A method for synthesizing pesticide intermediate benzyl carbazate

Abstract

The invention relates to the technical field of organic synthesis, and in particular to a method for synthesizing benzyl hydrazinecarboxylate, a pesticide intermediate. The method comprises the following steps: uniformly mixing methyl hydrazinecarboxylate, benzyl alcohol and a catalyst, stirring and heating to 70-90°C, carrying out a heat preservation reaction until no fraction is distilled out, then heating to 110-120°C and carrying out a heat preservation reaction for 1-10 hours, cooling a reaction solution to 40-80°C, removing the catalyst while hot, and then performing a reduced pressure distillation of a filtrate to obtain a crude product, and purifying the crude product to obtain a finished benzyl hydrazinecarboxylate product. The invention adopts a LnFeNi ternary hydrotalcite-based composite oxide with high catalytic activity as a catalyst, and the catalyst has a specific composition, a special structural morphology and a high specific surface area, and can reduce the reaction temperature to below 120°C, and still has a high yield and product purity.

Description

Technical Field

[0001] The invention relates to the technical field of organic synthesis, and in particular to a method for synthesizing a pesticide intermediate benzyl carbazate. Background Art

[0002] Benzyl carbazate is an important organic intermediate that can be used to prepare plant protection agents and transaminase inhibitors and has a wide range of uses in pesticide and pharmaceutical synthesis. Currently, there are reports that dimethyl carbonate and benzyl alcohol are used for complete transesterification to obtain dibenzyl carbonate, which is then reacted with hydrazine hydrate to obtain benzyl carbazate, but the process yield is only 50%, the synthesis route is long, and the product purity is also low. Summary of the invention

[0003] Purpose of the invention: In view of the above technical problems, the present invention provides a method for synthesizing benzyl carbazate, a pesticide intermediate.

[0004] The technical solutions adopted are as follows:

[0005] A method for synthesizing benzyl carbazate, a pesticide intermediate, is as follows:

[0006] Mix methyl carbazate, benzyl alcohol and a catalyst uniformly, first stir and heat to 70-90°C, keep the temperature to react until no fraction is distilled out, then heat to 110-120°C and keep the temperature to react for 1-10h, cool the reaction solution to 40-80°C, remove the catalyst while hot, and then distill the filtrate under reduced pressure to obtain a crude product, which is then purified to obtain a finished benzyl carbazate product;

[0007] The molar ratio of methyl carbazate to benzyl alcohol is 1:1-1.2, i.e., benzyl alcohol is slightly excessive;

[0008] Wherein, the catalyst is a ternary hydrotalcite-based composite oxide.

[0009] Furthermore, the ternary hydrotalcite-based composite oxide has a three-dimensional flower-like structure.

[0010] Furthermore, the ternary hydrotalcite-based composite oxide is a LnFeNi ternary hydrotalcite-based composite oxide, wherein Ln is a lanthanide rare earth element.

[0011] Lanthanide rare earth elements refer to the 15 elements from lanthanum, element 57, to lutetium, element 71, in the periodic table. They have similar chemical properties, form a separate series, and occupy a special position in the periodic table, including La (lanthanum), Ce (cerium), Pr (praseodymium), Nd (neodymium), Pm (promethium), Sm (samarium), Eu (europium), Gd (gadolinium), Tb (terbium), Dy (dysprosium), Ho (holmium), Er (erbium), Tm (thulium), Yb (ytterbium), Lu (lutetium), and Ln is preferably La and Ce.

[0012] Furthermore, the preparation method of the ternary hydrotalcite-based composite oxide is as follows:

[0013] Ln salt, Fe salt and Ni salt are added to the reaction solvent, mixed evenly, and then a precipitant containing an intercalation agent is added, and the reaction is sealed at 120-140° C. for 1-10 hours, and then the precipitate is collected to obtain a precursor, and finally the precursor is calcined.

