Preparation method of potassium p-hydroxybenzoate

Abstract

The invention relates to a method for preparing potassium p-hydroxybenzoate by taking phenol, potassium hydroxide and carbon dioxide as raw materials. The method comprises the following steps: firstly, carrying out liquid-liquid condensation reaction on phenol and potassium hydroxide in a condensation reactor to obtain a potassium phenolate material containing potassium hydroxide; then leaching the potassium phenolate material containing potassium hydroxide by taking acetone as a leaching agent to obtain an acetone solution of potassium phenolate; and carrying out gas-liquid carboxylation reaction on the acetone solution of the potassium phenolate and carbon dioxide, and carrying out reduced pressure flash separation to obtain the potassium p-hydroxybenzoate. The technology is reasonable, safe and environmentally friendly, the utilization rate of valuable components is high, continuous operation of the process can be achieved, and the technology is a green and clean production technology.

Description

technical field [0001] The invention relates to a method for preparing potassium p-hydroxybenzoate by using phenol, potassium hydroxide and carbon dioxide as raw materials. First, in the condensation reactor, phenol and potassium hydroxide undergo liquid-liquid condensation reaction to obtain potassium phenate material containing potassium hydroxide; solution; the acetone solution of potassium phenate is then subjected to gas-liquid carboxylation reaction with carbon dioxide, and is separated by flash evaporation under reduced pressure to obtain potassium p-hydroxybenzoate. It belongs to the technical fields of fine chemicals, separation engineering and chemical engineering. Background technique [0002] 1. Potassium Paraben [0003] Potassium parahydroxybenzoate, also known as potassium parahydroxybenzoate; potassium parahydroxybenzoate; potassium tetrahydroxybenzoate; potassium parahydroxybenzoate, molecular formula C 7 H 5 O 3 K, molecular weight 176.21, mainly used ...

AI Technical Summary

Problems solved by technology

[0010] ①In order to meet the condensation reaction and the separation and purification conditions of potassium phenate after the condensation reaction, the existing technology adopts potassium hydroxide as the reaction control component, and the reactant phenol is excessive, which will inevitably lead to many side reaction products, low phenol utilization efficiency and product The problem of high impurity content in medium

[0011] ② When potassium hydroxide solid is used as the reactant, due to the low solubility of potassium hydroxide in phenol, when potassium hydroxide particles and phenol are directly used for condensation reaction, the reaction system is a liquid-solid phase reaction system, and there must be a slow reaction rate. , long reaction time, potassium hydroxide is also easy to agglomerate, making it difficult to transform completely, etc.

[0014] ⑤ The process of preparing potassium phenate powder from anhydrous potassium phenate has problems such as difficult operation and control, low production efficiency and low yield, and the anhydrous potassium phenate material also has the danger of being flammable and explosive

Gas-solid phase reactions inevitably have problems such as low reaction rate, long reaction time, difficulty in removing heat during the reaction process, and easy local overheating to produce by-products.

[0017] ②Reaction selectivity is low, resulting in poor product quality: Potassium o-hydroxybenzoate will be generated during the reaction, and it is difficult to separate and refine the ortho- and para-position products, and it is difficult to obtain high-quality potassium p-hydroxyphenate

[0020] ⑤ Difficulty in continuous steady-state operation control: Because carbon dioxide and potassium phenate are gas-solid phase exothermic reaction systems, there must be problems of reaction operation process control and reactor operation instability

[0021] ⑥ The safety and reliability of the process is poor: the reactant potassium phenate is easily burned and exploded after being dehydrated into a dry powder, and there are potential safety hazards of burning and explosion in the preparation process of fine particle potassium phenate

[0026] ① Using sulfuric acid or hydrochloric acid as a neutralizing agent increases the consumption of acid;

[0028] ③ Potassium salts generated by using acid as a neutralizing agent have low utilization value and are difficult to utilize as resources, and usually can only be treated as solid waste