Preparation process of pinacolone

Abstract

The invention relates to a preparation process of pinacolone. The preparation process comprises steps as follows: (1) technical hydrochloric acid is cooled to subzero 5 DEG C to 5 DEG C, isopentene isslowly dropwise added under the stirring condition, the mixture is stirred for 1-3 h after isopentene is dropwise added, and 2-isoamyl chloride is produced; (2) 2-isoamyl chloride is pumped into a condensation reaction kettle, stirring is started, heating is performed slowly, formaldehyde is dropwise added when the temperature of a gas phase reaches 70-80 DEG C, the mixture is kept at the constant temperature for a reaction for 1-2 h after formaldehyde is dropwise added, cooling and still standing for layering are performed after the reaction ends, an upper-layer crude product enters a rectification device at the temperature of 70-80 DEG C for rectification, and a lower-layer acid liquid is pumped into a waste acid distillation kettle for fractionation; (3) rectified pinacolone is sent into a special azeotropic point distillation decoloration device and subjected to decoloration treatment at the temperature of 100-110 DEG C for 2-4 h, and a colorless pinacolone product with the purityhigher than or equal to 98% can be obtained. The preparation process has the advantages as follows: the colorless pinacolone product with the purity higher than or equal to 98% can be prepared.

Description

technical field [0001] The invention belongs to the technical field of chemical industry, in particular to a preparation process of pinacolone. Background technique [0002] Pinacolone, namely 3,3-dimethyl-2-butanone, is an important raw material for the production of pesticides such as fenzaine and pleiotrope, and an intermediate for various fine chemical products such as medicines and dyes. There are many synthetic methods of pinacolone, and the rearrangement method uses pinacol as a raw material, which is dehydrated and rearranged in an acidic environment to generate [Guizhou Chemical Industry 2006 4 (31 ): 4-6]. The disadvantage of this method is that the source of raw material pinacol is difficult and the reaction conditions are harsh. Oxidation method uses 2,3-dimethyl-2-butene as raw material, oxidizes with organic peroxyacid or hydrogen peroxide as oxidant, and then rearranges to obtain pinacolone [Liu Yuheng. Ring-opening reaction of epoxides. Hebei Normal Univers...

AI Technical Summary

Problems solved by technology

The disadvantage of this method is that a large amount of inorganic acid is still used and a large amount of waste acid containing various impurities is produced

[0006] The above-mentioned methods using isopentene as a raw material all produce a large amount of waste acid, which causes huge pressure on the environment and also increases the cost

[0007] In view of the above phenomenon, the patent CN 105503550A discloses a green preparation method of pinacolone, the process steps are as follows: first, slowly add isopentene to industrial hydrochloric acid under stirring conditions, and separate to obtain the upper intermediate tert-amyl chloride , the lower layer of acid solution for the next step of synthesis; put the obtained tert-amyl chloride in the reactor, add methanol or pinacolone as a solvent, slowly add paraformaldehyde in batches under stirring conditions, heat to reflux, and react The hydrogen chloride that produces imports in the acid solution that last step obtains; Stop reaction, the liquid in the reactor is naturally down to room temperature, obtains homogeneous material and is pinacolone crude product, and the hydrochloric acid that obtains simultaneously is used for next time synthetic, crude product pinacolone After rectification, the purity is ≧98%, and the process of the invention is simple, and no waste liquid is produced in the process of preparing pinacolone, which solves the pressure of the environment, but there are still certain defects in the preparation method: in the preparation process, industrial hydrochloric acid is used, In the industrial hydrochloric acid, some ferrous chloride is often mixed to make the industrial hydrochloric acid appear slightly yellow. In the production of pinacolone, the crude product pinacolone will be mixed with a certain amount of hydrochloric acid. Pinacolone is a colorless product, but due to the presence of industrial hydrochloric acid Make the product yellow and affect the color of the product