Method for continuously and efficiently preparing 2, 6, 6-trimethyl-2-cyclohexene-1, 4-diketone by oxidation

Abstract

The invention discloses a method for continuously and efficiently preparing 2, 6, 6-trimethyl-2-cyclohexene-1, 4-diketone by oxidation. The method includes the steps: (1) performing reaction of raw material liquid and oxygen-containing gas in a spraying and mixing manner to obtain reaction liquid; (2) performing gas-liquid separation on the reaction liquid, adjusting temperature of a liquid phase,and performing reaction of the liquid phase and the oxygen-containing gas in a spraying and mixing manner to obtain reaction liquid; (3) repeating process of the step (2) until reaction is complete to obtain 2, 6, 6-trimethyl-2-cyclohexene-1, 4-diketone liquid. The oxygen-containing gas in the step (2) is a gas phase acquired by gas-liquid separation or newly prepared gas. The raw material liquidcomprises a catalyst, a reaction raw material and a solvent. By the aid of a gas and liquid mixing and spraying mode, the mixing effect of the reaction liquid, the gas and the catalyst is greatly superior to that of a mechanically stirred reactor, bubbles are more uniformly dispersed and sufficiently contact, ideal mass transfer effects are achieved, and reaction is accelerated.

Description

technical field [0001] The invention relates to the field of synthesis of 2,6,6-trimethyl-2-cyclohexene-1,4-dione, in particular to a continuous oxidation of 3,5,5-trimethyl-3-cyclohexene -1-A method for preparing 2,6,6-trimethyl-2-cyclohexene-1,4-dione. Background technique [0002] 2,6,6-Trimethyl-2-cyclohexene-1,4-dione is an important chemical and pharmaceutical intermediate, which can be used as flavoring agent or fragrance in food additives, and can also be used in the synthesis of cosmetics, 2,6,6-Trimethyl-2-cyclohexene-1,4-dione is also an important intermediate for the preparation of vitamins and carotenoids. [0003] Due to the importance of 2,6,6-trimethyl-2-cyclohexene-1,4-dione in chemical and pharmaceutical fields, 3,5,5-trimethyl-2-cyclo Oxidation of hexen-1-one or 3,5,5-trimethyl-3-cyclohexen-1-one to 2,6,6-trimethyl-2-cyclohexene-1,4-dione It has always been a research hotspot in the field of chemistry and chemical engineering, especially for the oxidati...

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Problems solved by technology

However, the traditional mechanical stirring reactor has a slow stirring speed, which limits the degree of gas-liquid mixing in the reactor, and the mass transfer effect is general; at the same time, for the traditional reactor with agitator, its internal heat transfer area is limited. , the removal of oxidation reaction heat is not timely enough, which is an important reason for side reactions; moreover, the stirred reactor contains stirring parts, which have certain restrictions on sealing performance, and are not suitable for high-pressure reactions; there is still a reaction time in actual production Long, there are problems such as tail gas formation and solvent entrainment loss

[0011] Zhang Qin et al. (Zhejiang Chemical Industry, 2014, 5, 17-19) studied the oxidation reaction of the isomer 3,5,5-trimethyl-3-cyclohexen-1-one, using the spray oxidation reaction method, the amount of catalyst, temperature and oxygen content, etc. have been studied. The reaction has good mass transfer and heat transfer effects, but because the yield is lower than 80%, this method is used to synthesize 2,6,6-trimethyl-2 -Cyclohexene-1,4-dione can not meet the requirements of industrialization

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