Method for preparing acetophenone by biomimetic catalytic oxidation of ethylbenzene with oxygen

Abstract

The invention relates to a method for preparing acetophenone by biomimetic catalytic oxidation of ethylbenzene with oxygen, comprising the following steps: taking ethylbenzene 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 130-136 DEG C and then carrying out reaction at 70-110 DEG C for 4-10h, thus obtaining the acetophenone. 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 acetophenone by biomimetic catalytic oxygen oxidation of ethylbenzene. Background technique [0002] Acetophenone 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 acetophenone mainly include Friedel-Crafts acylation method, phenylethyl alcohol oxidation method and ethylbenzene oxidation method, etc., wherein ethylbenzene oxidation method is divided into chemical oxidation method and molecular oxygen oxidation method again, oxygen is cheap and easy to get, The oxidant which is clean and pollution-free and has good atom economy, the method of directly oxidizing ethylbenzene with oxygen to obtain acetophenone has significant advantages over other methods. [0003] US 20030144554 (publication date: January 15, 20...

AI Technical Summary

Problems solved by technology

[0007] (1) The amount of catalyst used in this method is relatively large (Co(o-PPHA) under high pressure 2 Dosage: 125ppm; Co(PPA) under normal pressure 3 consumption: 50ppm), the catalyst needs to be recycled, and the recovery of the catalyst needs to consume a lot of energy;

[0008] (2) Due to the low activity of the catalyst used in this method, even if the amount of catalyst used is more (125ppm), the reaction pressure (0.8MPa) and reaction temperature (130°C) are higher, but after 6 hours of reaction, the conversion rate of ethylbenzene Only 64%, the selectivity and chromatographic yield of acetophenone are only 81.4% and 52.1% respectively;

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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