Using industrial fluorene as raw material, sodium hydroxide as catalyst, and dimethyl sulfoxide as solvent, the material enters the reactor to be heated and dissolved, passes through the external circulation of the reactor, and returns to the reactor to react through the microbubble generator. After the reaction The material obtained by cooling crystallization, separation, washing and recrystallization to 9-Fluorenone;
Specific steps are as follows:
1) In the reaction kettle, dissolve the industrial fluorene in the dimethyl sulfoxide solvent at a temperature of 40-80°C, add the catalyst sodium hydroxide, and stir in the reaction kettle under normal pressure until it is completely dissolved;
2) The circulation pipeline connected to the reaction kettle starts to be fed with oxygen for oxidation, and the material flowing out from the bottom of the reaction kettle, together with oxygen, returns to the reaction kettle through the microbubble generator on the circulation pipeline for reaction. The microbubble generator uses gas, During the liquid mixing process, the gas is crushed into bubbles, so that the gas and the liquid are fully dissolved, and the high-speed rotating pump impeller mixes the liquid and the gas;
3) After the reaction is finished, the material is cooled and crystallized, and the crystals and mother liquor are separated by a centrifuge;
4) washing the crystals in step 3 with water to obtain crude fluorenone; the mother liquor is subjected to vacuum distillation treatment through a still, the top of the distillation is to recover dimethyl sulfoxide, and the bottom of the still is crude fluorenone;
5) Recrystallize the crude fluorenone obtained in step 4 and step 5 to obtain fluorenone, and then dry it to obtain the finished product 9-fluorenone.
The flow rate of oxygen is 0.04m3/h-1m3/h, and the oxidation time is 1-5 hours; the mass ratio of materials is fluorene: dimethyl sulfoxide: sodium hydroxide = 1:0.8-4:0.01-0.1.
The purity of the finished 9-fluorenone is >99%, and the yield of 9-fluorenone is >85%.
Compared with prior art, the beneficial effect of the present invention is:
The solvent of the present invention is non-benzene and pyridine solvents, which are low-toxic and environmentally friendly; the catalyst is a commonly used industrial catalyst, which is cheap and easy to obtain, and the production process is optimized, which greatly reduces the amount of catalyst and solvent used, and the solvent can be recycled to achieve repeated use; The invention has mild reaction conditions, simple and effective reaction equipment, sufficient reaction, fast rate, high yield of fluorenone, purity greater than 99%, and yield can reach more than 85%.