A kind of method for preparing and refining citral

Abstract

The invention discloses a preparation and refining method for citral. The method includes: 1) in an atmospheric oxygen-free environment, taking alcohol ether as a solvent and alkylsulfone as a cosolvent, adjusting the pH value by benzoic acid or phenylacetic acid, subjecting dehydrolinalool to catalytic rearrangement under catalysis of a molybdenum acetylacetonate catalyst so as to generate citral, with the dehydrolinalool, the solvent and the cosolvent being in a mass ratio of 1:(1-4):(0.2-0.8), and with the dosage of the catalyst accounting for 2-8% of that of dehydrolinalool, controlling the pH value at 3-5, the reaction time at 3-9h, and reaction temperature at 100-125DEG C; 2) subjecting a citral-containing reaction liquid to vacuum rectification to remove light components (including the cosolvent and unreacted dehydrolinalool), with a concentrated citral solution (mainly containing citral and the solvent) left at the tower bottom, and controlling the operation pressure at 0.02-0.08MPa, the tower bottom temperature at 40-80DEG C, and the reflux ratio at 4-10; and 3) carrying out vacuum rectification on the concentrated citral solution obtained at the tower bottom to obtain a high purity citral product, which has a citral purity up to 95.7%, and controlling the operation pressure at 0.008-0.06MPa, the tower bottom temperature at 40-80DEG C and the reflux ratio at 4-10. The method provided by the invention has very obvious positive effects, makes use of the good solubility of the molybdenum catalyst in the alcohol ether solvent, not only improves the citral yield, but also realizes recycling of the catalyst dissolved in the solvent. Complex processing steps in the prior art are avoided, and the process is simplified.

Description

technical field [0001] The invention provides a method for preparing and refining citral, in particular to a method for preparing citral by catalytic rearrangement of dehydrolinalool by using alcohol ether compounds as solvents. Background technique [0002] Citral is a terpene fatty aldehyde with a strong lemony aroma. Citral is an important fragrance intermediate, which can be used to manufacture citrus flavor food fragrances, or to synthesize other fragrances such as isopulegol, hydroxycitronellal and ionone. Important starting material for vitamin D, vitamin E and vitamin A. [0003] At present, the chemical methods for preparing citral mainly include aldol condensation, rearrangement and dehydrolinalool rearrangement. Among them, the aldol condensation and rearrangement method have complex steps and difficult to obtain raw materials, while the dehydrolinalool rearrangement method has the advantages of easy to obtain raw materials and simple synthesis steps. Along wit...

AI Technical Summary

Problems solved by technology

This process can realize the recycling of the catalyst and reduce the production cost, but the reaction yield of citral is still not ideal

Chinese patent CN101328111A discloses a method for purifying citral. The citral reaction solution is first cooled at low temperature, then filtered, repeatedly washed with water, washed with alkali, dried, and finally obtained by rectification to obtain high-purity citral. The steps are complicated. , and produce a large amount of waste water, waste salt, the yield of citral in this process is 88%

[0006] It can be seen that in the prior art, the process technology of dehydrolinalool catalytic rearrangement to generate citral cannot take into account the problems of catalyst recovery and citral yield

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