Method of preparing 3,5,5-trimethyl-cyclohex-2-en-1,4-dione by heterophase oxidation

Abstract

The invention discloses a new preparing method of 3, 5, 5-trimethyl-cyclic-2-alkylene-1, 4-diketone, which is characterized by the following: adopting activated porous carrier acetate or halide of transient metal as catalyst; preparing the product under 50-100 deg.c through molecular oxygen or oxygen-rich gas; making terminal transient rate reach more than 98%.

Description

technical field [0001] The present invention relates to a new method for preparing 3,5,5-trimethyl-cyclohex-2-ene-1,4-dione (oxyisophorone, OIP) by heterogeneous oxidation, which is a raw material 3,5,5-Trimethyl-cyclohex-3-en-1-one (β-isophorone, β-IP) in the presence of amines or nitrogen heterocyclic organic bases and aprotic solvents , using molecular oxygen or oxygen-enriched gas to generate oxyisophorone by heterogeneous catalytic oxidation at 50-100°C. The catalyst used therein is the acetate or halide of metal copper, iron, cobalt and manganese supported by active porous carrier. Background technique [0002] Oxyisophorone 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 in the synthesis of cosmetics. Oxyisophorone is also an important intermediate for the preparation of vitamins and carotenoids. [0003] Due to the importance of oxyisophorone in chemical and pharm...

AI Technical Summary

Problems solved by technology

[0005] In US4046813, 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 Although the method has a conversion rate of about 100%, it is also easy to make the isomerization of β-isophorone to α-isophorone in the reaction at the same time, and it is easy to form high-polymer by-products in the reaction, so decrease the selectivity of the reaction

[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 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 will polymerize in the presence of the catalyst to form by-products. products, and the large amount of waste that is eventually formed also increases the pressure on the environment

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