Method for preparing crude 2-hydroxy-4-methoxybenzophenone

Abstract

The invention discloses a method for preparing crude 2-hydroxy-4-methoxybenzophenone. The method comprises the following steps of: adding crude 2,4-dihydroxybenzophenone and sodium carbonate into dimethyl sulfate according to a proportion; raising temperature, and preserving heat and reacting at the temperature of between 70 and 78 DEG C in a reaction vessel; after the reaction, washing a product in water until pH value is 6.5 to 8.0; and standing and layering, taking the material of the lower layer, and performing dehydration to obtain the crude 2-hydroxy-4-methoxybenzophenone. The method is simple, can be operated safely and conveniently and is environmental-friendly; the obtained product has high yield and purity, and the purity of the crude 2-hydroxy-4-methoxybenzophenone is over 98.0 percent; and the residual solvent of the final product does not contain solvents of first class, such as alkanes and the like, and the method meets the standard requirement of the United States Pharmacopeia (USP).

Description

technical field

[0001] The invention relates to a preparation method of an ultraviolet absorber, in particular to a preparation method of crude 2-hydroxy-4-methoxybenzophenone. Background technique

[0002] 2-Hydroxy-4-methoxybenzophenone, commonly known as BP-3, benzophenone-3, is mainly used in sunscreen cosmetics such as sunscreen cream, cream, honey, lotion, oil, etc. It has light and heat stability It can also be used as an anti-tarnish agent for products that are discolored by photosensitivity.

[0003] At present, the preparation method of 2-hydroxyl-4-methoxybenzophenone is to take 2,4-dihydroxybenzophenone, soda ash and dimethyl sulfate as raw materials, take dichloroethane as solvent, adopt " Dimethyl sulfate was added dropwise and ethylene dichloride was distilled for synthesis. However, this method has high production cost, many process steps, low product yield and low purity, and the residual solvent of the final product contains alkane solvents such as dichlo...

Examples

Embodiment 1

[0018] Put 440kg of dimethyl sulfate into the reaction kettle, then add 600kg of crude 2,4-dihydroxybenzophenone and 205kg of soda ash at a stirring speed of 82r / m, then heat and raise the temperature to 75°C for heat preservation reaction , A total of 8h from the start of feeding to the end of the reaction. After the reaction is finished, the material is washed with water at 70-80° C. until the pH value is 6.5-8.0, and the layers are statically separated, and the material in the lower layer is removed, and the final product is obtained through dehydration.

[0019] Adopt ultraviolet-visible absorption spectrometry to characterize above-mentioned product (see figure 1 Middle curve a), and the ultraviolet-visible absorption spectrum (see figure 1 In the curve b) for comparison, by figure 1 As can be seen, the absorption peaks of curve a and curve b are basically consistent; the product of this embodiment is analyzed by high performance liquid chromatography (see figure 2 ),...

Embodiment 2～3

[0021] Keep 440kg dimethyl sulfate and 600kg 2,4-dihydroxybenzophenone crude product charging amount is constant, change the charging amount of soda ash, other operating conditions and product characterization method are all the same as embodiment 1, obtain 2-hydroxyl-4 -Methoxybenzophenone. The dosage of soda ash and the test results are shown in Table 1.

[0022] Table 1. The feeding amount and test result of embodiment 2~3 soda ash

[0023]

Embodiment 4～7

[0025] Keep 600kg 2, the feed intake of 4-dihydroxybenzophenone crude product and 205kg soda ash is constant, change the feed intake of dimethyl sulfate, other operating conditions and product characterization method are all identical with embodiment 1, obtain 2-hydroxyl- 4-Methoxybenzophenone. The feeding amount and test results of dimethyl sulfate are shown in Table 2.

[0026] Table 2. The charging capacity and test result of embodiment 4~7 dimethyl sulfate

[0027]

technical field

[0001] The invention relates to a preparation method of an ultraviolet absorber, in particular to a preparation method of crude 2-hydroxy-4-methoxybenzophenone. Background technique

[0002] 2-Hydroxy-4-methoxybenzophenone, commonly known as BP-3, benzophenone-3, is mainly used in sunscreen cosmetics such as sunscreen cream, cream, honey, lotion, oil, etc. It has light and heat stability It can also be used as an anti-tarnish agent for products that are discolored by photosensitivity.

[0003] At present, the preparation method of 2-hydroxyl-4-methoxybenzophenone is to take 2,4-dihydroxybenzophenone, soda ash and dimethyl sulfate as raw materials, take dichloroethane as solvent, adopt " Dimethyl sulfate was added dropwise and ethylene dichloride was distilled for synthesis. However, this method has high production cost, many process steps, low product yield and low purity, and the residual solvent of the final product contains alkane solvents such as dichlo...

Examples

Embodiment 1

[0018] Put 440kg of dimethyl sulfate into the reaction kettle, then add 600kg of crude 2,4-dihydroxybenzophenone and 205kg of soda ash at a stirring speed of 82r / m, then heat and raise the temperature to 75°C for heat preservation reaction , A total of 8h from the start of feeding to the end of the reaction. After the reaction is finished, the material is washed with water at 70-80° C. until the pH value is 6.5-8.0, and the layers are statically separated, and the material in the lower layer is removed, and the final product is obtained through dehydration.

[0019] Adopt ultraviolet-visible absorption spectrometry to characterize above-mentioned product (see figure 1 Middle curve a), and the ultraviolet-visible absorption spectrum (see figure 1 In the curve b) for comparison, by figure 1 As can be seen, the absorption peaks of curve a and curve b are basically consistent; the product of this embodiment is analyzed by high performance liquid chromatography (see figure 2 ),...

Embodiment 2～3

[0021] Keep 440kg dimethyl sulfate and 600kg 2,4-dihydroxybenzophenone crude product charging amount is constant, change the charging amount of soda ash, other operating conditions and product characterization method are all the same as embodiment 1, obtain 2-hydroxyl-4 -Methoxybenzophenone. The dosage of soda ash and the test results are shown in Table 1.

[0022] Table 1. The feeding amount and test result of embodiment 2~3 soda ash

[0023]

Embodiment 4～7

[0025] Keep 600kg 2, the feed intake of 4-dihydroxybenzophenone crude product and 205kg soda ash is constant, change the feed intake of dimethyl sulfate, other operating conditions and product characterization method are all identical with embodiment 1, obtain 2-hydroxyl- 4-Methoxybenzophenone. The feeding amount and test results of dimethyl sulfate are shown in Table 2.

[0026] Table 2. The charging capacity and test result of embodiment 4~7 dimethyl sulfate

[0027]

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