A preparation method of 1,4-dihydroxy-5,8-dichloroanthraquinone

Abstract

The present invention relates to the technical field of organic synthesis, and in particular to a method for preparing 1,4-dihydroxy-5,8-dichloroanthraquinone. The method adopts 1,4-dihydroxyanthraquinone as a main reaction raw material, fuming sulfuric acid as a reaction solvent, and boric anhydride as a catalyst, and introduces chlorine gas under the action of a co-catalyst to prepare the 1,4-dihydroxy-5,8-dichloroanthraquinone. The method adopts boric anhydride to increase acidity, and the co-catalyst adopted in the method improves reaction activity, reduces reaction temperature, reduces by-products, and improves product purity.

Description

Technical Field

[0001] The present invention relates to the technical field of organic synthesis, in particular to a method for preparing 1,4-dihydroxy-5,8-dichloroanthraquinone. Background Art

[0002] 1,4-Dihydroxy-5,8-dichloroanthraquinone is a key intermediate in dyes such as Solvent Green 20, Solvent Green 28, Disperse Green 5, and Acid Green 28 and 41, used in the synthesis of thermoplastic resins. Currently, no domestic manufacturer produces 1,4-dihydroxy-5,8-dichloroanthraquinone, resulting in a supply shortage for products like Solvent Green 20 and Solvent Green 28. Even Germany's Lanxess relies on imports of this intermediate to produce Macrolex Green G.

[0003] At present, there is relatively little relevant information on the preparation process of 1,4-dihydroxy-5,8-dichloroanthraquinone in China. The Journal of Tianjin University has a report titled "Synthesis Characterization and Properties of Chloro-1,4-Dihydroxyanthraquinone Intermediates". Using chlorophthalic anhydride hydroquinone as the starting material and anhydrous aluminum chloride as the catalyst, 1,4-dihydroxy-5,8-dichloroanthraquinone was synthesized through the Friedel-Crafts reaction with a yield of 58%. It does not meet the conditions for industrialization and is not suitable for large-scale production conditions.

[0004] Ma Xiamiao et al. presented "Synthesis, Characterization, and Properties of Chlorodihydroxyanthraquinones and Their Leuco Forms" at the National Conference on Organic and Fine Chemical Intermediates. Using chlorophthalic anhydride and hydroquinone as starting materials and anhydrous aluminum chloride as a catalyst, they synthesized various chloro-1,4-dihydroxyanthraquinones via the Friedel-Crafts reaction. The corresponding chloro-1,4-dihydroxyanthraquinone leuco forms were then synthesized by reduction with hydrosulfite. The resulting compounds were structurally characterized using IR and 1H NMR. The study found that chlorine atom substituents significantly blunted the acylation activity of chlorophthalic anhydride, and the greater the number of chlorine atoms, the stronger the blunting effect. The blunting effect of α-chlorine atoms was significantly greater than that of β-chlorine atoms, indicating that the conjugation effect of chlorine atoms is the dominant factor affecting the acylation activity of chlorophthalic anhydride.

[0005] The chlorinated phthalic anhydride used in the prior art is expensive, has low reactivity, and has low product purity, and has no industrial value. Summary of the Invention

[0006] Purpose of the invention: To address the deficiencies of the prior art, the present invention provides a method for preparing 1,4-dihydroxy-5,8-dichloroanthraquinone. The method comprises the following steps:

[0007] A1: Weigh 30-50 parts by weight of 1,4-dihydroxyanthraquinone, 400-600 parts of solvent, 8-20 parts of catalyst, and 0.2-0.8 parts of co-catalyst into a reactor. Under nitrogen protection, stir and slowly increase the temperature. Slowly introduce 12-40 parts of chlorine gas to carry out chlorination.

[0008] A2: After chlorination is completed, add 500-800 parts of ice water and 7-18 parts of sodium sulfite, stir, dilute, and filter press;

[0009] A3: Add 500-800 parts of hot water for pulping, filter press, and dry to obtain 1,4-dihydroxy-5,8-dichloroanthraquinone.

[0010] In a preferred technical solution, the solvent is fuming sulfuric acid.

[0011] In a preferred technical solution, the catalyst is boric anhydride.

[0012] In the preferred technical solution, the reaction temperature of A1 is 40-70°C, and the chlorination time is 2-5h.

[0013] In the preferred technical solution, the wastewater after dilution and pressure filtration of the A2 is used to make gypsum.

[0014] In the preferred technical solution, the wastewater after A3 beating and filtration is sent to a sewage station.

[0015] In the preferred technical solution, the preparation method of the co-catalyst is:

[0016] B1: 13-26 parts by weight of AlCl3·6H2O, 28-56 parts of 2-(2-mercaptobenzothiazole)succinic acid, and 0.5-3 parts of acetic acid are added to reactor 1, followed by 300-450 parts of methanol. The mixture is stirred at 30-40°C for 100-150 minutes, and the methanol is removed by distillation to obtain a 2-(2-mercaptobenzothiazole)succinic acid-aluminum complex.

