Novel process for efficiently preparing pyrogallic acid

Abstract

The invention belongs to the field of new materials of fine chemicals, tetra-halogen cyclohexanone is used as a raw material, efficient preparation of pyrogallic acid is realized under the action of carboxylate, and the preparation process is mild in reaction condition, simple to operate, high in yield and high in product purity, meets the detection standard, and has excellent industrial prospects.

Description

[Technical Field]

[0001] This invention belongs to the field of fine chemical new materials. It achieves the efficient preparation of pyrogallic acid using tetrahalogen cyclohexanone as raw material in a buffer system environment such as carboxylate. The process is mild, easy to operate, has high yield, high product purity, and meets testing standards, showing excellent prospects for industrialization. [Background Technology]

[0002] Pyrogallic acid, also known as pyrogallol, is a white, lustrous crystalline powder. It is widely used in fine chemicals, novel photosensitive materials, food preservation, new drugs for treating cardiovascular and cerebrovascular diseases, new anti-tumor drugs, drugs for treating Alzheimer's disease, drugs for treating mental disorders, textile printing and dyeing, light industry and daily chemicals, color printing plate making, microelectronics, rare metal analysis, gas analysis, and photographic development, among other industries.

[0003] Currently, the main preparation processes for pyrogallic acid are: (1) Gallic acid obtained from gallnut tannin or taratin through chemical processing of forest products is decarboxylated by heating to generate pyrogallic acid. The decarboxylation methods commonly used in industry are biological decarboxylation, atmospheric pressure catalytic decarboxylation and vacuum catalytic decarboxylation. This involves high labor costs, unstable products, difficult catalyst separation, large amounts of waste acid and wastewater, equipment corrosion, and high costs. In addition, the raw material, natural gallnut, is limited by domestic production capacity and needs to be imported; (2) Pyrogallic acid is prepared by chemical methods using glutaric acid ester (cumbersome steps, dangerous processes, equipment corrosion, etc.), tetrachlorocyclohexanone (sulfur dioxide environmental pollution, equipment corrosion, large amounts of solid waste, difficult catalyst recovery, etc.), cyclohexene (requires heavy metals, difficult separation), resorcinol (low yield, many by-products, difficult separation), and p-tert-butylphenol (involves bromine processes, long route) as raw materials. This method only exists in the laboratory research and development stage, with obvious scale-up effects and high costs. Currently, neither of the two main types of processes mentioned above has achieved large-scale production.

[0004] To address the above issues, we have developed a method for the efficient one-step preparation of pyrogallic acid using tetrahalogen cyclohexanone as a raw material and by modifying the process in a buffer system environment. This method is mild, produces less solid waste, has low cost, and produces high-purity products. The test results are consistent with published results, laying the foundation for subsequent large-scale production. [Summary of the Invention]

[0005] This application has now unexpectedly discovered that, as shown in reaction (I), tetrahalogen cyclohexanone A and carboxylate B can achieve the efficient preparation of pyrogallic acid C under certain conditions:

[0006]

[0007] Where X is a halogen atom, namely one of F, Cl, Br, I; R is a hydrogen atom or an alkyl, alkenyl, alkynyl or aromatic group with 1-24 carbon atoms; M is an alkaline earth metal ion or a group with basic properties; n is the charge number of the metal ion or basic group; and the reaction conditions are at least one of solvent, additive, temperature and pressure (or vacuum).

[0008] Carboxylate B is a mixture of one or more carboxylate salts, including but not limited to sodium carboxylate, potassium carboxylate, calcium carboxylate, zinc carboxylate, cesium carboxylate, lithium carboxylate, and ammonium carboxylate. The feed ratio of carboxylate B to tetrahalogen cyclohexanone A is 0.01:1-1000:1, preferably 4:1-30:1.

[0009] Adding acidic additives to the reaction system to prepare a buffer system can effectively improve the reaction yield shown in formula (I). These acidic additives are inorganic acids or saturated or unsaturated carboxylic acids having 1-24 carbon atoms, including but not limited to formic acid, acetic acid, propionic acid, butyric acid, oxalic acid, malonic acid, succinic acid, adipic acid, hydrochloric acid, sulfuric acid, and phosphoric acid. The feed ratio of the acidic additive to tetrachlorocyclohexanone A is 0.01:1-1000:1, preferably 1:1-20:1.

