Method for preparing aromatic acid by direct carboxylation of CO2

Abstract

The invention discloses a method for preparing aromatic acid by direct carboxylation of CO2. The method comprises the following steps: (1) adding aromatic hydrocarbon, organic alkali and lewis acid into a high pressure reaction kettle under an inert gas atmosphere, then feeding CO2 gas into the high pressure reaction kettle for reaction, and obtaining reaction liquid with aromatic acid at the endof the reaction; (2) adding water into the reaction liquid obtained in the step (1), then extracting the aromatic acid in the reaction liquid with an extracting agent to enable the aromatic acid in the reaction liquid to enter an extracting phase, separating the extracting phase from raffinate, and concentrating the extracting phase to obtain the aromatic acid. According to the method, complicatedpreparation of ionic liquid is avoided, and organic alkali is timely neutralized with halogen hydride produced by the reaction, so that the balance moves rightwards; at the end of the reaction, the organic alkali also can be recycled through alkali treatment. The method has the advantages of simple operation, mild conditions, green process, low cost and the like, and is expected to be applied toindustrial production.

Description

technical field [0001] The invention belongs to the field of fine chemical technology, in particular to a CO 2 A method for preparing aromatic acids by direct carboxylation. Background technique [0002] Aromatic acids are an important class of chemical products with a wide range of uses, and are widely used in the production of medicines, food additives, dyes, photosensitizers, plasticizers, spices and cosmetics. At present, the vast majority of aromatic acids are obtained through oxidation reactions and multi-step organic synthesis reactions, which have disadvantages such as low atom economy, complicated operations, harsh reaction conditions, many by-products, and serious environmental pollution. [0003] Compared with traditional methods, CO 2 The preparation of aromatic acids by direct carboxylation has the advantages of high atom economy, short reaction process, simple operation, low raw material cost, green and high efficiency, etc. But due to CO 2 It has strong th...

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Problems solved by technology

However, these catalysts still have disadvantages such as large dosage, low efficiency, poor substrate adaptability, high cost and poor safety, making CO 2 Direct carboxylation method is difficult to industrialize

[0004] In 2002, Olah et al. (J.Am.Chem.Soc., 2002,124:11379-11391) reported that AlCl 3 / The Al system can realize the highly selective synthesis of a variety of aromatic acids under relatively mild conditions. This method has the advantages of mild reaction conditions, high yield and good selectivity, and is expected to be used in CO 2 The industrialization of the preparation of aromatic acids by direct carboxylation method, but the system still has the disadvantages of large amount of catalyst, severe corrosion of equipment by strong Lewis, and potential explosion hazard of Al in contact with water, which needs to be further optimized

However, chloroaluminate ionic liquids usually need to be operated under vacuum conditions, and there are problems such as complicated preparation process, harsh operating conditions, and high cost, which restrict its industrialization.

[0006] Therefore, how to overcome the existing CO 2 The disadvantages of high catalyst cost, harsh operating conditions, and poor safety in the preparation of aromatic acids by direct carboxylation are still a challenging work, and the development of new CO 2 The preparation of aromatic acids by direct carboxylation can not only realize the transformation and upgrading of the aromatic acid industry, but also enrich CO 2 The content of chemical utilization, and at the same time of obtaining important chemicals, realizes the chemical cycle of carbon, making it a powerful supplement to the natural carbon cycle, and improving the deteriorating global greenhouse effect

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