Method for preparing avobenzone

Abstract

The invention provides a method for preparing avobenzone. The method comprises the steps that p-tert-butylbenzaldehyde and p-methoxyacetophenone serve as raw materials, a condensation reaction is performed under the alkaline condition, and prepared condensation products are oxidized into the avobenzone under the action of an oxidizing agent. The preparation method is simple, convenient, easy to perform and few in reaction steps, the preparation condition is mild and easy to control, and the prepared avobenzone is light in color, good in quality, pure in smell, high in market competitiveness and capable of easily achieving industrialization popularization.

Description

technical field [0001] The invention belongs to the technical field of fine chemicals, and relates to a method for preparing an organic intermediate, in particular to a method for preparing avobenzone. Background technique [0002] In recent years, the amount of ultraviolet radiation has been increasing with the destruction of the ozone layer. Among them, the near ultraviolet light of 320-400nm (UV-A for short) will cause radiation damage to the human body, induce gene mutation and cause skin cancer. In order to protect the human body from excessive ultraviolet radiation, ultraviolet absorbers with safe and efficient absorption of ultraviolet radiation are widely used in cosmetics, hair care products, fabric treatment and detergents. Wherein butylmethoxydibenzoylmethane (Parsol1789) is a class of anti-UV-A ultraviolet light absorber specially used in skin care cosmetics. Parsol1789 (avobenzone) was originally developed and produced by Roche, and the product was named: Parso...

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Problems solved by technology

[0004] (1) The synthesis method using p-methoxyacetophenone and methyl p-tert-butylbenzoate as raw materials uses a strong base as a catalyst for direct condensation, such as: Daily Chemical Industry, 2009,39(3):179 -182; Fine Petrochemical Industry, 2009,26(3):4-7; Chemical World, 2006,28(9):538-540; Chinese Patent CN1958549; Chinese Patent CN102786403; World Patent WO2012 / 084770; 2002, 3:8-10, the production of this method generally uses sodium amide, sodium hydride or sodium, sodium alkoxide, potassium alkoxide, etc. as catalysts, but sodium amide is prone to side reactions such as ammonolysis in the reaction process; sodium hydride and Sodium reacts violently with water, causing great safety hazards in the production process, and high requirements for equipment; and sodium amide, sodium hydride, potassium alcohol, etc. are expensive, and the cost required for large-scale production is high, and there is no price advantage in the market

[0005] (2) Condensation of p-tert-butylbenzaldehyde and p-methoxyacetophenone under the action of sodium methoxide to generate 3-[4-tert-butylphenyl]-1-(4-methoxyphenyl)-2 - propene-1-one; then through halogen addition, sodium methoxide dehalogenation synthesis, such as: Synthetic Chemistry, 2008, 16 (3): 342-343; Eur.Pat.Appl.994092, the yield of this method is higher, However, bromine or chlorine gas is needed in the synthesis of this method, which not only requires high equipment, but also causes serious harm to people and the environment.

[0006] (3) With p-tert-butyl acetophenone and p-methoxybenzoyl chloride as raw materials, diisopropylamide lithium, trimethylchlorosilane, triethylamine, dimethylimidazole, cuprous chloride and other reagents Under the action of catalyst and photoreaction rearrangement to obtain avobenzone, such as the world patent WO2006100225, the operation of synthesizing avobenzone by this method is too cumbersome, expensive reagents are needed, the reaction time is up to 20h, and the reaction yield is Less than 20%, it is necessary to use more toxic reagents such as tetrahydrofuran and chloroform

[0008] However, this method adopts the preparation method of first epoxidation and then rearrangement, which has many reaction steps, a large amount of raw material input, and low reaction yield and product purity.

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