[0017] B2: Weigh 2.4-4.8 parts of ethylene boric anhydride pyridine complex and add it to reactor 2, then add 0.01-0.1 parts of vinyl ferrocene, 10-17 parts of 2-(2-mercaptobenzothiazole) succinic acid-aluminum complex, 3-7 parts of triethylamine, and 300-450 parts of N,N-dimethylformamide; stir at 60-70°C for 100-150 minutes, and distill off N,N-dimethylformamide to obtain a co-catalyst.

[0018] In the preferred technical solution, the CAS number of the ethylene boron anhydride pyridine complex is 95010-17-6.

[0019] Preparation mechanism:

[0020]

[0021] The above co-catalyst preparation mechanism

[0022] AlCl3·6H2O reacts with 2-(2-mercaptobenzothiazole)succinic acid to obtain a 2-(2-mercaptobenzothiazole)succinic acid-aluminum complex; vinylboronic anhydride pyridine complex and vinylferrocene respectively undergo mercapto addition reaction with the 2-(2-mercaptobenzothiazole)succinic acid-aluminum complex to obtain a co-catalyst.

[0023] Technical effect:

[0024] The preparation method of 1,4-dihydroxy-5,8-dichloroanthraquinone of the present invention has the following significant effects compared with the prior art:

[0025] 1. The present invention adopts boric anhydride to increase the acidity;

[0026] 2. The present invention uses a ethylene boron anhydride pyridine complex and vinyl ferrocene to react with a 2-(2-mercaptobenzothiazole) succinic acid-aluminum complex to prepare a cocatalyst. The cocatalyst complex of the present invention has a large spatial structure, which increases the spatial volume of the electrophilic reagent, thereby obtaining a larger amount of 1,4-dihydroxy-5,8-dichloroanthraquinone product. This improves reaction activity, reduces reaction temperature, reduces byproducts, and improves product purity. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The following is a simplified process flow diagram for 1,4-dihydroxy-5,8-dichloroanthraquinone;

[0028] Figure 2 This is the chromatogram of 1,4-dihydroxy-5,8-dichloroanthraquinone. DETAILED DESCRIPTION

[0029] The present invention can be better understood based on the following examples. However, it is readily understood by those skilled in the art that the specific material ratios, process conditions, and results described in the examples are merely illustrative of the present invention and should not and will not limit the present invention described in detail in the claims.

[0030] Example 1

[0031] A method for preparing 1,4-dihydroxy-5,8-dichloroanthraquinone, comprising the following steps:

[0032] A1: Weigh 30g of 1,4-dihydroxyanthraquinone, 400g of solvent, 10g of catalyst, and 0.2g of co-catalyst into a reactor. Under nitrogen protection, stir and slowly heat the mixture. Slowly introduce 12g of chlorine gas to perform chlorination.

[0033] A2: After chlorination, add 500g ice water and 7g sodium sulfite, stir, dilute, and filter press;

[0034] A3: 500 g of hot water was added for pulping, filter pressing, and drying to obtain 1,4-dihydroxy-5,8-dichloroanthraquinone.

[0035] The solvent is fuming sulfuric acid.

[0036] The catalyst is boric anhydride.

[0037] The reaction temperature of A1 is 50°C and the chlorination time is 3 hours.

[0038] The wastewater after dilution and pressure filtration of the A2 is used to make gypsum.

[0039] The wastewater after A3 beating and filtration is sent to the sewage station.

[0040] The preparation method of the co-catalyst is:

[0041] B1: 13 g of AlCl3·6H2O, 28 g of 2-(2-mercaptobenzothiazole)succinic acid, and 0.5 g of acetic acid were added to reactor 1, followed by 300 g of methanol. The mixture was stirred at 30°C for 100 min, and the methanol was distilled off to obtain a 2-(2-mercaptobenzothiazole)succinic acid-aluminum complex.

[0042] B2: Weigh 2.4 g of ethylene boric anhydride pyridine complex and add it to reactor 2, then add 0.01 g of vinyl ferrocene, 10 g of 2-(2-mercaptobenzothiazole)succinic acid-aluminum complex, 3 g of triethylamine, and 300 g of N,N-dimethylformamide; stir at 60°C for 100 min, and distill off N,N-dimethylformamide to obtain a co-catalyst.

[0043] The CAS number of the ethylene boron anhydride pyridine complex is 95010-17-6.

[0044] Example 2

[0045] A method for preparing 1,4-dihydroxy-5,8-dichloroanthraquinone, comprising the following steps:

[0046] A1: Weigh 35g of 1,4-dihydroxyanthraquinone, 450g of solvent, 8g of catalyst, and 0.4g of co-catalyst into a reactor. Under nitrogen protection, stir and slowly heat the reactor. Slowly introduce 15g of chlorine gas to carry out chlorination.

