Method for preparing 3,5,5-trimethyl-hexamethylene-2-olefin-1,4 diketone

Abstract

A process for preparing 3,5,5-trimethyl-cyclohexyl-2-one-1,4-bione (oxyisophorone) features that under existance of organic alkali and the catalyst composed of ionic liquid [Cnmin][X] and halide of transition metal, the 3,5,5-trimethyl-cyclohexyl-3-ene-1-one (beta-isophorone) is oxidized by molecular oxygen or oxygen-enriched gas.

Description

Technical field [0001] The present invention relates to a new method for preparing 3,5,5-trimethyl-cyclohex-2-ene-1,4-dione (oxoisophorone, OIP), Background technique [0002] Oxoisophorone can be used as a flavoring or spice in food or cosmetic preparations, and it is also an important intermediate for the preparation of vitamins and carotenoids. [0003] Due to the importance of oxoisophorone, there have been many known methods for oxidizing β-isophorone to oxoisophorone for a long time. However, these methods of oxidizing β-IP with molecular oxygen or air all use transition metal organic coordination compounds as catalysts. Known catalysts include: transition metal Schiff bases (US6297404, DE19929362, EP1063217, US6300521, DE19929367, EP1063218 , US6255509), transition metal porphyrin or phthalocyanine complexes (JP1093556, US4898985, EP0311408), transition metal acetylacetone complexes (US4970347, EP0374416, DE3842547, JP2207058, US4026948, US4046813, DE2515304, JP50148332, G...

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Problems solved by technology

[0004] In US6297404 and US6300521, a method for preparing OIP by catalytic oxidation of β-IP using a catalytic system of Schiff base and lithium acetate or ammonium acetate in the presence of DMF or DMA and tripropylamine is described. A known shortcoming of this method is The reaction easily produces 3,5,5-trimethyl-cyclohex-2-ene-4-hydroxy-1-one, 2,2,6-trimethylcyclohexane-1,4-dione and other by-products , the separation of these by-products and OIP is quite difficult

[0005] In US4046813, a method for preparing OIP by catalytic oxidation of β-IP is described in the presence of pyridine, using the acetylacetonate complex of lead, vanadium, chromium, manganese, iron, and cobalt as a catalyst, although the method has about 100% Conversion rate, but at the same time, the reaction is easy to form high-polymer by-products, which makes the reaction selectivity decrease

[0006] In US4898985, a method for preparing OIP by catalytic oxidation of β-IP in the presence of triethylamine and ethylene glycol dimethyl ether, using porphyrin or phthalocyanine complexes of iron, cobalt, ketone, and manganese as a catalyst, is described , although this method has the highest yield of 98%, the transition metal catalyst of porphyrin is quite expensive, and the porphyrin catalyst is also easily destroyed in the reaction, making the process cost higher

In addition, ethylene glycol dimethyl ether combined with triethylamine as a base to maintain the reaction environment is very dangerous in the oxidation operation, because the ignition point of the mixture is very low, so for safety reasons, although the method has a high yield, it must be Can only be implemented on an industrial scale with very safe precautions

[0007] In the traditional reaction of using transition metal organic complexes as catalysts to catalyze the oxidation of β-IP to prepare OIP, the known reaction is very slow. In order to obtain a faster reaction rate, a higher concentration of β-IP must be maintained

The increase in the proportion of β-IP will increase the isomerization to produce α-isophorone (α-IP), thereby reducing the oxidation selectivity of β-IP.

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