[0010] In some preferred embodiments of the present invention, the solvent is selected from water, acetonitrile, methanol, ethanol, butanol, ethyl acetate, butyl acetate, dimethyl sulfoxide, dimethyl sulfone, benzyl sulfoxide, benzyl sulfone, cyclobutane sulfoxide, sulfolane, trichlorosilane, dichloromethane, trichloromethane, dichloroethane, dimethyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, chloroform, carbon tetrachloride, benzene, toluene, xylene, trimethylbenzene, tetramethylbenzene, acetonitrile, ethylbenzene, diethylbenzene, chlorobenzene, dichlorobenzene. The compound is selected from at least one of the following: anisole, nitrobenzene, heptane, hexane, petroleum ether, dioxane, tetrahydrofuran, methyltetrahydrofuran, methyl tert-butyl ether, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, propylene glycol methyl ether acetate, triethylamine, tributylamine, dimethylisopropylamine, pyridine, N,N-tetramethylethylenediamine, N-alkylmorpholine, N-alkylpyrrole, N,N-dimethylformamide, formylmorpholine, N,N-diethylformamide, and N-methylpyrrolidone. The solvent is preferably water or a mixture of water and an organic solvent, and the mass ratio of the raw material compound A to the solvent is 1:1 to 1:1000, preferably 1:3 to 1:30.

[0011] The reaction temperature is 40℃-400℃, preferably 80℃-200℃.

[0012] We will explain further in the embodiments.

Detailed Implementation Methods

[0013] The essence of the invention is further illustrated below with reference to specific embodiments:

[0014] Example 1:

[0015]

[0016] Tetrachlorocyclohexanone (10 g, 0.042 mol), sodium formate (14.4 g, 0.21 mol), and 200 mL of water were added to a 500 mL round-bottom flask. The mixture was stirred at 100 °C for 5 h, and the reaction was monitored by GC. After the reaction was completed, the mixture was cooled to room temperature, and ethyl acetate was added to the reaction system for extraction three times. The organic phase was dried with anhydrous sodium sulfate, and after rotary evaporation to remove solvent, crude pyrogallic acid was obtained. After vacuum sublimation, 3.85 g of pyrogallic acid was obtained, with a yield of 72.02%.

[0017] Example 2:

[0018]

[0019] Tetrachlorocyclohexanone (10 g, 0.042 mol), sodium formate (14.4 g, 0.21 mol), and 200 mL of water were added to a 500 mL round-bottom flask. The mixture was stirred at 100 °C for 5 h, and the reaction was monitored by GC. After the reaction was completed, the mixture was cooled to room temperature, and ethyl acetate was added to the reaction system for extraction three times. The organic phase was dried over anhydrous sodium sulfate, and after rotary evaporation to remove solvent, crude pyrogallic acid was obtained. After vacuum sublimation, 4.13 g of pyrogallic acid was obtained, with a yield of 77.3%.

[0020] Example 3:

[0021]

[0022] 10 g (0.042 mol) of tetrachlorocyclohexanone, 14.4 g (0.21 mol) of sodium formate, 5.04 g (0.084 mol) of acetic acid, and 200 mL of water were added to a 500 mL round-bottom flask. The mixture was stirred at 100 °C for 5 h. The reaction was monitored by GC. After the reaction was completed, the mixture was cooled to room temperature, and ethyl acetate was added to the reaction system for extraction three times. The organic phase was dried with anhydrous sodium sulfate, and the solvent was removed by rotary evaporation to obtain crude pyrogallic acid. After vacuum sublimation, 4.35 g of pyrogallic acid was obtained, with a yield of 81.4%.

[0023] Example 4:

[0024]

[0025] 10 g (0.042 mol) of tetrachlorocyclohexanone, 17.2 g (0.21 mol) of sodium acetate, 5.04 g (0.084 mol) of acetic acid, and 200 mL of water were added to a 500 mL round-bottom flask. The mixture was stirred at 100 °C for 5 h. The reaction was monitored by GC. After the reaction was completed, the mixture was cooled to room temperature, and ethyl acetate was added to the reaction system for extraction three times. The organic phase was dried with anhydrous sodium sulfate, and the solvent was removed by rotary evaporation to obtain crude pyrogallic acid. After vacuum sublimation, 4.68 g of pyrogallic acid was obtained, with a yield of 87.5%.

