A kind of preparation method of 5-acetoacetylaminobenzimidazolone

Abstract

The present invention belongs to the technical field of organic synthesis, and specifically relates to a method for preparing 5-acetoacetylaminobenzimidazolone. The present invention utilizes chitosan grafted around the 5-aminobenzimidazolone structure to prevent it from being oxidized, and simultaneously promotes the acylation reaction of 5-aminobenzimidazolone by phosphating chitosan, and uses boron trifluoride as a catalyst for the acylation reaction to further improve the conversion rate of 5-aminobenzimidazolone, and finally achieves a 5-acetoacetylaminobenzimidazolone yield of more than 92%, effectively improving production efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of organic synthesis, and particularly relates to a method for preparing 5-acetoacetylaminobenzimidazolone. Background Art

[0002] 5-Acetoacetylaminobenzimidazolone is an important chemical intermediate, which is widely used in organic synthesis, dye intermediates, pharmaceutical intermediates, and photographic industry. It is especially widely used in the field of dyes and special materials synthesis. It is mostly used in the synthesis of pigment yellow and pigment orange, etc. It is also a key intermediate for the synthesis of high-performance pigment varieties - benzimidazolone series.

[0003] At present, the industry mainly uses 5-aminobenzimidazolone and diketene as raw materials to undergo acylation reaction to prepare 5-acetoacetylaminobenzimidazolone. However, as an important raw material, the amino group in the structure of 5-aminobenzimidazolone is easily oxidized and has low solubility in water, which makes the yield of the final prepared 5-acetoacetylaminobenzimidazolone low, generally 70~80%. In order to improve the production efficiency of 5-acetoacetylaminobenzimidazolone, it is particularly important to explore a high-yield preparation method. Summary of the invention

[0004] Aiming at the problem of low yield in the method for preparing 5-acetoacetylaminobenzimidazolone in the prior art, the present invention provides a method for preparing 5-acetoacetylaminobenzimidazolone, wherein chitosan is grafted around the structure of 5-aminobenzimidazolone to prevent oxidation thereof, while phosphating chitosan to promote the acylation reaction of 5-aminobenzimidazolone, and using boron trifluoride as a catalyst for the acylation reaction to further improve the conversion rate of 5-aminobenzimidazolone, ultimately achieving a 5-acetoacetylaminobenzimidazolone yield of more than 92%, and effectively improving production efficiency.

[0005] The first aspect of the present invention provides a method for preparing 5-acetoacetylaminobenzimidazolone, comprising the following steps:

[0006] S1: Disperse 5-aminobenzimidazolone and chitosan in a mixed solvent of toluene and ethanol, stir well, then add 3-isocyanatepropyltrimethoxysilane, stir and react at 70-80°C for 8-10h to obtain chitosan-grafted 5-aminobenzimidazolone;

[0007] S2: soaking the chitosan-grafted 5-aminobenzimidazolone in a phosphoric acid solution for phosphating to obtain phosphated chitosan-grafted 5-aminobenzimidazolone;

[0008] S3: dissolving phosphated chitosan grafted 5-aminobenzimidazolone and boron trifluoride in a mixed solvent of polyvinyl alcohol and water, stirring and mixing at 70-80° C., then dropping diketene, continuing to react at 70-80° C., filtering and drying to obtain 5-acetoacetylaminobenzimidazolone.

[0009] Furthermore, the mass ratio of 5-aminobenzimidazolone to chitosan is 0.5-0.8:1.

[0010] Furthermore, the volume ratio of toluene to ethanol is 1:3.

[0011] Furthermore, the mass ratio of 5-aminobenzimidazolone to 3-isocyanatepropyltrimethoxysilane is 1:0.8-1.2.

[0012] Furthermore, the concentration of the phosphoric acid solution is 5-6 mol / L.

[0013] Furthermore, the chitosan-grafted 5-aminobenzimidazolone was immersed in a phosphoric acid solution and modified at 120-150° C. for 6-8 hours to perform a phosphating treatment.

[0014] Furthermore, the modification was carried out at 140°C for 6 hours and then phosphating was performed.

[0015] Furthermore, the mass ratio of 5-aminobenzimidazolone, boron trifluoride, polyvinyl alcohol and diketene grafted with phosphated chitosan is 1:0.3~0.5:10~15:0.9~1.2, and the mass ratio of polyvinyl alcohol and water is 1:4.