[0014] Further, wherein n(Ln):n(Fe):n(Ni)=1-50:1-50:1-50;

[0015] Furthermore, n(Ln):n(Fe):n(Ni)=1:23:48, Note: n is the amount of substance;

[0016] Furthermore, the reaction solvent includes glycerol and deionized water, and the mass ratio of the glycerol to the deionized water is 1-10:1-10.

[0017] Furthermore, the reaction solvent includes glycerol and deionized water, and the mass ratio of the glycerol to the deionized water is 1:9.

[0018] Furthermore, the precipitant is an aqueous solution containing sodium hydroxide and sodium carbonate, and the mass ratio of the sodium hydroxide to the sodium carbonate is 1-10:1-10.

[0019] Furthermore, the mass ratio of the sodium hydroxide to the sodium carbonate is 1:1.326.

[0020] Furthermore, the intercalant is an amino acid, specifically any one of glycine, alanine, valine, leucine, isoleucine, methionine (methionine), proline, tryptophan, serine, tyrosine, cysteine, phenylalanine, asparagine, glutamine, threonine, aspartic acid (aspartic acid), glutamic acid, lysine, arginine, and histidine.

[0021] Furthermore, the mass ratio of the intercalant, sodium hydroxide and sodium carbonate is 1-10:1-10:1-10

[0022] Furthermore, the calcination temperature is 450-550° C., and the calcination time is 1-10 h.

[0023] Furthermore, the amount of the catalyst used is 1-2% of the mass of methyl carbazate.

[0024] Furthermore, the crude product is purified as follows: the crude product is dissolved in hot ethyl acetate and then crystallized at low temperature, and the precipitated product is filtered out and dried.

[0025] Beneficial effects of the present invention:

[0026] The invention provides a method for synthesizing benzyl hydrazinecarboxylate, an intermediate of pesticides. At present, the temperature for synthesizing benzyl hydrazinecarboxylate by ester exchange is usually above 120°C. In order to obtain a higher yield, the reaction temperature even needs to be increased to 140-150°C, which undoubtedly consumes a large amount of energy in a large-scale industrial production process. The invention uses a LnFeNi ternary hydrotalcite-based composite oxide with high catalytic activity as a catalyst. The catalyst has a specific composition, a special structural morphology and a high specific surface area, and can reduce the reaction temperature to below 120°C while still having a high yield and product purity. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is the SEM image of the catalyst prepared in Example 1. DETAILED DESCRIPTION

[0028] If the specific conditions are not specified in the examples, the experiments were carried out under conventional conditions or the conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be purchased commercially. The techniques not mentioned in the present invention are all referenced to the prior art. Unless otherwise specified, the following examples and comparative examples are parallel experiments, using the same processing steps and parameters.

[0029] Embodiment 1:

[0030] A method for synthesizing benzyl carbazate, a pesticide intermediate:

[0031] 45g of methyl hydrazinecarboxylate, 59.4g of benzyl alcohol and 0.5g of catalyst were added to a flask with a thermometer, a condenser and a water separator, and mechanically stirred and mixed for 30min to make the system uniform, then stirred and heated to 80°C, and kept warm until no fraction was distilled out of the water separator, and then heated to 120°C and kept warm for 4h, and the reaction solution was cooled to 60°C, and the catalyst was removed by hot filtration, and the filtrate was distilled under reduced pressure at 65°C to remove unreacted benzyl alcohol and residual methanol to obtain a crude product, and the crude product was dissolved with an appropriate amount of hot ethyl acetate and then crystallized at 0-5°C in a cold trap for 10h, and finally the precipitated product was filtered out and dried;

[0032] The catalyst is a LaFeNi ternary hydrotalcite-based composite oxide with a three-dimensional flower-like structure.

