CN102408335A - A kind of synthetic method of p-fluorophenyl acetate - Google Patents

Abstract

The invention provides a synthesis method of p-fluorophenyl acetate. The invention relates to the field of chemical synthesis, in particular to a synthesis method of p-fluorophenyl acetate. In detail, the p-fluorophenol reacts with acetic anhydride in the presence of a catalyst at the temperature of 80-150 ℃ for 2-6 h to obtain the p-fluorophenylacetic ester. The catalyst is methanesulfonic acid, p-toluenesulfonic acid and sulfamic acid. The catalyst can be reused. The post-reaction treatment adopts a direct fractionation method for purification, and can adopt normal pressure fractionation or reduced pressure fractionation. The synthesis method can obtain high-purity p-fluorophenyl acetate, and the p-fluorophenyl acetate can be used as an organic synthesis intermediate and can also be used as an electrolyte additive of a lithium battery.

Description

A kind of synthetic method of p-fluorophenyl acetate

technical field

The invention relates to the field of chemical synthesis, in particular to a synthesis method of p-fluorophenyl acetate. Specifically, p-fluorophenol and acetic anhydride are reacted at 80-150°C for 2-6 hours in the presence of a catalyst to obtain p-fluorophenyl acetate. Catalysts are methanesulfonic acid, p-toluenesulfonic acid, sulfamic acid. The catalyst can be reused without significant change in catalytic effect. The post-reaction treatment adopts the method of direct fractional distillation to carry out purification, and can adopt normal pressure fractional distillation, also can adopt vacuum fractional distillation.

Background technique

There are currently several synthetic methods for p-fluorophenyl acetate. 1) U.S. Patent No. 4780471 uses p-fluorophenol, sodium acetate, and acetic anhydride to react in benzene under reflux, then adds water, neutralizes with sodium carbonate, separates layers, and drys the organic layer with anhydrous magnesium sulfate, and finally distills to obtain the product. This method uses toxic and carcinogenic benzene as a reaction solvent, and the post-processing is troublesome. 2) J.Med.Chem.1987, 30: 814-819 documents use concentrated sulfuric acid as a catalyst, and after the reaction is completed, multi-step operations such as neutralization, extraction, and drying are performed to obtain the final product. Due to the use of concentrated sulfuric acid as a catalyst in this method, the equipment is severely corroded, and the same aftertreatment is troublesome. 3) Chinese Journal of Advanced Chemical Engineering, 2007, 21 (3): 442-447 documents use pyridine as a catalyst for the reaction, and finally neutralize with hydrochloric acid, extract with ether, wash with sodium hydroxide, dry over sodium sulfate, and remove the solvent under reduced pressure to obtain Final product, this method has shortcomings such as reaction time is long, operation is loaded down with trivial details.

Contents of the invention

The object of the present invention is to provide a kind of simple and convenient synthetic method of p-fluorophenyl acetate, easy to operate, simple aftertreatment, can obtain the product of high purity conveniently. The product can be used as an organic reaction intermediate, and also as an additive for lithium battery electrolyte. The p-fluorophenyl acetate synthesized in the present invention is obtained by reacting p-fluorophenol and acetic anhydride raw materials under heating conditions in the presence of a catalyst. After the reaction is finished, the fractional distillation can be directly carried out to obtain the high-purity p-fluorophenyl acetate product.

The present invention adopts the following technical solutions.

In the synthesis of p-fluorophenylacetic acid, the raw materials used are p-fluorophenol and acetic anhydride, which can be used directly without any treatment. The molar ratio of p-fluorophenol to acetic anhydride is 0.8:1 to 1:1.2, and there is no special limitation on the ratio of p-fluorophenol to acetic anhydride. In terms of cost, excess acetic anhydride is more economical.

In the synthesis of p-fluorophenylacetic acid, the catalyst is methanesulfonic acid, p-toluenesulfonic acid, sulfamic acid, preferably p-toluenesulfonic acid. The amount of the catalyst used is 0.5-10% (weight ratio) of the amount of p-fluorophenol, preferably 2-5%. The catalyst can be reused many times without significant reduction in catalytic effect. The catalyst can be reused directly without any treatment. After the reaction is completed and the p-fluorophenyl acetate is extracted by fractional distillation, the catalyst remains in the reactor. After cooling down, new p-fluorophenol and acetic anhydride can be added according to the metering ratio to carry out the catalytic reaction again without adding a new catalyst.

