Preparation and application of p-methoxyacetophenone_Industrial additives

Background and overview^[1]

P-Methoxyacetophenone, also known as hawthorn flower ketone, is a white crystal. Friedel-Crafts acylation reaction is one of the important ways to synthesize p-methoxyacetophenone. Its typical preparation method is to use anisole as raw material, acetyl chloride or acetic anhydride as acylating reagent, and use Lewis acid through Friedel-Crafts acylation reaction. Domestic and foreign researchers have conducted extensive research on catalysts used in acylation reactions. The catalysts currently used mainly include metal halides (such as AlCl₃, FeCl₃ , TiCl₄, etc.), molecular sieves, heteropolyacids, etc.

Preparation^[2]

Solid acid catalyzes the preparation of p-methoxyacetophenone from anisole and acetyl chloride:

1) Preparation of catalyst MoSi (molar ratio 1:1): Dissolve 1gp123 in 12.4ml n-propanol in an ice-water mixed bath, add 3mmol tetraethyl orthosilicate, then add 3mmol MoCl, and stir until completely dissolved. Add 45 mmol of ammonia water drop by drop while stirring. At this time, the salt in the solution begins to hydrolyze to form a precipitate. Continue stirring the obtained slurry at room temperature for 24 hours, and then place it in an evaporating dish to be air-dried at 110°C and roasted at 500°C. After 5 hours (heating program 1.5°C/min), the MoSi composite metal oxide catalyst can be obtained.

2) Preparation of p-methoxyacetophenone: Add 0.05g of MoSi, 5ml of anisole, and 0.5ml of acetyl chloride into a 50ml round-bottomed flask, heat in a constant temperature oil bath at 80°C, and stir with magnetic r/ min, react for 10 hours.

Apply^[3-4]

P-Methoxyacetophenone is a food spice allowed by national regulations and is sensitive to light. Soluble in ethanol, slightly soluble in water. It has a strong hawthorn aroma and is an indispensable raw material for mimosa, hawthorn and other fragrances. It is suitable for scents such as hawthorn flower, acacia, mimosa, acacia, fragrant myrtle, succulent orchid, fresh mowing grass, clover and other scents. It has high stability in soap and is often used in herbal scent, woody scent and other high-end cosmetics and In soap fragrance; also used in the production of sunscreen, p-methoxyphenylacetic acid (puerarin intermediate), p-methoxystyrene and liquid crystal monomer.

Application 1. CN201210268091.8 relates to the preparation method of 4-tert-butyl-4”-methoxydibenzoylmethane, which belongs to the field of fine chemical technology. It includes the following steps: (1) Mix p-methoxyacetophenone and solvent evenly; (2) Mix p-tert-butyl methyl benzoate and solvent evenly, and add 60%~ of the mass of p-methoxyacetophenone. 100% sodium methoxide or sodium ethoxide, heat up to 40℃~100℃ and then add p-methoxyacetophenone solution dropwise until the mass ratio of p-methoxyacetophenone and p-tert-butyl methyl benzoate is 0.6 When ~2.0, the dropwise addition is completed, and the insulation reaction continues; (3) After the reaction is complete, the crude product is obtained, adjust the pH of the crude product to ≤ 5, dissolve it after stirring, and wash and separate the layers; (4) After the water-washed material is removed from the solvent , add methanol to dissolve, then decolorize with activated carbon, repeatedly add methanol, and refine again to obtain the product. The reaction molar yield of the invention is high, the reaction conditions are mild, and the reaction method is suitable for industrial production.

Application 2. CN201810391635.7 discloses a preparation method of avobenzone, in which a modified ZSM-5 zeolite solid acid catalyst is used to remove volatile by-products by distillation under reduced pressure without introducing a solvent. The product acetic acid is used to obtain p-methoxyacetophenone; at the same time, p-toluenesulfonic acid is used as the catalyst instead of traditional concentrated sulfuric acid to perform an esterification reaction to obtain p-tert-butyl benzoic acid methyl ester; then p-methoxyacetophenone is reacted with Methyl p-tert-butyl benzoate reacts to obtain avobenzone, forming a new preparation process of avobenzone.

References

[1]CN201910833139.7 A new green process for preparing p-methoxyacetophenone

[2]CN201810658864.0 A catalytic synthesis method of p-methoxyacetophenone

[3] Preparation method of CN201210268091.84-tert-butyl-4’-methoxydibenzoylmethane

[4]CN201810391635.7 A preparation method of avobenzone