[0033] The preparation method is as follows:

[0034] 1mmol La(NO 3 ) 3 6H 2 O, 23mmol FeCl 3 6H2 O and 48 mmol Ni(NO 3 ) 2 6H 2 O is added to a reaction solvent consisting of 50g glycerol and 450g deionized water, and a precipitant consisting of 1g L-threonine, 5.76g sodium hydroxide, 7.64g sodium carbonate and 100ml deionized water is added dropwise after mixing evenly. After the dropwise addition, the mixture is sealed and heated to 120°C, and the mixture is sealed and reacted for 10h, and then returned to room temperature. The precipitate is collected by filtration, washed with deionized water and anhydrous ethanol, and then dried to obtain a precursor. Finally, the precursor is placed in a muffle furnace and heated to 500°C at a rate of 5°C / min and calcined for 2h.

[0035] Embodiment 2:

[0036] A method for synthesizing benzyl carbazate, a pesticide intermediate:

[0037] 45g of methyl hydrazinecarboxylate, 59.4g of benzyl alcohol and 0.5g of catalyst were added to a flask with a thermometer, a condenser and a water separator, and mechanically stirred and mixed for 30min to make the system uniform, then stirred and heated to 80°C, and kept warm until no fraction was distilled out of the water separator, and then heated to 120°C and kept warm for 4h, and the reaction solution was cooled to 60°C, and the catalyst was removed by hot filtration, and the filtrate was distilled under reduced pressure at 65°C to remove unreacted benzyl alcohol and residual methanol to obtain a crude product, and the crude product was dissolved with an appropriate amount of hot ethyl acetate and then crystallized at 0-5°C in a cold trap for 10h, and finally the precipitated product was filtered out and dried;

[0038] The catalyst is a CeFeNi ternary hydrotalcite-based composite oxide with a three-dimensional flower-like structure.

[0039] The preparation method is as follows:

[0040] 1mmol Ce(NO 3 ) 3 6H 2 O, 23mmol FeCl 3 6H 2 O and 48 mmol Ni(NO 3 ) 2 6H 2 O is added to a reaction solvent consisting of 50g glycerol and 450g deionized water, and a precipitant consisting of 1g L-threonine, 5.76g sodium hydroxide, 7.64g sodium carbonate and 100ml deionized water is added dropwise after mixing evenly. After the dropwise addition, the mixture is sealed and heated to 120°C, and the mixture is sealed and reacted for 10h, and then returned to room temperature. The precipitate is collected by filtration, washed with deionized water and anhydrous ethanol, and then dried to obtain a precursor. Finally, the precursor is placed in a muffle furnace and heated to 500°C at a rate of 5°C / min and calcined for 2h.

[0041] Embodiment 3:

[0042] A method for synthesizing benzyl carbazate, a pesticide intermediate:

[0043] 45g of methyl hydrazinecarboxylate, 59.4g of benzyl alcohol and 0.5g of catalyst were added to a flask with a thermometer, a condenser and a water separator, and mechanically stirred and mixed for 30min to make the system uniform, then stirred and heated to 80°C, and kept warm until no fraction was distilled out of the water separator, and then heated to 110°C and kept warm for 4h, and the reaction solution was cooled to 60°C, and the catalyst was removed by hot filtration, and the filtrate was distilled under reduced pressure at 65°C to remove unreacted benzyl alcohol and residual methanol to obtain a crude product, and the crude product was dissolved with an appropriate amount of hot ethyl acetate and then crystallized at 0-5°C in a cold trap for 10h, and finally the precipitated product was filtered out and dried;

[0044] The catalyst is a LaFeNi ternary hydrotalcite-based composite oxide with a three-dimensional flower-like structure, and the preparation method is the same as that in Example 1.

[0045] Comparative Example 1:

[0046] Basically the same as Example 1, no intercalation agent (L-threonine) was added during the catalyst preparation process;

[0047] The preparation method of the catalyst is as follows:

[0048] 1mmol La(NO 3 ) 3 6H 2 O, 23mmol FeCl 3 6H 2 O and 48 mmol Ni(NO 3 ) 2 6H 2 O is added to a reaction solvent consisting of 50g glycerol and 450g deionized water, and a precipitant consisting of 5.76g sodium hydroxide, 7.64g sodium carbonate and 100ml deionized water is added dropwise after being evenly mixed. After the dropwise addition, the mixture is sealed and heated to 120°C, and the mixture is sealed and reacted for 10h, and then restored to room temperature. The precipitate is collected by filtration, washed thoroughly with deionized water and anhydrous ethanol, and then dried to obtain a precursor. Finally, the precursor is placed in a muffle furnace and heated to 500°C at a rate of 5°C / min and calcined for 2h. Scanning electron microscope observation shows that the structure is a relatively regular layered structure.

