A method for synthesizing 3,6-dibromo-9-bromophenyl-9h-carbazole

Abstract

The invention discloses a method for synthesizing 3,6-dibromo-9-bromophenyl-9H-carbazole, belonging to the technical field of chemistry. The steps of the synthesis method are as follows: at room temperature, dissolve N-phenylcarbazole and bromination reagent in an organic solvent, stir and add an oxidizing agent, react for 4-8 hours, after the reaction, recover the solvent, extract, and the organic layer is desolvated, Recrystallization obtains 3,6-dibromo-9-bromophenyl-9H-carbazole, wherein the process of adding the oxidizing agent adopts a stepwise addition method or a titration method, while controlling the temperature of the reaction system to be lower than the boiling point of the organic solvent. The preparation method of the present invention adopts a one-step method at room temperature, using commercially available N-phenylcarbazole as a raw material, and under the action of brominating reagents and oxidants, tribromo-NPC can be obtained with high yield and high purity. , the method has mild and simple conditions, simple operation, low cost, high yield, and is easy for enterprises to produce industrially.

Description

technical field [0001] The invention relates to the technical field of chemistry, in particular to a method for synthesizing tribromo-N-phenylcarbazole by oxidative bromination of N-phenylcarbazole. Background technique [0002] Organic electrophosphorescent light-emitting devices (PhOLEDs), which are materials with a host-guest structure, have extremely high application potential in the fields of display and lighting. Carbazole has π-electron conjugated system, intramolecular electron transfer characteristics and lone pair electron heteroatoms, so carbazole and its derivatives have strong charge transport ability and photoelectric performance. A single carbazole molecule has poor photoelectric properties due to its weak conjugation system. Therefore, it is usually necessary to modify the carbazole site by bromination to realize the arylation / heteroarylation of the carbazole site, further expand the electronic conjugated system, and improve the charge transport ability. 3,...

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Problems solved by technology

[0008] Among the above-mentioned synthetic routes, the reaction of route I has a low yield and requires the use of pre-modified carbazole bromide, which increases the cost of the route; Environmental challenges; the third is that it needs to be reacted at high temperature (150°C) for a long time (24h), which may lead to dark color of the reaction solution and increase the difficulty of later purification

[0009] The route II one needs to use expensive p-bromoiodobenzene as the aryl source, which increases the reaction cost and is unfavorable for industrialized production; the second is to use N-bromosuccinimide (NBS) as the bromine source, which has poor atom economy, The by-product of succinimide will be produced, which increases the difficulty and cost of purification in the later stage; the third is that this reaction requires a two-step method, and the total yield is low, which makes the route economically poor

[0010] For another example, in 2012, "Heilongjiang Science" 2012, Volume 3, Phase 1, Page 26-27, Li Meng et al published an article entitled "Synthesis of 3-bromo-9-phenylcarbazole", which Describes the one-step preparation of monobrominated or dibrominated compounds using N-phenylcarbazole and brominating reagents as raw materials. However, using NBS as a bromine source will generate butanediimine as a by-product after bromination, and the product Coexistence increases the treatment cost of the three wastes; in addition, this system requires the use of mixed solvents, which increases the difficulty of subsequent solvent recovery and further increases the process cost

Due to the chemical identity of the 3 and 6 positions of carbazole, the excess bromine source can simultaneously brominate the 3 and 6 positions to obtain dibrominated products, but for the weak electrophilicity of the N-phenyl para position, the bromine produced by NBS dissociation Positive ions are difficult to further efficiently add to it to complete the bromination process

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