Synthesis method of N-ethyl carbazole

Abstract

The invention discloses a synthesis method of N-ethyl carbazole, and belongs to the technical field of organic synthesis. The method comprises the following steps: (1) adding anhydrous acetonitrile, sodium and carbazole into a high-pressure reactor, introducing ethylene to replace air, continuously introducing ethylene until the pressure is 45 MPa, heating to 80-150 DEG C, carrying out a reactionat a constant temperature for 3-10 hours, and replacing gas in the high-pressure reactor with nitrogen after the reaction is finished; wherein the dosage of sodium is 0.5-2.0% of the mass of carbazole; and (2) after the reaction is finished, distilling the reaction liquid under normal pressure at the temperature of 80-90 DEG C, stopping distilling until the volume is 40-60%, recovering the distilled solvent, cooling to 68-80 DEG C, filtering when the solution is still hot, finally, carrying out reduced pressure distillation at the temperature of 90-110 DEG C under the vacuum degree of less than 1 mmHg, and drying to obtain N-ethyl carbazole. The method has the advantages of simple process, recyclable solvent, high yield, high purity and the like.

Description

technical field [0001] The invention relates to the technical field of organic synthesis, in particular to a method for synthesizing N-ethylcarbazole. The N-ethylcarbazole is prepared by a one-step method, most of the solvents can be recycled, and waste water does not need to be treated. Background technique [0002] N-Ethylcarbazole, white needle-like crystal, melting point: 68-70 ℃, CAS number: 86-28-2, is an intermediate for synthesizing dye vat blue GNX and pigment permanent violet RL. Permanent Violet RL, the dye index number is C.I Pigment Violet 23, has the characteristics of high tinting strength and bright color, and its heat resistance, light resistance, chemical resistance, oil penetration resistance and migration are very excellent, and it is widely used in coatings, Puree dyeing of inks, rubber, plastics and synthetic fibers, is currently one of the most expensive pigments in the world and the best purple pigment used so far in the plastics industry. [0003] T...

AI Technical Summary

Problems solved by technology

[0006] 3. Ethyl p-toluenesulfonate method: This method has higher cost, longer reaction time, and produces potassium p-toluenesulfonate by-product

At present, in industrial production, a phase transfer two-phase system is mainly composed of 50% NaOH aqueous solution and benzene as a solvent. After the reaction is completed, the layers must be statically separated, and the lower alkaline water must be discharged, and a small amount of benzene must be used to extract the residue in the alkaline aqueous layer. After the product is merged into the upper oil layer, the operation is cumbersome, and in actual operation, after most of the water layer liquid is released, another container needs to be used to collect the water layer that continues to be lowered, and when the oil layer is released, it is transferred to the oil-water layer In the separator, the water layer is separated, which brings great inconvenience to the operation

[0008] 5. European patent EP0858995 proposes to use o-dichlorobenzene as a solvent and N, N, N', N'-tetramethyl 1,3-propylenediamine as a catalyst to react ethyl chloride with carbazole to generate 99.3% of N-Ethylcarbazole, but high boiling point and toxic o-dichlorobenzene should be used as solvent in the whole process

[0012] (1) In the reaction process, high-boiling solvents such as dimethyl sulfoxide or N,N-dimethylformamide that are not easy to recover are often used, and the wastewater treatment pressure is high;

[0013] (2) After the reaction, a large amount of bromine-containing wastewater will be produced, which is difficult to treat; the bromine introduced at the same time will be discarded at last, which does not conform to atomic economics