[0016] Further, diketene was added dropwise, and the reaction was continued at 70-80° C. for 6-8 hours.

[0017] Furthermore, diketene was added dropwise and the reaction was continued at 80° C. for 6 h.

[0018] The beneficial effects achieved by one or more technical solutions of the present invention are as follows:

[0019] 1. The present invention utilizes chitosan grafted around 5-aminobenzimidazolone to prevent oxidation of the amino group. At the same time, through the surface phosphating of chitosan, not only the solubility of 5-aminobenzimidazolone can be improved, but also the surface active sites can be increased, thereby effectively promoting the acylation reaction of 5-aminobenzimidazolone and diketene, and improving the conversion rate of 5-aminobenzimidazolone and the yield of the product.

[0020] 2. The present invention uses boron trifluoride as a catalyst for the acylation reaction, which can further promote the acylation reaction, increase the conversion rate of 5-aminobenzimidazolone and the yield of 5-acetoacetylaminobenzimidazolone, and thus effectively improve production efficiency. DETAILED DESCRIPTION

[0021] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below in combination with specific embodiments and comparative examples.

[0022] Example 1

[0023] This embodiment provides a method for preparing 5-acetoacetylaminobenzimidazolone, comprising the following steps:

[0024] S1: 5-aminobenzimidazolone and chitosan are dispersed in a solvent in which toluene and ethanol are mixed in a volume ratio of 1:3, and the mass ratio of 5-aminobenzimidazolone to chitosan is 0.5:1. The mixture is stirred evenly, and then 3-isocyanatepropyltrimethoxysilane is added (the mass ratio of 5-aminobenzimidazolone to 3-isocyanatepropyltrimethoxysilane is 1:1). The mixture is stirred and reacted at 80°C for 8 hours to obtain chitosan-grafted 5-aminobenzimidazolone.

[0025] S2: immersing the chitosan-grafted 5-aminobenzimidazolone in a phosphoric acid solution with a concentration of 5 mol / L, modifying it at 140° C. for 6 h, and performing phosphating treatment to obtain phosphated chitosan-grafted 5-aminobenzimidazolone;

[0026] S3: Dissolve phosphated chitosan grafted 5-aminobenzimidazolone and boron trifluoride in a mixed solvent of polyvinyl alcohol and water, stir and mix at 80°C, then add diketene dropwise, and continue to react at 80°C for 6 hours. The mass ratio of phosphated chitosan grafted 5-aminobenzimidazolone, boron trifluoride, polyvinyl alcohol, and diketene is 1:0.5:15:1, and the mass ratio of polyvinyl alcohol to water is 1:4. Then, filter and dry to obtain 5-acetoacetylaminobenzimidazolone.

[0027] Example 2

[0028] This embodiment provides a method for preparing 5-acetoacetylaminobenzimidazolone, comprising the following steps:

[0029] S1: 5-aminobenzimidazolone and chitosan are dispersed in a solvent of toluene and ethanol mixed in a volume ratio of 1:3, the mass ratio of 5-aminobenzimidazolone to chitosan is 0.8:1, and the mixture is fully stirred. Then, 3-isocyanatepropyltrimethoxysilane (the mass ratio of 5-aminobenzimidazolone to 3-isocyanatepropyltrimethoxysilane is 1:1.2) is added, and the mixture is stirred and reacted at 80°C for 8h to obtain chitosan-grafted 5-aminobenzimidazolone;

[0030] S2: immersing the chitosan-grafted 5-aminobenzimidazolone in a phosphoric acid solution with a concentration of 5 mol / L, modifying it at 120° C. for 8 h, and performing phosphating treatment to obtain phosphated chitosan-grafted 5-aminobenzimidazolone;

[0031] S3: Dissolve phosphated chitosan grafted 5-aminobenzimidazolone and boron trifluoride in a mixed solvent of polyvinyl alcohol and water, stir and mix at 80°C, then add diketene dropwise, and continue to react at 80°C for 6 hours. The mass ratio of phosphated chitosan grafted 5-aminobenzimidazolone, boron trifluoride, polyvinyl alcohol, and diketene is 1:0.5:10:0.9, and the mass ratio of polyvinyl alcohol to water is 1:4. Then, filter and dry to obtain 5-acetoacetylaminobenzimidazolone.

