Method for preparing 9-fluorenone by oxidizing fluorene

Abstract

The invention relates to a method for preparing 9-fluorenone by oxidizing fluorene, belonging to the technical field of chemical material processing. The method comprises the following steps: mixing and stirring fluorene, polyethylene glycol dimetyl ether and a second solvent under normal pressure, and introducing air to perform oxidization by using aqueous alkali as a catalyst while controlling the reaction temperature, wherein the tail gas is absorbed by using cooled polyethylene glycol dimetyl ether; and after the reaction finishes, cooling the solution to crystallize, filtering to obtain a 9-fluorenone crude product, washing with water, and drying to obtain the 9-fluorenone finished product. The filtrate can be recycled repeatedly into the next reaction, and the finished product has the advantages of higher average yield and higher purity after repeated recycling. By using the cheap nontoxic non-volatile polyethylene glycol dimetyl ether as the solvent component and the solvent for absorbing the tail gas, no toxic phase-transfer catalyst is needed, so the solvent consumption is low. The filtrate and polyethylene glycol dimetyl ether with absorbed tail gas can be recycled repeatedly, thereby maximally reducing the solvent consumption and exhaust emission. The method makes obvious progress in the aspects of high efficiency, energy saving, environmental protection and the like.

Description

Technical field [0001] The invention belongs to the technical field of chemical material processing, and specifically relates to a method for preparing 9-fluorenone by oxidation of fluorene. Background technique [0002] Fluorene is one of the separation products of coal tar, with large supply and low price. 9-Fluorenone (commonly known as fluorenone) is one of the important fluorene derivatives, widely used in polymer materials, photoelectric materials, medicine, pesticides and other fields , Has a broad space for development. In actual production, the purity of industrial fluorene is generally 95%-98%. Purifying it to high-purity fluorene faces a substantial increase in cost, while the direct oxidation of industrial fluorene to fluorenone is easier to purify, which is why the downstream of fluorene has high The development of value-added products is the first choice. Therefore, it is of great significance to study the production method of fluorenone with a simplified process, ...

AI Technical Summary

Problems solved by technology

The post-treatment of the above processes all involves distillation and concentration of the reaction liquid, recovery of the solvent and separation of the product. The distillation process not only consumes a lot of energy, but also easily causes side reactions to the product under high-temperature conditions of strong alkalinity. Purification, easy to wrap inorganic salts, high yield, and DMSO and DMF are easy to decompose by high-temperature distillation

[0005] In terms of aromatic solvents, patent CN102020543A reports the use of toluene and quaternary ammonium salt system without adding alkali, and the actual conversion rate is very low; CN103787858A reports the use of toluene, ethanol mixed solvent and solid quaternary ammonium base, and the price of solid quaternary ammonium base is more expensive; The mixed system of ammonium salt and inorganic alkali aqueous solution can play the same effect, and CN103467264A, CN103435463A, CN103435456A and CN103787858A have reported the work in this respect, and the difference of four patents mainly is that used solvent is different, is successively toluene, xylene, quinoline and fluorenone, among them, the volatilization loss of toluene is too large, and xylene will inevitably be brought out in large quantities under heating and long-term air conditions, and quinoline solvent is toxic, and the post-treatment of the three requires washing, distillation, etc. , the impurities brought in by raw materials are not easy to remove. Distilling quinoline requires a high temperature. Fluorenone is used as a solvent to react at 70-80°C. In actual operation, the raw material fluorene has a large amount of volatilization loss. In addition, quaternary ammonium salts and strong bases The quaternary ammonium base generated in the reaction is easy to decompose and lose the phase transfer effect under long-term heating conditions, and it is necessary to add a catalyst when the water layer is applied mechanically. Decomposition problem, but there is no advantage in cost, and both quaternary ammonium salt and crown ether are toxic substances

In terms of tail gas emissions, although CN103435463A and CN105801389A use α-methylnaphthalene to absorb tail gas, they cannot be recycled and applied mechanically, which still cause waste and discharge pollution, which has little practical significance