[0047] A2: After chlorination, add 700g ice water and 12g sodium sulfite, stir, dilute, and filter press;

[0048] A3: 700 g of hot water was added for pulping, filter pressing, and drying to obtain 1,4-dihydroxy-5,8-dichloroanthraquinone.

[0049] The solvent is fuming sulfuric acid.

[0050] The catalyst is boric anhydride.

[0051] The reaction temperature of A1 is 40°C and the chlorination time is 2h.

[0052] The wastewater after dilution and pressure filtration of the A2 is used to make gypsum.

[0053] The wastewater after A3 beating and filtration is sent to the sewage station.

[0054] The preparation method of the co-catalyst is:

[0055] B1: 18 g of AlCl3·6H2O, 36 g of 2-(2-mercaptobenzothiazole)succinic acid, and 1 g of acetic acid were added to reactor 1, followed by 350 g of methanol. The mixture was stirred at 35°C for 110 min, and the methanol was distilled off to obtain a 2-(2-mercaptobenzothiazole)succinic acid-aluminum complex.

[0056] B2: Weigh 3.2 g of ethylene boric anhydride pyridine complex and add it to reactor 2, then add 0.05 g of vinylferrocene, 12 g of 2-(2-mercaptobenzothiazole)succinic acid-aluminum complex, 4 g of triethylamine, and 350 g of N,N-dimethylformamide; stir at 65°C for 110 min, distill off N,N-dimethylformamide to obtain a co-catalyst.

[0057] The CAS number of the ethylene boron anhydride pyridine complex is 95010-17-6.

[0058] Example 3

[0059] A method for preparing 1,4-dihydroxy-5,8-dichloroanthraquinone, comprising the following steps:

[0060] A1: Weigh 50g of 1,4-dihydroxyanthraquinone, 550g of solvent, 18g of catalyst, and 0.8g of co-catalyst into a reactor. Under nitrogen protection, stir and slowly heat the reactor. Slowly introduce 40g of chlorine gas to carry out chlorination.

[0061] A2: After chlorination, add 800g of ice water and 18g of sodium sulfite, stir, dilute, and filter press;

[0062] A3: 800 g of hot water was added for pulping, filter pressing, and drying to obtain 1,4-dihydroxy-5,8-dichloroanthraquinone.

[0063] The solvent is fuming sulfuric acid.

[0064] The catalyst is boric anhydride.

[0065] The reaction temperature of A1 is 70°C and the chlorination time is 5 hours.

[0066] The wastewater after dilution and pressure filtration of the A2 is used to make gypsum.

[0067] The wastewater after A3 beating and filtration is sent to the sewage station.

[0068] The preparation method of the co-catalyst is:

[0069] B1: 24 g of AlCl3·6H2O, 52 g of 2-(2-mercaptobenzothiazole)succinic acid, and 2 g of acetic acid were added to reactor 1, followed by 400 g of methanol. The mixture was stirred at 35°C for 140 min, and the methanol was distilled off to obtain a 2-(2-mercaptobenzothiazole)succinic acid-aluminum complex.

[0070] B2: Weigh 4.2 g of ethylene boric anhydride pyridine complex and add it to reactor 2, then add 0.08 g of vinyl ferrocene, 15 g of 2-(2-mercaptobenzothiazole)succinic acid-aluminum complex, 6 g of triethylamine, and 400 g of N,N-dimethylformamide; stir at 65°C for 140 min, distill off N,N-dimethylformamide to obtain a co-catalyst.

[0071] The CAS number of the ethylene boron anhydride pyridine complex is 95010-17-6.

[0072] Example 4

[0073] A method for preparing 1,4-dihydroxy-5,8-dichloroanthraquinone, comprising the following steps:

[0074] A1: Weigh 45g of 1,4-dihydroxyanthraquinone, 600g of solvent, 20g of catalyst, and 0.5g of co-catalyst into a reactor. Under nitrogen protection, stir and slowly heat the reactor. Slowly introduce 30g of chlorine gas to carry out chlorination.

[0075] A2: After chlorination, add 700g ice water and 15g sodium sulfite, stir, dilute, and filter press;

[0076] A3: 600 g of hot water was added for pulping, filter pressing, and drying to obtain 1,4-dihydroxy-5,8-dichloroanthraquinone.

[0077] The solvent is fuming sulfuric acid.

[0078] The catalyst is boric anhydride.

[0079] The reaction temperature of A1 is 60°C and the chlorination time is 4 hours.

[0080] The wastewater after dilution and pressure filtration of the A2 is used to make gypsum.

[0081] The wastewater after A3 beating and filtration is sent to the sewage station.