[0032] Example 3

[0033] This embodiment provides a method for preparing 5-acetoacetylaminobenzimidazolone, comprising the following steps:

[0034] S1: 5-aminobenzimidazolone and chitosan are dispersed in a solvent in which toluene and ethanol are mixed in a volume ratio of 1:3, and the mass ratio of 5-aminobenzimidazolone to chitosan is 0.5:1. The mixture is stirred evenly, and then 3-isocyanatepropyltrimethoxysilane is added (the mass ratio of 5-aminobenzimidazolone to 3-isocyanatepropyltrimethoxysilane is 1:0.8). The mixture is stirred and reacted at 70°C for 10 hours to obtain chitosan-grafted 5-aminobenzimidazolone.

[0035] S2: immersing the chitosan-grafted 5-aminobenzimidazolone in a 6 mol / L phosphoric acid solution, modifying it at 150° C. for 6 h, and performing phosphating treatment to obtain phosphated chitosan-grafted 5-aminobenzimidazolone;

[0036] S3: Dissolve the phosphated chitosan grafted 5-aminobenzimidazolone and boron trifluoride in a mixed solvent of polyvinyl alcohol and water, stir and mix at 70°C, then add diketene dropwise, and continue to react at 70°C for 8 hours. The mass ratio of the phosphated chitosan grafted 5-aminobenzimidazolone, boron trifluoride, polyvinyl alcohol, and diketene is 1:0.5:12:1.2, and the mass ratio of polyvinyl alcohol to water is 1:4. Then, filter and dry to obtain 5-acetoacetylaminobenzimidazolone.

[0037] Example 4

[0038] This embodiment provides a method for preparing 5-acetoacetylaminobenzimidazolone, comprising the following steps:

[0039] S1: 5-aminobenzimidazolone and chitosan are dispersed in a solvent in which toluene and ethanol are mixed in a volume ratio of 1:3, and the mass ratio of 5-aminobenzimidazolone to chitosan is 0.6:1. The mixture is stirred well and then 3-isocyanatepropyltrimethoxysilane is added (the mass ratio of 5-aminobenzimidazolone to 3-isocyanatepropyltrimethoxysilane is 1:1). The mixture is stirred and reacted at 70°C for 10 hours to obtain chitosan-grafted 5-aminobenzimidazolone.

[0040] S2: immersing the chitosan-grafted 5-aminobenzimidazolone in a 6 mol / L phosphoric acid solution, modifying it at 120° C. for 8 h, and performing phosphating treatment to obtain phosphated chitosan-grafted 5-aminobenzimidazolone;

[0041] S3: Dissolve phosphated chitosan grafted 5-aminobenzimidazolone and boron trifluoride in a mixed solvent of polyvinyl alcohol and water, stir and mix at 80°C, then add diketene dropwise, and continue to react at 80°C for 6 hours. The mass ratio of phosphated chitosan grafted 5-aminobenzimidazolone, boron trifluoride, polyvinyl alcohol, and diketene is 1:0.3:10:0.9, and the mass ratio of polyvinyl alcohol to water is 1:4. Then, filter and dry to obtain 5-acetoacetylaminobenzimidazolone.

[0042] Comparative Example 1

[0043] This comparative example provides a method for preparing 5-acetoacetylaminobenzimidazolone, comprising the following steps:

[0044] S1: 5-aminobenzimidazolone and chitosan are dispersed in a solvent in which toluene and ethanol are mixed in a volume ratio of 1:3, and the mass ratio of 5-aminobenzimidazolone to chitosan is 0.5:1. The mixture is stirred evenly, and then 3-isocyanatepropyltrimethoxysilane is added (the mass ratio of 5-aminobenzimidazolone to 3-isocyanatepropyltrimethoxysilane is 1:1). The mixture is stirred and reacted at 80°C for 8 hours to obtain chitosan-grafted 5-aminobenzimidazolone.

[0045] S2: Dissolve chitosan-grafted 5-aminobenzimidazolone and boron trifluoride in a mixed solvent of polyvinyl alcohol and water, stir and mix at 80°C, then add diketene dropwise, and continue to react at 80°C for 6 hours. The mass ratio of chitosan-grafted 5-aminobenzimidazolone, boron trifluoride, polyvinyl alcohol, and diketene is 1:0.5:15:1, and the mass ratio of polyvinyl alcohol to water is 1:4. Then, filter and dry to obtain 5-acetoacetylaminobenzimidazolone.