[0049] Comparative Example 2:

[0050] Basically the same as Example 1, except that the catalyst is replaced by potassium hydroxide.

[0051] Comparative Example 3:

[0052] Basically the same as Example 1, except that the catalyst is replaced by sodium methoxide.

[0053] Comparative Example 4:

[0054] Basically the same as Example 1, except that the catalyst is replaced by sodium carbonate.

[0055] The yield and purity test results of benzyl carbazate prepared in the above Examples 1-3 and Comparative Examples 1-4 are shown in Table 1 below:

[0056] ;

[0057] As can be seen from Table 1 above, the catalyst prepared by the present invention has an excellent catalytic effect on the synthesis of the pesticide intermediate benzyl carbazate, and both the yield and purity are very high;

[0058] From the comparison between Example 1 and Example 3, it can be seen that after the reaction temperature is reduced by 10°C, the reaction yield is still 70%;

[0059] From the comparison between Example 1 and Comparative Example 1, it can be seen that the catalyst obtained without intercalation treatment does not have a three-dimensional flower-like structure, and the reaction yield is also reduced;

[0060] From the comparison between Example 1 and Comparative Examples 3-4, it can be seen that the catalytic effect of the catalyst prepared by the present invention is better than that of the conventional transesterification catalyst at a lower temperature.

[0061] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for synthesizing a pesticide intermediate benzyl carbazate, characterized in that: The details are as follows: Mix methyl carbazate, benzyl alcohol and a catalyst uniformly, first stir and heat to 70-90°C, keep the temperature to react until no fraction is distilled out, then heat to 110-120°C and keep the temperature to react for 1-10h, cool the reaction solution to 40-80°C, remove the catalyst while hot, and then distill the filtrate under reduced pressure to obtain a crude product, which is then purified to obtain a finished benzyl carbazate product; Wherein, the catalyst is a ternary hydrotalcite-based composite oxide; The ternary hydrotalcite-based composite oxide has a three-dimensional flower-like structure; The ternary hydrotalcite-based composite oxide is a LnFeNi ternary hydrotalcite-based composite oxide, wherein Ln is La or Ce; The preparation method of the ternary hydrotalcite-based composite oxide is as follows: Add Ln salt, Fe salt and Ni salt to the reaction solvent, mix well, then add a precipitant containing an intercalation agent, react at 120-140° C. in a sealed state for 1-10 hours, collect the precipitate to obtain a precursor, and finally calcine the precursor; The intercalant is L-threonine.

2. The method for synthesizing the pesticide intermediate benzyl carbazate according to claim 1, wherein: The reaction solvent includes glycerol and deionized water, and the mass ratio of the glycerol to the deionized water is 1-10:1-10.

3. The method for synthesizing the pesticide intermediate benzyl carbazate according to claim 1, characterized in that: The precipitant is an aqueous solution containing sodium hydroxide and sodium carbonate, and the mass ratio of the sodium hydroxide to the sodium carbonate is 1-10:1-10.

4. The method for synthesizing the pesticide intermediate benzyl carbazate according to claim 1, characterized in that: The calcination temperature is 450-550° C., and the calcination time is 1-10 hours.

5. The method for synthesizing the pesticide intermediate benzyl carbazate according to claim 1, characterized in that: The amount of the catalyst used is 1-2% of the mass of methyl carbazate.

6. The method for synthesizing the pesticide intermediate benzyl carbazate according to claim 1, characterized in that: The crude product was purified as follows: The crude product was dissolved in hot ethyl acetate and then crystallized at 0-5°C. The precipitated product was filtered out and dried.

Images