[0026] Example 5:

[0027]

[0028] 10 g (0.042 mol) of tetrachlorocyclohexanone, 17.2 g (0.21 mol) of sodium acetate, 5.04 g (0.084 mol) of acetic acid, and 200 mL of water were added to a 500 mL round-bottom flask. The mixture was stirred at 120 °C for 3 h. The reaction was monitored by GC. After the reaction was completed, the mixture was cooled to room temperature, and ethyl acetate was added to the reaction system for extraction three times. The organic phase was dried with anhydrous sodium sulfate, and the solvent was removed by rotary evaporation to obtain crude pyrogallic acid. After vacuum sublimation, 4.61 g of pyrogallic acid was obtained, with a yield of 86.3%.

[0029] Example 6:

[0030]

[0031] 100 g (0.42 mol) of tetrachlorocyclohexanone, 172 g (2.1 mol) of sodium acetate, 50.4 g (0.84 mol) of acetic acid, and 2 L of water were added to a 5 L round-bottom flask. The mixture was stirred at 120 °C for 4 h. The reaction was monitored by GC. After the reaction was completed, the mixture was cooled to room temperature and extracted three times with ethyl acetate. The organic phase was dried with anhydrous sodium sulfate and dissolved by rotary evaporation to obtain crude pyrogallic acid. After vacuum sublimation, 45.7 g of pyrogallic acid was obtained, with a yield of 85.5%.

[0032] Example 7:

[0033]

[0034] 500 g (2.1 mol) of tetrachlorocyclohexanone, 860 g (10.5 mol) of sodium acetate, 252 g (4.2 mol) of acetic acid, and 10 L of water were added to a 50 L reactor. The mixture was stirred at 120 °C for 4 h, and the reaction was monitored by GC. After the reaction was completed, the mixture was cooled to room temperature, and ethyl acetate was added to the reaction system for three extractions. The organic phase was dried over anhydrous sodium sulfate, and after rotary evaporation to remove solvent, crude pyrogallic acid was obtained. After vacuum sublimation, 233.5 g of pyrogallic acid was obtained, with a yield of 87.3%. The LC purity was 99.95% and the GC purity was 99.94%.

[0035] It should be emphasized that the above embodiments are merely exemplary and not limiting. Based on the disclosure of this application, any adjustments or changes to the reaction conditions or parameters that a person skilled in the art might normally adopt will not deviate from the spirit of the invention. The scope of protection of this patent shall be determined by the relevant claims.

Claims

1. A process for preparing pyrogallic acid, as shown in reaction formula (I), wherein tetrahalogen cyclohexanone A is used as raw material and reacts in a carboxylate environment under conditions to obtain pyrogallic acid C. Where X is a halogen atom, namely one of F, Cl, Br, I; R is a hydrogen atom or an alkyl, alkenyl, alkynyl or aromatic group with 1-24 carbon atoms; M is an alkaline earth metal ion or a group with basic properties; n is the charge number of the metal ion or basic group; and the reaction conditions are at least one of solvent, additive, temperature and pressure (or vacuum).

2. According to claim (1), the carboxylate system B is a mixture of one or more carboxylates, including but not limited to sodium carboxylate, potassium carboxylate, calcium carboxylate, zinc carboxylate, magnesium carboxylate, cesium carboxylate, lithium carboxylate, ammonium carboxylate, and the feed ratio of carboxylate B to tetrahalogen cyclohexanone A is 0.01:1-1000:

1.

3. According to claim (1), adding acidic additives to the reaction system to prepare a buffer system can effectively improve the reaction yield shown in formula (1). These acidic additives are inorganic acids or saturated or unsaturated carboxylic acids having 1-24 carbon atoms, including but not limited to formic acid, acetic acid, propionic acid, butyric acid, oxalic acid, malonic acid, succinic acid, adipic acid, hydrochloric acid, sulfuric acid, and phosphoric acid, wherein the feed ratio of the acidic additive to tetrachlorocyclohexanone A is 0.01:1-1000:

1.

4. According to claim (1), the solvent in the reaction conditions is water, substituted or unsubstituted aromatic hydrocarbons, straight-chain or branched aliphatic hydrocarbons, (sulfoxide) sulfones, amides, ethers, alcohols, esters, ketones, carboxylic acids, amines, carbonates, ionic liquids, supercritical fluids, or a mixture of the above solvents and water, wherein the amount of solvent used is 1-1000 times (by mass) the amount of tetrahalogen cyclohexanone.

5. According to claim (1), the temperature described in the reaction conditions is 40℃-400℃.

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