Method for preparing oxo-isophorone by catalytic oxidation using metal free catalytic system

Abstract

The invention relates to a new method for preparing keto-isophorone, which utilizes metal free co-catalyst system to catalyze and oxidize Beta-isophorone. Beta-isophorone is used as the raw material; in the presence of an organic solvent, molecular oxygen or an oxygen rich gas is used as an oxidant; under the effect of the co-catalyst system composed by the main catalyst N-hydroxyphthalimide and the analogues of N-hydroxyphthalimide, and organic cocatalyst, keto-isophorone is prepared by catalytic oxidation; reaction temperature ranges from 0 to 120 DEG C; reaction time ranges from 5 to 50 hours; keto-isophorone with high selectivity can be generated. The method has the advantages that, the catalyst is metal free, cheap and easy to be obtained; reaction conditions are mild; operation is simple; the product has high selectively; recycling is easy, and multiple usage can be realized.

Description

technical field [0001] The invention relates to a new method for preparing oxoisophorone by catalytic oxidation of β-isophorone using a metal-free co-catalysis system, in particular to a method for preparing oxoisophorone by catalytic oxidation of a metal-free catalytic system. Its characteristics are: the raw material β-isophorone, in the presence of a solvent, uses N-hydroxyphthalimide and its analogues and organic co-catalysts to form a co-catalyst system, and uses molecular oxygen or oxygen-rich gas as the oxidant , oxidized to generate oxoisophorone. Background technique [0002] Oxyisophorone, referred to as KIP, is an important chemical and pharmaceutical intermediate, which can be used as a flavoring agent or fragrance in food additives, and can also be used to synthesize cosmetics. Oxyisophorone is also an important intermediate for the preparation of vitamins and carotenoids. It is a light yellow liquid or solid at room temperature. Its pure product has a strong ...

AI Technical Summary

Problems solved by technology

[0005] In US 4046813, a kind of acetylacetone complexes of lead, vanadium, chromium, manganese, iron, cobalt, etc. are used as catalysts to prepare oxoisophorone by catalytic oxidation of β-isophorone in the presence of organic base pyridine. The method of ketone, although the method has about 100% conversion rate, but simultaneously the reaction also easily makes β-isophorone isomerize to α-isophorone, and high polymeric by-products are easily formed in the reaction, Therefore, the selectivity of the reaction decreases

[0006] In US6297404 and US6300521, a method for preparing oxoisophorone by catalytic oxidation of β-isophorone using a catalytic system of Schiff base and lithium acetate or ammonium acetate in the presence of DMF or DMA and tripropylamine is described , one of the biggest disadvantages of this method is that the reaction is prone to produce 3,5,5-trimethyl-cyclohex-2-ene-4-hydroxyl-1-one, 2,2,6-trimethylcyclohexane-1 , 4-diketone and other by-products, because the molecular weight and properties of these by-products are similar to the product, so it is quite difficult to separate them from oxyisophorone

[0007] And in US4898985, described a kind of in the presence of triethylamine and ethylene glycol dimethyl ether, use the porphyrin or phthalocyanine complex of iron, cobalt, ketone, manganese as catalyst, catalytic oxidation β-isophorone The method for preparing oxoisophorone, although this method has very high yield, but the transition metal catalyst of porphyrin class is quite expensive, and also easily destroyed in reaction, makes this process cost higher

In addition, the alkaline environment formed by the combination of ethylene glycol dimethyl ether and triethylamine 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 in Can only be implemented on an industrial scale with very safe precautions

[0008] Judging from the situation summarized in the above patent, the transition metal-organic complex catalyst currently used for the reaction of oxidizing β-isophorone to prepare oxoisophorone has the problem that the reaction is relatively slow under low temperature conditions. Under high temperature, β-isophorone is easily isomerized into α-isophorone and other by-products, which greatly reduces the selectivity of the reaction and the yield of oxoisophorone; while the use of porphyrin catalysts can To overcome the above shortcomings, but the price of the synthetic porphyrin catalyst is much higher, and the catalyst is easily damaged or caused catalyst poisoning during the reaction, which greatly increases the instability of the reaction

At the same time, as a homogeneous transition metal catalyst, it cannot be directly separated from the reaction system after the reaction is completed, recycled and reused. As a result, it not only makes it difficult to separate the reaction solvent and products, but also some products are still in the presence of the catalyst. Coagulates to form by-products, and the resulting large quantities of scrap also add to environmental stress

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