Preparation method of oxoisophorone

Abstract

The invention discloses a preparing method of oxoisophorone, which is characterized by the following: adopting pyridine, 2-methyl pyridine, 4-methyl pyridine, methyl imidazole, phenylamine and diphenylamine as raw material; making acetylacetone based on ionic liquid as catalyst under one or two organic alkaline as catalyst; using molecular oxygen or oxygen-rich gas under 0-80 deg.c; oxidizing beta-isophorone to obtain the product; distilling under 5-15mmHg vacuum degree at 150-200 deg.c; making catalyst and relating solution separate to recycle catalyst; removing organic alkaline under 50-80 deg.c; using separating method of catalyst and oxoisophorone to use catalyst.

Description

technical field [0001] The invention relates to a method for oxidizing β-isophorone into oxoisophorone and recycling the catalyst. Background technique [0002] 3,5,5-Trimethyl-cyclohex-2-ene-1,4-dione (Oxoisophorone: OIP) can be used as a flavoring agent or fragrance in food or cosmetic preparations, and is also used in the preparation of Important intermediates of vitamins and carotenoids. Due to the importance of oxyisophorone, there have been many known methods for oxidizing β-isophorone (β-IP) to oxyisophorone for a long time. These methods with molecular oxygen or air oxidation β-IP all take the organic coordination compound of transition metal as catalyzer, and known catalyzer has: the Schiff base (US6297404, DE19929362, EP1063217, US6300521, DE19929367, EP1063218, US6255509), porphyrin or phthalocyanine complexes of transition metals (JP1093556, US4898985, EP0311408), acetylacetone complexes of transition metals (US4970347, EP0374416, DE3842547, JP2207058, US402694...

AI Technical Summary

Problems solved by technology

[0003] In US6297404 and US6300521, described a kind of in the presence of DMF or DMA and tripropylamine, use the catalytic system catalytic oxidation β-IP of Schiff base and lithium acetate or ammonium acetate to prepare the method for OIP, a known shortcoming of this method is The reaction is easy to produce 3,5,5-trimethyl-cyclohex-2-ene-4-hydroxy-1-ketone, 2,2,6-trimethylcyclohexane-1,4-dione and other by-products , the separation of these by-products and OIP is quite difficult

Described a kind of in the presence of pyridine in US4046813, use the acetylacetonate complex of lead, vanadium, chromium, manganese, iron, cobalt as catalyzer, the method that catalytic oxidation β-IP prepares OIP, although this 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

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

[0004] The use of homogeneous catalysts in the reaction also has its inherent disadvantages. Because the transition metal complexes have good solubility in the organic phase, they can be well dissolved in the reaction system, which brings great difficulties to the post-treatment process and the recycling of catalysts. Difficulty: by washing and extracting, it is difficult to recover transition metal complex catalysts due to their poor solubility in water; by rectification, many transition metal complexes are easily destroyed in the high-temperature rectification process

[0005] At the same time, 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 β-IP must be maintained. concentration

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