A kind of synthetic method of p-hydroxystyrene

Abstract

The invention discloses a synthesis method of p-hydroxystyrene, which specifically adopts a two-step method to synthesize p-hydroxystyrene, including: (I) obtaining p-hydroxycinnamic acid through condensation reaction of benzaldehyde and malonic acid; (II) p-hydroxycinnamic acid Hydroxycinnamic acid is deacidified to obtain p-hydroxystyrene. In the condensation reaction, the metal ion catalyst is used to promote the reaction in a rectification tower through reactive distillation; in the decarboxylation reaction, an organic or nonpolar base is used to catalyze the decarboxylation of p-hydroxycinnamic acid to form p-hydroxystyrene. The invention can reduce the self-decomposition of malonic acid in the synthesis of p-hydroxystyrene, improve the utilization rate of malonic acid, reduce the quantity of three wastes, and improve the atom economy of chemical reaction.

Description

technical field [0001] The invention relates to the field of fine organic chemical synthesis, in particular to the synthesis of a fine chemical intermediate p-hydroxystyrene. Background technique [0002] p-Hydroxystyrene (4-hydroxystyrene, 4-vinylphenol, 4-vinylphenol) English name 4-Hydroxystyrene (4-Vinylphenol, p-Vinylphenol), is an important chemical and pharmaceutical intermediates, in various It is widely used in the synthesis of polymer-like materials and pharmaceutical products. The most important chemical synthesis reaction of p-hydroxystyrene is as follows: [0003] [0004] The synthesis process introduced in conventional literature and patents is that malonic acid and p-hydroxybenzaldehyde are catalyzed by alkali to synthesize p-hydroxystyrene in one pot. The function of alkali catalyst is to ionize malonic acid to produce β-dicarbonyl carbanion, The carbanion attacks the carbonyl carbon of p-hydroxybenzaldehyde, and then a decarboxylation reaction occurs un...

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Problems solved by technology

[0017] 2. The atom economy of the main raw material is poor and the cost is high: malonic acid is an organic acid, and the catalyst is an organic base. During the reaction, some catalysts form organic salts with malonic acid and the activity decreases. In order to maintain the conversion rate of the reaction, it must be increased Catalyst dosage, which results in low catalyst utilization

This scheme can reduce the amount of DMF solvent used, but the ratio of malonic acid, diethylamine and p-hydroxybenzaldehyde is high, and the atom economy is very poor

Patent CN105175250A adopts the method of recovering the reaction solvent after the condensation and decarboxylation reaction to reduce the difficulty of solvent post-treatment, but there is still the problem that the ratio of malonic acid to p-hydroxybenzaldehyde is too high

Excessive malonic acid either decomposes during the reaction, or enters the water phase to form wastewater after the reaction, and the atom economy is poor

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