[0082] The preparation method of the co-catalyst is:

[0083] B1: 26 g of AlCl3·6H2O, 56 g of 2-(2-mercaptobenzothiazole)succinic acid, and 3 g of acetic acid were added to reactor 1, followed by 450 g of methanol. The mixture was stirred at 40°C for 150 min, and the methanol was distilled off to obtain a 2-(2-mercaptobenzothiazole)succinic acid-aluminum complex.

[0084] B2: Weigh 4.8 g of ethylene boric anhydride pyridine complex and add it to reactor 2, then add 0.1 g of vinyl ferrocene, 17 g of 2-(2-mercaptobenzothiazole)succinic acid-aluminum complex, 7 g of triethylamine, and 450 g of N,N-dimethylformamide; stir at 70°C for 150 min, distill off N,N-dimethylformamide to obtain a co-catalyst.

[0085] The CAS number of the ethylene boron anhydride pyridine complex is 95010-17-6.

[0086] Comparative Example 1

[0087] In this comparative example, during the preparation of 1,4-dihydroxy-5,8-dichloroanthraquinone, the catalyst was replaced by boric acid, and the other steps were the same as in Example 1.

[0088] Comparative Example 2

[0089] In this comparative example, no co-catalyst was added during the preparation of 1,4-dihydroxy-5,8-dichloroanthraquinone, and the other steps were the same as those in Example 1.

[0090] Comparative Example 3

[0091] In this comparative example, no ethylene boric anhydride pyridine complex was added during the preparation of the co-catalyst, and the other procedures were the same as in Example 1.

[0092] Comparative Example 4

[0093] In this comparative example, vinylferrocene was not added during the preparation of the co-catalyst, and other aspects were the same as in Example 1.

[0094] The test results of the 1,4-dihydroxy-5,8-dichloroanthraquinone products prepared in the above examples and comparative examples are shown in the following table:

[0095]

[0096] Through the data analysis of the above examples and comparative examples, the present invention improves the reaction activity, reduces the reaction temperature, reduces by-products, and improves the product purity from 70% to 86%.

Claims

1. A method for preparing 1,4-dihydroxy-5,8-dichloroanthraquinone, comprising the following steps: A1: Weigh 30-50 parts by weight of 1,4-dihydroxyanthraquinone, 400-600 parts of solvent, 8-20 parts of catalyst, and 0.2-0.8 parts of co-catalyst into a reactor. Under nitrogen protection, stir and slowly increase the temperature. Slowly introduce 12-40 parts of chlorine gas to carry out chlorination. A2: After chlorination is completed, add 500-800 parts of ice water and 7-18 parts of sodium sulfite, stir, dilute, and filter press; A3: adding 500-800 parts of hot water for pulping, filtering, and drying to obtain 1,4-dihydroxy-5,8-dichloroanthraquinone; The preparation method of the co-catalyst is: B1: 13-26 parts by weight of AlCl3·6H2O, 28-56 parts of 2-(2-mercaptobenzothiazole)succinic acid, and 0.5-3 parts of acetic acid are added to reactor 1, followed by 300-450 parts of methanol. The mixture is stirred at 30-40°C for 100-150 minutes, and the methanol is removed by distillation to obtain a 2-(2-mercaptobenzothiazole)succinic acid-aluminum complex. B2: Weigh 2.4-4.8 parts of ethylene boric anhydride pyridine complex and add it to reactor 2, then add 0.01-0.1 parts of vinyl ferrocene, 10-17 parts of 2-(2-mercaptobenzothiazole) succinic acid-aluminum complex, 3-7 parts of triethylamine, and 300-450 parts of N,N-dimethylformamide; stir at 60-70°C for 100-150 minutes, and distill off N,N-dimethylformamide to obtain a co-catalyst.

2. The method for preparing 1,4-dihydroxy-5,8-dichloroanthraquinone according to claim 1, wherein: The solvent is fuming sulfuric acid.

3. The method for preparing 1,4-dihydroxy-5,8-dichloroanthraquinone according to claim 1, wherein: The catalyst is boric anhydride.

4. The method for preparing 1,4-dihydroxy-5,8-dichloroanthraquinone according to claim 1, wherein: The reaction temperature of A1 is 40-70°C, and the chlorination time is 2-5h.

5. The method for preparing 1,4-dihydroxy-5,8-dichloroanthraquinone according to claim 1, wherein: The wastewater after dilution and pressure filtration of the A2 is used to make gypsum.

6. The method for preparing 1,4-dihydroxy-5,8-dichloroanthraquinone according to claim 1, wherein: The wastewater after A3 beating and filtration is sent to the sewage station.

7. The method for preparing 1,4-dihydroxy-5,8-dichloroanthraquinone according to claim 1, characterized in that: The CAS number of the ethylene boron anhydride pyridine complex is 95010-17-6.

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