The preparation method of citral

Abstract

The invention relates to a preparation method for citral. The method comprises the steps of: 1) in an atmospheric pressure and oxygen-free environment, and in the presence of an alcohol ether solvent and a cosolvent, using benzoic acid or phenylacetic acid to adjust the pH value in the range of 3-5, subjecting dehydrolinalool to catalytic rearrangement under the action of a Mo catalyst, keeping the dehydrolinalool, the alcohol ether solvent, and the cosolvent in a ratio of 1:2.5:0.5, with the dosage of the catalyst accounting for 5% of the weight of the dehydrolinalool, and controlling the reaction time at 5-7h and the reaction temperature at 115-120DEG C; and 2) subjecting the citral crude product obtained in step 1) to five-stage molecular distillation for separation. By making use of the good solubility of the molybdenum catalyst in the alcohol ether solvent, the method provided by the invention not only improves the citral yield, and the catalyst can be recycled due to its dissolution in the solvent. The method avoids complex processing steps in the prior art, and simplifies the process.

Description

technical field [0001] The invention provides a method for preparing citral, in particular to a method for preparing citral by catalytic rearrangement of dehydrolinalool 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, there are mainly two chemical methods to prepare citral: aldol condensation rearrangement method and dehydrolinalool rearrangement method. Among them, the aldol condensation rearrangement method has complicated 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 with th...

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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