent, and after mixing evenly, obtain a mixed solution; slowly drip liquid dimethylamine into the mixed solution, avoid light, keep the pH constant under constant temperature and pressure, and continuously stir and react; S2. After the reaction is complete, raise the temperature to recover dimethylamine, centrifuge and filter to recover the organic solvent. After washing the obtained filter cake, dry it under vacuum to obtain diuron; The NH2-MIL-101(Fe) / Co3O4 is prepared by the following steps: Dissolve FeCl3·6H2O and 2-aminoterephthalic acid in DMF, carry out a hydrothermal reaction, filter and wash, and dry under vacuum to obtain NH2-MIL-101(Fe); disperse Co(NO3)2·6H2O and 2-methylimidazole in methanol, mix evenly and let stand, wash and dry; raise the temperature for calcination, and after cooling, obtain Co3O4; ball-mill NH2-MIL-101(Fe) and Co3O4 evenly to obtain NH2-MIL-101(Fe) / Co3O4.

2. The addition method for preparing diuron according to claim 1, wherein The dosage ratio of FeCl3·6H2O, 2-aminoterephthalic acid and DMF is (2-3) g : (1.2-2) g : (40-60) mL.

3. The addition method for preparing diuron according to claim 1, wherein The hydrothermal reaction is carried out at 80-120 °C for 10-12 h; the filtration and washing are carried out by alternately washing 3 times with absolute ethanol and deionized water.

4. The addition method for preparing diuron according to claim 1, wherein, The dosage ratio of Co(NO3)2·6H2O, 2-methylimidazole and methanol is (1.5-2.5) g : (3.5-5) g : (60-80) mL.

5. A method for preparing diuron by addition according to claim 1, characterized in that The time for mixing evenly and letting stand is 12-16 h; the temperature raising and calcination is to raise the temperature to 300-350 °C at a heating rate of 2-5 °C / min and keep the constant temperature for 1-2 h.

6. The addition method for preparing diuron according to claim 1, characterized in that, The ball-milling is carried out in a ball mill at 30 Hz for 20-30 min.

7. A method for preparing diuron by addition according to claim 1, characterized in that The dosage ratio of NH2-MIL-101(Fe) and Co3O4 is (4-6) g : (0.5-2) g.

8. The addition method for preparing diuron according to claim 1, characterized in that, The dosage ratio of 3,4-dichlorophenyl isocyanate, NH2-MIL-101(Fe) / Co3O4, organic solvent and liquid dimethylamine is (1.8-2.5) g : (0.05-0.2) g : (40-60) mL : (0.5-0.7) g.

9. The addition method for preparing diuron according to claim 1, characterized in that, The organic solvent is a mixed solution of toluene and acetone; the dosage ratio of toluene and acetone is (85-90) : (10-15); the purity of the liquid dimethylamine is ≥99%.

10. The addition method for preparing diuron according to claim 1, characterized in that, The constant temperature range is 20-30 °C; the constant pressure range is 0.5-1.5 MPa; the pH range is 7-8; the temperature for raising the temperature is 70-80 °C; the filter cake washing is to alternately wash with alkali and water until it is neutral; the vacuum drying is carried out at 70-90 °C under vacuum.