[0046] Comparative Example 2

[0047] This comparative example provides a method for preparing 5-acetoacetylaminobenzimidazolone, comprising the following steps:

[0048] S1: 5-aminobenzimidazolone and chitosan are dispersed in a solvent in which toluene and ethanol are mixed in a volume ratio of 1:3, and the mass ratio of 5-aminobenzimidazolone to chitosan is 0.5:1. The mixture is stirred evenly, and then 3-isocyanatepropyltrimethoxysilane is added (the mass ratio of 5-aminobenzimidazolone to 3-isocyanatepropyltrimethoxysilane is 1:1). The mixture is stirred and reacted at 80°C for 8 hours to obtain chitosan-grafted 5-aminobenzimidazolone.

[0049] S2: immersing the chitosan-grafted 5-aminobenzimidazolone in a phosphoric acid solution with a concentration of 5 mol / L, modifying it at 140° C. for 6 h, and performing phosphating treatment to obtain phosphated chitosan-grafted 5-aminobenzimidazolone;

[0050] S3: Dissolve the phosphated chitosan grafted 5-aminobenzimidazolone in a mixed solvent of polyvinyl alcohol and water, stir and mix at 80°C, then add diketene dropwise, and continue to react at 80°C for 6 hours. The mass ratio of the phosphated chitosan grafted 5-aminobenzimidazolone, polyvinyl alcohol, and diketene is 1:15:1, and the mass ratio of polyvinyl alcohol to water is 1:4. Then, filter and dry to obtain 5-acetoacetylaminobenzimidazolone.

[0051] The conversion rate of 5-aminobenzimidazolone and the yield of 5-acetoacetylaminobenzimidazolone in Examples 1 to 4 and Comparative Examples 1 and 2 were tested, and the results are shown in Table 1.

[0052] Table 1

[0053]

Claims

1. A method for preparing 5-acetoacetylaminobenzimidazolone, characterized in that: The steps include: S1: Disperse 5-aminobenzimidazolone and chitosan in a mixed solvent of toluene and ethanol, stir well, then add 3-isocyanatepropyltrimethoxysilane, stir and react at 70-80°C for 8-10h to obtain chitosan-grafted 5-aminobenzimidazolone; S2: soaking the chitosan-grafted 5-aminobenzimidazolone in a phosphoric acid solution for phosphating to obtain phosphated chitosan-grafted 5-aminobenzimidazolone; S3: dissolving phosphated chitosan grafted 5-aminobenzimidazolone and boron trifluoride in a mixed solvent of polyvinyl alcohol and water, stirring and mixing at 70-80° C., then dropping diketene, continuing to react at 70-80° C., filtering and drying to obtain 5-acetoacetylaminobenzimidazolone.

2. The method for preparing 5-acetoacetylaminobenzimidazolone according to claim 1, wherein: The mass ratio of 5-aminobenzimidazolone to chitosan is 0.5~0.8:

1.

3. The method for preparing 5-acetoacetylaminobenzimidazolone as claimed in claim 1, characterized in that: The volume ratio of toluene to ethanol is 1:

3.

4. The method for preparing 5-acetoacetylaminobenzimidazolone according to claim 1, wherein: The mass ratio of 5-aminobenzimidazolone to 3-isocyanatepropyltrimethoxysilane is 1:0.8~1.

2.

5. The method for preparing 5-acetoacetylaminobenzimidazolone according to claim 1, wherein: The concentration of phosphoric acid solution is 5~6 mol / L.

6. The method for preparing 5-acetoacetylaminobenzimidazolone according to claim 1, wherein: The chitosan-grafted 5-aminobenzimidazolone is immersed in a phosphoric acid solution and modified at 120-150° C. for 6-8 hours for phosphating treatment.

7. The method for preparing 5-acetoacetylaminobenzimidazolone according to claim 6, wherein: Modify at 140℃ for 6h and perform phosphating treatment.

8. The method for preparing 5-acetoacetylaminobenzimidazolone according to claim 1, wherein: The mass ratio of 5-aminobenzimidazolone, boron trifluoride, polyvinyl alcohol and diketene grafted with phosphated chitosan is 1:0.3-0.5:10-15:0.9-1.2, and the mass ratio of polyvinyl alcohol and water is 1:

4.

9. The method for preparing 5-acetoacetylaminobenzimidazolone according to claim 1, wherein: Add diketene dropwise and continue the reaction at 70-80°C for 6-8h.

10. 5-acetoacetylamino as claimed in claim 9 The preparation method of benzimidazolone is characterized in that: Diketene was added dropwise and the reaction was continued at 80°C for 6 h.

Images