In the synthesis of p-fluorophenyl acetate, the reaction temperature is too low, the reaction time is long, and the reaction is incomplete; the reaction temperature is too high, the color of the reaction material is dark, and the product quality is affected, and the energy consumption is also high. Therefore, the optimum reaction temperature is 80-150°C, preferably 120-130°C. Under the above temperature conditions, the reaction can be completed within 2 to 6 hours.

After the reaction finishes, carry out fractionation purification directly, can adopt normal pressure fractionation, also can adopt vacuum fractionation, the required temperature of normal pressure fractionation is higher, may affect the quality of product, preferably vacuum fractionation. In the process of fractional distillation and purification, the by-product acetic acid is distilled first, and then excess acetic anhydride, unreacted p-fluorophenol and various low-boiling impurities are distilled off. Finally, receive the fraction with positive boiling point, which is the product p-fluorophenyl acetate. After such fractional distillation, p-fluorophenyl acetate with a purity of more than 99.5% can be obtained.

In the synthesis of p-fluorophenylacetic acid, no other organic solvents and chemical reagents are used, which can avoid the cost, safety, recovery and other problems caused by the use of organic solvents.

Detailed ways

The present invention will be further described below by specific examples, but the present invention is not limited to these examples.

Example 1

In a 1000ml three-neck flask equipped with a thermometer, an electric stirrer, and a reflux condenser, add 450g of p-fluorophenol, 450g of acetic anhydride, and then add 20g of p-toluenesulfonic acid catalyst, and stir the reaction at 120°C for 3.5h. After the reaction was finished, 550 g of p-fluorophenyl acetate was obtained by fractional distillation under reduced pressure, with a purity of 99.78% (GC).

Example 2

After the p-fluorophenyl acetate was extracted in Example 1, the temperature of the reaction bottle was lowered to room temperature, and then 450 g of p-fluorophenol and 450 g of acetic anhydride were added again without any catalyst, and the reaction was stirred at 125° C. for 4 h. After the reaction was completed, 535 g of p-fluorophenyl acetate was obtained by fractional distillation under reduced pressure, with a purity of 99.70% (GC).

Example 3

In a 500ml three-necked flask equipped with a thermometer, an electric stirrer, and a reflux condenser, add 112g of p-fluorophenol, 122g of acetic anhydride, and 5g of sulfamic acid catalyst, and stir the reaction at 115°C for 4h. After the reaction was completed, 123.3 g of p-fluorophenyl acetate was obtained by fractional distillation under reduced pressure, with a purity of 99.65% (GC).

Example 4

In a 5000ml three-necked flask equipped with a thermometer, an electric stirrer, and a reflux condenser, add 1700g of p-fluorophenol, 1750g of acetic anhydride, and 120g of p-toluenesulfonic acid, and stir and react the above materials at 130°C for 4h. After the reaction was completed, 2030 g of p-fluorophenyl acetate was obtained by fractional distillation under reduced pressure, with a purity of 99.83% (GC).

Claims (6)

1. A synthetic method for p-fluorophenyl acetate, characterized in that: p-fluorophenol and acetic anhydride are reacted for 2 to 6 hours at a temperature of 80 to 150°C in the presence of a catalyst, and fractionation is directly carried out after the reaction finishes. High-purity p-fluorophenyl acetate is obtained, and the catalyst can be reused. 2. the synthetic method of a kind of p-fluorophenyl acetate as claimed in claim 1 is characterized in that: described catalyzer is methanesulfonic acid, p-toluenesulfonic acid, sulfamic acid, preferred p-toluenesulfonic acid. 3. a kind of synthetic method of p-fluorophenyl acetate as claimed in claim 1 or 2 is characterized in that: the consumption of described catalyst is 0.5～10% of p-fluorophenol weight, preferably 2～5%. 4. a kind of synthetic method of p-fluorophenyl acetate as claimed in claim 1 and 2 is characterized in that: described catalyzer can be used repeatedly, directly uses without any treatment after reaction finishes. 5. a kind of synthetic method of p-fluorophenyl acetate as claimed in claim 1, is characterized in that: the temperature of reaction is 80～150 ℃, preferably 120～130 ℃. 6. the synthetic method of a kind of p-fluorophenyl acetate as claimed in claim 1 is characterized in that: described purification method can adopt the method for normal pressure fractionation, also can adopt the method for decompression fractionation, preferably reduces method of pressure distillation.