Method for preparing p-diacetylbenzene by biomimetic catalytic oxidation of p-diethylbenzene with oxygen

Abstract

The invention relates to a method for preparing p-diacetylbenzene by biomimetic catalytic oxidation of p-diethylbenzene with oxygen, comprising the following steps: taking p-diethylbenzene as the raw material, selecting any one of 1-30ppm of mononuclear metalloporphyrin and mu-oxo-dinuclear metalloporphyrin or the composition of the two substances as the catalyst under normal pressure and in the absence of solvents, introducing oxygen at the flow rate of 10-60mL / min, initiating reaction at 140-170 DEG C and then carrying out reaction at 80-130 DEG C for 10-20h, thus obtaining the p-diacetylbenzene. In the method, the way of high temperature quick initiation and low temperature reaction is adopted, thus minimizing the reaction initiation time, greatly shortening the reaction time, improving the reaction efficiency, reducing the energy consumption, lowering the operation cost and improving the reaction safety.

Description

technical field [0001] The invention relates to a method for preparing aromatic ketones, in particular to a method for preparing p-diacetylbenzene by biomimetic catalyzing oxygen oxidation of p-diethylbenzene. Background technique [0002] P-diacetylbenzene is an important intermediate in organic synthesis, widely used in the synthesis of medicines, pesticides, dyes, flavors and fragrances, perfumes, etc. At present, the preparation methods of p-diacetylbenzene are mainly Friedel-Crafts acylation method and p-diethylbenzene oxidation method, etc., wherein the p-diethylbenzene oxidation method is divided into chemical oxidation method and molecular oxygen oxidation method. Oxygen is cheap and easy to get, The method of preparing p-diacetylbenzene by directly oxidizing p-diethylbenzene with oxygen, which is a clean and pollution-free oxidizing agent with good atom economy, has significant advantages over other methods. [0003] JP2001226307 (publication date: February 16, 200...

AI Technical Summary

Problems solved by technology

The use of co-catalysts not only increases the production cost, but also causes very serious corrosion to the equipment. It is necessary to greatly increase the investment and operating costs of the equipment. In addition, a large amount of salty wastewater will be added after the reaction, which will cause greater harm to the environment. Pollution, consuming more energy and resources;

[0008] (3) Although the method has used multiple catalysts and added a co-catalyst, its activity and selectivity are still extremely low, as p-diethylbenzene can only reach a conversion rate of 87.4% after reacting for 40 hours, especially for p-diethylbenzene The selectivity and chromatographic yield of acetylbenzene are only 25.2% and 22% respectively, if do not have under the existence of pyridine and hydrobromic acid, the conversion rate of p-diethylbenzene is only 27.4%, and the conversion ratio of p-diacetylbenzene Selectivity and chromatographic yield were only 17.4% and 4.78%, respectively

Such a low selectivity not only wastes a lot of raw materials and increases production costs, but also the existence of a large number of by-products brings great difficulties to the post-treatment process, consumes a lot of energy and resources, and causes very serious environmental pollution at the same time. Therefore this method cannot be used for industrialized production at all;

[0009] (4) The air flow rate (150mL / min) used in this method is too large, and too high gas flow rate will not only cause waste of energy and resources, but also use a reflux condenser at the tail gas outlet in the actual production process. Produce more reaction raw materials and products, but have to consume more cooling medium to help them recover, the result will double the production cost

Not only because of its toxicity and harmfulness, it may cause serious environmental pollution, but also because of the increase of energy consumption due to the recovery of solvents, which greatly increases operating costs and production costs;

[0021] (3) Due to the use of high-pressure reaction conditions, equipment investment and operating costs are doubled, and energy consumption is extremely high, especially making production potentially dangerous and greatly reducing safety;

[0022] (4) The use of loaded or polymerized metalloporphyrins results in high energy consumption, high discharge of three wastes, complex processes, and increased costs due to the complex preparation process

In addition, due to the large amount of catalyst used (480ppm), it must be separated and recovered after use, and the cost of separating and recovering the catalyst is high, energy consumption is large, and three wastes are discharged.

In addition, because the reaction using supported or polymerized metalloporphyrins is a heterogeneous reaction, the high catalytic activity of metalloporphyrins cannot be well reflected.

[0023] (5) The induction time of the reaction is too long (up to 3h), thus prolonging the entire reaction time, resulting in serious waste of energy and increase in operating costs

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